The Effect of Potato Seed Treatment on the Chemical Composition of Tubers and the Processing Quality of Chips Assessed Immediately After Harvest and After Long-Term Storage of Tubers

Abstract

Potatoes intended for chip production must meet strict quality requirements. The objective of the study was to determine the optimal cultivation approach most favorable for chip potato cultivars (Beo, Picus, Pirol) through the application of various agronomic treatments, including a biostimulant and a fungicide. In the fresh tuber mass, the following components were determined: dry matter, starch, total and reducing sugars, as well as carotenoid and chlorophyll pigments. The chips were evaluated in terms of organoleptic traits: color, taste, aroma and consistency. All analyses were carried out directly after harvest and after 6 months of storage under constant temperature (8 °C) and relative air humidity (95%). In general, all experimental factors had a significant effect on the parameters studied. The potato cultivars differed significantly in the chemical composition of their tubers. The cultivar ‘Beo’ was characterized by the highest dry matter and starch content and, at the same time, the lowest content of total and reducing sugars (respectively, : 23.9%, 18.4%, 5.77 g kg⁻¹ f.m., 459 mg kg⁻¹ f.m.). The cultivar ‘Pirol’, on the other hand, contained the highest amounts of carotenoid and chlorophyll pigments (a, b and total): 10.31, 1.87, 0.927, 2.80 mg kg⁻¹ f.m., respectively. The preparations Moncut 460 SC (MC) and Supporter^® (SP) used in potato production showed a positive effect on the chemical composition of the cultivars studied. It was demonstrated that the combined use of both agents proved to be the most beneficial in this regard. The chips produced were characterized by high overall quality, averaging 4.6 points after harvest and 4.5 points after storage, fully meeting the standards required for this type of product. Chips fried from the tubers of the ‘Beo’ cultivar received the highest organoleptic scores: color—4.9, consistency—4.6, and taste—4.6 points. Regardless of the experimental factors, the chips were characterized by a very good aroma (5.0 points). The studies conducted generally demonstrated a positive effect of the potato seed treatments used in cultivation on the individual quality traits of the chips. The combined application of the preparations (MC and SP) generally had a significantly positive effect on the organoleptic characteristics of the chips. After long-term storage, the quality of tubers and chips slightly decreased overall, which indicates that appropriate conditions were maintained throughout the storage period and that proper handling of the tubers immediately after harvest was ensured.

1. Introduction

The potato (Solanum tuberosum L.) is one of the key crop plants worldwide, due to the high nutritional value of its tubers, wide availability, and good storability. Owing to these features, the species plays an important role in ensuring global food and nutritional security [1,2,3]. The strong position of the potato on the agricultural market also results from the versatile and multi-directional use of its tubers. In addition to direct consumption and use in the starch industry, a significant part of production is directed to food processing, particularly for fried products such as French fries and potato chips [4]. It is worth emphasizing that potato chips occupy an important position in the snack segment, being among the most frequently consumed products of this type on the market [5].

Potato tubers intended for chip processing must meet a range of strict quality requirements aimed at obtaining a final product with high sensory value, in line with consumer expectations. The key traits determining chip quality are taste, aroma, color and consistency. These properties largely depend on the technological parameters of the tubers, such as dry matter, starch, total sugars and reducing sugar content, as well as the presence of natural pigments [6,7,8,9]. The chemical composition of the tubers is genetically determined; however, environmental factors also have a significant influence—particularly soil conditions, weather during the growing season, and the cultivation technology applied. Efficient cultivation of potatoes intended for food processing requires not only appropriately selected mineral fertilizers and plant protection measures but also chemical agents that support plant growth and enhance and develop their physiological performance [6,7,8,9]. Among the products supporting potato production are biostimulants and growth regulators. Biostimulants, through the activation of natural physiological and biochemical mechanisms, contribute to enhancing plant tolerance to abiotic stresses such as drought, low temperature, soil salinity, or nutrient deficiencies. Moreover, they can support plant defense responses to biotic stresses, including pathogens and pests, by inducing systemic resistance or increasing the activity of natural defense mechanisms. Growth regulators, on the other hand, accelerate the growth and development of young plants, thus shortening the period of highest sensitivity to environmental stress. Additionally, these preparations support physiological processes such as photosynthesis and nutrient transport, which directly affect the yield and quality of potato tubers [10,11,12,13].

In this study, an amino acid-based biostimulant was applied to potato seed tubers in order to enhance plant productivity and increase the content of bioactive compounds and nutrients. In particular, tuber starch content influences the quality of potatoes used for food processing [12,13].

It is also important to note that potato cultivars differ significantly in their sugar content and related chemical composition, which can directly affect the quality of processed products such as chips. Investigating multiple cultivars provides a broader understanding of how different genetic backgrounds influence tuber chemical composition and processing traits [7,9,14]. Potatoes most desirable for chip production are those with tubers characterized by a high dry matter content (20–25%), of which 16–21% should be starch, and low contents of total and reducing sugars. Dry matter, whose main component is starch, greatly affects crispness, flavor, and consistency of chips. Higher levels of these components in the tubers reduce excessive oil absorption during frying [9,14]. Sugars, in turn, are the main factors determining the taste and color of fried products. Therefore, the total sugar content in potato tubers should not exceed 1%, while reducing sugars should account for less than 0.1% of the fresh weight [15]. Compliance with these guidelines prevents surface degradation (browning) during frying and ensures the desired, uniform golden color of chips [9,16,17].

The storage period is a stage in potato production that affects both the quality of tubers and the processed products derived from them, including chips [18,19,20]. During storage, changes occur in the chemical composition of the tubers that can significantly influence the sensory and technological properties of the final product. The content of reducing sugars may increase, leading to a deterioration of chip sensory quality—particularly in taste (bitterness) and color (browning) after frying. The color change results from the Maillard reaction, in which reducing sugars react with free amino acids to form melanoidin pigments and also produce undesirable and potentially harmful acrylamide [20,21]. In addition, tubers may show an increase in dry matter and starch content due to transpiration during storage. To minimize unfavorable quality changes, it is necessary to maintain stable and properly adjusted storage conditions throughout the storage period. Potatoes intended for food processing should be stored at a temperature of 6–8 °C, which limits undesirable biochemical processes and helps preserve raw material quality [18].

Despite existing studies on factors affecting potato tuber quality, such as fertilization, cultivar selection, and storage conditions, the effects of pre-planting growth-promoting preparations and plant protection agents on processing quality remain insufficiently documented. In particular, limited information is available on their influence on different potato cultivars under long-term storage conditions.

The aim of the present study was to determine the effect of selected agronomic factors—including the application of growth-promoting preparations before planting and long-term storage—on the chemical composition of potato tubers and the quality of chips produced from them.

2. Materials and Methods

2.1. Research Material

The material for the research consisted of tubers from three potato varieties (Solanum tuberosum L.): ‘Beo’ (early), ‘Picus’ (medium late), and ‘Pirol’ (medium early), intended for chip production, as described by the authors [22]. The research was conducted over a period of 3 years (2021, 2022, 2023). The method of conducting the field experiments—field factors in 2021 and 2022, as well as the applied agricultural techniques and the soil and weather conditions during that period, were described in the paper Brążkiewicz et al. [22].

The field experiment in 2023 was established using the randomized sub-blocks method in three replications and was conducted in the same location (Tomaszkowo), maintaining the same factors: potato variety (3 levels: Beo, Picus, Pirol) and potato seed treatment application (4 levels: Control—no application of treatments, Moncut 460 SC, Supporter^®, combined application of Moncut 460 SC and Suporter^®).

Moncut 460 SC is a systemic fungicide formulated as a suspension concentrate for potato seed treatment. The active substance is flutolanil, a benzamide compound, at a concentration of 460 g·L⁻¹. The product was applied to protect potato seed tubers against Rhizoctonia solani, at a recommended dose of 0.2 dm³ t^− 1 of seed tubers, in each year of the study: on 7 May 2021, 6 May 2022, and 4 May 2023.

Supporter^® is a plant growth regulator and yield modulator whose main active components are synthetic amino acids. The product stimulates early root system development and enhances plant growth by promoting beneficial interactions between soil microorganisms and the rhizosphere, particularly under suboptimal environmental conditions such as low temperature or limited nutrient availability. Supporter^® was applied as an additive to potato seed treatment during potato planting at a rate of 0.3 dm³ ha^− 1 in each year of the study on the same dates as the application of Moncut 460 SC.

The substances used in the study provide disease protection and stimulate plant physiology, supporting uniform growth and maintaining stable tuber quality [22].

Pre-planting treatments were applied to potato seed tubers, as these organs remain metabolically active, allowing for effective modulation of their chemical composition, primarily reducing sugar content, in developing tubers. In contrast, mature postharvest tubers are physiologically dormant, limiting the effectiveness of sugar reduction and potentially compromising chip quality [10,12,13,15,22].

The characteristics of the soil and weather conditions in 2023 are presented in

Table 1. Chemical properties of soil in 2023.

Growing Season	pH	Corg (g kg−1)	Available Macroelements (mg kg−1)
			P	K	Mg
2023	5.9	10.0	115.54	16.85	39

,

Table 2. Thermal conditions during the potato growing period in 2023.

Month	Decade			Monthly Average
	I	II	III
	Mean Daily Air Temperature (°C)
May	8.8	12.1	14.2	11.8
June	15.7	16.2	18.4	16.8
July	17.8	18.7	17.2	17.9
August	17.3	19.9	18.3	18.5
September	16.7	16.2	16.1	16.3
Average				16.3

and

Table 3. Total precipitation during the potato growing period in 2023.

