Influence of Torula yeast (Candida utilis) as a Fishmeal replacer on rheological and physical qualities of pelleted shrimp feed

Abstract

Global shrimp farming is increasing and it has become the potential in many countries. Fishmeal (FM) has been the major protein sources due to its nutritional qualities as well its reasonable price. The constant FM supply with the increasing demand lead to price elevation. Due to high demand and limited FM supply, many studies to identify the alternative protein sources have been conducted. The acceptable alternative source must have good nutrient qualities, reasonable price, environmental friendly and that cannot compete with human resources such as water, land and food. In this study Torula yeast (TY) Candida utilis seems to meet some of mentioned criteria among the other alternative sources of protein. The objective of this paper was to analyze the influence of TY as a FM replacer on rheological and physical qualities of pelleted shrimp feed. The rheological and physical qualities analyzed were moisture content, tensile strength, water activity (aw), surface water/ oil contact angle (CA) and under water pellet swell (UPS). Six-pelleted treatments were analyzed. In the first five treatments (Tr1, Tr2,Tr3, Tr4 and Tr5). FM were replaced by TY on the amount of 0%, 2.5%, 5%, 10% and 20% respectively whereby the last treatment ( Tr6) was 100% of TY as an ingredient. The rheological and quality characteristics results for all parameters were promising. Among all treatments, the replacement of FM with torula yeast (20%) in the pelleted shrimp feed has more promising rheological and physical qualities to all parameters analyzed. No negative influence on analyzed rheological and physical parameters. Perhaps TY can replace FM in the future.