Analysis of the Antioxidant Capacity of Whole-Fruit Tomato Powder Using the Ferric Reducing Antioxidant Power (FRAP) Assay—An Eco-Friendly Approach for the Valorization of Horticultural Products

Abstract

The present study aims to evaluate the antioxidant activity of tomato powders obtained from whole tomatoes of three local cultivars—Andrada, Hera, and Kristinica—using the Ferric Reducing Antioxidant Power (FRAP) assay. The cultivars were grown in open fields without additional treatments or fertilizer application. Ascorbic acid was used as a reference antioxidant standard. Results indicated that Andrada powder exhibited the highest antioxidant activity, at 248.1 ± 5.3 µmol Fe²⁺/100 g, followed by Hera (235.6 ± 4.9 µmol Fe²⁺/100 g) and Kristinica (212.8 ± 5.1 µmol Fe²⁺/100 g), while ascorbic acid, used as a positive control, showed the highest overall antioxidant capacity (260.0 ± 4.5 µmol Fe²⁺/100 g). The high lycopene and flavonoid content of the analyzed powders supports their potential as functional ingredients in food applications and their use in horticulture. This research is particularly relevant as it promotes a sustainable approach for the utilization of tomato products, aligning with the principles of circular agriculture.

1. Introduction

In recent years, the valorization of agricultural waste has become increasingly important as efforts intensify to reduce waste volumes and protect the environment. Tomato powder, produced by drying and grinding leftover tomato parts from processing, offers a simple and effective way to transform what was once waste into a valuable, multifunctional product [1].

Typically, imperfect tomato pulp is discarded in landfills, contributing to resource overuse and environmental pollution. However, by drying and converting these materials into powder, both waste volumes and the loss of valuable nutrients—such as dietary fiber and lycopene, a powerful antioxidant—can be significantly reduced [2].

Tomato powder can be added to various food products without the use of synthetic additives or artificial colors, enhancing their nutritional value, flavor, and appearance. Furthermore, it reduces the environmental impact along the food chain [3]. It is easier to transport and takes up much less space than fresh tomatoes [4].

This encourages a more responsible agricultural model that fully utilizes all components of the harvest, leaving no part unused, and offering both ecological and nutritional benefits [5]. Such practices also support international directives aimed at improving the sustainability of agriculture and the food sector [6].

In the case of tomatoes (Solanum lycopersicum), known for their rich composition in bioactive compounds, parts such as the pulp, skins, and seeds have significant potential. Their transformation into powder offers a practical solution for various industries [7]; as a concentrated and shelf-stable form of tomatoes that retains most of the vital nutrients and bioactive compounds, tomato powder has multiple environmental and health benefits. Nutritionally, it is rich in lycopene, a powerful antioxidant that protects cells against oxidative stress and reduces the risk of chronic diseases such as cardiovascular disease and certain types of cancer [8].

Furthermore, it provides essential vitamins and minerals, making it a valuable ingredient for improving the nutritional profile of processed foods without the need for synthetic additives [9]. Tomato powder also supports the sustainability of the food system; its extended shelf life, reduced food waste, and easier storage and transportation contribute to improving the efficiency of the supply chain [10]. In addition, it contributes to the circular economy and reduces the volume of food waste with an impact on the environment [11]. By reducing the volume and weight of raw materials, greenhouse gas emissions related to logistics are reduced, while the valorization of tomato residues helps prevent soil and water pollution caused by organic matter [12]. Therefore, this practice supports the global sustainability and environmental protection goals promoted by international organizations [13].

The current study investigates the antioxidant capacity of tomato powders from three local varieties using the FRAP assay and explores their potential applications in horticulture and functional nutrition. This research highlights, for the first time, the potential of local tomato varieties in the production of antioxidant-rich nutraceutical ingredients, without the need for genetic modification or costly post-harvest treatments.

2. Materials and Methods

Potassium ferricyanide, 0.2 M disodium hydrogen phosphate, hexane, ethanol, acetone, 10% trichloroacetic acid, ascorbic acid, and ferric chloride were purchased from Merck (Darmstadt, Germany). All aqueous solutions were prepared using ultrapure water in a Milli-Q system with a resistivity of 18.2 MΩ·cm at 25 °C and a total organic carbon (TOC) content of 5 ppb. Experimental analyses were performed at the SC Biosol PSI SRL laboratory, located in Ploiești, Romania, using a Hach Lange DR 3900 spectrophotometer.