Month	Decade			Monthly Sum
	I	II	III
	Total Monthly Precipitation (mm)
May	0.0	16.3	0.0	16.3
June	0.0	20.1	28.8	48.9
July	1.4	9.7	22.9	34.0
August	64.3	1.6	65.8	131.7
September	0.0	9.0	14.2	23.2
Total precipitation during the growing season				254.1

, while those for 2021 and 2022 were described in the manuscript [22].

In 2023, the soil had a slightly acidic reaction and was characterized by a high level of phosphorus (P), and medium levels of potassium (K) and magnesium (Mg). The soil properties were determined according to the description by Brążkiewicz et al. [22]. The potato forecrop in 2023 was winter triticale. Potatoes were planted in the first decade of May.

Of all the years in the experiment, 2023 was the most favorable in terms of average daily temperature (16.3 °C)—Table 2. Conversely, considering the total precipitation (Table 3), 2023 was the least favorable (254.1 mm). The warmest month in 2023 was August (18.5 °C), which also had the highest total precipitation (131.7 mm), exceeding the water requirements, even for late-maturing varieties. In both May and June (2023), there was a deficit of atmospheric precipitation at the level of 40–65% compared to the requirements for all earliness groups. A particularly significant precipitation deficit occurred in June—the month of tuber initiation. However, air temperatures, excluding May, during the potato growing season (Table 2), were optimal for tuber initiation and growth.

All agronomic practices and pesticide applications were performed in accordance with the principles of proper agricultural practice. To minimize weed infestation, hilling (ridging) was performed twice [22].

Tubers were harvested at full maturity according to the earliness group of each cultivar, based on physiological indicators such as foliage senescence and cessation of tuber growth. Samples of 20 kg of similarly sized tubers were randomly collected from each experimental plot. Of the collected mass, 10 kg were allocated for laboratory analyses immediately after harvest. The remaining 10 kg were stored for 6 months (October–March) in storage chambers (Thermolux Chłodnictwo Klimatyzacja, Raszyn, Poland). During the long-term storage, the thermo-humidity conditions were maintained at a constant level appropriate for varieties used for chip production, i.e., at a temperature of +8 °C and relative air humidity of 95%.

2.2. Dry Matter Content in Potato Tubers

The dry matter content in potato tubers was determined according to the AACC method [23]. The tubers were washed, dried, shredded, and homogenized in a laboratory mill Retsch 169 ZM 100 Ultra-Centuge (Retsch, Haan, Germany) to obtain a homogeneous mass. A mass of 10 g was weighed onto a Petri dish and dried in a laboratory dryer (WAMED, model SUP-100, Warsaw, Poland) at an air temperature of 60 °C for 24 h. Subsequently, the temperature in the dryer was raised to 105 °C for 1 h. After the drying process was complete, the samples were cooled to room temperature and weighed. The total dry matter content in the potato tubers was calculated based on the weight difference and expressed as a percentage (%).

Calculation:

$$DM={\displaystyle \frac{SWA}{SWB}}\times 100$$

• DM—dry matter content (%)
• SWB—sample weight before drying (g)
• SWA—sample weight after drying (g)

2.3. Starch Content in Potato Tubers

The starch content was determined according to ICC Standard No. 123 [24]. Ten grams of shredded potato tubers were weighed into an Erlenmeyer flask. 50 mL of 1.124% HCl solution (Chempur, Piekary Śląskie, Poland) was then added, and the flask contents were mixed. To carry out the starch hydrolysis process, the mixture was heated in a water bath for 25 min. The samples were then cooled to room temperature, and the suspension was transferred to a 100 mL volumetric flask; 1.5 mL of a 14.4% ammonium molybdate solution (Roth, Karlsruhe, Germany) was added. After mixing, the flasks were made up to volume with distilled water. The resulting mixture was filtered using filter paper No. 593 1/2 (Schleicher & Schuell, Taufkirchen, Germany). The filtrate was placed in a polarimeter tube (Krüss, type P 1000, Hamburg, Germany), which was used to determine the optical rotation of the solution. The starch content in the potato tubers was calculated as a percentage (%) according to Biot’s formula, assuming the specific rotation of starch dissolved in HCl is 183.7°.

Calculation:

$$\mathrm{SC}={\displaystyle \frac{\begin{array}{c}\\ 513\times \alpha \end{array}}{L\times a}}$$

• SC—starch content (g kg⁻¹ f.m.)
• a—weight of analyzed material (g)
• L—length of polarimeter tube (dm)
• α—measured rotation in degrees

2.4. Total and Reducing Sugars Content in Potato Tubers

The content of total and reducing sugars was determined using the spectrophotometric method [25]. A uniform 10 g sample of shredded potato was placed in a 250 mL volumetric flask and distilled water was added. The entire sample was shaken for 60 min and then filtered through Whatman filter paper (International Limited, Kent, UK). To determine reducing sugars, 1 mL of the filtrate was taken and placed in a glass test tube to which 3 mL of DNP [Dinitrophenol (Sigma Aldrich, St. Louis, MO, USA)] was added. The test tube was shaken on a Vortex (Grand-bio, Shepreth Cambridgeshire, UK) and then heated for 6 min in a boiling water bath. After cooling the tube and its contents, absorbance was measured at 600 nm in 1 × 1 cm cuvettes using a SHIMADZU UV-1800 spectrophotometer (Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto, Japan). The measured absorbance value of the tested sample was read from the glucose standard curve, and the results were reported in g kg⁻¹ f. m. (fresh matter). To determine total sugars, 40 mL of the filtrate was measured into an Erlenmeyer flask, and the filtrate was acidified with 36% HCl (Chempur, Piekary Śląskie, Poland). The flasks with the solution were heated and covered in a boiling water bath for 30 min. After cooling, the contents in the flasks were neutralized with 30% NaOH (POCH S.A., Gliwice, Poland). To determine total sugars, 1 mL of the neutralized solution was taken into glass test tubes. The procedure then followed the same steps as the determination of reducing sugars described above. The results were reported in mg kg⁻¹ f. m. (fresh matter).

2.5. Carotenoid and Chlorophyll Content in Potato Tubers

For the determination of chlorophyll pigments (chlorophyll a—Chl_a and chlorophyll b—Chl_b) and carotenoid pigments (total carotenoids—C_tot), potato tubers were subjected to freeze-drying. The tubers were washed, dried, and cut into 1 × 1 × 1 cm cubes. The material prepared in this way was frozen at −22 °C (Whirpool AFG 6402 E-B, Comerio, Italy). The frozen material was then subjected to sublimation drying (freeze-drying) until a constant mass was achieved. The lyophilization process was performed using a CHRIST ALPHA 1–4 LSC apparatus (Osterode am Harz, Germany). The operating parameters of the lyophilizer were: condenser temperature: −55 °C, vacuum: 4 kPa at 20 °C. The final moisture content of the material was below 2% and the drying time was 24 h.

To determine the pigments, 1.0 g of the lyophilized material was weighed and then quantitatively transferred to a plastic tube. Three ml of MeOH (methanol) was added to the dried sample and shaken on a Vortex for 1 min. Subsequently, the samples were placed in a laboratory shaker and shaken for 30 min. Next, the samples were centrifuged in a laboratory centrifuge (Hettina Zentrifugen, Rotina 420 R, Tuttlingen, Germany) for 15 min with cooling to 6 °C at 3500 revolutions/minute. From the obtained supernatant, the clear fraction was transferred to a 10 mL volumetric flask. This step was repeated twice, combining the resulting solutions. The volumetric flasks containing the clear supernatants were topped up with MeOH. The content of plant pigments was determined using a SHIMADZU UV-1800 spectrophotometer (Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto, Japan) at the following absorbances: 470 (C_tot), 653 (Chl_a), and 666 (Chl_b) nm. Formulas were applied to calculate the pigment content, and the results were converted to mg kg⁻¹ f.m.:

Content in Solution (µL ml⁻¹)

C_a = 15.65 A666 − 7.34 A653

C_b = 27.05 A653 − 11.21 A666

C_c = (1000 A470 − 2.86 C_a − 129.2 C_b)/221

Content in sample (µg g⁻¹ d.m.)

Chl_a = (25 × C_a)/sample weight [g]

Chl_b = (25 × C_b)/sample weight [g]

Chl_tot = Chl_a + Chl_b

C_tot = (25 × C_c)/sample weight [g]

2.6. Sensory Evaluation of Chips

The potato tubers were washed and cut into 1.2 mm thick slices using a vegetable slicer (Robot Coupe, type CL50 E, Vincennes, France). The slices were rinsed in cold water and dried on filter paper. They were then subjected to frying at a temperature of 175 °C in rapeseed oil for 3 min in three replications. Frying was carried out in deep fat fryers with a capacity of up to 14 dm³ (Royal Deep Fat Fryer, Model RCBG-18STHB, Zielona Góra, Poland), applying a charge consistent with the volume of the fat used.

The sensory attributes of the potato chip samples were determined according to the ISO 11136:2014 standard [26]. A 30-person panel from the university campus was selected and trained before the sensory tests to evaluate the characteristics of the potato chips. Chip samples were placed on disposable white plates with randomly assigned three-digit codes and presented to the panel members in random order. A specific time interval was maintained between the evaluation of each sample, and cold water was provided for rinsing the mouth before testing each sample. Panel members were asked to perform a hedonic evaluation of the following attributes: color, taste, aroma, consistency and overall acceptability on a five-point structured scale (1—poor, 2—insufficient, 3—sufficient, 4—good, 5—very good) according to Baryłko-Pikielna [27]. The same procedure was repeated with every panel member.

2.7. Statistics

The results obtained from the 3-year study were subjected to statistical calculations, and significant differences were assessed using Tukey’s confidence interval at a significance level of p < 0.05. The factorial structure was 2 (evaluation date) × 3 (cultivars) × 4 (biostimulants) × 3 (years). This factorial arrangement was used for the ANOVA model, and the F-tests were based on the interaction and main effects accordingly.

