Upcycling of Sunflower and Sesame Press Cakes as Functional Ingredients in Cookies

Abstract

The aim of the study was to evaluate the use of sunflower and sesame oilseed press cakes, which are by-products of oil extraction, as functional ingredients in cookie production. The quality characteristics of these by-products were assessed, including water activity, pH, total phenolic content, and antioxidant activity, and HPLC analysis of the phenolic compounds was performed. Subsequently, cookies were prepared by replacing wheat flour with 30% or 50% press cake. The addition of sunflower press cake significantly increased the total phenolic content (up to 8.6 mg GAE/g dm) and antioxidant activity (up to 75.9%) in the cookies, whereas adding sesame press cake showed a less pronounced effect, reaching 0.91 g GAE/g dm and 8.9% for total phenolic content and antioxidant activity, respectively. HPLC analysis indicated that chlorogenic acid and its derivatives dominated in sunflower-enriched cookies, while sesame samples contained lignans such as sesamol and sesamin. Our study shows that 50% substitution improves the health-promoting properties of cookies and does not differ significantly from the 30% level in consumer sensory evaluations. These findings support the use of sunflower and sesame press cakes as valuable ingredients in food applications. This represents an important step toward developing healthier and more nutritious food products while supporting the principles of the circular economy through the upcycling of valuable raw materials.

1. Introduction

The practical implementation of sustainable development principles is currently essential and requires a comprehensive approach to human–environment interactions. Ensuring sustainable consumption and production patterns is a key objective of the European Sustainable Development Goals. Initiatives focusing on resource efficiency and the circular economy aim to decouple economic growth from resource exploitation and environmental degradation [1,2]. There is growing interest in, and an increasing need for, a transition towards a circular economy and the promotion of healthier, more sustainable diets. One approach to achieving this aim is through the development of upcycled foods, which incorporate by-products from the food industry into new formulations [3,4].

Despite growing awareness of the relationship between diet and health, food-related diseases are continuing to rise in prevalence in Western societies. Significant effort is currently directed towards enriching food products with health-promoting and innovative ingredients [5,6]. Polyphenols are widely recognized as beneficial dietary components because of their antioxidative properties. Oxidative stress and chronic inflammation are increasingly acknowledged as major contributors to the development and progression of various pathological conditions, including atherosclerosis, obesity, diabetes, neurodegenerative diseases, and cancer. Epidemiological studies and associated meta-analyses consistently indicate that the long-term consumption of polyphenol-rich plant products provides protection against the development of these diseases. The consumption of foods rich in dietary antioxidants and anti-inflammatory compounds is increasingly considered a crucial strategy for mitigating oxidative stress and inflammation [7,8,9,10,11,12].

The concept of functional foods promotes the use of nutritionally valuable by-products as sources of bioactive compounds with antioxidant potential. According to the definition provided by Functional Food Science in Europe, a functional food is “a food that beneficially affects one or more target functions in the body beyond adequate nutritional effects in a way that is relevant to either an improved state of health and well-being and/or reduction of risk of disease. It is consumed as part of a normal food pattern. It is not a pill, a capsule or any form of dietary supplement” [13]. The enrichment of food products with oil press cakes, as sources of antioxidant compounds, exemplifies this concept.

Oilseed press cakes are by-products obtained after oil extraction from seeds. While they are primarily used as animal feed, their nutrient profile makes them suitable for the development of value-added products in the human diet. The oil extraction process, particularly cold pressing, preserves many of the beneficial properties of the raw material [14]. This preservation enables the subsequent use of these by-products in the formulation of functional foods. Sunflower and sesame cakes have attracted considerable interest because of their diverse nutritional composition, bioactive components, and potential health benefits. They serve as cost-effective sources of bioactive compounds, including flavonoids, phenolic acids, tocopherols, lignans, notably proteins, and dietary fibre, and also contain residual fat. Due to their high protein content and non-toxic nature, oilseed press cakes hold significant potential as ingredients for human nutrition [15,16,17,18,19,20].

The global production of sesame and sunflower seeds is estimated to total 6.8 and 58.6 million tonnes, respectively. The leading producers of sunflower seeds are Ukraine and Russia, while Sudan and India dominate the sesame seed market. In 2022, the production of sesame cakes was 1.1 million tonnes, whereas that of sunflower cakes reached 20.9 million tonnes. It is estimated that over 90% of sunflower and sesame cakes are utilized for animal feed [21]. From both an economic and a health perspective, there appears to be a compelling rationale for increasing the utilization of sesame and sunflower press cakes in food production.

Cookies are popular snacks but typically contain low-quality ingredients, including sugar and saturated fats. They exhibit a high glycemic response, high energy density, and low satiating potential [22,23]. Increasing consumer demand for nutritious and high-quality foods has driven research into new ingredients for bakery products [5,6,24,25].

