RESUMEN
Goat's whey was submitted to two cycles of block freeze concentration process, resulting in concentrate 1 and concentrate 2. Concentrate 1 was added with 5â¯g of inulin and both concentrates were inoculated with Bifidobacterium animalis ssp. lactis BB-12, the concentrates were then denoted as feed solutions 1 and 2, respectively. Feed solutions were spray-dried, resulting in powder 1 and 2. The stability of the bifidobacteria entrapped within the powders was evaluated for both spray-dried powders stored at 4⯰C and 25⯰C for 60â¯days. The spray-dried powders were also evaluated in relation to their physical and thermal properties. It was noted that Bifidobacteria displayed increased stability at refrigeration temperature. Analysis of physical properties indicated that the addition of inulin resulted in increased water solubility. However, both spray-dried powders displayed less flowability, as well as a yellow-greenish color. By evaluating the spray-dried powders thermal properties, it was possible to confirm that goat whey concentrates behave as excellent wall materials.
Asunto(s)
Bifidobacterium animalis/fisiología , Cabras , Inulina/química , Suero Lácteo/química , Animales , Manipulación de Alimentos/métodos , Congelación , Polvos , ProbióticosRESUMEN
Goat milk and goat milk and inulin were used as encapsulating agents of Bifidobacterium BB-12 and applied in Frozen Yogurt (GF2 and GF3, respectively) in order to evaluate the antagonistic effect against Escherichia coli. GF1 is a control containing only Escherichia coli. Simulation of gastrointestinal digestion occurred sequentially. Quantification of Bifidobacterium BB-12 was performed using plate counting while E. coli count was compared with quantification by qPCR with viable and nonviable cell differentiation. The Bifidobacterium BB-12 count was <1.0, 9.23 and 9.11 log CFU g-1 for GF1, GF2 and GF3, respectively. In the ascending colon, all samples showed E. coli counts of approximately 5 log CFU g-1 by plate counting and by qPCR. Throughout the transverse (24â¯h) and descending colon (48â¯h) samples GF2 and GF3 showed decrease in E. coli number. GF3 showed higher decrease of E. coli in the descending colon because of inulin bifidogenic characteristic. The production of organic acids by bifidobacteria was directly related to the decrease in the E. coli count. In plate counts, E. coli was not detected for the GF3 sample in the descending colon. However, when quantified by qPCR the sample presented amplification that corresponded to 3 log CFU g-1. In this way, it was possible to observe the phenomenon of the viable but not-culturable cells of E. coli. Finally, it is recommended the microcapsule produced with goat milk and the inulin for application in goat milk products, due to the better antagonist effect against E. coli.
Asunto(s)
Bifidobacterium animalis/metabolismo , Escherichia coli/metabolismo , Microbiología de Alimentos/métodos , Intestino Grueso/microbiología , Leche/microbiología , Yogur/microbiología , Animales , Congelación , Cabras , Leche/metabolismo , Probióticos/metabolismoRESUMEN
The effects of full-fat goat's milk and/or inulin and/or oligofructose, as carrier agents, were investigated to improve the survival rates of Bifidobacterium BB-12, and the physical properties of the microcapsules under storage conditions. On the day of their manufacture, the microcapsules were evaluated for morphology, particle size, and distribution of fat and bifidobacteria. The viability of the bifidobacteria, moisture and fat content, water activity, solubility, bulk and tapped density, flowability, cohesiveness and color properties were evaluated for 120â¯days at 4⯰C and 25⯰C. The full-fat goat's milk powder with or without inulin as encapsulating agents showed the highest survival rates of Bifidobacterium BB-12 after spray drying and storage. Considering the bifidobacteria survival, both of these spray-dried powders showed the most desirable physical properties, i.e., lowest water activity and solubility, respectively. Both properties are highlighted for better stability of spray-dried powders, with microcapsules, during storage time. These results are credited to full-fat goat's milk (200â¯gâ¯L-1) and the presence of inulin (100â¯gâ¯L-1), besides the fat content showing a high correlation with the solubility values. The lowest volume occupied by the spray-dried powders was noted when oligofructose was used as the carrier agent. The samples that showed the presence of cracks influenced negatively on the bifidobacteria viability. These cracks were responsible by the greater water escape, resulting in powders with more desirable lower water activity. In relation to the color parameters, lower stability was noted when oligofructose was used, while the best stability was also noted for the powders with full-fat goat's milk and/or inulin. During storage time, the best performance was achieved by the microencapsulation process that used only full-fat goat's milk and/or inulin and storage at 4⯰C.