Fortification of foods with phenolic compounds is becoming increasingly popular due to their beneficial physiological effects. The biological activities reported include antioxidant, anticancer, antidiabetic, anti-inflammatory, or neuroprotective effects. However, the analysis of polyphenols in functional food matrices is a difficult task because of the complexity of the matrix. The main challenge is that polyphenols can interact with other food components, such as carbohydrates, proteins, or lipids. The chemical reactions that occur during the baking technologies in the bakery and biscuit industry may also affect the results of measurements. The analysis of polyphenols found in fortified foods can be done by several techniques, such as liquid chromatography (HPLC and UPLC), gas chromatography (GC), or spectrophotometry (TPC, DPPH, FRAP assay etc.). This paper aims to review the available information on analytical methods to fortified foodstuffs while as presenting the advantages and limitations of each technique.

In this study, we examined the yield and oil quality of eight different grape varieties. For the experiments, the grape seeds were obtained from the Benedictine Pannonhalma Archabbey in the northwestern region of Hungary. The aim of the studies was to determine the oil yield obtained by extraction and to examine the differences between the fatty acid composition, antioxidant capacity, and total polyphenol content of the oils of different grape varieties. Based on the results, the oil content of the grape seeds varied between 99.91 g/kg and 126.74 g/kg. The grape seed oils analysed contained significant amounts of stearic acid (3.42–9.93%), palmitic acid (7.81–10.66%), oleic acid (14.29–19.92%), and linoleic acid (66.85–72.47%). Besides, the grape seed oils tested contained several other fatty acids in small amounts. There were significant differences in the total antioxidant and total polyphenol content of the oils. Total polyphenol content ranged from 0.24 to 1.13 mg GAE/g, while the total antioxidant content changed between 0.12 and 0.78 μg TEAC/g. The results show that the studied varieties are suitable for the production of table grape seed oil based on their oil yield, and the oils have favourable, health-protecting properties in terms of their quality.

Although wild fruits are significantly underutilized in most countries, they could be good sources of valuable bioactive compounds with antioxidant properties. Therefore the present study focused on the study of a conventional extraction technique (maceration with shaking; MAC_S) to extract natural antioxidants and anthocyanin colorants from six edible wild-growing fruits (European crab apple, bilberry, yellow-, red-, and purple-skinned greengage, and quince). One-factor-at-a-time (OFAT) methodology was chosen to investigate the influences of three different parameters (solvent type, extraction time and solvent acidity) on the total polyphenol contents (TPCs), total monomeric anthocyanin (TMA) contents, and antioxidant capacities, specifically ferric reducing power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity (DPPH). After optimization, the recorded TPCs and antioxidant activities proved to be significantly higher for all analyzed fruits when compared to differing extraction conditions. For European crab apple and purple-skinned greengage, the best extraction conditions were a ratio of 80:20 (v/v) EtOH–H₂O, 1% (v/v) of HCOOH, and an extraction time of 90 min. In the case of red-skinned greengage, the extraction parameters were the same as the above except for the acid concentration (0.5%; v/v) used. For quince, the optimized conditions required a 50:50 (v/v) EtOH–H₂O mixture, an extraction time of 90 min, and 0.5% (v/v) HCOOH concentration. The best conditions for the extraction of bilberry and yellow-skinned greengage were an EtOH–H₂O combination of 50:50 (v/v), extraction time of 60 min, and HCOOH concentration of 0.5% (v/v). The highest TPC and antioxidant activity were observed in quince (281–510 mg GAE/100g and 109–395 mg AAE/100g) whereas the lowest were measured in European crab apple (55.9–70.0 mg GAE/100g and 20.1–43.2 mg AAE/100g). Bilberry exhibited the highest TMA content (346 mg CGE/100g). Overall, our results showed that these wild fruits could be a good source of natural antioxidants for the local residents.