2.1. Raw Material Preparation and Powder Production

The three tomato varieties were grown in an open field at the Buzău Vegetable Station (Romania 45°09′ N, 26°49′ E). The average daily temperature during cultivation was 22–28 °C, with drip irrigation twice a week.

The soil used in the experiment presented a neutral pH (≈7), a condition attributed to the presence of carbonates. Under these conditions, ions such as Ca²⁺ and Mg²⁺ (at pH 7), as well as NH₄⁺ and MoO₄²⁻ (at pH 7–8), are preferentially absorbed. The pH values recorded are within the optimal range for tomato cultivation (5.5–7.0) [14]. High humus content (4.53%) and a high level of organic matter (6%) reflect good fertility of the substrate. No additional chemical treatments were applied.

Approximately five kilograms of fruits of each tomato variety, all at the ripe stage, were randomly collected from 10 different tomato plants grown in the same growing area.

Tomatoes were washed to remove surface contaminants, cut into uniform slices, and dehydrated in a hot air drier at 50 °C for 24 h. After drying, the slices were ground into powder using a mortar. The resulting powder was sieved through a 250 µm mesh and stored under controlled conditions, protected from moisture and light.

The choice of hot air drying at 50 °C for 24 h was motivated by its wide availability, low cost, and ability to preserve lycopene content while reducing microbial risk. Although some phenolic compounds may degrade at this temperature, several studies confirm that lycopene remains relatively stable, justifying this method for sustainable processing. While freeze-drying better retains thermolabile phenolic compounds, hot air drying at 50 °C offers low-cost scalability and acceptable lycopene retention; comparable FRAP ranges are reported in the literature for conventionally dried powders [14,15].

2.2. Physical and Chemical Characterization of Tomato Powder

The samples were analyzed to determine moisture content (U%) and dry matter (DM) content. The ripeness, storage condition, nutritional, and commercial value of tomatoes can be assessed by evaluating various physical and chemical parameters. For example, the texture, taste, and visual appearance of tomatoes are largely influenced by their moisture content.

Dry matter is the total amount of substance remaining in tomato fruits after the complete evaporation of water. The determination of dry matter content was performed by gravimetric analysis. The moisture content was determined using 3 g of sample placed in an oven set at 105 °C until constant weight was reached. The empty crucibles were pre-dried at 105 °C and stored in a desiccator before weighing.

$$\mathrm{U}\left(\mathrm{\%}\right)=\left({\mathrm{m}}_0-{\mathrm{m}}_{\mathrm{d}\mathrm{r}\mathrm{y}}\right)\times 100/{\mathrm{m}}_0$$

(1)

$$\mathrm{D}\mathrm{M}\left(\mathrm{\%}\right)=100-\mathrm{U}\left(\mathrm{\%}\right)$$

(2)

where

m₀ = initial sample mass (g); mdry = mass of the dried sample (g).

2.3. Extraction of Bioactive Compounds

The aim of the extraction process was to separate the phenolic compounds from the solid matrix. Methanol was chosen as the extraction solvent due to its ease of removal under vacuum and its significantly higher extraction yield, which is reported to be up to seven times higher than that obtained with water [16,17,18,19]. Techniques such as ultrasound-assisted extraction [19,20,21], maceration [22], and supercritical fluid extraction [23] are considered efficient and environmentally friendly approaches for the recovery of bioactive compounds from plant by-products. To obtain active compounds, 100 mL of a methanol–water (80:20 v/v) hydroalcoholic mixture was used to produce a crude hydroalcoholic extract.

The hydroalcoholic system, methanol–water (80:20 v/v), effectively solubilizes a wide range of phenolic and carotenoid phenolic co-extracts with high polarity, often outperforming the extraction yield of pure ethanol or acetone.

The methanol was subsequently evaporated using a rotary evaporator at 65 °C, and the resulting phenolic extract was stored at 6 °C until further use.

