Effects of chitosan and protein hydrolysates on cold-set gelation of salt soluble proteins and raw restructured chicken meat

Abstract

This research was aimed at investigating the proper characteristics of chitosan, chicken protein hydrolysates and their combinations as cold-set binders in chicken salt-soluble protein (SSP) gel and raw restructured chicken meat. The studying factors for chitosan in the SSP model were molecular weight (MW), degree of deacetylation (DD), and concentration (C), each at 3 levels (low, medium, and high), while those of the chicken protein hydrolysates were degree of hydrolysis (DH) at 4 levels and C at 3 levels. The cold-set gels were formed by setting the mixture of 8% w/v SSP and binders at 4 degree celsius for 24 hrs The physico-chemical properties of the formed gels, including pH, color, rheological characteristics, texture, disulfide content, non-denaturing gel-electrophoresis, and gel structure, were determined. The experimental results indicated that chitosan acted as good cold-set binder when using in alkali-precipitated form. The MW, DD and C affected all of the characteristics measured (p<=0.05). The inclusion of chitosan resulted in improvement of texture and rheological characteristics (p<=0.05), increasing of disulfide content (p<=0.05), and improvement of structure of the cold-set SSP gel, while the pattern on non-denaturing gel-electrophoresis remained unchanged. The most appropriate chitosan sample found was that with 1.84x10[superscript 5] Dalton MW, 94% DD and 1.5% by weight. Chicken protein hydrolysates at 6.42-35.80% DH enhanced cold-set gelation ability of SSP (p<=0.05). Both DH and C affected all parameters determined (p <= 0.05). The increase of disulfide content (p<=0.05) and the improvement of texture (p<=0.05), rheological characteristic and structure of the developed gels were observed. Results from the non-denaturing gel-electrophoretic patterns indicated the formation of cold-set gels which were partially stabilized with disulfide bonds. The highest quality improvement was observed in the gel sample containing 3% by weight of the 22.38% DH hydrolysates. When combination of the selected chitosan and hydrolysate samples were used as cold-set binder in SSP gel, the highest quality improvement of the gel was obtained. The most appropriate combination found were 1.5% by weight chitosan and 3% by weight chicken protein hydrolysates. Raw restructured chicken meats were prepared from ground chicken broiler tenderloin meats, 1% sodium chloride and the selected chitosan, hydrolysates or their combinations, and set at 4 degree celsius for 24 hrs before determining physico-chemical properties, including pH, color, rheological characteristics, texture, water binding properties and structure profiles. The experimental results indicated that the selected chitosan, hydrolysates and their combinations functioned as good cold-set binder in raw restructured chicken meats. The improving pattern of all quality characteristics of the raw restructured chicken meat was almost similar to that found in the SSP model system. The best quality product was obtained when combination of 1.5% by weight chitosan 3% by weight hydrolysate were used as the cold-set binder.