The field experiment was originally designed as a two-factor experiment, including cultivar and biostimulant as fixed factors. Therefore, a two-way analysis of variance was initially applied to reflect the experimental layout.

Subsequently, to evaluate the effect of storage and temporal changes in the measured traits, the evaluation date (after harvest and after storage) was incorporated as an additional factor. Consequently, the data were analyzed using a multifactor mixed-effects ANOVA, with evaluation date treated as a repeated measure. To determine whether the response of varieties and biostimulants depended on the evaluation date, the analysis of variance included the interaction terms A × B, A × C, and B × C. Analysis of variance (ANOVA) was performed using Statistica 13.1 software (StatSoft, Tulsa, OK, USA).

Prior to the analysis, the normality of residuals was assessed using the Shapiro–Wilk test. Residuals were normally distributed, permitting the use of ANOVA.

Mean results and standard deviation were presented in tables and figures. To obtain a synthetic picture of the overlapping dependencies between the characteristics studied, linear correlation analysis (Pearson’s) was performed.

3. Results and Discussion

3.1. Dry Matter and Starch

The dry matter and starch content of potato raw material are key quality indicators in the potato processing industry, as they are the main factors determining the crispness, color, oil absorption, taste, and consistency of potato chips [9,28]. In our study, regardless of the year of research, the dry matter and starch contents ranged, respectively, from 23.1 to 24.8% and from 16.8 to 19.6% directly after harvest, and from 22.4 to 24.5% and from 16.3 to 19.3% after storage (

Table 4. Dry matter and starch content in potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Dry Matter [%]			Starch [% f.m.]
	Treatment 4	AH *	AS **	Average	AH	AS	Average
BEO	CL	23.7 ± 0.3	23.4 ± 0.3	23.6 ± 0.4	18.1 ± 0.4	17.8 ± 0.4	18.0 ± 0.4
	MC	24.0 ± 0.5	23.8 ± 0.4	23.9 ± 0.5	18.7 ± 0.5	18.3 ± 0.4	18.5 ± 0.5
	SP	23.8 ± 0.3	23.6 ± 0.5	23.7 ± 0.5	18.3 ± 0.4	18.1 ± 0.5	18.2 ± 0.4
	MC + SP	24.3 ± 0.4	24.0 ± 0.4	24.2 ± 0.4	19.2 ± 0.4	18.7 ± 0.6	18.9 ± 0.5
Average 5		24.0 ± 0.5	23.7 ± 0.5	23.9 ± 0.5	18.6 ± 0.6	18.3 ± 0.5	18.4 ± 0.6
PICUS	CL	23.6 ± 0.2	23.3 ± 0.5	23.4 ± 0.5	17.8 ± 0.2	17.3 ± 0.2	17.6 ± 0.3
	MC	24.1 ± 0.3	23.6 ± 0.4	23.9 ± 0.4	18.4 ± 0.3	17.9 ± 0.2	18.1 ± 0.4
	SP	23.9 ± 0.3	23.4 ± 0.4	23.6 ± 0.4	18.1 ± 0.2	17.6 ± 0.2	17.8 ± 0.3
	MC + SP	24.2 ± 0.3	23.8 ± 0.4	24.0 ± 0.5	18.9 ± 0.3	18.4 ± 0.2	18.7 ± 0.3
Average		23.9 ± 0.5	23.6 ± 0.4	23.8 ± 0.5	18.3 ± 0.5	17.8 ± 0.5	18.1 ± 0.5
PIROL	CL	23.3 ± 0.4	22.9 ± 0.3	23.1 ± 0.4	16.9 ± 0.1	16.5 ± 0.2	16.7 ± 0.3
	MC	23.7 ± 0.5	23.3 ± 0.4	23.5 ± 0.5	17.8 ± 0.4	17.5 ± 0.4	17.7 ± 0.4
	SP	23.5 ± 0.3	23.1 ± 0.3	23.3 ± 0.4	17.1 ± 0.2	16.8 ± 0.2	17.0 ± 0.2
	MC + SP	23.8 ± 0.4	23.4 ± 0.4	23.6 ± 0.5	18.1 ± 0.2	17.7 ± 0.3	17.9 ± 0.3
Average		23.6 ± 0.3	23.2 ± 0.5	23.4 ± 0.5	17.5 ± 0.6	17.1 ± 0.5	17.3 ± 0.6
AVERAGES FOR TREATMENTS	CL	23.5 ± 0.4	23.2 ± 0.4	23.4 ± 0.4	17.6 ± 0.6	17.2 ± 0.6	17.4 ± 0.7
	MC	24.0 ± 0.4	23.6 ± 0.5	23.8 ± 0.6	18.3 ± 0.5	17.9 ± 0.4	18.1 ± 0.5
	SP	23.7 ± 0.6	23.4 ± 0.5	23.6 ± 0.5	17.8 ± 0.7	17.5 ± 0.6	17.7 ± 0.6
	MC + SP	24.1 ± 0.5	23.7 ± 0.6	23.9 ± 0.5	18.7 ± 0.5	18.3 ± 0.5	18.5 ± 0.6
AVERAGE FOR THE EXPERIMENT		23.8 ± 0.5	23.5 ± 0.5	23.7 ± 0.5	18.0 ± 0.7	17.7 ± 0.8	17.9 ± 0.7
LSD 1 α = 0.05		A 2 = 0.197 B = 0.221 C = 0.085 B/A = N.S. 3 A/B = N.S. C/A = N.S. A/C = N.S. C/B = N.S. B/C = N.S.			A = 0.095 B = 0.230 C = 0.080 B/A = N.S. A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.139 B/C = 0.259

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

, Tables S1 and S2).

The conducted study demonstrated that the dry matter and starch contents in the tubers of the tested potato cultivars were significantly affected by the applied experimental factors. Significant differences in dry matter and starch contents were found between cultivars, both immediately after harvest and after storage (p < 0.05) (Table 4, Tables S1 and S2). The ‘Beo’ cultivar generally showed the highest dry matter and starch contents, both immediately after harvest and after storage, followed by ‘Picus’ and ‘Pirol’. According to reports by Cătuna Petra et al. [29], Grudzińska et al. [30], Islam et al. [9], Ezekiel and Rani [31], Gościnna et al. [32], Koch et al. [33], and Zarzecka et al. [8], the dry matter and starch contents are largely determined by cultivar. However, cultivation technology and storage conditions also have a notable influence. This was confirmed by Das et al. [7], who observed significant differences among seven potato cultivars intended for chip production. Similarly, Mohamed [34], who cultivated 17 processing potato cultivars in three different locations, also reported significant differences in dry matter and starch contents between cultivars. In comparison, the dry matter and starch contents obtained by Mohamed [34] varied within a much wider range, from 19.08 to 27.1% and 10.0 to 17.6%, respectively, than those obtained in our study. This discrepancy results from the fact that Mohamed [34] analyzed a larger number of potato genotypes.

In the present study, considerable differences in dry matter and starch contents in potato tubers were observed between the research years. This variation could be attributed to the markedly diverse meteorological conditions during the growing seasons (Table 2 and Table 3). The most favorable year proved to be 2021, when optimal temperature and precipitation levels for potato growth and development were recorded. These findings are consistent with those of Zarzecka et al. [8], who obtained the highest dry matter and starch yields in a year characterized by the most favorable meteorological conditions for potato cultivation. Similar conclusions were reported by other authors [8,35,36,37], who confirmed the influence of weather conditions on the dry matter and starch contents of potato tubers. Dahal et al. [35] emphasized that unfavorable weather conditions, such as water deficit and excessively high temperatures, inhibit physiological processes in potatoes, leading to a substantial reduction in yield, deterioration of tuber quality, and limited growth, ultimately decreasing overall crop productivity. Our study also confirms the generally accepted view that starch is the main component of dry matter [7], as indicated by the highly significant correlation coefficients calculated for dry matter and starch contents both after harvest and after storage: r = 0.794 and r = 0.822, respectively (

Table 5. The correlation coefficients (r) according to the rank order of Pearson between the parameters studied directly after harvest.

Parameters	Dry Matter	Starch	Total Sugars	Reducing Sugars	Ctot	Chla	Chlb	Chltot	Color of Chips	Taste of Chips	Consistency of Chips
Starch	** 0.794
Total sugars	** −0.697	** −0.681
Reducing sugars	** −0.649	** −0.637	** 0.894
Ctot	n.s. 1	** −0.485	** 0.544	** 0.539
Chla	n.s.	** −0.551	* 0.370	** 0.555	n.s.
Chlb	n.s.	** −0.604	* 0.378	** 0.553	n.s.	** 0.837
Chltot	n.s.	** −0.589	* 0.386	** 0.575	n.s.	** 0.983	** 0.923
Color of chips	** 0.535	** 0.745	** −0.745	** −0.808	** −0.650	** −0.481	** −0.451	** −0.488
Taste of chips	** 0.591	** 0.743	** −0.720	** −0.752	* −0.424	** −0.533	** −0.501	** −0.541	** 0.712
Aroma of chips	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.
Consistency of chips	** 0.621	** 0.719	** −0.787	** −0.748	** −0.708	n.s.	n.s.	n.s.	** 0.736	** 0.885	n.s.
Total quality of chips	** 0.653	** 0.827	** −0.841	** −0.865	** −0.657	** −0.499	** −0.472	** −0.501	** 0.918	** 0.613	** 0.864

Significance levels are represented as * p ≤ 0.05; ** p ≤ 0.01; ¹ n.s.—no significant.

and

Table 6. The correlation coefficients (r) according to the rank order of Pearson between the parameters studied after 6 months of storage.

