Microencapsulação e estabilidade oxidativa do óleo de castanha-do-Brasil (Bertholletia excelsa) com concentrados proteicos vegetais

Abstract

Microencapsulation is a technique widely used by food industries for the conservation and protection of the natural properties of encapsulated material. Plant proteins have been increasingly applied as a wall material for the protection of compounds with bioactive properties, partially replacing carbohydrates and whey proteins. Brazil nuts (Bertholletia excelsa) is a seed that has about 60% of lipids that are mostly unsaturated fatty acids, mainly oleic and linoleic acids. These acids are related to the decreased incidence of cardiovascular disease. In order to create a method for the conservation of the natural properties of Brazil nut oil, it was encapsulated with three different types of vegetable protein concentrates: rice (CPA), pea (CPE) and soybean (CPS). For this purpose, the vegetable protein concentrates were characterized, and after the drying process, the physical and chemical characteristics of the microcapsules were evaluated, as well as their ability to keep the oil properties stable during storage for six weeks in the dark at 25ºC. During this period, water activity, humidity, acidity and peroxide index and microbiological quality of products were evaluated. The proteins had low solubility (35%) and Zeta potential values close to -30 mV. Thus 15% gum arabic (GA) was added to the emulsions to improve their stability. The most stable emulsion after seven days of evaluation was composed by CPA + GA. The encapsulation efficiency was 79.9 ± 1.4% for CPA + GA, 72.2 ± 0.9% for CPE + GA and 75.0 ± 1.4% for CPS + GA. The micrographs showed a more porous structure for CPE + GA, and the average particle size was as expected for lyophilized products. The acidity and peroxide indexes show that in storage (6 weeks) the microcapsules showed lower signs of oxidation. Humidity was below 3.5% and water activity <0.3 for all encapsulated products. The microorganism count was below 10 6 CFU / g, and the CPA + GA microcapsules were more stable. Fresh oil and microcapsules showed no signs of oxidation during storage (6 weeks) in their respective fatty acid profiles. It is therefore concluded that it is possible to microencapsulate the nut oil and that this product has potential as an ingredient for new formulations.