Partitioning of starter bacteria and added exogenous enzyme activities between curd and whey during Cheddar cheese manufacture

The microbial and metabolite composition of Gouda cheese made from pasteurized milk is determined by the processing chain

Gouda cheeses of different production batches and ripening times often differ in metabolite composition, which may be due to the starter culture mixture applied or the growth of non-starter lactic acid bacteria (NSLAB) upon maturation. Therefore, a single Gouda cheese production batch was systematically investigated from the thermized milk to the mature cheeses, ripened for up to 100 weeks, to identify the main bacterial species and metabolites and their dynamics during the whole production and ripening. As this seemed to be starter culture strain- and NSLAB-dependent, it requested a detailed, longitudinal, and quantitative investigation. Hereto, microbial colony enumeration, high-throughput full-length 16S rRNA gene sequencing, and a metabolomic approach were combined. Culture-dependently, Lactococcus lactis was the most abundant species from its addition as part of the starter culture up to the first two months of cheese ripening. Afterward, the NSLAB Lacticaseibacillus paracasei became the main species during ripening. The milk was a possible inoculation source for the latter species, despite pasteurization. Culture-independently, the starter LAB Lactococcus cremoris and Lc. lactis were the most abundant species in the cheese core throughout the whole fermentation and ripening phases up to 100 weeks. The cheese rind from 40 until 100 weeks of ripening was characterized by a high relative abundance of the NSLAB Tetragenococcus halophilus and Loigolactobacillus rennini, which both came from the brine. These species were linked with the production of the biogenic amines cadaverine and putrescine. The most abundant volatile organic compound was acetoin, an indicator of citrate and lactose fermentation during the production day, whereas the concentrations of free amino acids were an indicator of the ripening time.

Macroencapsulation of Limosilactobacillus reuteri DSPV002C as nutritional supplement for piglets: Storage stability and survival in gastrointestinal conditions

The aim of this study was to evaluate the protective effect of the encapsulation of Limosilactobacillus reuteri DSPV002C in macrocapsules made from industrial materials during production, storage and under simulated gastrointestinal conditions in vitro and in vivo. The production of macrocapsules involved the evaluation of different wall materials (matrix), namely, gelatin and pregelatinized starch, different inoculums, matrix ratios, and diverse cryoprotectants (whey permeate and maltodextrin). The different macrocapsules were arranged in molds of similar size to pig pelleted food and lyophilized. Then, the viability of the macrocapsules was assessed over time during storage at different temperatures (freezing, refrigeration and room temperature) and atmospheres (vacuum and non-vaccum). The macrocapsules with 10% w/v gelatin+5% w/v pregelatinized starch, permeated (10%, w/v), with a 9:1 inoculum:matrix ratio (GS7.5P9), stored under freezing conditions and vacuum, exhibited the highest viability of L. reuteri DSPV002C (9.3 log CFU/cap until 210 d). Under simulated gastrointestinal conditions, the encapsulated inoculum showed less viability loss (0.58±0.09 log CFU/ml, 26.53%), compared to the free culture (1.56±0.16 log CFU/ml, 2.85%). Finally, by administering GS7.5P9 to pigs, the tolerance of the bacteria to the gastrointestinal environment was verified, with viable counts equal to or greater than 3.72 log CFU/g of fecal matter throughout the trial. In this study, a high-density carrier probiotic macrocapsule of L. reuteri DSPV002C was obtained, which displayed a long shelf life, a suitable shape to be included in pig feed and an adequate survival of viable cells at the site of action.

The effect of storage conditions on the composition and functional properties of blended bulk tank milk

The objective of this study was to investigate the effects of storage temperature and duration on the composition and functional properties of bulk tank milk when fresh milk was added to the bulk tank twice daily. The bulk tank milk temperature was set at each of 3 temperatures (2, 4, and 6°C) in each of 3 tanks on 2 occasions during two 6-wk periods. Period 1 was undertaken in August and September when all cows were in mid lactation, and period 2 was undertaken in October and November when all cows were in late lactation. Bulk tank milk stored at the 3 temperatures was sampled at 24-h intervals during storage periods of 0 to 96 h. Compositional parameters were measured for all bulk tank milk samples, including gross composition and quantification of nitrogen compounds, casein fractions, free amino acids, and Ca and P contents. The somatic cell count, heat stability, titratable acidity, and rennetability of bulk tank milk samples were also assessed. Almost all parameters differed between mid and late lactation; however, the interaction between lactation, storage temperature, and storage duration was significant for only 3 parameters: protein content and concentrations of free cysteic acid and free glutamic acid. The interaction between storage temperature and storage time was not significant for any parameter measured, and temperature had no effect on any parameter except lysine: lysine content was higher at 6°C than at 2°C. During 96 h of storage, the concentrations of some free amino acids (glutamic acid, lysine, and arginine) increased, which may indicate proteolytic activity during storage. Between 0 and 96 h, minimal deterioration was observed in functional properties (rennet coagulation time, curd firmness, and heat stability), which was most likely due to the dissociation of β-casein from the casein micelle, which can be reversed upon pasteurization. Thus, this study suggests that blended milk can be stored for up to 96 h at temperatures between 2°C and 6°C with little effect on its composition or functional properties.