Parameters	Dry Matter	Starch	Total Sugars	Reducing Sugars	Ctot	Chla	Chlb	Chltot	Color of Chips	Taste of Chips	Consistency of Chips
Starch	** 0.822
Total sugars	** −0.573	** −0.700
Reducing sugars	** −0.605	** −0.647	** 0.888
Ctot	* −0.428	** −0.512	** 0.746	** 0.529
Chla	n.s. 1	** −0.453	* 0.336	** 0.528	n.s.
Chlb	n.s.	** −0.476	* 0.336	** 0.494	n.s.	** 0.849
Chltot	n.s.	** −0.475	** 0.347	** 0.535	n.s.	** 0.987	** 0.924
Color of chips	** 0.498	** 0.614	** −0.658	** −0.627	** −0.559	* −0.371	** −0.452	* −0.408
Taste of chips	** 0.571	** 0.709	** −0.676	** −0.710	* −0.382	** −0.468	** −0.481	** −0.487	** 0.505
Aroma of chips	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.
Consistency of chips	** 0.579	** 0.695	** −0.737	** −0.679	* −0.521	* −0.341	n.s.	* −0.345	** 0.466	** 0.513	n.s.
Total quality of chips	** 0.675	** 0.828	** −0.843	** −0.827	* −0.584	−0.489	** −0.517	** −0.514	** 0.783	** 0.861	** 0.794

Significance levels are represented as * p ≤ 0.05; ** p ≤ 0.01; ¹ n.s.—no significant.

).

In the present study, the least effect (p < 0.05) of the applied treatments, namely MC and SP, on the dry matter and starch contents was observed (Table 4, Tables S1 and S2). Each of the tested variants had a positive effect. The application of the growth modulator SP slightly increased the dry matter and starch contents by an average of 0.18 pp and 0.25 pp, respectively. In turn, the application of the fungicide MC resulted in an average increase of 0.40 pp and 0.70 pp, respectively. It was also noted that the highest increase in the components studied was obtained when both preparations were applied together, resulting in increases of 0.55 pp and 1.1 pp, respectively. The positive influence of growth stimulators on the chemical composition of potato tubers has been reported by many authors [8,38,39]. Their beneficial effect is attributed to their ability to reduce nutrient losses from the soil and to improve the efficiency of nutrient uptake and utilization, especially of macronutrients (N, P, K), which are crucial for potato growth [8,38,39]. It is worth noting that, although genotype, environmental factors, and storage had a stronger influence on the measured parameters than the applied treatments, the applied treatments still affected quality traits of potato tubers (Table 4).

Long-term storage of potato tubers always leads to a reduction in dry matter and starch contents [40]. This is a consequence of physiological processes occurring in the tubers, such as respiration, transpiration, and the conversion of starch into sugars and sucrose into reducing sugars. In the study conducted, a slight, but significant (p < 0.05) decrease in the contents of these components was observed after long-term storage, amounting to 0.40 pp for both dry matter and starch (Table 4, Tables S1 and S2, Figure 1 and Figure 2). Such a small loss indicates that the storage conditions were properly maintained and consistent with recommendations for cultivars intended for food processing. Some researchers have reported that the intensity of changes in dry matter and starch contents during storage depends not only on the storage conditions but also on the genetic characteristics of the potato, which vary in periderm thickness and the amount of suberin, a compound that limits water migration [41,42,43]. It was also noted that among the preparations applied during the potato growing season, the smallest decrease in dry matter and starch contents (−1.4 and −2.0%, respectively) was obtained following the application of the SP preparation.

3.2. Total and Reducing Sugars

Sugars are an important component of potato tubers, directly determining the quality of chips, in particular their color. Due to the key importance of sugars in the chips production process, desirable levels of sugars in tubers have been determined [9,44]. In our studies, the total sugars content and simple sugars content in tubers were not exceeded (

Table 7. Total and reducing sugars content in potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Total Sugars [g kg−1 f.m.]			Reducing Sugars [mg kg−1 f.m.]
	Treatment 4	AH *	AS **	Average	AH	AS	Average
BEO	CL	5.89 ± 0.3	6.25 ± 0.2	6.07 ± 0.2	492 ± 81.	544 ± 33	518 ± 67
	MC	5.49 ± 0.3	5.83 ± 0.1	5.66 ± 0.2	421 ± 53	444 ± 83	433 ± 64
	SP	5.63 ± 0.3	5.97 ± 0.1	5.80 ± 0.3	454 ± 76	508 ± 33	481 ± 63
	MC + SP	5.36 ± 0.3	5.72 ± 0.1	5.54 ± 0.2	381 ± 62	428 ± 46	405 ± 55
Average 5		5.59 ± 0.2	5.94 ± 0.2	5.77 ± 0.3	437 ± 6	481 ± 80	459 ± 73
PICUS	CL	6.40 ± 0.3	6.77 ± 0.1	6.59 ± 0.3	602 ± 55	646 ± 48	624 ± 51
	MC	5.99 ± 0.4	6.43 ± 0.2	6.21 ± 0.2	429 ± 64	492 ± 45	461 ± 54
	SP	6.25 ± 0.3	6.61 ± 0.1	6.43 ± 0.3	496 ± 56	543 ± 42	520 ± 50
	MC + SP	5.72 ± 0.3	6.16 ± 0.0	5.94 ± 0.3	367 ± 52	420 ± 41	394 ± 47
Average		6.09 ± 0.3	6.49 ± 0.3	6.29 ± 0.4	473 ± 97	525 ± 97	499 ± 99
PIROL	CL	6.60 ± 0.4	7.03 ± 0.1	6.82 ± 0.3	720 ± 76	777 ± 52	749 ± 67
	MC	6.36 ± 0.3	6.78 ± 0.1	6.57 ± 0.1	618 ± 48	657 ± 34	638 ± 42
	SP	6.50 ± 0.4	6.88 ± 0.3	6.69 ± 0.3	678 ± 50	729 ± 39	704 ± 47
	MC + SP	6.21 ± 0.3	6.59 ± 0.1	6.40 ± 0.2	533 ± 82	581 ± 51	557 ± 74
Average		6.42 ± 0.2	6.82 ± 0.2	6.62 ± 0.3	641 ± 89	686 ± 93	664 ± 92
AVERAGES FOR TREATMENTS	CL	6.30 ± 0.4	6.68 ± 0.4	6.29 ± 0.4	605 ± 111	656 ± 116	631 ± 113
	MC	5.95 ± 0.4	6.34 ± 0.4	6.31 ± 0.5	489 ± 101	531 ± 113	510 ± 106
	SP	6.13 ± 0.5	6.48 ± 0.4	6.49 ± 0.6	543 ± 111	594 ± 113	569 ± 112
	MC + SP	5.77 ± 0.4	6.16 ± 0.4	6.15 ± 0.4	427 ± 93	476 ± 96	452 ± 95
AVERAGE FOR THE EXPERIMENT		6.03 ± 0.5	6.42 ± 0.4	6.23 ± 0.5	516 ± 129	564 ± 125	540 ± 124
LSD 1 α = 0.05		A 2 = 0.046 B = 0.057 C = 0.039 B/A = N.S. 3 A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.067 B/C = 0.081			A = 43.46 B = 21.14 C = 15.45 B/A = N.S. A/B = N.S. C/A = N.S. A/C = N.S. C/B = 26.76 B/C = 31.35

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

, Tables S3 and S4). In addition, a significant influence of all the factors used on the sugars content was demonstrated. However, the greatest influence (p < 0.05) on the content of these traits was exerted by the cultivar, the year of the study, and the storage (Table 7).

The tested varieties differed significantly (p < 0.05) in the content of these compounds. Their highest average content, regardless of the year and date of the tests, was characterized by the ‘Pirol’ variety, followed by ‘Picus’ and ‘Beo’. The influence of genetic factors on the sugars content of potato tubers has also been reported by other authors [9,32,45,46]. Islam et al. [9], who analyzed six potato cultivars intended for processing, obtained reducing sugars content ranging from 591 to 809 mg kg⁻¹ fresh matter, which is similar to the results of our study, where reducing sugars content ranged from 330 to 828 mg kg⁻¹ f.m. According to Islam et al. [9], apart from genotype, sugars content in potato tubers is also influenced by agronomic, environmental, and weather factors. This thesis is confirmed by our research, in which significant differences in total sugars content and reducing sugars content were observed within the same cultivar across the individual years of the study (Table 7, Tables S3 and S4), which differed in meteorological conditions (Table 2 and Table 3). The most favorable period for potato cultivation in terms of tuber sugars content proved to be the first year of the study. In that year, the average temperature was 15.8 °C with a high total precipitation (494.6 mm). The least favorable was the third year, during which a substantial precipitation deficit occurred. In our study, the average total sugars content and reducing sugars content after harvest in the first year amounted to 5.86 g kg⁻¹ f.m. and 470 mg kg⁻¹ f.m., respectively. In contrast, in the third year they were 6.20 g kg⁻¹ f.m. and 564 mg kg⁻¹ f.m., respectively. This results from the fact that water deficiency during the growing season increases plant stress, which may lead to the accumulation of reducing sugars. As reported by Khorramifar and Rasekh [45], the soil type on which the crop is grown, as well as the mineral fertilization and the type of plant growth–supporting products used, may also have an impact. The significant influence (p < 0.05) of agronomic conditions on sugars content is confirmed by our own study results. The applied products MC and SP least significantly altered sugars content (Table 7, Tables S3 and S4). Each of the applied agents, regardless of timing or year of study, reduced the concentration of total and reducing sugars. The most beneficial effect in this regard was observed after the combined application of MC and SP. The observed changes may result from the indirect effect of the applied preparations on plant condition, through the reduction in biotic stress and the support of physiological processes, which favors an improvement in the chemical composition of the tubers. When judiciously applied to crops, biostimulants exhibit the ability to enhance plant metabolism, increase productivity, and improve resilience to adverse environmental conditions. By modulating molecular mechanisms and inducing epigenetic changes, biostimulants influence key signaling molecules, transcription factors, and hormone levels, which collectively contribute to stress tolerance [12,13].

