Leites fermentados ou cultivados contendo bifidobacterium: enumeração seletiva das culturas probióticas e bioajustadoras

Abstract

Probiotics are defined as live microorganisms that when administered in adequate amounts, confer a health benefit on the host. Among the several genera of microorganisms with probiotic properties there are the species of Bifidobacterium and Lactobacillus. In some conditions, the bifidobacteria used in the preparation of dairy products lose viability before the end of the useful life of the products due to conditions such as exposure to acid (during or after their fermentation) and contact with oxygen during distribution and storage refrigerated, reaching the consumer with insufficient quantity to exercise their probiotic action. In addition, starter cultures can be added (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus) in the preparation of fermented milks in conjunction with probiotic microorganisms, which bring technological benefits but do not possess probiotic activity. Such microorganisms can mask a result of viable probiotic microorganism count when the enumeration is not selective. The overall objective of this research was to quantify selectively Bifidobacterium sp viable cells in fermented commercial milks as well as bio adjusted cultures. To quantify the probiotic culture were necessary to conduct an assessment of three cultures as productivity for Bifidobacterium and selectivity for bio adjusted cultures through ecometric method. Fermented milks were collected from three different strawberry flavor brands sold in the city of Rio de Janeiro, containing Bifidobacterium sp. Fermented milks were analyzed according to the period of production, group I: up to 20 days after manufacturing and group II 21-45 days of manufacture. When available, were also analyzed full fermented milk and skim. A comparison was also carried out in the probiotic count the use of two solvents: 0.1% peptone water and pre-reduced peptone water. It was concluded that the MRS culture medium and added cysteine was supplemented with antibiotics effective for the isolation of Bifidobacterium sp in fermented milks. The experiment was performed in triplicate using as diluent pre-reduced peptone water. No significant differences were observed in the counts of probiotic cultures and starters regarding the date of manufacture and post this fat content in the milk fermented. It was verified the adequacy of labeling and the agreement of the results of the counts of Bifidobacterium sp, as the values required by legislation. According to statistical method ANOVA, there was a significant effect of diluent on the type Bifidobacterium sp count in fermented milk samples of group I, but significant differences in brands of fermented milks and the interaction between the experimental variables have not been verified. All brands in different manufacturing groups maintain the minimum values in the probiotic count in accordance with the rules for probiotic fermented milks.