Abstract: The effect of co-fermentation on the quality of yogurt during storage and the underlying mechanism were investigated. With this aim, we monitored changes in some physicochemical properties (pH value, titratable acidity, water-holding capacity and texture properties), and we also analyzed the color, flavor compounds and microstructure of yogurt using a color difference meter, headspace solid phase microextraction-gas chromatography-mass spectrometry and scanning electron microscopy, respectively. The results obtained showed that co-fermentation markedly decreased the pH value, increased the acid production and gelation and enhanced the water-holding capacity and texture properties of yogurt. At the same time, co-fermentation endowed the yogurt with better color and flavor as well as a more compact, continuous, stable structure three-dimensional network structure. To sum up, co-fermentation could significantly improve the quality of fresh and stored yogurt.

Key words: co-fermentation; yogurt; storage; quality; mechanism

摘要： 通过测定酸乳发酵及贮藏过程中的pH值、可滴定酸度、持水力及质构特性等指标的变化，采用色差色度仪、顶空固相微萃取-气相色谱-质谱联用和扫描电镜分别对共发酵型酸乳的颜色、风味成分和微观结构进行分析，分析和探讨共发酵工艺对酸乳贮藏过程中品质的影响及相关机理。结果表明：共发酵工艺能显著降低酸乳的pH值，促进酸乳产酸和凝胶，增强酸乳的持水力和质构特性；共发酵工艺的应用能赋予酸乳更好的颜色、风味以及更加致密、连续和稳定的三维立体网状结构。因此，共发酵工艺在酸乳的生产与贮藏过程中能显著改善其品质，提高酸乳的质量。

关键词: 共发酵工艺；酸乳；贮藏；品质；作用机理