A significantly positive effect of growth promoters on sugar content in potato tubers is also reported by Zarzecka and Gugała [47], Głosek-Sobieraj et al. [48] and Cortiello et al. [49].

It is known that during storage, there is an increase in the concentration of total sugars and reducing sugars [32,50,51]. After long-term storage, each year saw a significant (p < 0.05) increase in total sugars and reducing sugars content of 6.5 and 6.0%, 6.1 and 12.2%, and 6.5 and 9.2%, respectively (Figure 3 and Figure 4). Genetic factors have a significant impact on sugars content during storage [9,16,52]. It should also be remembered that improper storage conditions for tubers, especially for varieties intended for food processing, such as sudden temperature fluctuations and inadequate oxygen and humidity levels, can lead to starch hydrolysis, resulting in its conversion into sugars [15,30]. Pobereżny et al. [53] disagree, showing that the increase in sugars content during storage is associated with increased activity of invertase, an enzyme responsible for the breakdown (hydrolysis) of sucrose into simple sugars. These processes can significantly affect the quality of fried products, leading to changes in their organoleptic properties, including taste, consistency and color [15,30].

3.3. Carotenoids

Pigments, mainly carotenoids, are a component that has a significant impact on quality, particularly on the color of potato tubers and the chips produced from them. The carotenoid pigments found in potatoes are primarily xanthophylls [54,55]. In our study, the total carotenoid content depended significantly on all factors of the experiment. It should be noted, however, that among the factors studied, the cultivar had the greatest influence on carotenoid content (p < 0.05). The tested varieties differed significantly (p < 0.05) in carotenoid content, which ranged from 7.22 to 11.0 mg kg ⁻¹ f.m. immediately after harvest and from 6.93 to 10.9 mg kg ⁻¹ f.m. after six months of storage (

Table 8. Carotenoid content in potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Ctot [mg kg −1 f.m.]
	Treatment 4	AH *	AS **	Average
BEO	CL	7.29 ± 0.06	7.05 ± 0.09	7.17 ± 0.15
	MC	7.70 ± 0.12	7.55 ± 0.19	7.63 ± 0.19
	SP	7.45 ± 0.09	7.21 ± 0.11	7.33 ± 0.17
	MC + SP	7.90 ± 0.08	7.73 ± 0.07	7.82 ± 0.12
Average 5		7.58 ± 0.26	7.39 ± 0.31	7.49 ± 0.30
PICUS	CL	9.28 ± 0.61	9.05 ± 0.65	9.17 ± 0.69
	MC	9.53 ± 0.55	9.37 ± 0.54	9.45 ± 0.58
	SP	9.48 ± 0.57	9.30 ± 0.54	9.39 ± 0.59
	MC + SP	9.75 ± 0.61	9.56 ± 0.59	9.66 ± 0.66
Average		9.51 ± 0.62	9.32 ± 0.62	9.42 ± 0.61
PIROL	CL	10.09 ± 0.22	9.71 ± 0.15	9.90 ± 0.29
	MC	10.60 ± 0.20	10.33 ± 0.26	10.47 ± 0.29
	SP	10.17 ± 0.16	9.92 ± 0.13	10.05 ± 0.20
	MC + SP	10.87 ± 0.18	10.72 ± 0.12	10.80 ± 0.19
Average		10.43 ± 0.39	10.19 ± 0.44	10.31 ± 0.43
AVERAGES FOR TREATMENTS	CL	8.88 ± 1.30	8.60 ± 1.26	8.74 ± 1.25
	MC	9.28 ± 1.32	9.09 ± 1.28	9.19 ± 1.27
	SP	9.03 ± 1.27	8.81 ± 1.27	8.92 ± 1.24
	MC + SP	9.50 ± 1.36	9.33 ± 1.38	9.42 ± 1.32
AVERAGE FOR THE EXPERIMENT		9.17 ± 1.27	8.96 ± 1.23	9.07 ± 1.27
LSD 1 α = 0.05		A 2 = 0.054 B = 0.522 C = 0.074 B/A = N.S. 3 A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.128 B/C = 0.534

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

and Table S5).

Among the tested varieties, the highest average carotenoid content, regardless of the date and year of the study, was found in the ‘Pirol’ variety (10.31 mg kg ⁻¹ f.m.), followed by ‘Picus’ (9.42 mg kg ⁻¹ f.m.) and ‘Beo’ (7.49 mg kg ⁻¹ f.m.). This had a direct impact on the color of the flesh of raw tubers, which translated into the color of fried chips. This is confirmed by the highly significant (p < 0.01) correlation coefficients obtained between the carotenoid content and the color of the fried chips both immediately after harvest and after storage, respectively: r = −0.650 and r = −0.559 (Table 5 and Table 6). Among the many factors that directly influence the total carotenoid content in potato tubers, genotype is considered to be the most important [54,56,57,58,59,60]. This is due to the fact that different potato varieties differ in the color of their flesh and skin. Potatoes with white and yellow flesh have a similar carotenoid composition, and the yellow color is only due to higher levels of certain xanthophylls [61]. Brown et al. [62] report that the color of tuber flesh is correlated with specific carotenoid content. For white-fleshed varieties, the carotenoid content ranges from 0.50 to 3.50 mg kg ⁻¹ f.m., while yellow-fleshed varieties contain from 8.00 to 20.00 mg kg ⁻¹ f.m. [63]. Our own research confirms the results of Brown et al. [63], as the carotenoid content for yellow and light-yellow varieties ranged from 7.24 to 10.6 mg kg ⁻¹ f.m. (Table 8 and Table S5). This is also confirmed by the results obtained by Tatarowska et al. [54]. The authors, studying three potato varieties and seven tetraploid breeding lines with white and yellow flesh, showed a total carotenoid content in tubers ranging from 5.57 to 20.20 mg kg ⁻¹ f.m. Higher carotenoid contents were found for varieties with yellow flesh. However, it should be remembered that, apart from varietal characteristics, the location of cultivation, agrotechnology used, production systems, and meteorological conditions also have a significant impact on the carotenoid content in potato tubers [54,55,58,60,64,65]. Weather conditions are particularly important in the context of carotenoid content. Hamouz et al. [66], studying 12 potato varieties, proved that higher carotenoid content was found in tubers from a growing year characterized by higher air temperatures. The same trends were observed in our own research, as the highest total carotenoid content was obtained in the third year of the study, which was characterized by the highest average temperature. Cuéllar-Cepeda et al. [67] also report on the significant impact of meteorological conditions. Furthermore, Tatarowska et al. [54] emphasize that the concentration of carotenoids in potato tubers is highly dependent on environmental factors that cannot be controlled, as they vary depending on the year of cultivation.

The plant growth and development promoters used in the studies, i.e., MC and SP, slightly (p < 0.05) increased the total carotenoid content in tubers (Table 8 and Table S5). Each of the agents used, regardless of the date and year of the study, increased the carotenoid content. This increase averaged 2.09% for SP and 5.04% for MC. However, the combined use of the preparations proved to be the most beneficial, as the carotenoid content increased by an average of 7.75%. Application of the treatments resulted in higher carotenoid accumulation in tubers, likely due to the positive influence of the preparations on plant health and metabolic processes. Biostimulants influence the balance of endogenous hormones, alter the expression of genes involved in nutrient transport across cell membranes, promote photosynthesis, and reduce stress-related responses [12,13].

The positive effect of plant growth and development stimulants on the concentration of carotenoids in potato tubers is also noted by Mystkowska et al. [65]. The authors, using the biostimulants Agro-Sorb Folium, Aminoplant, and PlonoStart together with the herbicide Avatar 293 ZC, obtained a significant increase in the carotenoid content in potato tubers, by 10.8, 8.2, and 6.4%, respectively. In contrast, Vaitkevičienė et al. [68] showed the highest increase in carotenoid concentration in tubers when growing potatoes using a biodynamic system with the use of preparations supporting plant growth and development.

Many authors [60,69,70,71] indicate that the results concerning carotenoid content after storage are inconclusive. The discrepancies may result from varying storage conditions for the tubers. In our study, after 6 months of storage, a significant, albeit slight decrease (p < 0.05) in carotenoid content was observed in the tubers of the potato varieties tested (Table 8 and Table S5, Figure 5). On average, the smallest losses were observed in the ‘Picus’ variety (2.0%), followed by Pirol (2.3%) and Beo (2.5%). Slight decreases in carotenoid content in edible potato tubers after storage were also observed by Morris et al. [72] and Sturaro [60]. The authors emphasize that the carotenoid content during storage is characterized by high stability. The authors also report that during storage, there is a change in the type of carotenoids.

