| Pinctada fucata muscle,an important low-valued protein resource,has various physiological activities,but has not been fully utilized yet.So it is ideal for the development of natural functional seafood seasoning.However,there are many shortcomings in the flavor and odor of the enzymatic hydrolysate,such as with a poor flavor and a strong fishy smell.In this thesis,the optimum conditions for flavor improvement of Pinctada fucata muscle by enzymatic hydrolysis and microbial fermentation were studied.Its effected on non-volatile and volatile flavors,which were evaluated with sensory evaluation,instrument analysis and chemical analysis,seasoning powder was prepared by spray drying,expecting to provide theory foundation for the development of high-grade seafood seasoning using Pinctada martensii entrails.The main research contents and results are as follows:1.Response surface method was used to optimize the hydroiysis conditions of Pinctada fucata muscle.The effects of the dose of protease,liquid-material ratio,enzymolysis time and enzymolysis temperature were investigated by degree of hydrolysis.The results showed that the optimized conditions were as follows: 5680 U/g of the amount of enzyme,liquid-material ratio 2.8:1(V:m),6.5 h of enzymolysis time,55? of the enzymolysis temperature.Under the optimized conditions,the degree of hydrolysis was 44.27±1.23% which was almost same with the theoretical value.2.Orthogonal experiment method was used to optimize the fermentation process of Pinctada fucata enzymatic hydrolysate.The effects of the dose of protease,strain ratio,seeding amount,temperature,time,were investigated by flavor value and free amino nitrogen content of fermented liquor.On foundation of factor experiment and orthogonal experiment,the following optimal parameter: strain ratio 1:2,seeding amount 4%,fermentation temperature of 32?,time of 80 h.Under these conditions,the sensory evaluation score of the product was 96.77 and the content of free amino nitrogen was 2.83 g/L.3.Volatile flavor compounds in before and after fermentation of Pinctada fucata enzymatic hydrolysates were extracted by headspace solid phase microextraction(HS-SPME),and were analyzed by gas chromatography-mass spectrometry(GC-MS).A total of 77 volatile compounds were identified and quantified in this study.29,56,compounds were found in Pinctada fucata enzymatic hydrolysate and Pinctada fucata hydrolytic liquid,respectively.The main flavor compounds were increasing,among them the area ratio of furfural,benzaldehyde,2,5-octanedione,2-Nonanone,Furancontent had 0.21%,0.09%,0%,0%,0.07% to 1.78%?6.74%?1.16%?1.04%?0.33%.The non-voiatile taste active compounds,including free amino acids,peptides and mineral salts in the enzymatic hydrolysate before and after fermentation were analyzed by chemical analysis and instrument analysis.The results showed that after the mixed fermentation,the content of deliciousamino acid and essential amino acid increased by 6.35% and 2.93%;the content of mineral salts has no significant difference;peptides were the major components before and after fermentation of Pinctada fucata enzymati hydrolysates.There were 5 different molecular weights in enzymatic hydrolysate before and after fermentation,after fermentation,molecular weight distribution indicated that peptides were mainly consisted of <3 KDa fraction,especially <1 KDa fraction was 86.9%.4.Effects of inlet air temperature,flow rate,drying aid species and additionon spray drying technology of Pinctada fucata muscle hydrolysates were investigated by gathering rate of powder and sensory evaluation score.On foundation of single factor experiment,maltodextrin was selected as drying aid.The spaying dying conditions were optimized by orthogonal experiments and results showed that the optimal spray drying condition was inlet air temperature 170?,feed flow rate 2.30 mL/min,maltodextrin addition 25%.Under the conditions,the color of flavouring was faint yellow,gathering rate of powder was 92.1% and sensory evaluation score of the seasoning was 90.0. |
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