高温发酵处理对苹果品质和风味变化的影响

Effects of High-temperature Fermentation Treatment on the Quality and Flavor Changes of Apples

以新鲜苹果为原料,在高温(50~90℃)和相对湿度(50%~90%)条件下,探究苹果发酵过程中品质和风味的变化规律。研究结果显示,与新鲜苹果相比,苹果在外观、色泽、质地和口感上均发生显著变化。发酵过程中总色差(ΔE)显著增加,从29.07±1.04增至50.11±0.93,表明苹果色泽变为深褐色。蔗糖、果糖和葡萄糖含量分别降到(6.64±0.78)、(77.04±0.58)mg/g DM和(24.75±0.73)mg/g DM,还原糖含量则增加到(409.36±0.64)mg/g DM。在酶活性方面,多酚氧化酶(polyphenol oxidase,PPO)酶活性在发酵初期达到峰值后开始降低,超氧化物歧化酶(superoxide dismutase,SOD)酶活性和苯丙氨酸解氨酶(phenylalanine ammonia-lyase,PAL)酶活性在发酵中期达到峰值后有所下降,而过氧化物酶(peroxidase,POD)酶活性在整个发酵过程中保持稳定。黑苹果的总酚含量较新鲜苹果提高1.45倍,5-羟甲基糠醛含量在发酵后期显著增加到(16.21±0.36)mg/g DM,抗氧化活性显著提高,但总黄酮含量有所减少。挥发性风味物质分析显示,高温发酵降低醇类和酯类化合物的含量,促进醛类化合物的形成,这些醛类化合物作为美拉德反应的主要产物,对黑苹果的整体风味有重要贡献。

In this study,fresh apples were used as raw materials to investigate the changes in quality and flavor during apple fermentation under strictly controlled conditions of high temperature(50-90℃)and humidity(50%-90%relative humidity).Compared with fresh apples,significant changes occurred in appearance,color,texture,and taste.The results showed that the total color difference(ΔE)increased significantly from29.07±1.04 to 50.11±0.93 during the fermentation process,indicating that the color of the apples changed to dark brown.Sucrose,fructose,and glucose content decreased to(6.64±0.78),(77.04±0.58)mg/g DM,and(24.75±0.73)mg/g DM,respectively,while reducing sugar content increased to(409.36±0.64)mg/g DM.In terms of enzyme activities,polyphenol oxidase(PPO)activity peaked at the beginning of the fermentation period and then started to decrease,while superoxide dismutase(SOD)activity and phenylalanine ammonia-lyase(PAL)activity peaked and decreased in the middle of the fermentation period.Peroxidase(POD)activity remained stable throughout the fermentation.The total phenolic content of black apples increased 1.45-fold compared to fresh apples,and the 5-hydroxymethylfurfural content increased significantly to(16.21±0.36)mg/g DM at the late fermentation stage,with a significant increase in antioxidant activity but a decrease in total flavonoid content.Analysis of volatile flavor substances revealed that high temperature fermentation reduced the content of alcohols and esters and promoted the formation of compounds such as aldehydes,which,as a major product of the Maillard reaction,contributed significantly to the overall flavor of black apples.