Stankov Jovanović Vesna, Djurić Vladan, Mitić Violeta, Barjaktarević Ana, Cupara Snežana, Ilić Marija, Nikolić Jelena
Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš, Serbia.
Faculty of Agriculture, University of Priština in Kosovska Mitrovica, Kopaonička bb, 38228 Lešak, Serbia.
Foods. 2025 Jul 16;14(14):2486. doi: 10.3390/foods14142486.
With the growing interest in natural and health-supporting foods, oak acorns () are gaining renewed attention for their nutritional and antioxidant potential. This study explored how different processing methods affect bioactive compounds in three acorn-based products: raw acorn flour, roasted "coffee," and washed-and-roasted "super coffee." Extracts were obtained using methanol, acetone, and hexane to evaluate total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity via ABTS, DPPH, CUPRAC, FRAP, and TRP assays. Methanol proved to be the most effective solvent, extracting up to 66.53 mg GAE/g dw of phenolics in raw flour and 76.50 mg GAE/g dw in roasted "coffee," reflecting a 15% increase in TPC after thermal treatment. However, the same treatment resulted in a 17% decrease in flavonoid content, from 181.5 mg RE/g dw in raw flour to 150.67 mg RE/g dw in "super coffee." Antioxidant activity followed a similar pattern, with methanol extracts showing the highest values, up to 584 mg TE/g dw in the CUPRAC assay and 126.7 mg TE/g dw in ABTS. Safety was also assessed through the quantification of 16 priority polycyclic aromatic hydrocarbons (PAHs). The total PAH levels in the roasted "coffee" and "super coffee" samples were 222 ng/g dw and 290 ng/g dw, respectively. Importantly, PAH4 compounds, used as key safety indicators in EU regulations, were present in low concentrations, primarily as benzo[a]anthracene (34.3-39.8 ng/g), and none exceeded the maximum limits established for cocoa-based products. Benzo[a]pyrene, a major carcinogen, was not detected. The results confirm that acorns of , especially in their native flour form, are rich in antioxidants, naturally gluten-free, and safe when thermally processed, making them a strong candidate for use in functional foods.
随着人们对天然和健康食品的兴趣日益增长，栎属橡子因其营养和抗氧化潜力而重新受到关注。本研究探讨了不同加工方法如何影响三种以橡子为基础的产品中的生物活性化合物：生橡子粉、烘焙“咖啡”和水洗烘焙“超级咖啡”。使用甲醇、丙酮和己烷提取提取物，通过ABTS、DPPH、CUPRAC、FRAP和TRP测定法评估总酚含量（TPC）、总黄酮含量（TFC）和抗氧化活性。结果表明，甲醇是最有效的溶剂，在生面粉中提取的酚类物质高达66.53 mg GAE/g干重，在烘焙“咖啡”中为76.50 mg GAE/g干重，表明热处理后TPC增加了15%。然而，同样的处理导致黄酮含量下降了17%，从生面粉中的181.5 mg RE/g干重降至“超级咖啡”中的150.67 mg RE/g干重。抗氧化活性呈现类似模式，甲醇提取物显示出最高值，在CUPRAC测定中高达584 mg TE/g干重，在ABTS中为126.7 mg TE/g干重。还通过对16种优先多环芳烃（PAHs）的定量评估了安全性。烘焙“咖啡”和“超级咖啡”样品中的总PAH水平分别为222 ng/g干重和290 ng/g干重。重要的是，作为欧盟法规关键安全指标的PAH4化合物浓度较低，主要为苯并[a]蒽（34.3 - 39.8 ng/g），且均未超过为可可基产品设定的最大限量。未检测到主要致癌物苯并[a]芘。结果证实，栎属橡子，尤其是其天然面粉形式，富含抗氧化剂，天然无麸质，热处理后安全，使其成为功能性食品应用的有力候选者。
