Chemical and viability changes during fermentation and cold storage of fermented milk manufactured using yogurt and probiotic bacteria

Abstract

The objective of the present work was to study probiotic fermented milks during fermentation process and cold storage. Two strains of probiotic bacteria were used: Lactobacillus acidophilus (LA) and Bifidobacterium animalis subsp. lactis (BL). The yogurt culture Lactobacillus bulgaricus (LB) was used as control. All strains were employed in coculture with the starter Streptococcus thermophilus (ST). Commercial skimmed milk powder was diluted in distilled water (12.4g 100g -1 ) and heat treated. All inoculated milks were incubated for fermentation at 42°C in a water bath until pH 4.50 was reached. Chemical changes during fermentation were followed by measuring: V m (maximum acidification rate that measures the decrease of pH units per minute and the values are expressed as mUpH/min), t Vmax (time to achieve the maximum acidification rate, in h), t pH5,0 (time to achieve pH5.0, in h) and t pH4.5 (time necessary to reach pH 4.5, in h). Rheological behavior was determined at d1 and firmness, pH and viability were followed until 28 days of storage at 4ºC. Fermentation time for probiotic cultures was longer than for yogurt culture. pH decreased and firmness increased during storage. The main change occurred in the first week. Probiotic bacteria grow during fermentation. ST dominated over the other strains and remained stable during all storage period. B. lactis and L. bulgaricus attain the final storage period stable. L. acidophilus, however, decreased before 14 days of storage and at d 28 doesn't fit the minimum requirements to achieve beneficial properties to health.

Microbial, physical and sensory properties of yogurt supplemented with lentil flour

“…It is generally recommended that yogurt or fermented milk should contain at least 10 8 CFU/serving (EFSA, 2010), which represents approximately one million viable cells per gram at the time of consumption. To maintain these numbers, it is important to follow viability during cold storage (Damin, Minowa, Alcântara, & Oliveira, 2006).…”

Effect of Cold Storage on the Nutritive and Microbiological Quality of Fermented Soy Drink from Tamarind and Nono

“…Lactobacillus acidophilus decreased during cold storage until 28 days to a level that doesn't fulfill the minimum viable counts to reach health beneficial effects. Bifidobacterium lactis and yoghurt bacteria remained stable [8]. Health associated benefits related with the consumption of probiotic microorganisms could be concise as: enhancement of immune modulation and prevention of certain diseases and ailments in humans [9,8].…”

“…Bifidobacterium lactis and yoghurt bacteria remained stable [8]. Health associated benefits related with the consumption of probiotic microorganisms could be concise as: enhancement of immune modulation and prevention of certain diseases and ailments in humans [9,8]. The aim of this study was therefore to determine the effect of refrigeration on the nutritive and microbiological quality of fermented soy drink from tamarind and nono.…”