3.4. Chlorophylls

Chlorophyll pigments are present in small amounts in potato tubers. Chlorophyll biosynthesis occurs mainly when tubers are exposed to light, which can lead to their greening. This phenomenon occurs as a result of the transformation of amyloplasts into chloroplasts and the formation of a photosynthetic apparatus [73,74]. The content of Chl_a, Chl_b, and Chl_tot in tubers analyzed immediately after harvest ranged from 1.63 to 2.01 mg kg ⁻¹ f.m., from 0.853 to 1.036 mg kg ⁻¹ f.m., and from 2.49 to 3.04 mg kg ⁻¹ f.m., respectively. This is consistent with the results of Zgórska et al. [73]. However, after six months of storage, the values ranged from 1.59 to 1.92 mg kg ⁻¹ f.m., from 0.821 to 0.984 mg kg ⁻¹ f.m. and from 2.41 to 2.91 mg kg ⁻¹ f.m., respectively (

Table 9. Chlorophyll a and chlorophyll b content in potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Chla [mg kg−1 f.m.]			Chlb [mg kg−1 f.m.]
	Treatment 4	AH *	AS **	Average	AH	AS	Average
BEO	CL	1.93 ± 0.05	1.85 ± 0.06	1.89 ± 0.07	0.969 ± 0.034	0.913 ± 0.000	0.941 ± 0.031
	MC	1.87 ± 0.03	1.8 ± 0.02	1.84 ± 0.05	0.938 ± 0.039	0.886 ± 0.000	0.912 ± 0.031
	SP	1.80 ± 0.07	1.72 ± 0.04	1.76 ± 0.08	0.909 ± 0.033	0.865 ± 0.001	0.887 ± 0.026
	MC + SP	1.75 ± 0.05	1.69 ± 0.03	1.72 ± 0.05	0.889 ± 0.031	0.841 ± 0.002	0.865 ± 0.027
Average 5		1.84 ± 0.08	1.77 ± 0.08	1.81 ± 0.09	0.926 ± 0.033	0.876 ± 0.029	0.901 ± 0.040
PICUS	CL	1.85 ± 0.04	1.78 ± 0.03	1.82 ± 0.06	0.918 ± 0.075	0.871 ± 0.004	0.895 ± 0.060
	MC	1.8 ± 0.05	1.73 ± 0.03	1.77 ± 0.06	0.922 ± 0.031	0.877 ± 0.014	0.900 ± 0.027
	SP	1.73 ± 0.05	1.66 ± 0.02	1.70 ± 0.06	0.896 ± 0.030	0.851 ± 0.004	0.874 ± 0.026
	MC + SP	1.67 ± 0.05	1.6 ± 0.03	1.64 ± 0.05	0.862 ± 0.024	0.827 ± 0.008	0.845 ± 0.021
Average		1.76 ± 0.08	1.69 ± 0.08	1.73 ± 0.09	0.900 ± 0.038	0.857 ± 0.033	0.879 ± 0.041
PIROL	CL	1.97 ± 0.04	1.89 ± 0.02	1.93 ± 0.05	1.029 ± 0.046	0.960 ± 0.017	0.995 ± 0.041
	MC	1.94 ± 0.04	1.88 ± 0.04	1.91 ± 0.05	0.947 ± 0.028	0.909 ± 0.09	0.928 ± 0.023
	SP	1.88 ± 0.03	1.81 ± 0.01	1.85 ± 0.05	0.937 ± 0.041	0.886 ± 0.014	0.912 ± 0.032
	MC + SP	1.84 ± 0.04	1.75 ± 0.04	1.80 ± 0.05	0.902 ± 0.038	0.84 ± 0.01	0.871 ± 0.034
Average		1.91 ± 0.06	1.83 ± 0.07	1.87 ± 0.08	0.954 ± 0.049	0.899 ± 0.047	0.927 ± 0.055
AVERAGES FOR TREATMENTS	CL	1.92 ± 0.06	1.84 ± 0.06	1.88 ± 0.07	0.972 ± 0.058	0.915 ± 0.049	0.944 ± 0.060
	MC	1.87 ± 0.07	1.8 ± 0.07	1.84 ± 0.08	0.936 ± 0.0123	0.891 ± 0.020	0.914 ± 0.028
	SP	1.81 ± 0.08	1.73 ± 0.08	1.77 ± 0.09	0.914 ± 0.020	0.867 ± 0.020	0.891 ± 0.031
	MC + SP	1.75 ± 0.08	1.68 ± 0.07	1.72 ± 0.08	0.884 ± 0.020	0.836 ± 0.010	0.860 ± 0.029
AVERAGE FOR THE EXPERIMENT		1.84 ± 0.11	1.76 ± 0.09	1.80 ± 0.10	0.927 ± 0.054	0.877 ± 0.039	0.902 ± 0.050
1 LSD α = 0.05		A 2 = 0.008 B = 0.014 C = 0.016 B/A = N.S. 3 A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.028 B/C = 0.028			A = 0.007 B = 0.012 C = 0.015 B/A = N.S. A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.025 B/C = 0.025

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

and

Table 10. Total chlorophyll content in potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Chltot [mg kg−1 f.m.]
	Treatment 4	AH *	AS **	Average
BEO	CL	2.90 ± 0.12	2.76 ± 0.05	2.83 ± 0.09
	MC	2.81 ± 0.11	2.69 ± 0.02	2.75 ± 0.08
	SP	2.71 ± 0.14	2.59 ± 0.04	2.65 ± 0.11
	MC + SP	2.64 ± 0.10	2.53 ± 0.03	2.59 ± 0.08
Average 5		2.76 ± 0.12	2.64 ± 0.11	2.70 ± 0.13
PICUS	CL	2.77 ± 0.15	2.65 ± 0.03	2.71 ± 0.11
	MC	2.72 ± 0.11	2.61 ± 0.04	2.67 ± 0.08
	SP	2.63 ± 0.11	2.51 ± 0.03	2.57 ± 0.08
	MC + SP	2.53 ± 0.07	2.43 ± 0.01	2.48 ± 0.06
Average		2.66 ± 0.11	2.55 ± 0.13	2.61 ± 0.11
PIROL	CL	3.00 ± 0.12	2.85 ± 0.03	2.93 ± 0.09
	MC	2.89 ± 0.09	2.78 ± 0.05	2.84 ± 0.07
	SP	2.82 ± 0.12	2.69 ± 0.02	2.76 ± 0.08
	MC + SP	2.74 ± 0.11	2.59 ± 0.04	2.67 ± 0.09
Average		2.86 ± 0.11	2.72 ± 0.13	2.80 ± 0.11
AVERAGES FOR TREATMENTS	CL	2.89 ± 0.12	2.76 ± 0.11	2.83 ± 0.13
	MC	2.80 ± 0.08	2.69 ± 0.09	2.75 ± 0.10
	SP	2.72 ± 0.10	2.60 ± 0.10	2.66 ± 0.12
	MC + SP	2.63 ± 0.10	2.52 ± 0.08	2.58 ± 0.11
AVERAGE FOR THE EXPERIMENT		2.76 ± 0.16	2.64 ± 0.13	2.70 ± 0.15
LSD 1 α = 0.05		A 2 = 0.012 B = 0.013 C = 0.022 B/A = N.S. 3 A/B = N.S. C/A= 0.031 A/C = 0.029 C/B = N.S. B/C = N.S.

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

, Tables S6–S8).

In the studies conducted, the chlorophyll content in potato tubers depended significantly on all factors of the experiment. The varieties tested differed significantly (p < 0.05) in terms of chlorophyll content in tubers. The highest average content of these components, regardless of the year and date of the study, was found in the ‘Pirol’ variety, and the lowest in the ‘Picus’ variety. Zgórska et al. [73] and Tanios et al. [74] share a similar opinion, stating that genetic factors have the greatest impact on the chlorophyll content in potato tubers, followed by environmental factors such as planting depth, physiological age of tubers, temperature, atmospheric oxygen level, and lighting conditions. The literature on the subject shows that the chlorophyll content in potatoes, especially those intended for processing, is correlated with the earliness group of varieties [73,75]. Early varieties contain significantly more chlorophyll than late varieties. This thesis is confirmed by the results of our own research, as the ‘Picus’ variety had the lowest chlorophyll content and the longest growing season among the varieties studied.

The studies also showed a significant effect (p < 0.05) of the applied treatments on chlorophyll a, b and total content (Table 9 and Table 10, Tables S6–S8). There are few studies in the literature devoted to the effect of biostimulants on chlorophyll content in potato tubers, which suggests that this biochemical aspect has not yet been analyzed in detail or taken into account in the context of the physiology of this plant. In our studies, each of the preparations used caused a decrease in chlorophyll content in potato tubers both after harvest and after storage. The largest decrease, regardless of the year and date, was obtained after the simultaneous application of MC and SP (8.7%), while MC reduced the content by an average of 5.8% and SP by 2.7% compared to the control (Table 9 and Table 10, Tables S6–S8). Observed decrease may reflect a shift in plant metabolism towards the accumulation of compounds important for tuber quality.

In addition, the use of biostimulants may have a positive impact on various plant processes, such as cell division and elongation, resulting in increased leaf area and ultimately more photosynthesis. The authors [12,13] commented on the importance and involvement of amino acids in the tolerance to abiotic stress, mentioning that this class of molecules comprises certain amino acids (particularly proline) and quaternary ammonium compounds. These substances are believed to be essential for plants to change their cytoplasmic osmotic balance in response to osmotic stress.

Hara [76], using the biostimulating preparations Kelpak SL and Aminoplant, obtained a decrease in chlorophyll a and b content in potato leaves compared to the control by 8.4% and 14.7%, respectively. The author points out that the chlorophyll content depends on the type of preparation used, which is confirmed by the results of our research.

After long-term storage of tubers, there was a slight but significant decrease (p < 0.05) in Chl_a, Chl_b, and Chl_tot content (Table 9 and Table 10, Tables S6–S8, Figure 6, Figure 7 and Figure 8). Wang et al. [77] showed that tubers exposed to light during storage contained as much as 25.5 times more chlorophyll than potatoes stored in the dark. However, they did not find any difference in chlorophyll content in potatoes stored in the dark. Therefore, the slight decrease in chlorophyll content after 6 months of storage obtained in our own research may indicate that the technological regime was maintained during the storage of tubers for chip production and that the tubers were handled properly immediately after harvesting.

