Preparation of Bifidobacterium breve encapsulated in low methoxyl pectin beads and its effects on yogurt quality

摘要

Yogurt is a popular product worldwide partly becauseof the health-promoting effects of the probiotics that itcontains. Probiotics with high survivability constitutea promising direction for fortified yogurt products.This study aimed to prepare Bifidobacterium breve-loaded yogurt with the bacteria surviving transit to thelower part of small intestine or colon. Bifidobacteriumbreve beads were prepared through an ion-crosslinkingmethod using low methoxyl pectin as the encapsulatingmaterial. Features such as encapsulation efficiencyand stability during storage and passage through thesimulated gastrointestinal tract were studied in vitro.A commercial starter was used for yogurt fermentation,and B. breve with or without encapsulation wasadded as a probiotic supplement with the starter or 3to 4 h after fermentation. The effects of B. breve beadson yogurt characteristics were evaluated after differentfermentation processes: BC, milk fermented withmarketed yogurt starter; UBFF, unencapsulated B.breve added to fresh milk and then fermented; EBFF,encapsulated B. breve added to fresh milk and thenfermented; UBAF, unencapsulated B. breve added afterfermentation with the starter; and EBAF, encapsulatedB. breve beads added 3 to 4 h after fermentation withthe starter. Evaluation was based on texture, electronicnose, and electronic tongue analyses. The particle sizeanalysis of B. breve beads showed that they were uniform,mostly spherical, 1 to 1.5 mm in diameter withencapsulating efficiency higher than 99%. Followingtreatment with the simulated gastrointestinal tractconditions, the number of B. breve decreased by 1.76and 4.82 log cfu/g for B. breve beads and unencapsulatedB. breve, respectively. The EBAF group showedthe lowest viscosity (2,235.67 cP) at d 0, and the lowerpostfermentation degree was reflected by the slow increasein yogurt viscosity. All groups kept a relativelystable pH during storage. The cohesiveness values ofthe EBAF and UBAF groups were significantly higherthan those of the other groups. The trends in texturechanges within the BC, UBFF, and EBFF groups weresimilar, and the UBAF and EBAF groups showed similartrends. In conclusion, B. breve beads showed goodstability in vitro and improved yogurt characteristicsby increasing the survival rate of the encapsulated cells.Good compatibility of low methoxyl pectin beads withyogurt was also observed.