| dc.description.abstract | Functional foods have been given great attention and demand from consumers because of concern for health and well-being. Divided into several categories, dairy products have stood out as foods that carry numerous functional agents, including probiotics and prebiotics. Probiotics are living and active microorganisms that confer benefits to the intestinal microbiota. On the other hand, prebiotics are nondigestible components by the digestive tract, but fermentable by probiotic bacteria stimulating their activity in the intestinal colon. The presence of probiotic cultures added to probiotic ingredients characterizes a symbiotic food. For the beneficial effect to be conferred by ingestion of this food, it is necessary that the probiotic remains viable and active during the product’s shelf life, and this will depend, among other factors, on the pH, product’s acidity, the substrate concentration, the total solids content, as well as storage time and temperature. In order to characterize and control environmental factors and conditions that directly affect the growth and viability of bacteria in fermented milk, predictive mathematical modeling has been presented as a viable and useful technique. This work evaluated the effects of the total solids content (10, 12.5 and 15 g.100mL-1), prebiotic inulin concentrations (1.5, 2.3 and 3.0 g.100mL-1) and concentration of sucrose (10, 12.5 and 15 g.100mL-1), on the stability of the probiotic Lactobacillus acidophilus in yoghurt during the shelf life of 45 days, through predictive mathematical modeling. In the 15-day period, it was found that only sucrose had a negative statistically significant effect (p≤0,05) on the growth of L. acidophilus, this effect being explained by the substrate inhibition phenomenon caused by excessive amounts of substrate in the medium. On the 30th day, the total solids interactions with the other two variables had a positive effect and on the last day observed, sucrose as well as its interaction with total solids had a negative influence on growth. From the 11 tests obtained, the first 4 treatments were considered ideal because they presented the highest counts over the storage time. In these tests the sucrose concentration was at the lower level (10 g.100mL-1) while inulin and total solids ranged from 1.5 to 3.0 g.100mL-1 and from 10 to 15 g.100mL-1 respectively. It is concluded that only a substrate is needed to increase the stability of the probiotic being this the inulin. Yoghurts presented lactic acid counts higher than 108CFU.mL-1. The tests also met the technical regulation of identity and quality of fermented milks regarding pH, acidity and protein content. The results showed that from the elaboration conditions employed it was possible to obtain a functional yogurt, with probiotic and prebiotic characteristics, of quality and with a longer shelf life. | |