2.4. Evaluation of Antioxidant Activity via the FRAP Assay

The FRAP assay is appreciated for its speed, simplicity, and reproducibility, being suitable for the analysis of plant extracts, including tomatoes, due to high concentration in lycopene, flavonoids, and other phenolic compounds [16]. However, it does not detect all classes of antioxidants—for example, thiol compounds, such as glutathione, are not efficiently assessed.

This method has been validated in numerous studies on plant extracts, including tomato-derived products [3,4], and is recognized as one of the most representative techniques for the assessment of total antioxidant capacity under controlled experimental conditions.

In addition to the FRAP test, there are other ways to evaluate antioxidant activity: DPPH and ABTS (radical scavenging), ORAC (peroxyl-radical inhibition), and CUPRAC (Cu²⁺ reduction).

Compared with DPPH and ABTS (radical-based assays), FRAP quantifies electron-donation capacity, aligning with lycopene/phenolic redox behavior in tomato matrices. FRAP is rapid, uses readily available reagents, and shows high repeatability; nevertheless, it does not capture thiol antioxidants and may be influenced by free iron—limitations acknowledged in this study [17].

The FRAP assay was selected for its reproducibility and suitability for tomato matrices rich in lycopene and phenolics. Unlike radical-based methods (DPPH, ABTS), FRAP focuses on electron-donating capacity, which is a key characteristic of tomato antioxidants.

In this study, a modified version of the FRAP (Ferric Reducing Antioxidant Power) assay was applied, based on the procedure described by [24], which differs from the classical method using the TPTZ (2,4,6-tripyridyl-s-triazine) complex. In this modified methodology, potassium ferricyanide acts as the primary oxidizing agent, supplying Fe³⁺ ions that undergo a redox reaction with antioxidant compounds present in the extract. These antioxidants reduce Fe³⁺ to Fe²⁺, leading to the formation of ferrocyanide.

Upon the addition of ferric chloride, a blue–green coloration develops due to the formation of the Prussian Blue complex. The intensity of the resulting color is directly proportional to the antioxidant power of the sample and is measured spectrophotometrically at 700 nm [1].

A volume of 0.5 mL of the sample at different concentrations (25, 50, and 100 mg/mL) was mixed with 1.25 mL of 0.2 M phosphate buffer solution (pH 6.6) and 1.25 mL of 1% potassium ferricyanide solution. The mixture was incubated in a water bath at 50 °C for 20 min and then cooled to room temperature. Subsequently, 2.5 mL of 10% trichloroacetic acid was added to stop the reaction, followed by centrifugation at 3000 rpm for 10 min. From the resulting supernatant, 1.25 mL was taken and mixed with 1.25 mL of distilled water and 250 µL of freshly prepared 0.1% ferric chloride solution. Absorbance was measured at 700 nm against a blank. Ascorbic acid was used as a positive control, with its absorbance measured under the same experimental conditions as the samples.

An increase in absorbance indicates a higher reducing power of the extracts. The results were expressed as µmol Fe²⁺/100 g dry weight.

This technique is highly valued for its sensitivity and suitability in the analysis of plant extracts, offering a rapid and efficient evaluation of the reducing potential of bioactive compounds. It requires readily available reagents, and the reaction is completed within 30 min. The method is applicable to food, plant materials, and dietary supplements, and it does not involve free radicals, relying solely on a redox reaction.

However, the method also presents certain limitations: it does not detect glutathione or other thiol-based antioxidants, may overestimate antioxidant activity in the presence of free iron ions, and cannot distinguish between enzymatic and non-enzymatic antioxidants [2,3].

The FRAP values were calculated using the formula:

$$\mathrm{F}\mathrm{R}\mathrm{A}\mathrm{P}=\left[{\displaystyle \frac{\left({\mathrm{A}}_{\mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}}-{\mathrm{A}}_{\mathrm{b}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{k}}\right)}{\mathrm{s}}}\right]\times \mathrm{D}\times \left({\displaystyle \raisebox{1ex}{$100$}\!\left/ \!\raisebox{-1ex}{$\mathrm{W}$}\right.}\right)$$

(3)

where FRAP (μmol Fe²⁺/100 g DM); Asample—absorbance of the sample at 593 nm;

Ablank—absorbance of the blank; s—slope of the Fe²⁺ calibration curve (Abs/μmol Fe²⁺); D—dilution factor; W—sample mass (g); DM—dry weight basis.

