Study of the effect of soy protein isolate on macaroni characteristics

Macaroni and pasta products are one of the favorite dishes in the world. In Iran, it improves its position in family food programs. In recent years, using additives and different components to improve quality and nutritional properties of this product have been used. Soy protein isolate (SPI) added to semolina to improve quality and quantity of protein and amino acid profile of final product such as macaroni. The aim of this study was the effects of adding different level of SPI (1, 2, 4 and 6% on semolina basis) on the properties of macaroni have been investigated. Result showed that by increasing the amount of SPI, water absorption of dough was decreased. Also by increasing the amount of SPI, the value of protein and ash contents were increased. Although the amount of soluble solid, cooking quality index, moisture content and pH value had fluctuation. Sensory evaluation of products in terms of color, taste, chew ability and stickiness were determined by 5 trained panelists. These two samples and control sample were evaluated by 30 untrained panelists with using preference test. The result showed that the sample contained 2% SPI was recognized the best regarding chemical, rhological and cooking quality index. In order to determine amino acid profile, the sample containing 2% SPI and the control sample were analyzed by HPLC. The result indicated that the amounts of amino acids were increased but methionine did not. Lysin and Hysidin showed maximum and minimum increase respectively 32.1% and 2.2%.