Inorganic constituents of cheese: analysis of juice from a one-month-old Cheddar cheese and the use of light and electron microscopy to characterize the crystalline phases

Abstract

SummaryA method of extracting cheese juice is described. Juice from a single one-month-old Cheddar cheese was used to investigate the relationship between the composition of the cheese juice and the occurrence of crystalline aggregates in the cheese. Two classes of crystalline aggregates were identified by light microscopy and also by electron microscopy in combination with X-ray microanalysis: the larger class contained both Ca and P whereas the smaller class contained Ca but not P. Concentrations of ions in the cheese and cheese juice were determined and corrected for the excluded volume of co-solutes and other phases present. When this was done, comparison of the concentrations of Na, K, Cl and lactate in the cheese and the cheese juice indicated that they were virtually entirely in solution, whereas appreciable amounts of the total Ca, P and P1 in the cheese were not extracted in the cheese juice. The amounts of the non-extractable salts were consistent with the volume fractions of the crystalline aggregates found by microscopy; calculations of the ion equilibria in the cheese juice showed that it was supersaturated with respect to various Ca phosphate salts and to tricalcium citrate. It is concluded that the physicochemical origin of the crystalline aggregates was the nucleation and growth of crystals from a supersaturated solution, though the sites of nucleation may have been formed by the microbial activity in the cheese. Of the free amino acids found in the juice, none was at a sufficiently high concentration to form a saturated solution, indicating that in this relatively young cheese the crystalline aggregates were not formed from amino acids.

Influence of medium-concentration factor microfiltration treatment on the characteristics of low-moisture Mozzarella cheese

“…Initially constituted by whey proteins and κ-GMP, this form was progressively enriched by the release of small and large peptides produced by the action of rennet and starter proteases and peptidases hydrolyzing the cheese casein matrix [19]. The higher content at pH 4.6-SN observed in MMC during ripening compared to CMC did not agree with the reported retarded proteolysis in cheese made from protein-enriched cheese milk [27]. Further work is required for identifying the casein fragments causing this increase.…”

“…Further work is required for identifying the casein fragments causing this increase. One possibility could be that the κ-GMP molecule is highly resistant to the action of milk and starter proteases [27]. The 12% TCA-SN/TN ratios which measure both the initial milk NPN and the content of very small peptides and amino acids released by peptidases from the curd increased significantly with aging time (Fig.…”

“…The extraction procedure was determined by an equipment similar to Morris et al [27]. A stainless steel mold was designed and fabricated at Beijing Sanyuan Food Co. Ltd., Hengtai Workshop.…”

“…In this study, the manufacture of a low-moisture Mozzarella cheese is presented, in which the cheese milk was first pretreated using 1.4-μm MF to remove bacteria and then enriched 2.3 times in micellar casein using 0.1-μm MF. As far as we know, although low, medium, and high concentrations of cheese milk using UF for Cheddar and Mozzarella cheese [27] and low (20% more) [28] and high enrichment in micellar casein with preacidification for Mozzarella cheese [1] have been reported, medium-concentration factor (CF) MF milk for cheese-making has not been reported. The consequences of both these pretreatments on the cheese composition, milk component recovery, proteolysis, oiling off, and textural characteristics were determined and compared to those of a control cheese manufactured from normal cheese milk.…”

“…It has made rapid progress because of its potential benefits including higher plant capacity, increased cheese yield, homogeneity of the quality of cheese products, and decreased rennet usage compared to traditional practices. It is now employed for the production of many cheese varieties with specific adjustment of the general parameters to take into account the physicochemical properties of the UF retentates, resulting from the whey protein content and the concentration of micellar calcium [27].…”