All determinations were performed in triplicate. Results are presented as mean ± standard deviation, and significance of differences was tested using ANOVA PROGRAMS (Analysis of Variance) with a significance threshold of p < 0.05.

To strengthen the relationship between chemical composition and antioxidant activity, the Pearson correlation coefficient was used:

$$r={\displaystyle \frac{\sum (x_{i -}\overline{x)\left(y_{i-\overline{y}}\right)}}{\sqrt{\sum \left(x_{i- }\overline{x}\right)2}\sum \left(y_{i- }\overline{y}\right)2}}$$

(4)

where

r—Pearson correlation coefficient; $x_i,y_i-$are individual sample points; $\overline{x},\overline{y}$—are the sample means.

Linear Regression Equation

$$\mathrm{y}=\mathrm{a}·\times +\mathrm{b}$$

(5)

where

a = slope, b = intercept.

Sustainability Factor (SF)

$$\mathrm{S}\mathrm{F}=0.4\times {\mathrm{F}\mathrm{R}\mathrm{A}\mathrm{P}}_{\left(\mathrm{n}\right)}+0.4\times {\mathrm{L}\mathrm{y}\mathrm{c}\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{n}\mathrm{e}}_{\left(\mathrm{n}\right)}+0.2\times {\mathrm{D}\mathrm{M}}_{\left(\mathrm{n}\right)}$$

(6)

where

FRAP(n), Lycopene(n), DM(n)-normalized values of FRAP, lycopene content, and dry matter, respectively.

Antioxidant Efficiency Index (AEI) was computed as a weighted average of antioxidant activity (FRAP) and dry matter content (DM%), which serves as an indicator of by-product valorization potential

$$\mathrm{A}\mathrm{E}\mathrm{I}=0.5\times {\displaystyle \frac{{\mathrm{F}\mathrm{R}\mathrm{A}\mathrm{P}}_{\mathrm{i}}}{{\mathrm{F}\mathrm{R}\mathrm{A}\mathrm{P}}_{\mathrm{m}\mathrm{a}\mathrm{x}}}}+0.5\times {\displaystyle \frac{{\mathrm{D}\mathrm{M}}_{\mathrm{i}}}{{\mathrm{D}\mathrm{M}}_{\mathrm{m}\mathrm{a}\mathrm{x}}}}$$

(7)

where

FRAPi—the antioxidant activity (µmol Fe²⁺/100 g) of cultivar i; DMi—the dry matter percentage for cultivar i; FRAPmax and DMmax are the maximum values in the dataset, used for normalization. The weights 0.5 and 0.5 reflect equal importance assigned to antioxidant power and processability, but these can be adjusted depending on the specific application (nutritional vs. technological).

The Integrated Eco-Nutritional Sustainability Index (IENSI) is calculated based on antioxidant activity, lycopene content, and the level of by-product valorization, offering a comparative method to assess the comprehensive benefits provided by each cultivar.

$$\mathrm{I}\mathrm{E}\mathrm{S}\mathrm{N}\mathrm{I}=\mathsf{\alpha }·{\displaystyle \frac{{\mathrm{F}\mathrm{R}\mathrm{A}\mathrm{P}}_{\mathrm{m}\mathrm{a}\mathrm{x}}}{{\mathrm{F}\mathrm{R}\mathrm{A}\mathrm{P}}_{\mathrm{i}}}}+\mathsf{\beta }·{\displaystyle \frac{{\mathrm{L}\mathrm{y}\mathrm{c}\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{n}\mathrm{e}}_{\mathrm{m}\mathrm{a}\mathrm{x}}}{{\mathrm{L}\mathrm{y}\mathrm{c}\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{n}\mathrm{e}}_{\mathrm{i}}}}+\mathsf{\gamma }·{\displaystyle \frac{{\mathrm{D}\mathrm{M}}_{\mathrm{m}\mathrm{a}\mathrm{x}}}{{\mathrm{D}\mathrm{M}}_{\mathrm{i}}}}+\mathsf{\delta }·{\displaystyle \frac{{\mathrm{P}\mathrm{r}\mathrm{o}\mathrm{c}\mathrm{e}\mathrm{s}\mathrm{s}\mathrm{i}\mathrm{n}\mathrm{g}}_{\mathrm{m}\mathrm{a}\mathrm{x}}}{{\mathrm{P}\mathrm{r}\mathrm{o}\mathrm{c}\mathrm{e}\mathrm{s}\mathrm{s}\mathrm{i}\mathrm{n}\mathrm{g}}_{\mathrm{i}}}}$$