We found some studies in which sesame and defatted sunflower seeds were added into products. Defatted flours or press cakes derived from sesame and sunflower seeds have been incorporated into various food products to improve their nutritional value and technological properties. One of the investigated applications was pasta: Al-Khamaiseh and Saleh [26] incorporated powdered sesame press cake into semolina at levels of 5%, 7.5%, 10%, 12.5%, and 15% for pasta production. In the case of cookies, sesame hull flour was tested at substitution levels of up to 50%; however, sensory results indicated that cookies supplemented with sesame peel flour were acceptable only at incorporation levels not exceeding 30% [27]. Similar substitution levels of defatted sesame flour were examined by Prakash et al. [25]. Bread has also been explored as a potential vehicle for such enrichment. Nouska et al. [28] incorporated sesame press cake into wheat flour-based bread formulations at substitution levels of 6%, 12%, and 20% (relative to the flour content). Blicharz-Kania et al. [29] fortified gluten-free bread with sunflower press cake at 5%, 10%, and 15% of the total rice flour content. Grasso et al. [24] developed cookies in which 18% and 36% of wheat flour were replaced with defatted sunflower flour. In another study, Grasso et al. [30] examined the incorporation of defatted sunflower flour into muffins at levels of 15% and 30%. Sunflower and sesame seed press cakes, which are by-products of the oil extraction industry, have been used less frequently and typically at substitution levels not exceeding 30%.

Therefore, we tested the hypothesis that it is possible to produce consumer-acceptable cookies with the addition of 30% and 50% sunflower and sesame press cakes (by-products of the oil extraction industry), which could open up new opportunities in terms of sustainability. We also aimed to characterize and potentially enhance the health-promoting properties of such cookies enriched with oilseed by-products. Finally, we sought to compare whether either of these additions had an important effect on the sensory acceptance of the final products, and whether one of them more significantly improved their pro-health characteristics. Accordingly, the aim of this study was to investigate the enrichment of cookies with sesame or sunflower cakes.

2. Materials and Methods

2.1. Materials

Sesame (Sesamum indicum) and sunflower (Helianthus annuus) cakes (SES and SUN, respectively), by-products of cold-pressed oil production, were obtained directly from a company producing cold-pressed oils (Vitacorn, Poznań, Poland). The obtained press cakes were ground using a WZ-1S electric grinder (Sadkiewicz Instruments, Bydgoszcz, Poland). The grinding process lasted 10 s and was repeated four times for all press cakes until a powder with a uniform structure was obtained, with a final particle size below 0.4 mm. The moisture content of the sunflower press cakes was 8.0%, while that of the sesame press cakes was 4.9%. Moisture content in oilseed press cakes and baked cookies was determined in accordance with the PN-EN ISO 665:2004 standard [31] using the oven-drying gravimetric method. For each sample, 1.5 g was accurately weighed (to the nearest 0.001 g) into pre-dried and weighed glass moisture dishes. The samples were placed in a laboratory drying oven (Memmert, Schwabach Germany) and dried for 1.5 h at 105 °C. After drying, the dishes were transferred to a desiccator and left to cool for approximately 30 min.

Wheat flour Poznańska - ash content 0.5% (Młyn Wągrowiec, Wągrowiec, Poland), powdered sugar Diamant (Pfeifer & Langen Poland, Poznań, Poland), shortening Palma (Bielmar, Bielsko-Biała, Poland), sodium chloride (Kopalnia Soli Kłodawa, Kłodawa, Poland) and sodium bicarbonate (Delecta, Warsaw, Poland) were acquired from commercial outlets within the locality.

2,2-diphenyl-1-picrylhydrazyl (DPPH), Folin–Ciocalteu reagent, gallic acid, and phenolic acid standards were obtained from Sigma (Sigma Chemical Co., St. Louis, MO, USA). Acetonitrile, methanol, and ethanol (HPLC purity) were obtained from POCh (Gliwice, Poland). Water was purified with the Milli-Q-system (Millipore, Bedford, MA, USA).

2.2. Methods

2.2.1. Preparation of Cookies

The cookie dough was prepared using a Zelmer food processor. The base formula of cookies was as follows: 480 g (48.5%) of fine wheat flour, 204 g (20.6%) of powdered sugar, 192 g (19.4%) of shortening, 6 g (0.6%) of sodium chloride, 2.4 g (0.2%) of sodium bicarbonate, and 105.6 mL (10.7%) of water (sample C).

Wheat flour was replaced with sunflower or sesame cakes to a level of 30% (Sample SUN30 and SES30, respectively) and 50% (SUN50 and SES50, respectively) in the cookie recipe. Powdered sugar, salt, sodium bicarbonate, and margarine were combined and mixed for 3 min using a stand mixer. Ammonium bicarbonate was dissolved in water and added to the mixture, followed by an additional 1 min of mixing. In a separate bowl, wheat flour and press cakes were pre-mixed to ensure a uniform colour. The powder was then added to the wet ingredients and mixed for 1–2 min until a uniform, cohesive dough was obtained and chilled in a refrigerator for 5–10 min. The dough was kneaded and rolled to a uniform thickness of 2 mm, then cut into 50 mm diameter circular shapes. The baking process occurred at 190 °C in an electric oven for 5 min. After baking, the cookies were cooled at room temperature, packed in polypropylene bags, and sealed and stored at 20 °C for further analysis.

