Effect of Brazil nut oil (Bertholletia excelsa HBK) on the physical, chemical, sensory and microbiological characteristics of a mayonnaise-type emulsion

Abstract

The objective of this study was to evaluate the influence of emulsifiers on the chemicophysical, colorimetric, microscopic and sensorial properties, and the stability of a mayonnaise-type emulsion prepared with Brazil nut oil (Bertholletia excelsa H.B.K). For this purpose, two emulsifiers were used: a soya protein isolate and dehydrated and pasteurised egg yolk as a source of protein. Both formulations had high energy and lipid contents but low mineral and carbohydrate contents. The formulation with egg yolk exhibited higher levels of minerals, such as potassium and calcium, than the emulsion with soya. The mean particle diameter of the Brazil nut-soya emulsion ranged from 8.78 to 24.15 µm, and that of the Brazil nut-yolk emulsion ranged from 0.85 to 22.41 µm, indicating that size directly influences the viscosity of the emulsion. Thus, the Brazil nut-soya emulsion can be characterised as a monodisperse emulsion. The Brazil nut-yolk emulsion was darker, or had lower lightness (L*), compared to the Brazil nut-soya emulsion. The formulation with soya protein was demonstrated to be unsuitable for consumption due to a high microbial load, specifically moulds and yeasts, and was excluded from the sensory evaluation. However, the egg yolk emulsion showed acceptable microbiological parameters according to current legislation. The consumer acceptance means were greater than 6.95 (maximum of 9 on the hedonic scale). Acceptance of the emulsion was also confirmed by purchasing attitude, for which 75% of consumers stated they would purchase the product. Thus, soya protein is not viable for the production of an emulsion with Brazil nut oil, whereas egg yolk is a better emulsifier, which can influence the physicochemical, nutritional and sensory parameters. Additionally, the product can be stored at room temperature, which is an economically feasible feature for the consumer market.