Improvement of gelation properties of myofibrillar proteins from porcine longissimus dorsi muscle through microwave combined with air convection thawing treatment

The effects of the microwave combined with air convection thawing(MAT)on the gelling properties of pork myofibrillar proteins(MPs)were further studied and compared with those of fresh meat(FM),and single thawing methods(microwave thawing(MT)and air convection thawing(AT)).Results revealed that the thawing methods,excluding MAT,induced deterioration in the gelling properties of MPs.There was no significant difference(p>0.05)in the water holding capacity(WHC),cooking loss,whiteness,and strength of gel samples subjected to MAT and those of FM samples,demonstrating that the gelling properties were retained after MAT.As well,protein aggregation was limited,since MAT reduced the change in zeta potential and turbidity compared to that observed with MT or AT.The dynamic rheology and scanning electron microscopic results were relatively consistent,revealing that among the different thawing techniques,MAT had the least negative impact on the microstructure of MPs gel,leading to the generation of a more elastic and uniform gel structure than that of the MT or AT gels.Moreover,MAT resulted in higher water retention in the gels than that achieved with MT or AT.These findings indicated that MAT improved the gelling properties of MPs,thereby confirming the suitability of this treatment for use in the meat processing industry.

Biotechnological preparation of chicken skin gelatine using factorial design of experiments

Poultry meat production steadily increases and its by-products including legs or skins may be further utilized to prepare gelatine,generally by using alkali or acid substances.Since they are toxic,different methods are desirable,e.g.applying proteolytic enzymes.Using enzymes is beneficial as they shorten processing time and reduce the required water amount.Processing conditions(the enzyme amount during the pre-treatment,first and second extraction temperature and time)of the process may influence gelatine quality and its yield.In this study,gelatines were prepared from chicken skin at different conditions in the series of combined factorial design of experiments.The significance of the influence of the conditions on the quality(gel strength,viscosity,melting and gelling point)and yield of chicken skin gelatine(CSG)was observed.The highest yield(31.5%)was obtained at the conditions of the enzyme amount of 0.8%,first extraction temperature 80℃ and time 30 min,second extraction temperature 90℃ and time 60 min.Furthermore,the highest CSG quality of gel strength(190 Bloom),viscosity(4.06 mPas),melting point(38.3℃)and gelling point(20.5℃)was obtained at the conditions of 0.2%/50℃/30 min in the first extraction.