2.2.2. Sample Preparation

Cake and cookies samples were ground using a laboratory grinder (particle size below 0.4 mm) (WZ-1, ZBPP, Bydgoszcz, Poland) and defatted twice by adding n-hexane to the sample at a 5:1 ratio. The mixture was shaken using a magnetic stirrer for 1 h 45 min, placed in an ultrasonic bath for 15 min, and then centrifuged at 500× g for 10 min (MPW-223e centrifuge, MPW, Warsaw, Poland). After a second lipid extraction and separation of the supernatant, the samples were left to allow complete evaporation of the solvent for 12 h at room temperature under the fume cupboard

2.2.3. Preparation of Press Cake and Cookies Extracts

A total of 2.5 g of defatted material was suspended in 80% ethanol (v/v), stirred for 2.5 h at room temperature, and centrifuged at 1780× g for 10 min. The supernatant was transferred to a 25 mL volumetric flask and brought to volume with deionized water.

2.2.4. Antioxidant Activity Assessment—DPPH Test

The antioxidative activity of extracts was measured using the DPPH radical scavenging method as described by Sánchez-Moreno et al. [32]. A volume of 0.1 mL of extract (Section 2.2.3) was added to 2.4 mL of the DPPH solution. The decrease in absorbance was determined spectrophotometrically at 515 nm after 30 min of incubation in the dark. For each type of extract, a reference sample was also prepared by replacing the extract with 0.1 mL of 80% ethanol. The DPPH radical reduction was calculated as the inhibition percentage. All absorbance measurements were performed using a UV–VIS spectrophotometer (Metertech SP-8001, Metertech Inc., Taipei, Taiwan).

2.2.5. Determination of Phenols

The total phenolic content was measured using the Folin–Ciocalteu spectrophotometric method [33]. A volume of 0.1 mL of the extract (Section 2.2.3) was mixed with 5 mL of distilled water and 0.5 mL of Folin–Ciocalteu reagent. The mixture was mixed and kept in the dark for 3 min, after which 1.5 mL of a 20% aqueous sodium bicarbonate solution and 2.9 mL of distilled water were added. The samples were incubated in the dark for 2 h, and the absorbance was then measured spectrophotometrically at 725 nm (Metertech SP-8001, Metertech Inc., Taipei, Taiwan). A reference sample was prepared by replacing the extract with 0.1 mL of 80% ethanol. Gallic acid was used as the standard for the calibration curve. Standard solutions of gallic acid were prepared at concentrations ranging from 0.1 to 0.7 mg/mL in 80% ethanol. From each standard solution, 0.1 mL was taken and subjected to the same analytical procedure as the test samples.

2.2.6. HPLC Analysis of Phenolic Compounds

Phenolic compound separation was carried out using an Agilent 1200 Rapid Resolution HPLC system (Agilent Technologies, Palo Alto, CA, USA) equipped with a Zorbax SBC-18 column (5 µm, 4.6 mm × 150 mm). The chromatographic conditions were as follows: injection volume, 20 μL; flow rate, 1.0 mL/min. Solvent A consisted of 6% acetic acid in 2 mM sodium acetate (v/v), and solvent B was acetonitrile. A linear gradient elution was applied as follows: 0–15 min, 0–5% B; 15–25 min, 5–20% B; 25–30 min, 20–30% B; 30–35 min, 30–50% B; 35–40 min, 100% B. For compound identification, the scan mode was employed in the 200–700 nm range. Quantification was performed using external calibration with gallic acid as the standard for compounds detected at 280 nm and chlorogenic acid for those detected at 320 nm. Identification was based on spectral characteristics and retention times, compared with available standards and literature data.

2.2.7. Colour Measurement

The colour of the cookies was assessed using a Konica Minolta CM-3600d spectrophotometer (Konica Minolta Holdings Inc., Tokyo, Japan). The results were expressed as CIE L*, a*, and b* colour system coordinates. Measurements were conducted with a D65 illuminant, a 25.4 mm diameter measurement hole, 10° standard observers, and an SCE (Spectral Component Excluded) measurement model. The data represent the average of twenty-one measurements taken at different locations on the different cookies. The colour difference between the samples was calculated according to Equation (1):

$$\mathsf{\Delta }E=\sqrt{{\left(L_1-L_2\right)}^2+{\left(a_1-a_2\right)}^2+{\left(b_1-b_2\right)}^2}$$

(1)

where L₁, a₁, and b₁ denote the mean colour parameters measured for the control cookies (without press cake addition), while L₂, a₂, and b₂ correspond to the respective values for the cookies with press cake addition.

