新疆红肉苹果3个品系的风味品质与抗氧化能力评价

Evaluation of Flavor Quality and Antioxidant Capacity of Apple Fruits from Three Xinjiang Red-Flesh Lines

【目的】明确新疆红肉苹果风味物质组成与含量特征,了解其营养品质状况,为开发利用提供信息。【方法】分别采用高效液相色谱(High Performance Liquid Chromatography,HPLC)和气相色谱-质谱联用(Gas Chromatography-Mass Spectrometer,GC-MS)技术,以富士苹果‘长富2号’为对照,检测分析3个新疆红肉苹果品系果皮和果肉的糖、酸和挥发性成分的组成及含量,并测定评价其提取物的总酚、总黄酮的含量以及抗氧化活性。【结果】3个供试品系的可滴定酸含量为21.01—27.71 mg·mL^(-1),是对照的3.68—4.85倍,p H为3.12—3.39,显著低于对照(P<0.05)。共检测到果糖、葡萄糖、蔗糖3种可溶性糖,其中以果糖(56.71%—64.07%)为主,蔗糖的含量最低,仅仅占总糖含量的8.89%—31.12%。供试品系中可溶性糖的含量均显著低于对照;果肉中果糖的含量显著高于果皮,而葡萄糖和蔗糖的含量无显著差异(P<0.05)。共检测到5种有机酸,包括柠檬酸、酒石酸、草酸、苹果酸和奎宁酸,以苹果酸(56.53%—95.07%)的含量最高,其次为柠檬酸(2.11%—40.72%),其他酸的含量均低于0.6 mg·g^(-1) FW,奎宁酸只在‘13-3’中检测到。果皮、果肉中,苹果酸含量分别是对照的6.56—8.99倍和5.58—6.61倍,柠檬酸的含量是对照的16.80—117倍和4.50—16.17倍;果肉中苹果酸的含量显著高于果皮,而柠檬酸的含量显著低于果皮(P<0.05)。共检测到85种挥发性成分,醛类、酯类和萜类的含量最为丰富,共占总香气物质的92.32%—97.84%。‘13-3’与对照相似,以酯类和萜类为主,丁酸乙酯、2-甲基丁酸乙酯、己酸甲酯、乙酸己酯是主要酯,苏合香烯、D-柠檬烯、α-法尼烯是主要萜,而‘P3’和‘新农’以醛类和萜类为主,己醛和反-2-己醛是主要的醛。果皮中挥发性成分的含量显著高于果肉(P<0.05)。果皮中总酚、总黄酮的含量分别是对照的2.31—2.65倍和1.23—1.61倍,果肉中分别是对照的5.53—16倍和1.43—3.49倍,3种自由基清除能力也显著高于对照。果皮的总酚、总黄酮含量均高于果肉,且抗氧化活性也远高于果肉,‘13-3’的总酚、总黄酮及抗氧化能力最高。【结论】3个供评价的品系材料均属于新疆红肉苹果中的高酸类型;低可溶性糖、高苹果酸、高柠檬酸、低总糖苹果酸比,以及特征香气成分己醛、2-己烯醛、丁酸乙酯、己酸乙酯、乙酸己酯、2-甲基丁酸乙酯在其独特的风味品质决定中有重要作用,‘P3’和‘新农’属"青香型"苹果,‘13-3’属"果香型"。供试品系风味特征鲜明、营养价值高,是研究风味品质及选育功能性加工苹果的良好材料,其中‘13-3’的表现最优。

[ Objective ] In order to characterize the flavor quality of Xinjiang red-flesh apple, the composition and content of flavor compounds were analyzed and a preliminary evaluation on nutritional quality of these fruits was made, which will provide useful information for exploitation and utilization of these apple fruits. [ Method ] High performance liquid chromatography （HPLC） and gas chromatography-mass spectrometer （GC-MS） were employed to detect and analyze sugars, organic acids and volatile compounds in the peels and pulps of three Xinjiang red-flesh apple lines, and compared with the control Fuji apple ＇Changfu 2＇. The contents of total phenols （TP）, total flavonoids （TF） and antioxidant activity were also measured and evaluated. [Result] The titratable acid （TA） of apple tested were 21.01-27.71 mg mLl, which were 3.68-4.85 times of the control. The pH values were 3.12-3.19, which was significantly lower than the control （P〈0.05）. Fructose, glucose and sucrose were identified in these fruits, fructose was the dominant sugar （56.71%-64.07%）, while sucrose content was the least and it only accounted for 8.89%-31.12% of total sugar. The contents of soluble sugars in three Xinjiang red-flesh apple were significantly lower than those in the control. Fructose in pulps was higher than those in peels, while no significant differences of glucose and sucrose were found between them （P〈0.05）. Five organic acids, including oxalic acid, tartaric acid, malic acid, citric acid, and quinic acid, were identified from the lines tested. Malic acid （56.51%-95.11%） was the richest component, followed by citric acid （2.07%-40.72%）. The contents of other acids were less than 0.6 mg g-1 fresh weight （FW）. Quinic acid was only detected in ＇13-3＇. The content of malic acid in peels and pulps was 6.56-8.99 times and 5.58-6.61 times as much as that in control, and the content of citric acid was 16.80-117 times and 4.50-16.17 times of that in control, respectively. The content of malic acid in pulps was significantly higher than that in peels, while citric acid in pulps is significantly lower than that of peels （P〈0.05）. Totally, 85 volatile compounds were identified from the fruits tested. Aldehydes, esters and terpenes were the most abundant components, accounting for 92.32%-97.84% of the total volatile compounds. Similar with the control, ＇13-3＇ was characterized by esters and terpenes. Ethyl butyrate, ethyl 2-methylbutyrate, methyl hexanoate and hexyl acetate were the main esters, while styrene, D-limonene and a-farnesene were the dominant terpenes. ＇P3＇ and ＇Xinnong＇ were mainly characterized by aldehydes and terpenes, hexanal and （E）-2-hexenal were the main aldehydes. The content of volatile components in peels were significantly higher than those in pulps （P〈0.05）. The contents of TP and TF in peels and pulps of three Xinjiang red-flesh apple lines were 2.31-2.65 times and 1.23-1.61 times as that of the control, and as 5.53-16 times and 1.43-3.49 times as that of the control, respectively. Free radical scavenging ability of extraction from these fruits were also significantly higher than the control. The contents of TP and TF in peels were higher than those in pulps, and its antioxidant capacity were significantly higher than those in pulps. Among the tested lines, ＇ 13-3＇ presented the highest TP and TF contents and antioxidant capacity. [ Conclusion] The apple lines tested belong to the high-acid type of Xinjiang red-flesh apple. Low soluble sugar, high malic acid and citric acid, low ratio of total sugar to malic acid and the characteristic aroma components, such as hexanal, （E）-2-hexenal, ethyl butyrate, ethyl hexanoate, hexyl acetate and ethyl 2-methylbutyrate, play an important role in flavor quality decision. ＇13-3＇ belongs to ＂fruity odor＂ fruit, while ＇P3＇ and ＇Xinnong＇ are the ＂grassy odor＂ type. The three lines tested presented characteristic flavor and high nutritional quality, which could be good materials for studying flavor quality and breeding functional processing apple, and ＇ 13-3＇ is the optimal.