The effect of storage time and temperature on the quality of natural yoghurt

Abstract

Cooling temperature and storage time have a significant effect on the quality of natural yogurts and their durability in retail. The aim of the study was to perform a physicochemical, microbiological and organoleptic assessment of commercial yogurt, immediately after purchase and during 3 weeks of storage at 2°C and 8°C. The following physicochemical parameters were measured: pH, titratable acidity, color (CIEL a*, b*) and basic chemical composition. The organoleptic assessment included the general appearance and color, consistency, aroma and taste and desirability of yogurt. Microbiological tests have determined the amount of Lactobacillus, Streptococcus, Enterobacteriaceae bacteria, and checked the presence of mold and fungi. We have observed a significant effect of storage time on titratable and active acidity in the tested samples. No statistically significant effect of storage time on color of yogurt was observed. As the storage time increased, the number of yogurt microorganisms was decreasing. The minimum normative total amount of lactic acid bacteria was recorded on the day of purchase and after one week of storage at 8°C. As the storage time and the storage temperature increased, the taste and aroma of yogurt was decreasing significantly.

The Effect of Sweet Lupine Seed Hulls on the Probiotic Viability of Strained Yogurt

“…In contrast, as pH values were dropped during the first 7 days, a slight increase was noted on the 14 th day of storage. This result agrees with the previous study conducted by Jakubowska and Karamucki (2020) (Turnbull et al, 2005), which can dilute the produced acidity. An assessment was made of the acidity levels of the strained yogurt supplemented with different concentrations of SLSH.…”

“…Sady et al (2007) reported that the concentration of S. thermophilus and L. bulgaricus in natural yogurt was increased slightly during the first three days, then decreased to the lowest level after 14 days storage. Also, the reduction in S. thermophilus was higher than L. bulgaricus, as S. thermophilus is less tolerant to high acidity, while L. bulgaricus strains can survive in an environment with a pH below 4.0 (Jakubowska and Karamucki, 2020). Generally, the yogurt whey containing large numbers of S. thermophilus, and L. bulgaricus, was lost during the production of the strained yogurt.…”

Lactose Content and Selected Quality Parameters of Sheep Milk Fermented Beverages during Storage

“…In our research, when we examined the color components of the fermented sheep milk beverages, no statistically significant change in their brightness (L*) was found over the 21 days of the storage period. Jakubowska and Karamucki obtained similar results for retailed cow’s milk yogurts [ 44 ]. When the fermented milk drinks in our study were compared on a specific storage day, it was found that Greek-type yogurt had the highest value of this parameter just after production and the lowest on day 21.…”

Water deprivation in poultry in connection with transport to slaughter—a review

“…Magnesium is another electrolyte present in the blood and therefore would be expected to increase in response to water deprivation. Jakubowska et al (2017) exposed birds to 3 pretransport fasting conditions for a 12-h period. The treatment group of birds deprived of both feed and water showed significantly lower blood magnesium concentrations than the treatment with only feed withdrawn and continued access to water.…”