Jiao Jingkai, Zheng Zhiqiang, Liu Zhenmin, You Chunping
State Key Laboratory of Dairy Biotechnology, Shanghai Engineering Research Center of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., Shanghai, China.
Front Nutr. 2021 Apr 16;8:649611. doi: 10.3389/fnut.2021.649611. eCollection 2021.
Red-Veined Cheese is an experimental internal mold-ripened cheese using red koji powder as the red starter. The objective of this study was to characterize the physicochemical parameters, microorganisms, proteolysis, lipolysis, and volatile profile of the cheese during 33 days of ripening. The gross composition was 56.7% (w/w) for total solids, 45.8% (w/w) for fat-in-dry matter, 2.58% (w/w) for salt content and 37.8% (w/w) for protein. The pH increased from 4.88 to 5.23 during ripening. The density first rose and then fell, while total mesophilic bacteria count declined steadily throughout the maturation. Proteolysis degree in experimental group was significantly higher than in control group without inoculation of red koji powder. Analysis of the fatty acid profile showed that the internal -fermentation also promoted lipolysis. A total of 63 volatile compounds, including 12 ketones, 14 alcohols, 15 acids, 13 esters, 5 aldehydes, 3 lactones and 1 phenol, were identified by gas chromatography-mass spectrometry (GC-MS) coupled with headspace solid-phase microextraction (HS-SPME). The main chemical groups of volatile compounds were ketones, alcohols, acids and esters whereas aldehydes, lactones, and phenols represented only minor components. At the end of ripening, the levels of ketones, alcohols, esters were significantly higher in the experimental cheese compared with the control. Our results therefore show that the internal -fermentation is not only a suitable technology to form red veins in the paste but also an effective method to impact the composition of volatile compounds in cheese, which can thus distinguish it from other internal mold-ripened cheeses and surface-ripened -fermented cheese.
红脉奶酪是一种以红曲粉作为红色发酵剂的实验性内部霉菌成熟奶酪。本研究的目的是表征奶酪在33天成熟过程中的理化参数、微生物、蛋白水解、脂肪水解和挥发性成分。其总成分中，总固形物为56.7%（w/w），干物质中脂肪为45.8%（w/w），盐含量为2.58%（w/w），蛋白质为37.8%（w/w）。成熟过程中pH值从4.88升高到5.23。密度先上升后下降，而总嗜温菌数在整个成熟过程中稳步下降。实验组的蛋白水解程度显著高于未接种红曲粉的对照组。脂肪酸谱分析表明，内部发酵也促进了脂肪水解。通过气相色谱-质谱联用（GC-MS）结合顶空固相微萃取（HS-SPME）共鉴定出63种挥发性化合物，包括12种酮类、14种醇类、15种酸类、13种酯类、5种醛类、3种内酯类和1种酚类。挥发性化合物的主要化学类别为酮类、醇类、酸类和酯类，而醛类、内酯类和酚类仅占次要成分。在成熟结束时，实验奶酪中酮类、醇类、酯类的含量显著高于对照组。因此，我们的结果表明，内部发酵不仅是在奶酪糊中形成红脉的合适技术，也是影响奶酪中挥发性化合物组成的有效方法，从而使其有别于其他内部霉菌成熟奶酪和表面成熟发酵奶酪。
