Preparation of protein products from collagen-rich poultry tissues

Abstract

Chicken stomachs are by-products of the meat industry which are obtained when the poultry is processed in the slaughterhouse; they are animal tissue that contains fat, minerals and proteins (mainly collagen). Chicken stomachs can be used for the preparation of hydrolysates and gelatines of different molecular weight and subsequently applied mainly in the pharmaceutical-, cosmetic- and food industry. The aim of the study was to verify the possibility of extracting gelatines from chicken stomachs after pretreatment with proteolytic enzyme Protamex. Prior to extraction, accompanying non-collagenous proteins were removed from chicken stomachs using 0.2 M NaCl and 0.03 M NaOH. The mixture was then defatted with acetone and Lipolase. The purified collagen was then treated with a proteolytic enzyme and the gelatine was extracted with hot water. The influence of selected technological conditions, which mainly influenced gel strength and process yield, was studied. The extraction conditions were: amount of enzyme added (0.0-0.9%), extraction temperature (63-69 degrees C) and extraction time (1-3 hours). The process yield was 38.80 to 95.90% and the gel strength of hydrolysates/gelatines was 0 to 155 Bloom. The prepared gelatines (with a gel strength of 50-155 Bloom) would be suitable for application in the food industry for the manufacture of confectionery or in the pharmaceutical industry for the production of soft gelatine capsules.