2.2.8. Determination of Water Activity

The determination of water activity was conducted at a temperature of 20 °C, using a Novasina ms1 aw (Novasina, Lachen, Switzerland). Prior to measurement, the sample was subjected to homogenization in a mortar, followed by stabilization for a minimum period of 24 h. The sample was then placed into vessels and placed inside the measuring chamber. The result was read after the values had stabilized. The aw values represent arithmetic averages derived from a minimum of three independent determinations.

2.2.9. Determination of pH

The determination of the pH of the cookies was conducted via the utilization of an Elmetron pH meter (Elmetron, Zabrze, Poland). The device had been calibrated using a pH 7.0 and pH 4.0 buffer by Elmetron. Five grams of the crushed sample was mixed with distilled water and left to stabilize for 20 min. The measurement was performed in three repetitions, and the pH meter enabled automatic temperature compensation.

2.2.10. Consumer Hedonic Test of Cookies

The consumer sensory testing was conducted by 33 untrained consumers (18 women and 15 men) aged 18 to 34 in isolated cabins with the same lighting and temperature conditions. The degree of liking the cookies’ colour, aroma, taste, texture, and overall acceptance was assessed on a 9-point hedonic scale, ranging from 1 = “extremely dislike” to 9 = “extremely like”. Participants were instructed to record the code of the tested sample at the corresponding point on the scale.

No ethical approval was required for this study, and it was conducted in accordance with the 1975 Helsinki Declaration, revised in 2013. Participants were informed about the study’s aim and that participation was voluntary. They were informed about the list of ingredients prior to participation. Participants could withdraw from the study at any time without any consequences. They could stop the analysis at any point, and all responses were anonymous. The authors did not request any sensitive data or personal information. Formal dependence was not used to recruit subjects for the study. All subjects gave written informed consent to participate in the analysis.

2.2.11. Sensory Panel Evaluation

Qualitative descriptive analysis (QDA) was used as a suitable method [34]. The sensory panel members (8 person) were chosen based on their ability to discriminate between samples during the sensory acuity screening. The descriptors were selected based on the literature and the recommendations of the expert from the Department of Food Quality and Safety, Institute of Quality Science, Poznań University of Economics and Business. The sensory attributes were as follows: for aroma—sweet, buttery, nutty, sunflower, sesame, fatty, and other; for taste—sweet, bitter, nutty, sunflower, and sesame; and for texture—crumbliness. Moreover, the overall quality of each cookie was assessed. The order of the sample presentation was randomized. Nonstructured line scales measuring 10 cm with labelled ends (“not detectable”–“strongly detectable”, “low”–“high”) were applied [34,35].

2.2.12. Statistical Analysis

All experiments were performed in triplicate. Statistical analysis was carried out using Microsoft Excel 2003 (Microsoft Corporation, Redmond, WA, USA) and Statistica 12 StatSoft (StatSoft, Inc., Tulsa, OK, USA) software. Tukey’s multiple means comparison test was applied to verify differences between the samples. The criterion of significance was α < 0.05. Pearson correlation coefficients (ToolPak of EXCEL-Microsoft Corporation, Redmond, WA, USA) were used for the correlation studies and their significance was evaluated.

3. Results and Discussion

3.1. Polyphenol Composition, Radical Scavenging Capacity, and Water Activity of Press Cakes

The total polyphenol content measured in the raw materials used in our study was 1.17 mg GAE/g dm for sesame press cakes and 24.59 mg GAE/g dm for sunflower press cakes (

Table 1. Total phenolic content (TPC), antioxidant activity, and water activity of sesame and sunflower press cakes.

Sample	TPC mg GAE/g dm	DPPH % Inhibited	apw
SES	1.17 ± 0.09 a	16.6 ± 1.9 a	0.257 ± 0.003 a
SUN	24.59 ± 0.41 b	87.4 ± 1.0 b	0.447 ± 0.009 a

Averages marked with different letters in the same column differ significantly (p < 0.05, Tukey test). Values are the mean ± standard deviation of three replicates.

). Other researchers have reported total polyphenol contents in sesame press cakes at 5.98 mg/g [36] and, in a review by Sahin and Elhussein [20], values ranging from 0.82 to 22.8 mg GAE/g, indicating the influence of cultivar and extraction method on phenolic yield.

For sunflower press cakes, Grasso et al. [24] reported a total polyphenol content of approximately 16.5 mg GAE/g dm. In the same study, the antioxidant activity of defatted sunflower seed flour measured by the DPPH assay yielded approximately 3.2 mg Trolox equivalents per gram, which cannot be directly compared with our results because of differences in reporting units. However, Karamać et al. [17] demonstrated that a sunflower seed extract inactivated over 90% of the DPPH radical, a finding that aligns with our results. Sesame press cakes’ antiradical activity has also been described using the DPPH assay, with antioxidant activity values, depending on the type, ranging from 70.17 to 46.78 Trolox equivalents per 100 g of dry mass [28]. The water activity values for both types of press cake (0.257 for sesame and 0.447 for sunflower) are relatively low, which is beneficial in terms of their stability during storage and their subsequent application in food products.