The aim of the present study was to determine the antioxidant capacity and total polyphenol content of raw milk, dairy products (ricotta and cottage cheese), and by-products (sweet and acid whey) from different animal breeds (cow, goat). Overall, the total polyphenol content of raw milk ranged from 420.34 to 490.72 mg GAE/100 mL, while the total antioxidant content changed between 8.95 and 28.72 mg AAE/100 mL. These values in the case of cottage cheeses were 32.29–124.29 mg GAE/100 mL for polyphenols and 14.12–16.38 mg AAE/100 g for antioxidants. Significant differences were observed between the total polyphenol content and antioxidant properties of sweet- (10.85–197.55 mg AAE/100 g antioxidant; 32.29–124.29 mg GAE/100 g polyphenol) and acid whey (13.28–158.69 mg AAE/100 g antioxidant; 43.50–98.03 mg GAE/100 g polyphenol). In addition, slight differences in total polyphenol content (10.55–19.01 mg GAE/100 g) and antioxidant capacity (10.84–15.93 mg AAE/100 g) were observed for ricotta cheeses made from milk of different animal breeds. The results show that milk and dairy products are excellent sources of antioxidants and polyphenols.

This study aimed to examine the differences between the antioxidant capacity, and the total polyphenol content of the seed of eight different grape varieties. We also attempt to create a functional loaf enriched with grape seed meal. To achieve this goal, 3, 6, and 9% of the grape seed meal were added to the loaves made of bread flour and gluten-free flour mixture, and then the changes in their antioxidant and polyphenol content were examined. Based on the results, there were significant differences between the polyphenol and antioxidant content of grape seed varieties. The antioxidant content of the grape seeds varied between 228.50 mg AAE/g (94.80 mg TE/g) and 438.33 mg AAE/g (181.86 mg TE/g) in case of fatty samples, and between 176.29 mg AAE/g (41.24 mg TE/g) and 424.91 mg AAE/g (99.40 mg TE/g) in case of defatted samples. The total polyphenol content of the fatty samples changed between 91.16 and 221.81 mg GAE/g; in case of defatted samples, it ranged from 46.01 to 207.68 mg GAE/g. Rhine Riesling contained the greatest amount of these compounds. The functionality of loafs was confirmed by spectrophotometric analysis. Total polyphenol content ranged from 0.91 to 3.16 mg GAE/g in case of wheat loafs, and from 1.39 to 5.92 mg GAE/g in case of gluten-free loafs, while the total antioxidant content changed between 0.70 and 6.44 mg AAE/g in case of wheat loafs, and ranged from 2.55 to 9.75 in case of gluten-free loafs. Graphic abstract

The aim of the present study is to evaluate the antioxidant properties of wild blackberry fruits as well as their possible use in powdered form as a functional ingredient. For this, ultrasound-assisted extraction optimization, ripening stage evaluation, and wild blackberry powder incorporation into a real food matrix were applied. The optimum conditions for extraction were as follows: 60% MeOH, 20 min of extraction time, acidification with 0.5% HCl, and a 1:40 g/mL solid-to-solvent ratio, which allowed the following yields: total polyphenol content (TPC): 53.8 mg GAE/g; total flavonoid content (TFC): 5.78 mg QE/g; total monomer anthocyanin content (TMA): 11.2 mg CGE/g; 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH): 71.5 mg AAE/g; IC₅₀: 52.3 µg/mL. The study also highlighted that, during the ripening process, the TPC (41.4%), TFC (17.0%), and DPPH levels (66.4%) of the fruits decreased while the TMA yield increased. The incorporation of blackberry powder at different levels (5–20%) increased the TPC, TFC, TMA, and antioxidant properties of muffins. Although the muffins enriched with 20% wild blackberry powder had the best chemical properties (TPC: 3.15 mg GAE/g; TFC: 0.52 mg QE/g; TMA: 0.23 mg CGE/g; DPPH: 1.70 mg AAE/g; IC₅₀: 1.65 mg/mL), the sensory analysis showed that the addition of blackberry fruit at a concentration of 10% to the muffins resulted in the best consumer acceptability.