beta-glucan prepared from spent brewer's yeast as a fat replacer in mayonnaise

Application of beta-glucan prepared from spent brewer's yeast as a fat replacer in mayonnaise was studied. Fat was partially substituted by beta-glucan at levels of 25, 50, and 75% which were referred to as 25B, 50B, or 75B formulations, respectively. The full fat (FF) (100% oil) mayonnaise without beta-glucan substitution was used as a control experiment. Physicochemical, rheological, and microbiological analyses, and sensory evaluation of the FF and reduced fat (RF) mayonnaises were performed. The results indicated that all RF mayonnaises had significantly lower energy content, but higher water content than their FF counterpart and these differences increased with increasing substitution levels of beta-glucan. With regard to pH, there were no significant differences between the FF and RF mayonnaises after one-day storage. However, pH values of the RF samples decreased with an increasing degree of substitution after 2 months storage. In terms of texture, the 50B and 75B formulations showed similar firmness and adhesiveness values as those of the FF sample. Microstructure analysis showed close packing structures of large droplets for the FF and 25B and loose structures of a network of aggregated small droplets for the 50B and 75B samples. Both FF and RF mayonnaises exhibited thixothopic shear thinning behaviour under steady shear tests and were rheologically classified as weak gels under small amplitude oscillatory shear tests. Microbial loadings of all mayonnaises tested were in the acceptable limit throughout the storage time. The RF mayonnaises exhibited higher storage stability than the FF sample. Sensory evaluation demonstrated that mayonnaises substituted with beta-glucan of not more than 50% were acceptable. This study shows good potential for spent brewer's yeast beta- glucan to be used as a fat replacer in mayonnaise. (c) 2005 Elsevier Ltd. All rights reserved.