3.2. Properties of Cookies

3.2.1. Total Phenolic Content (TPC), Antioxidant Activity, pH and Water Activity of Cookies

The addition of both types of press cake had a statistically significant effect on increasing the total polyphenol content in comparison with the control cookies (C) (

Table 2. Total phenolic content (TPC), antioxidant activity, pH, and water activity of cookies.

Sample	TP mg GAE/g dm	DPP % Inhibited	pH	apw
C	0.69 ± 0.01 e	1.92 ± 0.74 d	7.81 ± 0.03 a	0.267 ± 0.006 a
SES30	0.80 ± 0.06 d	6.82 ± 2.05 c	7.59 ± 0.09 b	0.240 ± 0.004 b
SES50	0.91 ± 0.06 c	8.85 ± 1.36 c	7.87 ± 0.05 a	0.173 ± 0.003 d
SUN30	5.60 ± 0.21 b	66.75 ± 3.51 b	7.49 ± 0.11 c	0.173 ± 0.001 d
SUN50	8.60 ± 0.18 a	75.91 ± 1.71 a	7.30 ± 0.10 d	0.184 ± 0.002 c

Averages marked with different letters in the same column differ significantly (p < 0.05, Tukey test). Values are the mean ± standard deviation of three replicates.

). Control samples (0.69 mg GAE/g dm) showed the lowest phenolic compound level, while cookies with 50% sunflower cake had the highest (8.6 mg GAE/g dm). The polyphenol content increased with the proportion of cake added. In cookies enriched with sesame press cake, the polyphenol content reached 0.80 mg GAE/g dm and 0.91 mg GAE/g dm for 30% and 50% addition levels, respectively. Cookies supplemented with sunflower cake exhibited markedly higher values, 5.6 mg GAE/g dm and 8.6 mg GAE/g dm, respectively.

These findings indicate that sunflower press cakes are a significantly richer source of phenolic compounds compared to sesame press cakes. The antioxidant activity, measured by means of the DPPH radical scavenging method, followed the same trend as the total polyphenol content. The lowest radical scavenging capacity was observed for extracts from cookies without any press cake addition, while the highest activity was found in the cookies with 50% sunflower press cake. A substantial increase in antioxidant activity was already evident at a 30% inclusion level of sunflower press cake.

For the sesame-enriched samples, the DPPH scavenging capacity was 6.82% and 8.85% for the 30% and 50% inclusion levels, respectively. Although this represented a statistically significant increase compared to the control, the values were markedly lower than those observed for sunflower-enriched cookies.

A strong and statistically significant positive correlation (r = 0.96) was observed between total polyphenol content and antioxidant activity. This shows that phenolic compounds present in the press cakes are primarily responsible for the antioxidant properties of the cookies. The increase in both parameters with the rising proportion of press cake suggests the potential of these byproducts to be used as functional ingredients in bakery products.

These results are consistent with findings reported by other authors. For example, Blicharz-Kania et al. [29] reported that gluten-free bread enriched with 15% sunflower seed press cake contained 2.22 mg GAE/g dm of total polyphenols, which is comparable to the levels observed in our study, considering the scale of enrichment. Grasso et al. [24] described a total polyphenol content of 6.42 mg GAE/g dm in cookies enriched with 36% sunflower press cake, a similar level observed in our study for cookies with 30% sunflower press cake added.

In bread fortified with 20% low-fat sesame press cake, Nouska et al. [28] reported a total polyphenol content of 0.44 mg/g dm, which is lower than the values observed in our study (Table 2). This difference may stem from variability in the polyphenol content of sesame as well as effect of differences in culinary treatment. In cookies without any cake addition, polyphenol contents of 0.14 mg/g dm and 0.74 mg/g dm were reported by Sady & Sielicka [37] and Grasso et al. [24], respectively. The value observed in our study was 0.69 mg/g dm. These discrepancies may result from differences in the base cookie recipe and possibly from the composition of the core ingredients used in different studies.

Regarding antioxidant capacity, Grasso et al. [24] reported a DPPH value of 247 mg Trolox equivalents/100 g for cookies enriched with 36% sunflower cake, compared to 29 mg Trolox equivalents/100 g in the cookies without press cake additives, representing an 88% increase. In contrast, our study observed a 97% increase at only 30% sunflower cake addition (Table 2).

Physicochemical parameters, such as pH and water activity, are important indicators of product quality, microbiological stability, and shelf life. The control cookies (C) exhibited a pH value of 7.81, which may be caused by their alkaline components, such as sodium bicarbonate. Incorporating press cakes had a variable impact on the pH of the cookies, generally showing a tendency to decrease this value. Notably, only the cookies enriched with 50% sesame press cake (SES50) did not exhibit this effect, indicating the complexity of the chemical transformations occurring during dough preparation and baking. A markedly greater reduction in pH was observed in samples with sunflower press cake addition (Table 2).

