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Relationship between bitterness of brewer’s yeast hydrolysate and hydrophobic amino acid content

In this study, we used enzymatic mixture alcalase and flavourzyme, yeast treatment methods to hydrolyse brewer’s yeast. The hydrolysate and fractions of protein hydrolysate obtained after filtration with 10 kDa and 3 kDa filters were used for determination of bitterness and hydrophobic amino acids content. The bitter taste of hydrolysate was determined by sensory method (using quinine standard) and amino acid content was analysed by HPLC method. | Journal of Science and Technology 54 (2C) (2016) 458-464 RELATIONSHIP BETWEEN BITTERNESS OF BREWER’S YEAST HYDROLYSATE AND HYDROPHOBIC AMINO ACID CONTENT Nguyen Thi Thanh Ngoc1, Quan Le Ha2, * 1 2 East Asia University of Technology, A2CN8, Tu Liem Industrial, Hanoi, Vietnam School of Biotechnology and Food Technology, Hanoi University of Science and Technology, 1 Dai Co Viet, Hanoi, Vietnam * Email: ha.quanle@hust.edu.vn; ngoc.nguyen@polyco.com.vn Received: 15 June 2016 ; Accepted for publication : 28 October 2016 ABSTRACT Brewer’s yeast spent, obtained after the main fermentation stage, is a rich- in-protein source (protein content accounts for 48 - 50 % dry matter). In order to use efficiently this source, it was hydrolysed by different methods. Protein hydrolysate products are normally mixtures of peptides and amino acids. Protein hydrolysates have a wide range of applications in food. It can be used as emulsifying agents in a number of applications such as salad dressings, spreads, ice cream, coffee whitener, cracker, and meat products like sausages. However, bitterness in hydrolysates is one of the major undesirable aspects for various applications in food processing. In this study, we used enzymatic mixture alcalase and flavourzyme, yeast treatment methods to hydrolyse brewer’s yeast. The hydrolysate and fractions of protein hydrolysate obtained after filtration with 10 kDa and 3 kDa filters were used for determination of bitterness and hydrophobic amino acids content. The bitter taste of hydrolysate was determined by sensory method (using quinine standard) and amino acid content was analysed by HPLC method. The result showed the close relationship between bitter taste and hydrophobic amino acid content. The bitter taste of protein hydrolysate was reduced as the hydrophobic amino acid content decreased. When the bitter taste (equivalent to quinine concentration) decreased from 16.25 μmol/l to 3.59 μmol/l, the total content of hydrophobic amino acids in .