Tulum cheeses were manufactured from raw ewe's milk and ripened in goat's skin bags (tulums) or plastic containers to understand the effect of ripening container on the chemical composition, biochemistry, microbiology, and volatile composition of Tulum cheeses during 150 d of ripening. Chemical compositions of the cheeses ripened in tulums were significantly different and the moisture contents decreased rapidly in those cheeses because of the porous structure of the tulum. Higher microbial counts were detected in the cheeses ripened in plastic than in cheeses ripened in tulums. Differences in nitrogenous compounds and total free AA of the cheeses were not significant. Total concentrations of free AA in cheeses increased with age and Glu, Ala, Val, Leu, and Phe were the most abundant AA in the cheeses. Urea-PAGE of pH 4.6-insoluble fractions of the cheeses during ripening showed similar degradation patterns in all cheeses. Peptide profiles by reversed-phase HPLC of pH 4.6- and ethanol-soluble or ethanol-insoluble fractions of the cheeses revealed only minor differences in the concentrations of some peptides among the cheeses; however, age-related changes in peptide concentrations were significantly different among the cheeses. Cheeses were analyzed at 90 d of ripening for volatile compounds by solid-phase microextraction gas chromatography-mass spectrometry. One hundred volatile components were identified, including 11 acids, 16 esters, 12 methyl ketones, 7 aldehydes, 22 alcohols, 7 sulfur compounds, 6 terpenes, and 19 miscellaneous compounds. The main components were short-chain fatty acids, 2-butanone, diacetyl, and primary alcohols. Quantitative differences in several volatile compounds were evident among the cheeses. Cheeses ripened in tulums or plastic had similar aroma patterns, but the concentrations of some components were different.

No abstract

No abstract

Nine Italian ewes' milk cheeses were compared for compositional, microbiological, biochemical, and volatile profile characteristics. Mean values for the gross composition were rather similar among cheeses. The lowest pH values were found for cheeses that used primary starters. At the end of ripening, cheeses made from raw milk contained >6.0 log10 cfu/g of nonstarter lactic acid bacteria. Several species of lactobacilli were identified, but Lactobacillus plantarum and Lactobacillus paracasei were dominant. Random amplified polymorphic DNA-PCR analysis showed the biodiversity among the strains, and in several cases a relationship with the cheese of provenance. Cheeses differed mainly for secondary proteolysis, as shown by the principal component analysis applied to reversed-phase fast protein liquid chromatography data of the pH 4.6-soluble fractions and by determination of the free AA. A total of 113 volatile components were identified in the Italian Pecorino cheeses by solid-phase microextraction coupled with gas chromatography-mass spectrometry analysis. The volatile profiles of the 9 cheeses differed significantly. Quantitatively, alcohols were the most abundant chemical class for some cheeses, whereas ketones were the most abundant for other cheeses. Esters and carboxylic acids were largely found. Specific volatile components seemed to distinguish specific cheeses.

No abstract