Development of a milk chocolate added with fish oil and probiotics: physicochemical characterization, sensory acceptability and its effect on cognitive skills of rats

Abstract

Nowadays, new trends have been developed where society seeks to consume healthier foods to improve their health and, consequently, life expectancy. These new eating habits can help prevent neurodegenerative diseases such as Alzheimer's and Parkinson's. Industries seek consumer satisfaction through the development of new-generation, wide-range products, which are called functional foods. These foods have a very high potential to provide both support and prevention for these conditions. The health of future generations is one of the factors that must be taken into account today because childhood is a very important stage for their cognitive development. To satisfy this type of market, the development of functional foods added with bioactive components that help to improve memory and that, in turn, have a pleasant flavor have been increasing. An example may be the use of milk chocolate as a vehicle for compounds that have been found to improve cognitive decline, highlighting omega-3 (ω3) and probiotics. The first phase of this research consisted of developing a milk chocolate added with fish oil and probiotics. The physicochemical characterization [rheology, texture, water activity (aw), instrumental color] and sensory acceptability test of the formulations obtained were carried out. Two different concentrations of FO were added to chocolate, which provided 76.0±5.2 mg and 195.8 ± 6.5 mg of ω3 polyunsaturated fatty acids (PUFAs) per serving size (12 g). Likewise, chocolates were added with probiotics (L. plantarum 299v and L. rhamnosus GG) associated with cognitive function improvement. Chocolates added with both fish oil concentrations showed adequate probiotic bacteria counts (>1x106 CFU per serving size). Likewise, rheology, texture, aw, and instrumental color showed that the treatment that contained a lower concentration of ω3 PUFAs added with probiotics presented a similar behavior as compared with the control. Likewise, this treatment showed adequate overall sensory acceptability (> 7, meaning that it was moderately liked by consumers). Chocolate with the highest concentration of FO showed a low overall acceptability (< 6, around 5.5, meaning that the chocolate neither like or dislike). Therefore, the chocolate formulation containing probiotics and the lower concentration of FO (with 76.0±5.2 of ω3 PUFAs per serving size) was selected to evaluate its effect on rats' development of cognitive skills. In the second phase of this thesis, the effect of chocolate consumption, added with FO and probiotics, on the development of cognitive skills in rats and on the microbial content (Lactobacillus, Bifidobacterium, Enterobacteriaceae, and total bacteria) in the cecum was evaluated. Cognitive skills in rats was determined by the memory and behavior tests using the Barnes open maze test of the individuals in the short (day 1 to 4) and long term (at day 7). Results showed that the great majority of latency times and errors of the Chocolate group improved with respect to the control. Likewise, the combination of chocolate together with fish oil and probiotics showed a positive effect on the memory of rats compared with the effect of the bioactive components added alone. Blood sugar levels, epididymal adipose tissue weight, and brain weight were not affected by the treatments. On the other hand, the consumption of probiotics alone or in combination with chocolate decreased the bacterial count of Enterobacteria, whereas Lactobacillus and Bifidobacteria counts were not affected. Results shown in this thesis showed that chocolate could be used as an adequate vehicle of omega 3 PUFA and probiotics. Furthermore, this chocolate exerted a positive effect on rats' cognitive skills, representing a potential functional food to be introduced in the nutraceutical market. Further studies could be directed performing clinical trials to confirm the positive effect of the formulations on children's cognitive development.