(8)

where

FRAP—the antioxidant activity (µmol Fe²⁺/100 g); Lycopene—the lycopene content (mg/100 g); DM—dry matter (%)—a measure of final product yield; Processing—the processability score (1 to 3, where 3 = highest efficiency); α, β, γ, δ are the weighting factors (percentages summing to 100), which can be adjusted according to the intended application focus.

2.5. Determination of Lycopene Content

Research has shown that lycopene exhibits a superior antioxidant capacity compared to other carotenoids such as β-carotene or lutein, and it may even outperform certain simple phenolic antioxidants, particularly in lipophilic systems [25]. A significant correlation has also been demonstrated between lycopene concentration and antioxidant activity as measured by methods including the FRAP (Ferric Reducing Antioxidant Power) assay, suggesting that lycopene is one of the main contributors to the antioxidant capacity of tomatoes and their derived products [7].

Moreover, in the case of tomato powder, the antioxidant effect appears to be enhanced due to the high concentration of active compounds per gram of dehydrated product. Therefore, lycopene, together with other carotenoids and phenolic compounds, contributes synergistically to the overall antioxidant potential, explaining the high FRAP values observed in this study. These findings support the concept that, in addition to its nutritional benefits, lycopene plays a key role in the effectiveness of tomato powder as an ingredient for healthy food products, cosmetics, or sustainable agricultural applications.

This technique is highly valued for its simplicity and speed, delivering accurate results without requiring sophisticated equipment. Therefore, it is particularly suitable for comparative analyses of lycopene content across different tomato samples or related products.

Lycopene content in tomato powder was determined spectrophotometrically following a modified method of Fish [18]. Briefly, 1 g of dry tomato powder was mixed with 10 mL of hexane: acetone: ethanol (2:1:1, v/v/v), vortexed for 1 min, and incubated in the dark for 30 min at room temperature. The mixture was centrifuged at 5000 rpm for 10 min, and the supernatant was collected. Absorbance was measured at 505 nm using a UV–Vis spectrophotometer with a 1 cm path-length cuvette.

Lycopene concentration was calculated using the Beer–Lambert law:

$${\mathrm{C}}_{\mathrm{l}\mathrm{y}\mathrm{c}}\left({\displaystyle \frac{\mathrm{m}\mathrm{g}}{\mathrm{L}}}\right)={\displaystyle \raisebox{1ex}{${\mathrm{A}}_{505}$}\!\left/ \!\raisebox{-1ex}{$\left({\mathsf{\epsilon }}_{505}·\mathrm{l}\right)$}\right.}$$

(9)

where ${\mathrm{C}}_{\mathrm{l}\mathrm{y}\mathrm{c}}$ (mg/L) is the lycopene concentration, ${\mathrm{A}}_{505}$ is the absorbance, ${\mathsf{\epsilon }}_{505}$ = 17.2 × 10³ L$·$mol⁻¹$·$cm⁻¹, and l = 1 cm. Lycopene content in the powder was expressed as mg per 100 g dry weight (DW):

$$\mathrm{L}\mathrm{y}\mathrm{c}\mathrm{o}\mathrm{p}\mathrm{e}\mathrm{n}\mathrm{e}\left({\displaystyle \frac{\mathrm{m}\mathrm{g}}{100\mathrm{g}}}\mathrm{D}\mathrm{W}\right)=\left[{\mathrm{C}}_{\mathrm{l}\mathrm{y}\mathrm{c}}·\mathrm{V}·10000\right]/\mathrm{m}$$

(10)

where Lycopene (mg/100 g DW)—lycopene content expressed per 100 g of dry weight; ${\mathrm{C}}_{\mathrm{l}\mathrm{y}\mathrm{c}}$—lycopene concentration determined spectrophotometrically (mg/mL); V—volume of the extract (mL); m—mass of the dried tomato sample (mg); 10,000—conversion factor to express the result in mg/100 g DW.