3.5. Chips Quality

3.5.1. Total Sensory Quality and Color

The most important quality characteristics of potato chips include color, taste, aroma, and consistency. The studies conducted showed a varied impact of the tested factors on individual quality characteristics of potato chips. Nevertheless, all chips produced were characterized by generally good sensory quality (an average of 4.6 points immediately after harvesting and 4.5 points after storage), meeting the requirements for this type of refined product (

Table 11. The total sensory quality of chips fried from the analyzed potato tubers, depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Total Sensory Quality [5-Point Scale]
	Treatment 4	AH *	AS **	Average
BEO	CL	4.7 ± 0.1	4.5 ± 0.0	4.6 ± 0.2
	MC	5.0 ± 0.1	4.8 ± 0.1	4.9 ± 0.1
	SP	4.8 ± 0.1	4.7 ± 0.1	4.8 ± 0.1
	MC + SP	5.0 ± 0.0	4.8 ± 0.0	4.9 ± 0.1
Average 5		4.9 ± 0.2	4.7 ± 0.2	4.8 ± 0.2
PICUS	CL	4.7 ± 0.1	4.6 ± 0.2	4.6 ± 0.1
	MC	4.7 ± 0.2	4.5 ± 0.1	4.6 ± 0.2
	SP	4.7 ± 0.1	4.5 ± 0.1	4.6 ± 0.1
	MC + SP	4.9 ± 0.1	4.8 ± 0.1	4.8 ± 0.1
Average		4.8 ± 0.2	4.6 ± 0.2	4.7 ± 0.2
PIROL	CL	4.1 ± 0.2	3.9 ± 0.1	4.0 ± 0.2
	MC	4.4 ± 0.1	4.2 ± 0.1	4.3 ± 0.1
	SP	4.2 ± 0.2	4.3 ± 0.1	4.3 ± 0.1
	MC + SP	4.4 ± 0.2	4.3 ± 0.0	4.3 ± 0.1
Average		4.3 ± 0.3	4.2 ± 0.2	4.2 ± 0.1
AVERAGES FOR TREATMENTS	CL	4.5 ± 0.8	4.3 ± 0.7	4.4 ± 0.3
	MC	4.7 ± 0.3	4.5 ± 0.3	4.6 ± 0.3
	SP	4.6 ± 0.3	4.4 ± 0.2	4.5 ± 0.3
	MC + SP	4.8 ± 0.3	4.6 ± 0.3	4.7 ± 0.3
AVERAGE FOR THE EXPERIMENT		4.6 ± 0.4	4.5 ± 0.4	4.5 ± 0.3
LSD 1 α = 0.05		A 2 = 0.080 B = 0.055 C = 0.066 B/A = N.S. 3 A/B = N.S. C/A =N.S. A/C =N.S. C/B = 0.114 B/C = 0.113

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

and Table S9, Figure 9).

The desired color of the chips should be light, evenly golden, without brown discoloration or spots [78,79]. In the studies conducted, the color rating of fried chips ranged between 3.5 and 5.0 points (five-point scale) both after harvesting and after storage (

Table 12. Assessment of the color of chips fried from the analyzed potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		COLOR [5-Point Scale]
	Treatment 4	AH *	AS **	Average
BEO	CL	5.0 ± 0.1	4.7 ± 0.2	4.8 ± 0.2
	MC	4.9 ± 0.1	4.7 ± 0.1	4.8 ± 0.1
	SP	4.8 ± 0.3	4.8 ± 0.3	4.8 ± 0.2
	MC + SP	5.0 ± 0.0	4.8 ± 0.1	4.9 ± 0.1
Average 5		4.9 ± 0.2	4.8 ± 0.2	4.9 ± 0.2
PICUS	CL	4.8 ± 0.1	4.6 ± 0.3	4.7 ± 0.2
	MC	4.6 ± 0.2	4.4 ± 0.3	4.5 ± 0.2
	SP	4.8 ± 0.3	4.6 ± 0.4	4.7 ± 0.3
	MC + SP	5.0 ± 0.0	4.7 ± 0.0	4.9 ± 0.2
Average		4.8 ± 0.2	4.6 ± 0.2	4.7 ± 0.3
PIROL	CL	3.7 ± 0.3	3.7 ± 0.2	3.7 ± 0.2
	MC	4.0 ± 0.3	3.9 ± 0.2	4.0 ± 0.2
	SP	4.1 ± 0.3	4.3 ± 0.0	4.2 ± 0.3
	MC + SP	4.3 ± 0.2	4.3 ± 0.0	4.3 ± 0.1
Average		4.0 ± 0.3	4.1 ± 0.3	4.1 ± 0.3
AVERAGES FOR TREATMENTS	CL	4.5 ± 3.1	4.3 ± 0.1	4.4 ± 0.6
	MC	4.6 ± 0.4	4.4 ± 0.4	4.5 ± 0.4
	SP	4.6 ± 0.5	4.6 ± 0.3	4.6 ± 0.4
	MC + SP	4.8 ± 0.4	4.6 ± 0.2	4.7 ± 0.3
AVERAGE FOR THE EXPERIMENT		4.6 ± 0.2	4.5 ± 0.3	4.5 ± 0.4
LSD 1 α = 0.05		A 2 = N.S. B = 0.108 C = 0.154 B/A = N.S. 3 A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.267 B/C = 0.255

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

and Table S10).

The highest color rating was given to chips fried from the ‘Beo’ variety (4.9 points), followed by the ‘Picus’ variety (4.7 points) and the ‘Pirol’ variety (4.1 points). The component that has a key influence on the color of chips is sugars, mainly reducing sugars [9,59,80,81]. This is confirmed by the highly significant (p < 0.01) correlation coefficients obtained in the studies between the color of chips and total sugar content, amounting to r = −0.745 after harvesting and r = −0.658 after storage, and reducing sugars r = −0.808 immediately after harvesting and r = −0.627 after storage (Table 5 and Table 6). This indicates that chips containing lower amounts of total and reducing sugars generally had better color. Considering that color is the first visual aspect influencing consumer choice in the case of fried products, it is therefore extremely important to select the right variety for their production. Too high a content of sugars, which react with free amino acids during heat treatment, can result in a darker, brown color [82,83]. The dark color of chips, as an indicator of the Maillard reaction, may indicate the formation of harmful acrylamide. In addition, it should be emphasized that refined products with a lighter color are perceived as safer. Darker products indicate a higher degree of acrylamide formation, which may raise concerns about consumer safety [79,84].

The significant impact of the preparations used and long-term storage of tubers on the color of chips was also demonstrated (Table 11 and Table S10). The most favorable effect on this characteristic was achieved by the combined use of MC and SP preparations during the growing season (an average of 4.7 points). After long-term storage of the tubers, there was generally a slight deterioration in the color of the chips, by an average of 0.1 points (Figure 10). This is due to the fact that sugars are largely responsible for the color of fried products. This is confirmed by the higher correlation coefficients obtained between the color of the chips and sugars compared to the coefficients between the color of the chips and pigments (carotenoids and total chlorophyll, as well as chlorophyll a and b), both after harvest and after storage (Table 5 and Table 6). It is worth recalling here that the lowest content was obtained after the combined use of MC and SP and that an increase in sugar content was observed after storage, as described above. The influence of sugars on the color of fried products, both after harvest and after storage, is reported by Pobereżny et al. [53].

3.5.2. Consistency and Taste

In the studies conducted, the consistency and taste of the chips depended significantly on all factors of the experiment. However, the greatest influence (p < 0.05) on consistency and taste of chips from all factors was exerted by the evaluation date, while the applied treatments had the least effect (

Table 13. Assessment of the consistency of chips fried from the analyzed potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Consistency [5-Point Scale]
	Treatment 4	AH *	AS **	Average
BEO	CL	4.7 ± 0.2	4.2 ± 0.0	4.5 ± 0.3
	MC	4.9 ± 0.1	4.7 ± 0.3	4.8 ± 0.3
	SP	4.5 ± 0.2	4.2 ± 0.1	4.4 ± 0.2
	MC + SP	4.9 ± 0.1	4.9 ± 0.1	4.9 ± 0.1
Average 5		4.8 ± 0.2	4.5 ± 0.2	4.7 ± 0.2
PICUS	CL	4.3 ± 0.2	4.0 ± 0.2	4.2 ± 0.2
	MC	4.6 ± 0.3	4.2 ± 0.3	4.4 ± 0.3
	SP	4.5 ± 0.3	4.1 ± 0.1	4.3 ± 0.3
	MC + SP	4.6 ± 0.4	4.5 ± 0.3	4.6 ± 0.3
Average		4.5 ± 0.2	4.2 ± 0.2	4.4 ± 0.3
PIROL	CL	3.9 ± 0.3	3.7 ± 0.1	3.8 ± 0.2
	MC	4.1 ± 0.1	3.8 ± 0.0	3.9 ± 0.1
	SP	4.1 ± 0.1	3.9 ± 0.1	4.0 ± 0.1
	MC + SP	4.1 ± 0.1	3.9 ± 0.2	4.0 ± 0.1
Average		4.1 ± 0.3	3.8 ± 0.3	3.9 ± 0.2
AVERAGES FOR TREATMENTS	CL	4.3 ± 1.3	4.0 ± 0.4	4.1 ± 0.4
	MC	4.5 ± 0.4	4.3 ± 0.4	4.4 ± 0.4
	SP	4.3 ± 0.3	4.1 ± 0.1	4.2 ± 0.3
	MC + SP	4.5 ± 0.4	4.5 ± 0.5	4.5 ± 0.3
AVERAGE FOR THE EXPERIMENT		4.4 ± 0.4	4.2 ± 0.4	4.3 ± 0.4
LSD 1 α = 0.05		A 2 = 0.210 B = 0.203 C = 0.120 B/A = N.S. 3 A/B = N.S. C/A = 0.169 A/C = 0.249 C/B = 0.207 B/C = 0.271

