Preliminary investigation of the combined effect of heat treatment and incubation temperature on the viability of the probiotic micro-organisms in freshly made yogurt (original) (raw)
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Effect of refrigerated storage temperature on the viability of probiotic micro-organisms in yogurt
International Journal of Dairy Technology, 2007
The effect of refrigerated storage temperature was studied at 2, 5 and 8 ° C on the viability of probiotics in ABY ( Lactobacillus acidophilus, Bifidobacterium lactis BB-12 and yogurt bacteria. Bulgaricus, i.e. Streptococcus thermophilus and Lactobacillus delbrueckii ssp. Bulgaricus) probiotic yogurt. The study was carried out during a 20-day refrigerated storage period to identify the best storage temperature(s). Also, the viability change of the probiotic micro-organisms was analysed at 5-day intervals throughout the refrigerated storage period. After 20 days, storage at 2 ° C resulted in the highest viability of L. acidophilus, whereas for Bifidobacterium lactis the highest viability was obtained when yogurt was stored at 8 ° C.
Pure and Applied Biology
Yogurt is a well-known popular food that contains probiotics, such as Lactobacillus acidophilus, this strain is commonly incorporated in yogurt in some countries. Probiotics of yogurt found to have anti-oxidative properties and boost the immune system. Unfortunately in Pakistan there is no trend of accumulation of probiotics in dairy foods. Present study has been designed to incorporate probiotics in yoghurt, to study the best storage temperature and adequate level of probiotics for best yogurt production. The effect of refrigerated storage temperature at 4, 5 and 6°C on the viability after addition of probiotics (Lactobacillus acidophilus & Bifidobacterium bifidum) in set type yogurt was observed for 28 th day's to identify the best storage temperature for probiotics. The viability of the probiotic microorganisms were analyzed at 07 days interval. Results showed that storage at 4°C showed the highest viability of Lactobacillus acidophilus and Bifidobacterium bifidum probiotics and the lowest viability was observed when yogurt was stored at 6°C.
International Journal of Dairy Technology, 2009
This study investigated the viability of probiotic (Lactobacillus acidophilus LA5, Lactobacillus rhamnosus LBA and Bifidobacterium animalis subsp. lactis BL-04) in milk fermented with Lactobacillus delbrueckii subsp. bulgaricus LB340 and Streptococcus thermophilus TAO (yoghurt-Y). Each probiotic strain was grown separately in co-culture with Y and in blends of different combinations. Blends affected fermentation time(s), pH and firmness during storage at 4°C. The product made with Y plus B. animalis subsp. lactis and L. rhamnosus had counts of viable cells at the end of shelf life that met the minimum required to achieve probiotic effect. However, L. acidophilus and L. delbrueckii subsp. bulgaricus were inhibited.
The survival of two microbial probiotics, Lactobacillus acidophilus and Bifidobacterium infantis, after inoculation into yogurts manufactured from cowmilk and soymilk during storage for 45 days at 4 and 12 °C was investigated. The sensory panel test carried out before the microbiological analyses showed that the flavour of soy yogurts made with cocoa powder or malt did not have the beany taste of soy beans. The survival of L. acidophilus in yogurts was significantly greater than the survival of B. infantis during storage at 4 and 12 °C. At 4 °C, the population remained between 10 7 -10 8 CFU /ml for the former organism throughout the 45 day experiment. B. infantis reached a population of over 10 7 CFU /ml during the first 24 days at both temperatures but then it showed a marked decrease. The survival of B. infantis decreased substantially during storage at 12 o C, when no viable cells were found at day 31. In soy yogurts the survival of both probiotics was quite remarkable; B. infantis showed a significant increase of survival in plain-and flavoured-yogurts and more than 10 6 CFU/ml were detected in cocoa-flavoured yogurts after 38 days of storage.
Iranian Journal of Veterinary Research, 2012
Summary In the present study, the effects of milk supplementation on growth and viability of yogurt (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and probiotic bacteria (Lactobacillus acidophilus and bifidobacteria) were studied during yogurt production and 33 days of refrigerated storage. The incubation time to reach pH = 4.5 was greatly affected by the addition of milk powder (MP), tryptone (TRY) and sucrose (SUC). Also, the increase in titrable acidity depended on added supplement. Viable counts of L. delbrueckii subsp. bulgaricus were significantly (P<0.05) increased in yogurt supplemented with whey powder (WP), TRY and milk powder plus five fold starter culture (MP-SC). However, milk supplementation did not affect the counts of S. thermophilus in probiotic yogurt until the end of storage. Supplementation with TRY and MP-SC promoted the growth and viability of L. acidophilus, whereas milk supplementation with whey protein concentrate (WPC), yeas...
Journal of Food Science, 2002
ABSTRACT: Multiple species cultures, including 2 strains of Streptococcus thermophilus and Lactobacillus acidophilus NCFM plus 1 strain each of Bifidobacterium longum and Lactobacillus casei, were used to make yogurt-like products. The lactobacilli and bifidobacteria were tested for growth in the products and subsequent viability during refrigerated storage. During fermentation, L. casei Com-5 actually declined in numbers, while L. casei E5 and E10 increased about 2 fold. Numbers of B. longum S9 increased about 3 fold while B. longum Com-4 did not increase. During storage, L. acidophilus NCFM appeared stable in all mixtures and both strains of bifidobacteria decreased. Lactobacillus casei E5 and E10 were more stable than was L. casei Com-5.