All measurements were performed in triplicate and presented as mean ± SD [2,3].

3. Results

3.1. Determination of Moisture Content (H%) and Dry Matter Content (DM%)

According to the obtained results, the Hera variety stands out with the lowest moisture content (91.99%) while exhibiting the highest dry matter content (8.01%). This makes it ideal for processing (puree, paste, dehydration) due to its lower water content and valuable dry matter components (sugars, acids, antioxidants). The Andrada variety contains the highest moisture level (94.23%) but the lowest dry matter (5.77%), which may result in a juicier texture but makes it less suitable for industrial processing due to dilution. The Kristinica variety holds an intermediate position, with a good balance between moisture and dry matter, making it suitable both for fresh consumption and some forms of processing (

Table 1. Physical and chemical characterization of different tomato fruit samples.

Tomato Varieties	Moisture (%)	Dry Matter (%)
Kristinica	93.71	6.29
Andrada	94.23	5.77
Hera	91.99	8.01

Values expressed as the arithmetic mean obtained from five measurements per tomato cultivar.

).

3.2. Lycopene Determination

Lycopene concentration was determined using a spectrophotometric method, employing a solvent mixture composed of hexane, ethanol, and acetone (2:1:1). Absorbance measurements were taken at wavelengths of 453, 505, and 645 nm, and lycopene content was expressed in mg per 100 g of powder.

Spectrophotometric analysis revealed notable differences among the three varieties. Hera and Andrada exhibited the highest lycopene contents (81.4 ± 1.1 mg/100 g and 81.4 ± 1.2 mg/100 g, respectively), followed by Kristinica (73.4 ± 1.3 mg/100 g), supporting the correlation between the concentration of this compound and the antioxidant capacity measured by the FRAP assay (Figure 1).

The results highlight the differences in absorbance intensity, indicating the presence and variation of carotenoids and chlorophyll pigments among cultivars.

Spectrophotometric analysis revealed cultivar-dependent differences in antioxidant activity. Positive absorbance values at 470 nm and 663 nm indicated the major contribution of carotenoids and porphyrinic pigments, respectively. Conversely, at 645 nm, Kristinica and Andrada showed negative values, suggesting negligible levels of chlorophyll b-related antioxidants or pigment degradation. Consequently, their antioxidant activity is predominantly associated with carotenoids and other compounds. This trend was consistent with the FRAP assay, which confirmed that the antioxidant potential of these cultivars is mainly driven by non-chlorophyll antioxidants.

3.3. Antioxidant Activity Determined by FRAP Assay

The results indicated significant differences among the three analyzed varieties. A consistent increase in antioxidant activity was observed with increasing extract concentration (25, 50, and 100 mg/mL). At 25 mg/mL, the FRAP values were 112.5 ± 3.2 µmol Fe²⁺/100 g for Kristinica, 126.8 ± 2.9 µmol Fe²⁺/100 g for Hera, and 135.2 ± 3.1 µmol Fe²⁺/100 g for Andrada. At the concentration of 50 mg/mL, values rose to 158.7 ± 4.0 µmol Fe²⁺/100 g, 176.4 ± 4.1 µmol Fe²⁺/100 g, and 189.2 ± 4.0 µmol Fe²⁺/100 g for Kristinica, Hera, and Andrada, respectively.

At 100 mg/mL, these values increased significantly to 212.8 ± 5.1 µmol Fe²⁺/100 g, 235.6 ± 4.9 µmol Fe²⁺/100 g, and 248.1 ± 5.3 µmol Fe²⁺/100 g, respectively. Ascorbic acid, used as a positive control, recorded a value of 260.0 ± 4.5 µmol Fe²⁺/100 g, very close to those obtained for the studied varieties, highlighting the high potential of these powders as natural sources of antioxidants (Figure 2).

The results indicate a concentration-dependent increase in reducing power, with Andrada showing the highest activity, followed by Hera and Kristinica. Error bars represent the standard deviations of triplicate measurements.

