Seleção, otimização da produção e aplicação de óleo microbiano em iogurtes

Abstract

Oleaginous yeasts are able to produce high levels of lipids and have great biomass productivity, for this reason they are excellent candidates for research involving the accumulation and use of microbial oil for various purposes, considering that this oil may be rich in mono and polyunsaturated fatty acids. Many factors can influence the characteristics of the oil produced by yeasts from the use of different yeast species to changes in culture conditions, such as, carbon and nitrogen sources, medium temperature and aeration. These modifications result in a lipid profile with different ratios of some fatty acids. The purpose of this study was the selection and development of an optimal culture medium for oil accumulation by oleaginous yeasts, as well as, extraction of the oil produced, oil microencapsulation and application of it in non fat yogurts. Firstly, this study aimed at the identification (by molecular techniques) of 16 oleaginous yeast strains. They were identified as Yarrowia lipolytica, and the lipid profile of the oil accumulated by them was analyzed. Two strains (QU22 and QU137) were selected for been α-linolenic acid producers. Strains were then evaluated for optimal conditions for lipid accumulation (cultivation time, nitrogen source, shaker speed and incubation temperature). Optimization resulted on cultivation time of 72 hours, peptone as nitrogen source, shaker speed of 150 rpm and temperature of 25 °C. Secondly, strains were cultivated in bioreactors. The use of bioreactors resulted on higher biomass and total lipids production and the oil was extracted at the end of this process and microencapsulated. Microencapsulation process was performed by spray drying, zein protein was used as wall material, and the microencapsulation efficiency of the final products were over 85%. The third part of this study was the use of microbial oil and microencapsulated oil in non fat yogurts as an animal fat substitute. Physicochemical characteristics and lipid profile of yogurts were analyzed for 30 days. In addition, sensory analysis was performed, and results showed that yogurts produced with oil addition were well accepted by consumers, showing the potential application of the oils produced.