Journal of Dairy Science, 2014
Currently, the food industry wants to expand the range of probiotic yogurts but each probiotic bacteria offers different and specific health benefits. Little information exists on the influence of probiotic strains on physicochemical properties and sensory characteristics of yogurts and fermented milks. Six probiotic yogurts or fermented milks and 1 control yogurt were prepared, and we evaluated several physicochemical properties (pH, titratable acidity, texture, color, and syneresis), microbial viability of starter cultures (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) and probiotics (Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus reuteri) during fermentation and storage (35 d at 5°C), as well as sensory preference among them. Decreases in pH (0.17 to 0.50 units) and increases in titratable acidity (0.09 to 0.29%) were observed during storage. Only the yogurt with S. thermophilus, L. delbrueckii ssp. bulgaricus, and L. reuteri differed in firmness. No differences in adhesiveness were determined among the tested yogurts, fermented milks, and the control. Syneresis was in the range of 45 to 58%. No changes in color during storage were observed and no color differences were detected among the evaluated fermented milk products. Counts of S. thermophilus decreased from 1.8 to 3.5 log during storage. Counts of L. delbrueckii ssp. bulgaricus also decreased in probiotic yogurts and varied from 30 to 50% of initial population. Probiotic bacteria also lost viability throughout storage, although the 3 probiotic fermented milks maintained counts ≥10 7 cfu/mL for 3 wk. Probiotic bacteria had variable viability in yogurts, maintaining counts of L. acidophilus ≥10 7 cfu/mL for 35 d, of L. casei for 7 d, and of L. reuteri for 14 d. We found no significant sensory preference among the 6 probiotic yogurts and fermented milks or the control. However, the yogurt and fermented milk made with L. casei were better accepted. This study presents relevant information on physicochemical, sensory, and microbial properties of probiotic yogurts and fermented milks, which could guide the dairy industry in developing new probiotic products.
Bacteria Empire, 2019
Currently, the food industry wants to expand the range of probiotic yogurts but each probiotic bacteria offers different and specific health benefits. This study examined the viable counts of Lactobacillus acidophilus and percentage syneresis of probiotic yoghurt produced from reconstituted skim and whole milk powder stored for 35 days at 4±2 o C. Skim milk probiotic yoghurt (SMPY) and Whole milk probiotic yoghurt (WMPY) were produced by reconstituting dry milk powder (130 g/900 ml w/v), which was pasteurized at 85 o C for 15 mins, cooled to 43 o C and inoculated with freeze dried probiotic yoghurt mixed starter culture containing Streptococcus thermophilus (ST), Lactobacillus bulgaricus (LB) and Lactobacillus acidophilus (LA). The yoghurt samples were analyzed for viability of ST, LB, LA and also syneresis. During storage, the viable counts of ST in SMPY decreased from 5.43x10 8 to 5.18x10 6 cfu/ml, LB (2.47x10 8 to 8.10x10 5 cfu/ml) and LA (1.83x10 8 to 5.78x10 5 cfu/ml). Similarly, the viable counts of ST in WMPY decreased significantly from 5.40x10 8 to 5.15x10 6 cfu/ml, LB (2.43x10 8 to 7.82x10 5 cfu/ml) and LA (1.80x10 8 to 5.84x10 5 cfu/ml). Although the mean viable counts of the LA decreased during storage, both SMPY and WMPY still contained an average of 1.48x10 6 cfu/ml of probiotic cells up to 28 days of storage, which is above the "therapeutic minimum" of 10 6 cfu/ml. The percentage syneresis of SMPY and WMPY increased significantly during the 35 days of storage, from 24.4-32.0 % and 24.8-32.7 % respectively. There was a positive correlation between storage time and syneresis thus affecting the texture. In conclusion, yoghurt made from either skim or whole milk powder can be used as an adequate carrier of LA (probiotic bacteria) up to a period of 28 days at 4±2 o C and a stabilizer should be used to reduce the separation of whey and thus maintain the texture.
Technological advances in probiotic stability in yogurt: a review
Research, Society and Development
Yogurt is one of the fermented dairy products widely produced and recognized around the world, in addition it is considered excellent vehicle for probiotics, which are live microorganisms that provide beneficial effects to the individual when consumed in adequate amounts. Thus, the aim of this literature review was to address the factors that affect the viability of probiotics in yogurt during the processing steps (heat treatment, homogenization, and fermentation), storage (acidification rate, pH, carbohydrate fraction, organic acids, oxygen, temperature, time, water activity and moisture content), consumption (gastric juice and bile salts) and shelflife (addition of other ingredients and packaging). However, to preserve the probiotics stability in yogurt and improve the quality and shelf life of products, several new technologies such as microencapsulation, ohmic heating, ultrasound, the addition of prebiotics, and advances in the use of packaging in production with an emphasis on ...
Probiotic Culture Survival and Implications in Fermented Frozen Yogurt Characteristics
Journal of Dairy Science, 2000
Low-fat ice cream mix was fermented with probioticsupplemented and traditional starter culture systems and evaluated for culture survival, composition, and sensory characteristics of frozen product. Fermentations were stopped when the titratable acidity reached 0.15% greater than the initial titratable acidity (end point 1) or when the pH reached 5.6 (end point 2). Mix was frozen and stored for 11 wk at -20°C. The traditional yogurt culture system contained the strains Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The probiotic-supplemented system contained the traditional cultures as well as Bifidobacterium longum and Lactobacillus acidophilus. We compared recovery of Bifodobacterium by three methods, a repair-detection system with rolltubes and plates on modified bifid glucose medium and plates with maltose + galactose reinforced clostridial medium.