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

and

Table 14. Assessment of the taste of chips fried from the analyzed potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Taste [5-Point Scale]
	Treatment 4	AH *	AS **	Average
BEO	CL	4.0 ± 0.3	3.8 ± 0.0	3.9 ± 0.2
	MC	4.9 ± 0.1	4.7 ± 0.0	4.8 ± 0.2
	SP	4.9 ± 0.1	4.8 ± 0.3	4.9 ± 0.2
	MC + SP	5.0 ± 0.0	4.7 ± 0.0	4.9 ± 0.2
Average 5		4.7 ± 0.2	4.5 ± 0.4	4.6 ± 0.4
PICUS	CL	4.6 ± 0.1	4.4 ± 0.4	4.5 ± 0.2
	MC	4.7 ± 0.0	4.6 ± 0.2	4.6 ± 0.2
	SP	4.5 ± 0.4	4.0 ± 0.2	4.2 ± 0.3
	MC + SP	5.0 ± 0.0	4.8 ± 0.0	4.9 ± 0.2
Average		4.7 ± 0.2	4.5 ± 0.3	4.6 ± 0.4
PIROL	CL	3.7 ± 0.3	3.2 ± 0.0	3.5 ± 0.3
	MC	4.3 ± 0.2	4.1 ± 0.1	4.2 ± 0.2
	SP	3.8 ± 0.4	3.7 ± 0.2	3.8 ± 0.3
	MC + SP	4.1 ± 0.3	3.9 ± 0.2	4.0 ± 0.3
Average		4.0 ± 0.3	3.7 ± 0.4	3.9 ± 0.4
AVERAGES FOR TREATMENTS	CL	4.1 ± 1.5	3.8 ± 2.5	3.9 ± 0.5
	MC	4.6 ± 0.3	4.4 ± 0.3	4.5 ± 0.3
	SP	4.3 ± 0.5	4.2 ± 0.6	4.2 ± 0.5
	MC + SP	4.7 ± 0.5	4.5 ± 0.4	4.6 ± 0.5
AVERAGE FOR THE EXPERIMENT		4.4 ± 0.4	4.2 ± 0.3	4.3 ± 0.5
LSD 1 α = 0.05		A 2 = 0.156 B = 0.090 C = 0.146 B/A = N.S. 3 A/B = N.S. C/A = N.S. A/C = N.S. C/B = 0.252 B/C = 0.236

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

, Tables S11 and S12).

The varieties tested differed in their consistency ratings, which ranged from 3.7 to 5.0 points both after harvest and after storage. In contrast, the taste rating ranged from 3.5 to 5.0 points after harvest and from 3.2 to 4.8 points after long-term storage. Among the varieties tested, the best consistency was found in the ‘Beo’ (4.7 points), ‘Picus’ (4.4 points) and ‘Pirol’ (3.9 points), respectively. (Table 13 and Table S11). In the case of taste assessment, the trend generally remained the same as for consistency assessment (‘Beo’—4.6 points, ‘Picus’—4.6 points, ‘Pirol’—3.9 points). However, it was noted that the taste ratings for the ‘Beo’ and ‘Picus’ varieties were similar (Table 14 and Table S12). According to Vaitkevičienė et al. [59], the taste of chips depends largely on their consistency. This is confirmed by the highly significant (p < 0.01) correlation coefficients between taste and consistency obtained in these studies, amounting to r = 0.613 immediately after harvesting and r = 0.513 after 6 months of storage (Table 5 and Table 6). According to many authors [9,59,85], the dry matter and starch content in tubers have the greatest impact on the consistency and crispness of fried chips. This is confirmed by the highly significant positive (p < 0.01) correlation coefficients obtained between consistency and dry matter and starch immediately after harvest and after storage, respectively: r = 0.621 and r = 0.719, and r = 0.579 and r = 0.695 (Table 5 and Table 6). Chips made from potatoes with a high dry matter content have a hard consistency, which translates into the desired crispness of the chips. On the other hand, chips made from potatoes with a low dry matter content contain more oil, have a greasy appearance and a sticky consistency [9]. This is confirmed by the results obtained in the studies conducted, as the best consistency was found in chips made from varieties with the highest dry matter and starch content (Table 4 and Table 13, Tables S1, S2 and S11). Similar results were obtained in the studies by Islam et al. [9], as when testing six potato varieties, the crispiest chips were those produced from varieties with the highest dry matter content. Properly fried chips should have a crispy and delicate consistency.

Sugars and amino acids contained in potatoes play an important role in shaping the taste of chips [86,87]. This thesis is confirmed by studies that have shown significant negative correlation coefficients between the discussed characteristics (Table 5 and Table 6). However, it should be remembered that the sugar content in fried snacks cannot be too high, as this may result in a bitter taste [82]. According to the requirements of the Polish standard PN-A-74780:1996, potato chips should have a specific, fresh taste with a distinct sensation of the spices used [87]. According to this standard, chips that receive a score below three points on a five-point scale for any sensory quality characteristic are classified as unsuitable for sale on the market. Taking this classification into account, it can be concluded that the tested chips had an appropriate taste and met the necessary quality requirements.

The MC and SP preparations used in the experiment had a significant positive effect (p < 0.05) on the tested quality characteristics of the chips (taste and consistency). However, it was noted that their effect was ambiguous. For the taste and consistency of the chips, the most favorable results were achieved with the combined application of MC + SP (an average of 4.6 points and 4.5 points, respectively). This indicates that these characteristics depend not only on the reaction of the variety to the treatment preparations used in the study.

After long-term storage of the tubers, a significant decline (p < 0.05) in the quality of the chips was observed, mainly due to a lower rating for taste and consistency in each year of the study (Table 13, Tables S11 and S12, Figure 11 and Figure 12). The decline was 6.5, 4.5, and 4.7%, respectively. These changes were caused by a deterioration in the chemical composition of the tubers during long-term storage, mainly dry matter, starch, and sugars, as described above. The preparations used to treat the tubers had the same effect on the taste and consistency of the chips, both after harvesting and storage. It is worth noting that storage had the most significant (p < 0.05) impact on the texture and taste (Figure 11).

3.5.3. Aroma

The aroma of the tested chips was consistently natural, pleasant, and typical for this type of product, and showed high stability regardless of the test factors used (

Table 15. Assessment of the aroma of chips fried from the analyzed potato tubers depending on the research date, genotype, and growth- and development-stimulating preparations (average of 3 years of research).

Variety		Aroma [5-Point Scale]
	Treatment 4	AH *	AS **	Average
BEO	CL	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC + SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
Average 5		5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
PICUS	CL	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC + SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
Average		5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
PIROL	CL	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC + SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
Average		5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
AVERAGES FOR TREATMENTS	CL	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
	MC + SP	5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
AVERAGE FOR THE EXPERIMENT		5.0 ± 0.0	5.0 ± 0.0	5.0 ± 0.0
LSD 1 α = 0.05		A 2 = N.S. 3 B = N.S. C = N.S. B/A = N.S. A/B = N.S. C/A = N.S. A/C = N.S. C/B = N.S. B/C = N.S.

* AH—Directly after harvest, ** AS—After 6 months of storage. ¹ LSD—least significant difference, ³ N.S.—no significant, ² Experimental factors: A—Evaluation date, B—Variety, ⁴ C—Treatment application (CL—Control, MC—Moncut 460 SC, SP—Supporter^®), ⁵ Bold font indicates mean values for easier identification and comparison within the table.

and Table S13). All analyzed samples met the aroma requirements, showing no deviations from the norm. This indicates that the quality requirements for the analyzed potato varieties are consistent with their use in chips.

4. Conclusions

Studies have shown that both the potato genotype and the chemical treatments applied before planting significantly shape the chemical composition of the tubers and the quality of the resulting chips. The early variety ‘Beo’ was distinguished by the most favorable quality parameters of the tubers. The cultivar was characterized by the highest dry matter (23.9%) and starch content (18.4%), while showing the lowest total and reducing sugars (5.77 g kg⁻¹ f.m. and 459 mg kg⁻¹ f.m.). The cv. ‘Pirol’ contained the highest levels of carotenoid and chlorophyll pigments (a, b and total): 10.31; 1.87; 0.927; 2.80 mg kg⁻¹ f.m. The combined application of the preparations MC and SP improved the technological characteristics of the tubers and positively influenced the color (mean 4.7 points), consistency (mean 4.5 points), and taste (mean 4.6 points) of the refined products. The quality of tubers and chips experienced a slight deterioration after long-term storage, which proves that the storage conditions were maintained in line with the intended use of the tested varieties. Produced chips were of high overall quality (averaging 4.6 points after harvest and 4.5 points after storage). Chips from the cv. ‘Beo’ received the highest organoleptic scores: color 4.9, consistency 4.7, taste 4.6, and a very good aroma 5.0, regardless of experimental factors.

This also indicates well-chosen agricultural techniques during cultivation and proper handling of the potatoes immediately after harvest. Furthermore, it was shown that the influence of the factors applied during cultivation was maintained even after long-term storage. The key elements ensuring high raw material quality are primarily the selection of the variety and the rational use of preparations applied directly before planting the tubers. Due to the dynamic development of the market for fried potato products and the growing expectations of consumers regarding food quality and safety, it is essential to conduct successive and systematic research on tuber quality and the factors determining the quality parameters of chips. Continuous improvement of knowledge in this area will not only allow for the enhancement of raw material parameters but will also help increase the competitiveness of the final product.