National Key Laboratory for Efficient Production of Forest Resources, Beijing Key Laboratory of Food Processing and Safety in Forestry, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, P. R. China.
J Food Sci. 2024 Aug;89(8):4884-4898. doi: 10.1111/1750-3841.17186. Epub 2024 Jul 14.
Walnut oil is an edible oil with high nutritional value, and the roasting process influences its quality and flavor. This study aimed to investigate the effects of roasting on the fatty acid composition, bioactive compounds (tocopherols, polyphenols, and phytosterols), and antioxidant capacity of walnut oil. Additionally, the aroma compounds and sensory characteristics were evaluated to comprehensively assess the variations in walnut oil after roasting. Roasting resulted in no notable impact on the fatty acid composition of walnut oil but increased the content of tocopherols and polyphenols in walnut oil, increasing its antioxidant capacity. Heavy roasting (160°C/20 min) reduced the phytosterol content in walnut oil by 2.3%. In total, 146 volatile compounds were detected in both cold-pressed and roasted walnut oil using headspace solid-phase microextraction-gas chromatography-mass spectrometry, and 32 key aroma compounds were identified. Aromatic aldehydes, aliphatic aldehydes, and heterocyclic compounds significantly contributed to fragrant walnut oil. Furthermore, the principal component analysis based on quality characteristics and sensory evaluation indicated that moderate roasting (130°C/20 min, 130°C/30 min, and 160°C/10 min) provided walnut oil with a sweet, nutty, and roasted aroma, as well as high levels of linoleic acid, phytosterols, and γ-tocopherol. Although heavy roasting (160°C/15 min and 160°C/20 min) enhanced the antioxidant capacities of walnut oils due to high levels of polyphenols, the oils exhibited an unpleasant burnt aroma. This study showed that roasting promoted the quality and flavor of walnut oil, and moderate conditions endowed walnut oil with a characteristic-rich flavor while maintaining excellent quality.
核桃油是一种具有高营养价值的食用油，其烘烤过程会影响其质量和风味。本研究旨在探讨烘烤对核桃油脂肪酸组成、生物活性化合物（生育酚、多酚和植物甾醇）和抗氧化能力的影响。此外，还评估了香气化合物和感官特性，以综合评估烘烤后核桃油的变化。烘烤对核桃油的脂肪酸组成没有显著影响，但提高了核桃油中生育酚和多酚的含量，从而提高了其抗氧化能力。重度烘烤（160°C/20 分钟）使核桃油中的植物甾醇含量降低了 2.3%。总共使用顶空固相微萃取-气相色谱-质谱法在冷榨和烘烤核桃油中检测到 146 种挥发性化合物，鉴定出 32 种关键香气化合物。芳香醛、脂肪醛和杂环化合物对香核桃油的香气有显著贡献。此外，基于质量特性和感官评价的主成分分析表明，适度烘烤（130°C/20 分钟、130°C/30 分钟和 160°C/10 分钟）使核桃油具有甜、坚果和烘烤香气，以及高水平的亚油酸、植物甾醇和γ-生育酚。尽管重度烘烤（160°C/15 分钟和 160°C/20 分钟）由于多酚含量高而提高了核桃油的抗氧化能力，但油的烧焦味令人不快。本研究表明，烘烤可以改善核桃油的质量和风味，适度的条件赋予核桃油丰富的特征风味，同时保持优良的品质。
