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- MakaleYalnız künye2026Scopus SJRQ2Drying temperature-dependent changes in grape seed bioactives and oxidative status: integrated HPLC/GC and multivariate analysis
Karaca Sanyürek, Nesrin
Abstract: Drying temperature (40–80 °C) critically influences the stability of bioactive compounds in grape seeds and their functional responses. In this study, we evaluated the vitamin and phytosterol content of Boğazkere grape seeds using high-performance liquid chromatography (HPLC) and the fatty acid content using gas chromatography (GC). Antioxidant capacity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and the oxidative stress marker, malondialdehyde (MDA). Temperature-dependent and compound-specific alterations were observed: while selected vitamins and phytosterols showed distinct thermal susceptibilities, fatty acid profiles exhibited measurable remodeling. Antioxidant activity revealed non-linear dose- and temperature-dependent patterns, whereas MDA consistently decreased with increasing temperature, reflecting the reduced oxidative metabolism in dehydrated tissues. Multivariate analysis, including principal component analysis (PCA) and heatmap visualization, effectively discriminated temperature treatments and revealed correlations between compositional and functional parameters. The combined use of univariate and multivariate analyses revealed that the drying temperature reshaped not only individual bioactive compounds but also the overall biochemical profile of grape seeds. These findings establish a mechanistic link between thermal processing and bioactive stability, providing a chemical basis for optimizing grape seed valorization in food systems.
- MakaleAçık Erişim2026Scopus SJRQ1Comprehensive Analysis of Phytochemical Compounds in Seeds of Indigenous Grape Varieties Cultivated in Southeastern Anatolia: Fatty Acids, Tocopherols, Phytosterols, Vitamins, and Antioxidant Properties
Odabaşioğlu, Mehmet İlhan; Çakır, Atilla; Karaca Sanyürek, Nesrin; İşlek, Fırat
Aim: In this study, the phytochemical composition of the seeds of twelve different local grape (Vitis vinifera L.) varieties traditionally cultivated in the Southeastern Anatolia Region (Diyarbakır, Türkiye) was investigated using a holistic approach. The main objective of the study was to evaluate the associations of the effects of berry skin colour, the ripening stage and utilization type on the fatty acid profile, tocopherol and phytosterol contents, vitamin K and D levels, antioxidant capacity (DPPH) and lipid peroxidation (MDA) of grape seeds. Method: The seeds of grape varieties belonging to four different colour groups, grown on their own roots, were harvested during the 2017 growing season and analysed. Fatty acid composition was determined by gas chromatography (GC), vitamin and phytosterol contents by HPLC-UV, MDA content by the thiobarbituric acid reactive substance (TBARS) method, and antioxidant capacity by the DPPH radical scavenging assay. Findings: Linoleic acid was identified as the predominant fatty acid in all varieties (53.68–67.06%), followed by oleic acid (13.80–27.32%). α-Tocopherol was identified as the predominant tocopherol form (1.597–4.703 mg kg−1), whilst β-sitosterol was the phytosterol component present at the highest level (915.67–3340.42 µg g−1). Statistically significant varietal differences were detected for most measured phytochemical parameters. Group-wise differences associated with berry skin colour and ripening stage were observed for selected traits. Overall, varietal differences appeared to be more pronounced than those associated with berry skin colour or ripening stage. It was observed that the differences in phytochemical composition between the various commercial classifications of grapes were very limited. Result: The findings reveal that the seeds of the local grape varieties studied exhibit a rich phytochemical profile and represent an important source of bioactive compounds that could be utilised, particularly in the functional food, nutraceutical and cosmetics industries. The ‘Tahannebi’ variety stood out as the one with the highest values across many parameters. Differences observed among samples of the same cultivar collected from different vineyards suggest that vineyard-specific conditions may contribute to variation in selected phytochemical traits. Future multi-year and multi-location studies are needed to confirm the stability of these phytochemical profiles and to further clarify genotype × environment interactions.
