Javed Hafiz Umer, Wang Dong, Andaleeb Rani, Zahid Muhammad Salman, Shi Ying, Akhtar Saeed, Shiping Wang, Duan Chang-Qing
Center for Viticulture & Enology, College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Tsinghua East Road, Beijing 100083, China.
Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing 100083, China.
Foods. 2021 Mar 8;10(3):559. doi: 10.3390/foods10030559.
Raisin aroma is a vital sensory characteristic that determines consumers' acceptance. Volatile organic compounds (VOCs) in fresh grapes, air-dried (AD), pre-treated air-dried (PAD), sun-dried (SD), and pre-treated sun-dried (PSD) raisins were analyzed, with 99 and 77 free- and bound-form compounds identified in centennial seedless grapes, respectively. The hexenal, (E)-2-hexenal, 1-hexanol, ethyl alcohol, and ethyl acetate in free-form while benzyl alcohol, β-damascenone, gerenic acid in bound-form were the leading compounds. Overall, the concentration of aldehydes, alcohols, esters, acids, terpenoids, ketones, benzene, and phenols were abundant in fresh grapes but pyrazine and furan were identified in raisin. Out of 99 VOCs, 30 compounds had an odour active value above 1. The intensity of green, floral, and fruity aromas were quite higher in fresh grapes followed by AD-raisins, PAD-raisins, SD-raisins, and PSD-raisins. The intense roasted aroma was found in SD-raisins due to 2,6-diethylpyrazine and 3-ethyl-2,5-dimethylpyrazine. Among raisins, the concentration of unsaturated fatty acid oxidized and Maillard reaction volatiles were higher in SD-raisins and mainly contributed green, fruity and floral, and roasted aromas, respectively.
葡萄干香气是决定消费者接受度的重要感官特征。对新鲜葡萄、风干（AD）、预处理风干（PAD）、日晒（SD）和预处理日晒（PSD）葡萄干中的挥发性有机化合物（VOCs）进行了分析，在百年无核葡萄中分别鉴定出99种游离态和77种结合态化合物。游离态的己烯醛、（E）-2-己烯醛、1-己醇、乙醇和乙酸乙酯，以及结合态的苯甲醇、β-大马酮、gerenic酸是主要化合物。总体而言，新鲜葡萄中醛、醇、酯、酸、萜类、酮、苯和酚的浓度较高，但在葡萄干中鉴定出了吡嗪和呋喃。在99种VOCs中，有30种化合物的气味活性值高于1。新鲜葡萄中绿色、花香和果香的香气强度相当高，其次是AD葡萄干、PAD葡萄干、SD葡萄干和PSD葡萄干。由于2,6-二乙基吡嗪和3-乙基-2,5-二甲基吡嗪，SD葡萄干中发现了强烈的烤香。在葡萄干中，不饱和脂肪酸氧化产物和美拉德反应挥发物的浓度在SD葡萄干中较高，分别主要贡献了绿色、果香和花香以及烤香。