The water activity determined in our studies (Table 1 and Table 2) is a critical determinant of microbial stability. Other studies [25] confirm the potential for microbial growth during storage, notably identified in biscuits without functional additives. This may be explained by multiple authors reporting that press cake additions reduce product moisture. For example, Zouari et al. [27] found that incorporating sesame peel flour with a moisture content of 9.97% reduced moisture in wheat composite flours. The moisture content in sesame oil press cakes was reported at 7.5% [26]. In gluten-free bread, the addition of 10% and 15% sunflower press cake statistically significantly decreased crumb moisture by 0.5–0.7% [29]. Besides reducing available water for microbial growth, sesame and sunflower press cakes are also rich sources of phenolic compounds (Table 2 and

Table 3. Phenolic compound content (mg/100 g dm) in sunflower and sesame press cakes and cookies with press cake addition.

Compound	SUN30	SUN50	SUN	SES30	SES50	SES	Control Cookies
Gallic acid	3.24 ± 0.05 c	4.85 ± 0.00 b	6.87 ± 0.62 a	1.60 ± 0.65 d	1.61 ± 0.03 d	2.93 ± 0.11 cd	0.85 ± 0.02 e
Gallic acid derivative 1	9.78 ± 0.31 b	4.61 ± 0.00 c	19.1 ± 0.2 a	nd	nd	nd	nd
Chlorogenic acid	121.0 ± 4.5 c	236.7 ± 10.3 b	392.1 ± 8.7 a	3.37 ± 0.09 d	0.33 ± 0.00 d	7.72 ± 4.43 d	1.15 ± 0.01 d
Chlorogenic acid derivative 1	135.9 ± 0.3 c	265.3 ± 19.4 b	1848.4 ± 36.6 a	nd	nd	nd	nd
Chlorogenic acid derivative 2	32.6 ± 1.3 c	57.9 ± 4.0 b	126.3 ± 0.3 a	nd	nd	nd	nd
Caffeoylquinic acid derivative 1	11.5 ± 0.1 c	23.6 ± 1.8 b	141.7 ± 3.6 a	nd	nd	nd	nd
Caffeoylquinic acid derivative 2	22.7 ± 0.2 c	46.8 ± 3.1 b	206.1 ± 4.3 a	nd	nd	nd	nd
Caffeoylquinic acid derivative 3	18.9 ± 2.0 b	36.5 ± 1.1 a	35.1 ± 1.2 a	nd	nd	nd	nd
Catechin derivative 1	1.86 ± 0.06 c	3.86 ± 0.07 a	nd	2.13 ± 0.05 b	2.13 ± 0.05 b	nd	1.34 ± 0.03 d
Catechin derivative 2	6.31 ± 0.38 b	12.7 ± 1.6 a	nd	13.4 ± 0.2 a	11.5 ± 0.1 a	nd	12.6 ± 0.2 a
Caffeic acid	nd	nd	nd	2.85 ± 0.09 c	4.18 ± 0.04 b	6.63 ± 0.10 a	nd
Sesamol	nd	nd	nd	6.64 ± 0.07 c	10.3 ± 0.1 b	28.1 ± 0.1 a	nd
Sesamin	nd	nd	nd	9.17 ± 0.05 c	14.3 ± 0.1 b	40.5 ± 0.1 a	nd
Sesamolin	nd	nd	nd	0.70 ± 0.00 c	0.95 ± 0.01 b	3.58 ± 0.01 a	nd
Unknown	25.6 ± 1.1 cd	49.4 ± 4.2 b	234.9 ± 7.0 a	12.5 ± 0.8 de	9.73 ± 0.31 e	34.8 ± 6.5 bc	1.84 ± 0.25 e
Total phenolics	389.5 ± 2.1 c	755.8 ± 46.7 b	3010.7 ± 57.9 a	49.5 ± 1.0 d	57.7 ± 1.0 d	125.0 ± 10.8 d	17.8 ± 0.5 d

Averages marked with different letters in the same row differ significantly (p < 0.05, Tukey test), nd—not detected. Values are the mean ± standard deviation of three replicates.

), demonstrating antimicrobial activity [15,25].

3.2.2. HPLC Analysis of Phenolic Compounds in Press Cakes and Cookies

HPLC analysis of ethanolic extracts from press cakes and cookie samples revealed a diverse and abundant polyphenolic profile. The identification of phenolic compounds was performed by comparing retention times and spectra with available standards and literature data. Among the tested materials, sunflower press cakes exhibited the highest concentration of polyphenolic compounds, reaching approximately 3010 mg/100 g dry matter (Table 3). In this product, chlorogenic acid and its derivatives dominated, constituting over 50% of all phenolic compounds. Chlorogenic and caffeic acids, as well as their derivatives and gallic acid, have also been reported in sunflower seeds by other authors [38,39]. Sesame press cakes contained a considerable amount of polyphenols, although their content was approximately four times lower than in sunflower press cakes. The dominant compounds in the sesame phenolic profile were lignans, particularly sesamol, sesamin, and sesamolin [40,41]. In contrast, control cookies prepared without the addition of press cakes contained the lowest levels of phenolic compounds. The main ingredients of the cookies, such as wheat flour, sugar, margarine, and water, are rather poor sources of phenolic compounds.

