Influence of Different Sterilization Conditions on the Growth and Exopolysaccharide of <i>Streptococcus thermophilus</i> and Co-Cultivation with <i>Lactobacillus delbrueckii</i> subsp. <i>bulgaricus</i> OLL1073R-1

Abstract

The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product's qualities. In this study, the fermentation properties of Streptococcus thermophilus, alone and in combination with Lactobacillus delbrueckii subsp. bulgaricus, were evaluated in skim milk that had been subjected to distinct sterilization conditions. Growth, organic acid generation, and EPS production were determined using pasteurized or autoclaved milk. When S. thermophilus was cultivated in pasteurized skim milk, the growth was strain-dependent. On the other hand, growth of S. thermophilus was accelerated in autoclaved milk. Exocellular polysaccharide (EPS) production by L. bulgaricus was not affected by the combination of S. thermophilus strains. Thus, we observed that yogurt fermented by L. bulgaricus was minimally affected by the combination of S. thermophilus strains; growth of L. bulgaricus was maintained under the constant environment. These results should facilitate the development of fermented milk produced from L. bulgaricus in the dairy industry.

An NMR Metabolomics Approach to Investigate Factors Affecting the Yoghurt Fermentation Process and Quality

“…Succinate shows a different behavior, with LB having the greater concentration (data not shown). This was also found in previous studies [ 25 , 26 ]. It was speculated that heat treatment could generate some compounds that alter the carbohydrate metabolism of LB, causing this production of succinate [ 26 ].…”

Characterization of volatile compounds and organic acids in ultra-high-temperature milk packaged in tetra brik cartons

“…[5,38] It was reported that formic acid increased 150 times in sterilized milk compared to pasteurized milk. [33] Formic acid is primarily responsible for the drop in pH. [31] This confirmed that UHT milk with the highest formic acid had the lowest pH value.…”

“…[30][31][32] With these factors the raw milk keeping conditions and the technological process (the severity and method of heat-treatment and homogenization pressure and temperature) and subsequent the storage conditions affect the concentrations of OAs in UHT milk. [3,5,33] There is no available data in literature on the variations and concentrations of OAs in UHT milk samples. The OAs in UHT milk samples are given in Table 2.…”

“…The mean value of succinic acid was slightly lower than that reported by Gadaga et al [36] for UHT milk, and was higher than those (265 and 104 mg/L) in raw milk and pasteurized milk. [32,33] Compared to citric acid, succinic acid showed a wide coefficient of variation (35 versus 23%) which could explain that succinic acid has been derived from the different sources such as the oxidation of fatty acids during heat-treatment [33] and the fermentation of cellulose by cellulolytic bacteria in ruminants. [37] As shown in Table 2, the mean values of lactic and formic acids were higher than the findings (588 and 402 mg/L, respectively) of Ruas-Madiedo et al [34] for cow milk pasteurized at 63°C for 30 min.…”

Different Ultrasound Exposure Times Influence the Physicochemical and Microbial Quality Properties in Probiotic Goat Milk Yogurt

“…Therefore, lactose accumulation ( Table 2 ) accompanied by galactose reduction ( Figure 1 B,F,J; Tables S1 and S2 ) in our US-treated yogurt samples indicates a reduction in the activity of β-galactosidase released by LAB when the US was applied. Then, the glucose released from lactose is converted to pyruvate, which is metabolized by lactic dehydrogenase [ 17 ] or pyruvate-formate-lyase [ 57 ] to lactic acid or formic acid, respectively. Therefore, the highest glucose ( Table 2 ) indicates that exposure times to the US of 3 and 6 min reduced the activity of enzymes converting glucose to organic acids.…”