Protein Quality of Extruded Egg-Based Whole Wheat Snack

Abstract

This paper aims to evaluate the protein quality and the effect of extrusion on the extrudates from whole-wheat flour and chicken egg and also, the effect of storage on amino acid profile and protein solubility of the extrudates. The whole-wheat flour was mixed separately either with the raw whole egg, egg yolk or egg albumen, a twin-screw extruder was used for the extrusion of the samples. After production, one portion of the extrudates was used for initial quality evaluation (protein solubility, protein digestibility and amino acid profile). The second portion was stored at ambient room condition and the third portion was stored at 37 oC in a thermostatically controlled oven. The extrudates were stored for twelve weeks. Ambient room relative humidity and temperature were monitored throughout the period of storage. Amino acid profile of the extrudates were determined at the beginning and at the end of the storage period of the extrudates stored at ambient temperature conditions. Protein solubility of the extrudates were determined at the beginning and subsequently two weeks interval for the samples stored at ambient room condition and the samples stored at 37 oC for ten weeks. Protein digestibility of the extrudates were determined at the beginning for the samples stored at ambient room condition. Data analysis was carried out using one-way analysis of variance. Results show that extrusion cooking decreased the protein digestibility of the samples. Storage had no effect on the protein solubility of the samples which were in the same range (69.50 - 88.50%) in all of the samples. However, temperature of storage had a slight effect, samples stored at 37 oC reduced more in solubility compared to those stored at ambient room temperatures. Storage had no effect on the amino acid contents of the samples.