The incorporation of press cakes significantly enhanced the polyphenol content of the cookie samples. Notably, the addition of milled sesame press cake more than doubled the polyphenol content compared to the control, whereas a 50% addition of milled sunflower press cake increased polyphenol levels to 714 mg/100 g, representing a 40-fold enhancement relative to the control. The appearance of catechin derivatives may result from the degradation of procyanidins [42]; however, we did not have the standards for these compounds available at the time of analysis.

The polyphenol reduction during baking, especially in cookies, exceeded the level predicted from the formulation proportions, suggesting further losses because of thermal or chemical transformations. Thermal processing appears to be a principal factor in the degradation of certain phenolic compounds [43]. The degree of degradation (Table 3) often depends on the chemical structure of each compound. For instance, in cookies enriched with white grape seed press caks, the losses of epicatechin gallate and epigallocatechin gallate reached 70% and 79%, respectively [5]. In wheat bread containing sesame press cake, sesaminol triglucoside content decreased by 74%, and that of sesaminol diglucoside decreased by 26%, whereas sesamolin remained relatively stable [28], which is also confirmed in our findings (Table 3). Thus, phenol loss may result from the combined influence of alkaline pH, interactions of phenolic compounds with other dough components, and oxidative degradation during mixing and baking.

Compared to bread, cookie matrices contain markedly higher levels of lipids and sugars, along with alkaline components such as sodium bicarbonate [5]. Our data (Table 2) indicate that press cake additions generally lower the pH, which can mitigate such alkaline effects. Moreover, increased acidity was also observed with the addition of sesame press cakes to pasta [26].

3.2.3. Effect of Sunflower and Sesame Press Cakes on the Colour of Cookies

Colour is an important quality parameter of food products influencing consumer expectations of taste and other sensory features. The results of instrumental colour measurements of cookies are presented in

Table 4. Colour parameters of CIE L*, a*, and b* colour system of cookies’ surfaces.

Sample	L*	a*	b*	ΔE
C	75.5 ± 1.2 a	1.53 ± 0.45 c	26.4 ± 1.2 a	---
SES30	74.4 ± 2.2 a	3.28 ± 1.03 b	25.0 ± 1.9 b	2.5
SES50	71.8 ± 4.8 b	4.06 ± 0.87 a	26.3 ± 2.0 a	4.4
SUN30	63.1 ± 1.1 c	2.99 ± 0.82 b	26.2 ± 1.4 ab	12.4
SUN50	58.4 ± 2.6 d	3.46 ± 0.75 b	21.5 ± 2.0 c	17.9

Averages marked with different letters in the same column differ significantly (p < 0.05, Tukey test). Values are the mean ± standard deviation of twenty one replicates.

. The control sample with no addition possessed the highest lightness (L* = 75.5) and yellowness (b* = 26.4) and the lowest redness (a* = 1.53). Visually, this colour is typical for properly baked cookies with a golden brown hue. The addition of sesame press cake slightly decreases lightness and increases redness, but colour changes considered perceptible to the human eye (ΔE = 4.4) were only observed with the addition of 50% sesame press cake. More pronounced colour changes were observed with the addition of sunflower press cake.

A significant darkening of the samples occurred, as shown by a decrease in the L value by 12.4 and 17.1 for SUN30 and SUN50, respectively, compared to the control samples without press cake. The ΔE values reached as high as 12.4 and 17.9 with higher levels of press cake addition. Values of a* and b* remained relatively unchanged compared to the control sample. The dark colour of the cookies is not necessarily undesirable. It is perceived to be due to the Maillard reaction, which is responsible for the development of flavour and aroma compounds. Similarly, ref. [24] reported a decrease in lightness as the inclusion level of defatted sunflower seed flour in cookies increased. This was attributed to the flour being significantly darker than wheat flour, resulting in the darkening of the cookies. Prakash et al. [25] stated that the colour of cookies depends on the type of sesame used for defatted sesame press cake production. Cookies with a 50% addition of defatted white sesame flour exhibited colour values nearly identical to those of the control, whereas the L*, a*, and b* values decreased significantly with the addition of defatted black sesame flour.

3.2.4. Impact of Sesame Press Cakes and Sunflower Press Cakes on Sensory Quality and Consumer Liking of Cookies

The sensory characteristics of enriched cookies were assessed by rating the intensities of thirteen specific attributes and the overall quality of the products. The incorporation of press cake resulted in a significant reduction in the intensity of the buttery, fatty, and sweet aroma of the enriched cookies (Figure 1). The intensities of nutty taste in the enriched cookies were higher than in the control sample. The intensity of the sesame and sunflower aroma and flavour was directly proportional to the amount of addition of each press cake. The highest intensity of sweet taste was found in cookies with 50% addition of sunflower press cake (at the level of 6.2). The addition of press cake resulted in an enhancement of the intensity of the bitter taste. In a similar vein, Grasso et al. [24] observed a comparable relationship when they incorporated defatted sunflower seed flour into cookies at levels of 18% and 36%.

