Study On Preparation Of Dry-Cured Ham Base By Fermentation Combined With Enzymatic Hydrolysis Technology

Dry-cured ham as a traditional typical meat products was beloved by humans because of it’s beautiful appearance and the distinct flavor. In this study, ham butt was used as the raw material on dry-cured ham base preparation, through cured, hydrolyzed by netrol protease and netrol lipase, fermentaed by lactobacillus plantarum and saccharomyces cerevisiae, the dry-cured ham base was got.First, protease and lipase salt tolerance and nitrite tolerance were studied to determine the proper salt additive amount and nitrite additive amount. The optimal material pre-process condition was NaCl content 6%, nitrite content 0.15g/kg. Enzymolysis process was optimized by single factor and Box-Behnken design, combined score consisted with sensory score, FAA content and FFA content was used as the evaluation index. The optimal condition was:protease additive amount 650u, lipase additive amount 4000u, enzymatic hydrolysis time 2.5h, enzymatic hydrolysis temperature 45℃, then a 18.19 combined score was got.Starter culture were screened by salt tolerance, nitrite tolerance. Result of salt test showed that under the 6% salt content,0.15g/kg nitrite content most of the strains couldn t grow well except lactobacillus plantarum and saccharomyces cerevisiae. So the two were selected to be the starter cultures. Then growth curve of lactobacillus plantarum and saccharomyces cerevisiae were obtained. It showed logarithmic phase of the two strains were 4-12h and 5-20h respectively. Seed culture solution during this period of time could choose as the starter culture.Enzymatic hydrolysate was fermented by lactobacillus and saccharomyces cerevisiae, fermentation condition was optimized by single factor experiment and orthogonal test, the optimal fermentation condition was:fermentation temperature 30℃, fermentation time 36h, innoculam size 10, strain ratio lactobacillus plantarum:saccharomyces cerevisiae,4:1, 85.2 of sensory score was obtained at last.Several complicated physico-chemical reactions occurring along with dry-cured ham base producing. Changes of physico-chemical index caused by this. Protein reduced from 19.84 of raw meat to 9.09% in the end with 10.75% reduction. Fat content decreased from 15.2% of raw meat to 7.9%. these protein and fat degraded to 3.16% free amino acid and 3.03% free fatty acid. Thus, there also some changes in composition of free fatty acid. pH became 5.03 after fermentation, then reduced to 4.67 through oxidation. Residual quantity of nitrite reduced from 144.00mg/kg to 10.67%mg/kg after fermentation. Acid value kept increasing from 1.26mgKOH/g fat of ham butt to 9.16mgKOH/g of dry-cured ham base after oxidation. Peroxide value increased at first then climbed up at last, from 0.67mg/g of raw material to 0.82mg/g after cured, then decreased to 0.52mg/g after oxidiation.