促成熟牦牛乳半硬质(切达)干酪成熟特性及挥发性风味物质变化研究

Changes of ripening characteristics and volatile flavor compounds of accelerate-ripening yak milk semi-hard(cheddar)cheese

为探究牦牛乳半硬质干酪促成熟特性并确定经促成熟处理后的最佳成熟期,该实验选用经促成熟工艺处理的干酪与未处理干酪进行对比研究成熟期间(20、40、60、80 d)干酪质构与理化性质,并探究促成熟干酪在不同成熟期挥发性风味物质的变化。结果表明,在促成熟条件下牦牛乳半硬质干酪40~60 d硬度、黏性、弹性、凝聚性、咀嚼性变化明显(P<0.05)。理化性质方面水分含量逐渐降低,pH值升高,脂肪含量下降,实验组干酪酸价及过氧化值均上升,且高于对照组,表明促成熟效果好。采用固相微萃取-气相色谱-质谱联用技术检测出促成熟牦牛乳半硬质干酪成熟期间产生66种风味物质,其中主要特征风味物质包括酯类(丁酸丁酯)、酸类(丁酸)、酮类(2-丁酮)、醇类(1-丁醇)。促成熟干酪中酸类、酮类、醇类物质的含量显著增加。综上所述,促成熟干酪在成熟40~60 d质构与营养成分均达较高标准,特征风味物质含量上升,显著缩短成熟时间,为牦牛乳半硬质干酪的快速成熟和市场发展提供了理论依据。

To study the ripening characteristics of yak milk semi-hard cheese and determine the optimal ripening time after ripening process,this experiment compared the texture and physicochemical properties of accelerate-ripening cheese with untreated cheese during ripening(20,40,60 and 80 d)and investigated the changes in volatile flavor substances of ripened cheese at different ripening stages.The results showed that the hardness,viscosity,elasticity,cohesiveness and chewiness of yak milk semi-hard cheese changed significantly(P<0.05)between 40 and 60 d after maturation.In terms of physicochemical properties,the moisture content gradually decreased,pH value increased,fat content decreased,and the acid value and peroxide value of accelerate-ripening cheese increased and were higher than those in control,indicating a good ripening effect.Sixty-six flavor compounds were detected during ripening of yak milk cheese by solid-phase microextraction combined with gas chromatography-mass spectrometry(SPME-GC-MS).The main characteristic flavor compounds included esters(butyl butyrate),acids(butyric acid),ketones(2-butanone),alcohols(1-butanol).The content of acids,ketones and alcohols in accelerate-ripening cheese increased significantly.In summary,the texture and nutrients of accelerate-ripening cheese reached high standards during 40-60 d of ripening,the content of characteristic flavor substances increased,and the ripening time was significantly shortened,which provided a theoretical basis for the rapid ripening and market development of yak milk semi-hard cheese.