FRAP assay results indicated a linear response up to 100 mg/mL, with no plateau in sight. Literature on tomato extracts shows FRAP responses up to ~6.7 mM Fe (II) Eq./kg FW without saturation [26]. Consequently, higher concentrations (150–200 mg/mL) will be tested to confirm assay linearity and exclude inner-filter effects. This behavior parallels findings in date palm fruit extracts, which also exhibited maximal FRAP response at approximately 100 mg/mL before declining at higher concentrations, suggesting potential matrix limitations or saturation effects [27]. To further validate the assay’s linearity and mitigate any possible inner-filter interference, forthcoming experiments will extend the range to 150–200 mg/mL.

The value of the Pearson correlation coefficient calculated with the relationship between chemical composition and antioxidant activity (Equation (4)) is r = 0.95, for p < 0.05, indicating a strong positive correlation between lycopene content and FRAP values for the three varieties studied.

Compared to the literature, these results align closely with previously reported average values for similar products. For example, Silva [5] reported a FRAP value of approximately 215 µmol Fe²⁺/100 g for tomato powders dried by conventional methods, while García-Salinas [2] reported values ranging from 173 µmol Fe²⁺/100 g to 286 µmol Fe²⁺/100 g depending on the drying method used. Even in studies using freeze-dried tomatoes, known for efficiently preserving bioactive compounds, values rarely exceed 300 µmol Fe²⁺/100 g [28].

The values obtained in this study suggest that the drying techniques used, together with the choice of varieties and harvest timing, contributed to obtaining powders with antioxidant activity comparable to that of ascorbic acid, a reference antioxidant. Furthermore, the Andrada variety excelled by exhibiting the highest antioxidant activity among the analyzed cultivars, similar to values reported by [7] for industrially processed tomatoes (≈41.1 µmol TE/g), TE = Trolox Equivalent—Trolox is a synthetic antioxidant, derived from vitamin E, used as a reference standard in antioxidant assays. These variations can be associated not only with the drying method but also with the initially higher carotenoid and polyphenol contents of the local varieties investigated. Additionally, the harvest time, ripening level, and minimal processing most likely contributed to the ideal preservation of antioxidants.

These findings not only attest to the significant nutritional value of tomato powder but also indicate its potential functional use as a natural antioxidant ingredient in processed foods, supplements, or sustainable horticultural products.

This confirms the potential of tomato powder as a functional ingredient suitable for applications in the food industry, pharmaceuticals, or in the development of natural antioxidant supplements.

4. Discussion

A significant linear relationship was identified between lycopene content and FRAP values (r² ≈ 0.91), which supports the use of lycopene as a direct predictor of the antioxidant activity of tomato powders. The resulting linear regression model is expressed as the Sustainability Factor (SF).

This relationship allows for the rapid estimation of antioxidant potential based on lycopene concentration, serving as a practical tool for selecting crops for both the production of health-promoting products and various industrial applications.

To provide an integrated assessment of nutritional value and processing yield, a Sustainability Factor (SF) was calculated as a weighted average of antioxidant activity (FRAP)—40%, lycopene content—40%, and dry matter content—20%. The calculated values were as follows: Hera—0.980, Andrada—0.944, and Kristinica—0.860. These results support the selection of the variety Hera as the optimal candidate for sustainable and functional applications in horticulture and food systems (Figure 3).

The total score obtained highlights Hera as the optimal for processing (total score: 0.963), due to its balanced combination of high dry matter content, elevated lycopene levels, strong antioxidant activity, and enhanced processability. Although Andrada exhibited the highest FRAP value, it was limited by its lower dry matter content and moderate processability, while Kristinica recorded the lowest overall score (

Table 2. Decision matrix for selecting the optimal tomato cultivar for processing.

Tomato Varieties	Dry Matter (DM%)	Lycopene (mg/100 g)	FRAP (µmol Fe2+/100 g)	Processing Ease (Score 1–3)	Total Score
Andrada	5.77	81.4	248.1	2	0.902
Hera	8.01	81.4	235.6	3	0.963
Kristinica	6.29	73.4	212.8	2	0.849

).

To further evaluate the performance of each tomato variety, two indicators were calculated: The Antioxidant Efficiency Index (AEI), which serves as an indicator of the potential for product valorization. AEI is a composite score that simultaneously reflects the nutritional/functional potential of the powder (via FRAP) and the efficiency of by-product valorization (via dry matter content).

