Physicochemical, Sensorial and Microbiological Characterization of PoroCheese, an Artisanal Mexican Cheese Made from Raw Milk

Application of an Electronic Nose and HS-SPME/GC-MS to Determine Volatile Organic Compounds in Fresh Mexican Cheese

Electronic devices have been used to describe chemical compounds in the food industry. However, there are different models and manufacturers of these devices; thus, there has been little consistency in the type of compounds and methods used for identification. This work aimed to determine the applicability of electronic nose (e-nose) Cyroanose 320 to describe the differentiation of volatile organic compounds (VOCs) in fresh Mexican cheese (F-MC) formulated with milk from two different dairy cattle breeds. The VOCs were described using a device manufactured by Sensigent and Solid-Phase Micro-extraction (SPME) coupled to GC-MS as a complementary method. The multivariate principal components analysis (PCA) and the partial least squares discriminant analysis (PLS-DA) were used to describe the relationships of VOCs to electronic nose data, sensory data, and response levels. In addition, variable importance in projection (VIP) was performed to characterize the e-nose signals to the VOCs. The e-nose distinguishes F-MC prepared with milk from two dairy breeds. Sensor number 31 correlated with carboxylic acids most in F-MC from Jersey milk. The HS-SPME/GC-MS identified eighteen VOCs in F-MC made with Holstein milk, while only eleven VOCs were identified for F-MC made with Jersey milk. The more significant peaks in both chromatogram analyses were Propanoic acid, 2-methyl-, 1-(1,1-dimethylethyl)-2-methyl-1,3-propanediyl ester in cheese made from Holstein milk and Propanoic acid, 2-methyl-, 3-hydroxy-2,4,4-trimethylpentyl ester in Jersey milk cheese. Both compounds are considered essential carboxylic acids in the dairy industry. Thus, sensor 31 in the electronic nose Cyranose 320 increased its response by essential carboxylic acids identified by HS-SPME/GC-MS as a complementary method. The e-nose Cyranose 320 is potentially helpful for evaluating fresh Mexican cheese authentication independent of cows’ milk samples from different breeds.

Use of Autochthonous Lactic Acid Bacteria as Starter Culture of Pasteurized Milk Adobera Cheese

Adobera, a genuine, brick-shaped, lightly ripened, unstretched pasta filata-like cheese from Western México, is one of the most important market-share wise but is usually made with raw milk and prepared following artisanal procedures. A pasteurized milk cheese is needed to assess its safety and guarantee standardized quality features. However, no commercial Adobera cheese culture is available, as specific lactic acid bacteria relevant for its production have not been thoroughly identified. This study is aimed at comparing the technological and quality features of Adobera cheeses made with pasteurized milk inoculated with a mixture of autochthonous lactic acid bacteria (Lactobacillus and Leuconostoc strains) to those of traditional raw milk cheeses, hypothesizing that no significant differences would be found between them. Milk pasteurization promoted water retention into the cheese matrix, impacting its texture and color profiles. Raw milk cheeses were harder, more cohesive, and less elastic than pasteurized milk cheeses. Ripening markers were significantly higher in raw milk cheeses at all sampling times, although its evolution over time showed that the starter culture could exhibit similar proteolytic activity than that of native milk microbiota under favorable ripening conditions. The principal component analysis revealed apparent overall differences between raw Adobera cheeses and those made with pasteurized cheese milk.