Solid-state NMR spectroscopy for disentangling structural and motional features of lyophilized ripened cheese water-soluble extracts related to antimicrobial activity

Present work comprises the use of different solid-state Nuclear Magnetic Resonance strategies for characterizing structural and motional aspects of the peptide matrix that compose a set of four lyophilized Mexican cheese aqueous soluble extracts, each with a controlled ripening. Heteronuclear dipolar coupling modulation schemes allowed to characterize local mobility and structural homogeneity of cheeses' peptide segments in the solid-state as a function of ripening. Results suggest that ripened samples with certain local flexibility but important structural homogeneity present efficient microbial inhibition against tested bacterial strains, whilst high local rigidity of peptides within ripened cheese soluble fractions could partially explain the observed lack of antimicrobial activity. The present study attempts to propose novel observables for lyophilized cheese water soluble extracts that could be partially associated to their ripening-dependent antimicrobial activities, whereas said observables shall contribute to the better targeting, design and optimization of solid-state natural food bio-preservatives.

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

Poro cheese is a regional product originally from the area of Los Rios, Tabasco in Mexico. In the context of preserving the heritage of Poro cheese and protecting the specific characteristics that define its typicity through an origin designation, the present study was conducted to establish a general profile of Poro cheese by characterizing their physicochemical, textural, rheological, sensorial and microbiological characteristics. Differences in moisture, proteins, fats, NaCl, titrable acidity, pH, color texture and rheology amongst cheese factories were observed and ranges were established. Fifteen descriptors were generated to provide a descriptive analysis, eight of which were significantly different amongst the factories with no differences in the global acceptability of cheese. The favorite cheese had the highest scores for aroma attributes. Conventional and molecular methods were used to identify the main microorganisms, for which Lactobacillus plantarum, L. fermentum, L. farciminis and L. rhamnosus were the main microorganisms found in Porocheese. The obtained data constituted the parameters for characterizing Poro cheese, which will strongly help to support its origin appellation request process.

Sensory Profile of Chihuahua Cheese Manufactured from Raw Milk

Chihuahua cheese is a local artisanal cheese traditionally produced from raw milk. When this cheese is produced with pasteurized milk, cheesemakers complain that there are differences in taste and aroma as compared with traditional manufacturing. This work aimed to obtain a descriptive sensory analysis of Chihuahua cheese manufactured with raw milk under traditional conditions. Samples were collected in five cheese dairies at two different seasons (summer and autumn), and a Quantitative Descriptive Sensorial Analysis was done by a panel of trained judges. For aroma descriptors, cooked descriptor showed differences between dairies, and whey was different among dairies and sampling seasons (P<0.01); diacetyl, fruity (P<0.01), as well as free fatty acids, nutty and sulphur (P<0.05) descriptors varied between seasons. For flavour descriptors, bitter perception was different between dairies and seasons (P<0.01). Salty and creamy cheese was also different among dairies (P<0.01). A Principal Component Analysis for differences among dairies and sampling season demonstrated that the first three components accounted for 90% of the variance; variables were more affected by the sampling seasons than by the geographical location or if the dairy was operated by Mennonites. Chihuahua cheese sensorial profile can be described as a semi-matured cheese with a bitter flavour, slightly salted, and with a cream flavour, with aroma notes associated with whey and sour milk. Principal Component Analysis demonstrated season influence on flavour and aroma characteristics.