The Integrated Eco-Nutritional Sustainability Index (IENSI) is an indicator through which a comparison can be made to evaluate the full benefits offered by each variety.

The results indicate that Hera had the highest AEI value (0.975), suggesting an optimal balance between antioxidant activity and processing yield. This was followed by Andrada (AEI = 0.860) and Kristinica (AEI = 0.821).

Among the analyzed cultivars, Hera recorded the highest IENSI value (0.983), demonstrating an optimal balance between nutritional benefits and ecological processing efficiency. This was followed by Andrada (0.926) and Kristinica (0.847). The IENSI provides a valuable metric for prioritizing tomato cultivars in functional, economic, and sustainability-driven applications.

These results demonstrate a clear positive correlation between lycopene content and antioxidant capacity measured by the FRAP method. As shown in Figure 2, varieties with higher lycopene content, such as Andrada (81.4 ± 1.2 mg/100 g), also exhibited the highest FRAP values (248.1 µmol Fe²⁺/100 g dry weight), suggesting an essential role of this carotenoid in scavenging reactive oxygen species. The elevated antioxidant activity identified in tomato powder, particularly from the Kristinica variety, aligns with literature highlighting the role of lycopene and flavonoids in antioxidant processes [22].

The dose-dependent response observed in this study supports the potential to optimize the use of tomato powder according to concentration.

From an applicability perspective, these results create concrete opportunities for the sustainable use of degraded tomato pulp. Within the transition towards circular agriculture and the global efforts to minimize food waste, incorporating tomato powder as a functional additive in processed foods or as an ingredient in dietary supplement formulations represents an effective, cost-efficient, and sustainable strategy.

Moreover, tomato powder can be incorporated into horticultural treatment formulations designed to enhance the antioxidant capacity of plants, thereby contributing to the mitigation of oxidative stress induced by adverse environmental conditions such as drought, UV radiation, or atmospheric pollutants [16,28,29].

To support the optimal selection of tomato cultivars for industrial processing, a multicriteria evaluation matrix was developed, based on weighted scores for dry matter content, lycopene concentration, and antioxidant activity.

Andrada obtained the highest overall score, highlighting its potential for use in functional foods or fortified nutritional products. (

Table 3. Multicriteria evaluation matrix for selecting the optimal tomato cultivar for industrial processing.

Cultivar	Dry Matter (DM%)	Lycopene (mg/100 g)	FRAP (µmol Fe2+/100 g)	Weighted Score	Functional Suitability
Andrada	5.77	81.4	248.1	0.944	Very High
Hera	8.01	81.4	235.6	0.980	Excellent (Optimal)
Kristinica	6.29	73.4	212.8	0.860	Moderate

).

Hera is identified as the overall optimal cultivar, whereas Andrada, with the highest FRAP value, is especially suited for antioxidant-targeted applications.

5. Conclusions

Tomato powders obtained from whole tomatoes of the Andrada, Hera, and Kristinica cultivars exhibit remarkable antioxidant activity, with results proportional to the applied dose. Kristinica demonstrated the highest antioxidant capacity and lycopene content, approaching the efficacy of ascorbic acid. These observations highlight the potential of these products to be used as natural, functional, and sustainable ingredients, with significant applications in horticulture and nutrition.

Their efficient utilization could contribute to reducing losses in the agri-food chain and to the development of sustainable agricultural solutions. Given their high antioxidant potential and the stability of active compounds in powdered form, an emerging approach is their integration into natural dermo-cosmetic products—such as antioxidant creams, anti-aging serums, or tomato-extract-based facial masks—in line with current clean beauty trends.

The present study demonstrated that tomato powder retains significant antioxidant potential, as confirmed by FRAP analysis, highlighting its richness in lycopene and associated bioactive compounds. These findings support its role as a functional ingredient capable of enhancing the nutritional and antioxidant profile of food products. Moreover, the use of tomato powder represents an efficient strategy for valorizing tomato processing by-products, thereby reducing waste and contributing to sustainable food chain practices. Taken together, the results emphasize that tomato powder is not only a stable and microbiologically safe alternative to conventional tomato derivatives but also a valuable source of natural antioxidants with promising applications in both dietary supplements and clean-label food formulations.