Effect of defatted wheat germ addition on dough empirical rheology

Abstract

Wheat germ is separated during milling as a by-product and the most of the germ is generally used in animal feed formulations. It is the most nutritious part of the wheat kernel and has great potential as a highly nutritious food supplement. However, the raw germ has very short shelf life and limited use due to a high risk of hydrolytic and oxidative rancidity. One of the possible ways to stabilize the wheat germ is to remove the oil fraction. Results obtained in this study showed that defatted wheat germ provides three times as much protein, four times as much dietary fiber (especially insoluble), and eight times as much mineral content than standard wheat flour. Replacement of wheat flour with defatted wheat germ at levels of 0-30% was investigated for its effect on rheological characteristics of dough. Using a Farinograph, it was found that wheat germ addition increased water absorption, dough stability and degree of softening. Development time also increased up to 15% substitution of wheat flour with defatted germ, while at the rates of 20-30% development time decreased to the values similar to control sample (100% wheat flour). Results obtained with Extensograph showed that with increasing the germ level up to 20% the dough energy and extensibility decreased. At level of 5% germ incorporation, resistance of extension increased while futher addition of germ decereased the mentioned parameter. Similar results were obtained with texture analyzer. Wheat flour and mixtures of flour and defatted wheat germ showed extremely high Amilograph peak viscosity.