Studies On Enzymatic Hydrolysis Processes Of Bovine Bone Protein And Thermal Reaction System Building Of Hydrolysates Hydrolysates

This research mainly focused on three aspects:the dried bovine bone meal was firstly enzymatic hydrolyzed by protease into hydrolysates, and the hydrolyzing process was optimized; secondly, the effect of processing conditions of the thermal reaction between the bone meal hydrolysates and other additives was studied; thirdly, the SPME-GC-MS (Solid Phase Microextraction and Gas Chromatography-Mass Spectrometry) and GC-O (Gas Chromatography Olfactometry) technology were combined to analyze the volatile flavor compounds.Four kinds of protease (Papain, Neutral protease, Alcalase and commercial combined enzyme) were selected for hydrolyzing the bovine bone meal. Hydrolysis conditions were optimized by single factor test and orthogonal test using hydrolysis degree as indicator. The results demonstrated as follow:heat pretreatment under 90℃for 30min can improve the hydrolysis of the bovine bone meal; the optimum hydrolysis conditions using Papain were pH 5.0, temperature 40℃, reaction time 2h, E/S 8000u/g, substrate concentration 1:12.5; the optimum hydrolysis conditions using commercial combined enzyme were pH 6.6, temperature 40℃, reaction time 2h, E/S 10000u/g, substrate concentration 1:14.The effects of hydrolysis under impulse condition and normal condition were compared and the results showed that, the effect of impulse pretreatment was not as good as heat pretreatment and the effect of hydrolysis under impulse condition was not as good as normal condition. Furthermore, the free amino acid composition of the hydrolysates were analyzed and the results showed that, the quantity of free amino acids in hydrolysates which hydrolyzed by commercial combined enzyme reached 79.5866mg/100ml, the quantity of free amino acids in hydrolysates which hydrolyzed by Papain was just 12.0022mg/100ml, and the quantity of free amino acids in hydrolysates which hydrolyzed by Papain under impulse condition was just 2.2238mg/100ml.The hydrolysates which hydrolyzed by Papain were used as the basic material for the thermal reaction. Other additives such as reducing sugar and amino acid were added to produce a bone flavoring juice. Furthermore, other addictives such as salts, spices and stabilizers were added into the juice to form a sauce. The sensory evaluation was used as the indicator and results showed that, the most favored juice was generated at 120℃, pH 7.0 for 40min, with the hydrolysate sample which concentrated once with initial reactant contents:2% xylose and 0.3% cysteine,0.3% thiamin and 0.1% aminoethylsulfonic acid; the most favored sauce was formed using juice which concentrated once with initial reactant contents:1% salts,0.1% spices and 0.6% CMC.The free amino acid composition and the volatile compounds of the thermal reaction products were analyzed. Results showed that, the quantity of free amino acids in thermal reaction products was more than that in hydrolysates, the quantity of free amino acids in hydrolysates which hydrolyzed by commercial combined enzyme reached 94.9614mg/100ml, the quantity of free amino acids in hydrolysates which hydrolyzed by Papain was just 33.8478mg/100ml, and the quantity of free amino acids in hydrolysates which hydrolyzed by Papain under impulse condition was just 31.3200mg/100ml.The thermal reaction products which made from three kinds of hydrolysates were analyzed and the results showed that, three kinds of products all contain furan, aldehyde, alcohols, esters, hydrocarbons. In particular, they all include 2,5-dimethyl-Furan, Furfural, Benzaldehyde and 3,3,3-Trifluoropropene. The differences among three kinds of products were that, products which made by commercial combined enzyme contained pyrane and pyridazine but that made by single enzyme didn't contain; products which made by single enzyme contained acid but that made by commercial combined enzyme didn't contain.61 volatile compounds were identified in products which made by Papain. The volatile compounds contained 24.50% heterocyclic compounds and 70.09% aliphatic compounds.22 volatile compounds were identified in products which made by commercial combined enzyme. The volatile compounds contained 28.90% heterocyclic compounds and 71.12% aliphatic compounds.37 volatile compounds were identified in products which made under impulse condition. The volatile compounds contained 16.21% heterocyclic compounds and 72.97% aliphatic compounds. Finally, the compounds which mainly formed the flavor were discussed.