The cookies without any additives were characterized by the highest crispiness (8.1). With increasing press cake addition, crispness decreased and was 7.0 and 7.1 for 30% sesame and sunflower press cake addition (respectively) and 6.0 and 5.8 for 50% sesame and sunflower press cake addition (respectively). The overall quality of the cookies with the addition of press cake was evaluated positively by experts and was 5.2 for the SUN30 sample, 5.4 for the SUN50 sample, 6.6 for the SES30 sample, and 6.7 for the SES50 sample. In the study conducted by Mildner-Szkudlarz et al. [5], an increase in the incorporation of grape press cake was observed to result in a decline in the “overall acceptance” parameter. However, a contrasting trend was noted in the present study. Figure 2 presents a visual representation of the cookies produced using press cake, in comparison with the control sample.

All cookies were evaluated positively by consumers, as the average ratings exceeded 5 points on the 9-point hedonic scale for the feature “overall acceptance” (Figure 3). Statistically significant differences in the parameter “overall acceptance” were not observed for the press-cake-supplemented samples. The study showed that liking the colour of the cookies depended on the type and amount of additive used, and that preference was stronger for samples containing 30% or 50% sesame press cake (SES30 and SES50).

The colour of the cookies with defatted sesame press cake did not demonstrate a statistically significant difference when compared to the control sample. Prakash et al. [25] obtained analogous results, finding that the colour of cookies containing defatted white sesame flour was equivalent to that of the control sample. Conversely, the taste and aroma of the samples containing 30% and 50% sunflower press cake were more desirable than the sample with 30% and 50% sesame press cake. Of the samples with press cake addition, those with 50% sesame press cake and 30% sunflower press cake had the highest texture scores (6.3 and 6.2, respectively). As demonstrated in previous studies, consumers have been found to favour the incorporation of novel and innovative raw materials in cookies including composite flour containing sprouted and malted ingredients [44] or coconut testa flour [45]. The correlation coefficients between individual sensory descriptors and overall acceptance for all created cookies together were statistically significant (p < 0.05) and were as follows: colour, R = 0.225; aroma, R = 0.276; texture, R = 0.368; and taste, R = 0.741. These results indicate that taste was the most influential factor in determining overall consumer acceptance. Additionally, the correlation between sweet taste and overall acceptance was assessed for each cookie variant. The correlation values were statistically significant (p < 0.05) and reached the following levels: R = 0.738 for C, R = 0.699 for SES30, R = 0.728 for SES50, R = 0.576 for SUN30, and R = 0.854 for SUN50. For each cookie variant, the correlation between sweet taste and overall acceptance was the strongest among all tested sensory attributes.

4. Conclusions

The results obtained from this study are particularly encouraging, especially in the case of sunflower press cakes, which have been shown to possess a high degree of antioxidant potential. The high production of sunflower cakes, coupled with its health-promoting potential, renders them well-suited for increased utilization in the production of functional foods. Sesame press cakes have been shown to possess lower antioxidant activity and the presence of allergenic substances, which may limit their use. Among the studies we found, 36% was the highest reported and sensorily accepted level of press cake addition in cookies. However, our study shows that 50% substitution is also possible and, importantly, does not differ significantly from the 30% level in consumer sensory evaluations. Further research is required, including the reformulation of the biscuit recipe to reduce sugar content.

Our study demonstrated that there were no statistically significant differences in consumer acceptance of cookies in which sunflower or sesame press cakes replaced 30% or 50% of the wheat flour. Considering the specific needs of consumers, sunflower press cakes may be a better option for individuals seeking higher levels of total polyphenols and antioxidants. Conversely, sesame press cakes may be more appropriate in situations requiring an increased intake of phytoestrogens, particularly lignans. The production of such cookies creates substantial opportunities to increase the utilization of oilseed press cakes and reduce wheat flour usage. However, our study has certain limitations. These include the lack of a comprehensive nutritional value assessment of the product, which would depend on the specific seed variety, cultivation region, and agrometeorological practices used.

The type of oil extraction from seeds, leading to the formation of press cakes, will also significantly influence the quality of the raw material. Sesame is recognized as an allergen, which limits its application. Additionally, due to significantly higher production volumes and consequent availability, sunflower press cake appears to have greater utilization potential. The consumer group involved in our study was small, comprising only 33 untrained participants. The applied recipe did not focus on process optimization for incorporating large quantities of press cake, instead involving a simple flour substitution. Furthermore, storage stability tests were not conducted. The low water activity indicates minimal microbial growth risk under proper packaging. However, the issue of residual oil in the press cakes and its potential oxidation during both baking and storage, particularly in the context of antioxidants present in the product, should be the subject of future investigation. Further research is also required to characterize the substances formed during the baking process of cookies enriched with sesame and sunflower pomaces.