Investigation On The Taste-active Peptide And Functionality Of Bovine Bone Marrow Extract And The Preparation Of The Maillard Reaction Flavorings

In this study,two meat flavorings were made from bovine bone marrow extract(BBME)and bovine bone marrow extract which was filled with 30% fat(Fat-BBME).The changes of taste substances(amino acids,nucleotides,<1000 Da peptide distribution,taste peptide sequence)during enzymatic hydrolysis and the Maillard reaction were investigated.The Maillard reaction mechanism system was constructed by synthesizing pure taste-active peptide and 13C5-labeled xylose and the typical flavor compounds generated by taste-active peptide were revealed by isotope labeling method.The functional properties of BBME,enzymatic hydrolysate of bovine bone marrow extract(EH-BBME)and the Maillard reaction products(MRPs-BBME)were analysed,so as to improve the nutrition and added value of BBME.Two kinds of MRPs were prepared from BBME and Fat-BBME,respectively.In this process,the range of hydrolysis,selection of enzymes,optimization of enzymatic conditions and the Maillard reaction conditions were investigated.BBME-derived MRPs and EH-BBME-derived MRPs were compared,and the thermal reaction substrate was identified as EH-BBME.The effects of the Maillard reaction precursors derived from different degree of hydrolysis(DH,5-25%)of BBME were investigated,the results suggesting that EH-BBME with DH of 10% was the most suitable DH to produce flavorings.Four enzymes were selected as ProtamexTM,FlavourzymeTM 500 MG,trypsin and papain,as well as the combinations of four enzymes,as a result,the best enzymatic hydrolysis scheme was the combination of ProtamexTM and FlavourzymeTM 500 MG.Single factor experiments and response surface methodology experiments were used to optimize the time of enzymatic hydrolysis,the amount of ProtamexTM and FlavourzymeTM 500 MG.Finally the optimum conditions of enzymatic hydrolysis were developed: both in 50 ?water bath,23433.3 U ProtamexTM and 2914 U FlavourzymeTM 500 MG were added in 50 g BBME,and the enzymatic hydrolysis time was 3.4 h;19950 U ProtamexTM and 2459.5 U FlavourzymeTM 500 MG were added in 50 g Fat-BBME,and the enzymatic hydrolysis time was 5 h.The Maillard reaction formula of BBME and Fat-BBME was optimized by orthogonal experiment.The reaction temperature,time,and the content of xylose,cysteine,BBME/Fat-BBME,VB1,hydrolyzed vegetable protein(HVP)were optimized.The optimum thermal reaction conditions of BBME were determined as follows: xylose 2.6%,cysteine 0.6%,BBME 70%,VB1 1.2%,HVP 10% were mixed uniformly,then reacted 70 min in 125?.The optimum thermal reaction conditions of Fat-BBME were as follows: xylose 2.0%,cysteine 0.5%,Fat-BBME 60%,VB1 1.2%,HVP 12%,then reacted 60 min in 125?.The regulation of umami and kokumi taste-active components in BBME produced during enzymatic hydrolysis and the Maillard reaction was studied.The total content of umami taste-active amino acids(Asp,Glu)was slightly changed during enzymatic hydrolysis and the Maillard reaction.Sweet-taste amino acids(Ser,Pro,Gly,Thr,Ala)had high Maillard reaction activity and consumed a lot during the Maillard reaction.The content of bitter-taste amino acids were reduced after the enzymatic hydrolysis and the Maillard reaction,suggesting the taste of BBME was increasingly improved by such reactions.After enzymatic hydrolysis,the content of nucleotides drastically increased,but it rapidly decreased after the Maillard reaction.These findings suggested that a large amount of such nucleotides might participate in the Maillard reaction and nucleotides should be added to provide adequate thermal reaction base material.Eight umami/kokumi taste-active peptides were identified in BBME and EH-BBME,separately.In contrast,12 peptides were found in the MRPs-BBME.Most of these taste-active peptides had functional characteristics,such as regulating blood sugar and having good benefits to cardiovascular.Eight potential umami/kokumi taste-active peptides were synthesized to confirm sensory characteristics and taste thresholds.The study confirmed that the N-terminal Cys residue could result in strong kokumi taste;by contrast,the C-terminal Cys residue has no such effect.The peptide-labeled xylose reaction model was constructed by pure taste-active peptide Pro-Cys,Cys-Glu,Cys-Met-Thr,Ala-Gln detected from EH-BBME reacted with 13C5-labeled xylose and xylose.Then structured the amino acids-labeled xylose reaction model with corresponding amino acids and labeled/unlabeled xylose to explore the diversity of peptide and amino acid in generation of typical flavor compounds,as well as the mechanism formation pathways.The study showed that xylose was a very important material basis for the production of pyrazines and thiols.Dimethyl trisulfide was not formed on the basis of dimethyl disulfide,but directly formed during the Maillard reaction.Some compounds could be directly formed without the participation of xylose carbon skeleton,indicating that the taste-active peptides could produce unique flavor substances in the process of thermal reaction,providing a mellow and gentle fragrance for flavoring.Antioxidant and antihypertensive effects of BBME were investigated in functional aspects.Both enzymatic hydrolysis and the Maillard reaction could improve the in vitro chemical indicators of reduction ability and antihypertensive ability of BBME,so as to increase the added value of flavoring products.