Study On The Flavor Compounds Formation And Functional Properties In The Maillard Reaction Meat Falworing

Parabramis pekinensis is fresh-water fish, which has off-flavor and a lot of tiny bones. Parabramis pekinensis is only sold fresh currently, rarely processed products existed. Parabramis pekinens is rich in protein, protease hydrolyzed protein is used to prepare fish protein hydrolysate. The fish protein hydrolysate then is used in Maillard reaction to produce meat flavoring, which can not only enhance the economic value, but also provide a new technological method for our fresh-water fish processing. Analysis of the flavor of Maillard reaction flavoring and MRPs'(Maillard Reaction Products) functional properties could provide new idea to the development of Maillard reaction products.Firstly, Parabramis pekinensis protein was hydrolyzed by selecting the appropriate protease enzyme. Then fish protein hydrolysate was added with glucose, using the Uniform Designs to optimize the Maillard reaction conditions and prepare flavoring which had meat flavor. Volatiles from meat flavoring were first investigated by solid phase microextraction (SPME) combined with gas chromatography and mass spectrometry (GC-MS). Then the characteristic compounds which contribute to meat flavor were determined, and the pathway of the formation of which was analyzed the combined with the model reaction. At last chose three methods, DPPH assay, superoxide anion scavenging and ABTS assay to study the antioxidant activity of MRPs, and did initially study of MRPs' antihypertensive activity.The results show that: (1) The optimum process parameters of the Parabramis pekinensis enzymatic hydrolysis were determined by Box-Behnken response surface methodology (RSM). The model equations were regard to the effects of temperature, time, pH and enzyme dosages on the DH. The temperature of 51.5℃, time of 5.7 h, pH 7.7 and enzyme dosage of 0.80% were found to be the optimum conditions to obtain a high degree of hydrolysis of 79.47%(with the model estimates a difference of±0.20) using Flavourzyme and Protamex.(2) The Maillard reaction parameters were optimized by the method of Uniform Designs. Polynomial regression type's mathematical model of reaction system was constructed. The temperature of 110℃, time of 100min, pH of 8.5 and glucose to substrate level of 2.5% were found to be the optimum conditions to obtain a higher score of 3.47 with an error of 0.86% to the prediction score. Under these conditions, prepared sample had a full meat flavor.(3) The volatile compounds which drived from Maillard reaction meat flavoring were identified by SPME-GC-MS. A total of 74 compounds were identified, among those, mostly are nitrogen-and oxygen-containing heterocyclic compounds and aldehyde compounds. The study found pyrazines (2,5-dimethylpyrazine,2,6-dimethylpyrazine), furans (2-pentylfuran and 5-hydroxy-maltol), a number of aldehydes (3-methybutanal,2-methybutanal, hexanal, nonanal and benzaldehyde) and sulfur-containing compounds (dimethyl disulfide, dimethyl trisulfide and 2-hexylthiophene) had a major contribution to meat flavor. Above compounds were identified in others meet products, so it is achievable that Parabramis pekinensis as a material to produce Maillard reaction meat flavoring.(4) The analysis of the formation of some important flavor compounds which drived from Maillard model reaction samples found that mostly saturated aldehydes, ketones and alcohols compounds were identified in the model reaction samples. But some unsaturated aldehydes, ketones and alcohols compounds were identified in self-sample, it supposed that they were derived from the degradation of unsaturated fatty acids. Amino acid degradation products, such as H2S and NH3 could participate in the Maillard reaction to form the nitrogen-and sulfur-containing heterocyclic compounds. Furans and pyrans,such as 2-pentylfuran, could generate not only by Fatty acids degradation but also by the reaction of amino acids and glucose. In addition,5-hydroxy-maltol (2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one) which could enhance the sauce flavor was formed by glucose degradation. Three sulfur-containing compounds might come from other sulfur-containing amino acids,such as cysteine or methionine, because of they were not detected in the model reaction samples.(5) Chose tea polyphenols and TBHQ as a reference substance in order to study on the MRPs'antioxidant capacity in three different anoxidant assays. It found that MRPs in different dilution level had different antioxidant activity and showed a certain degree of concentration-dependent relationship. Here are some results which obtained from three assays and chose IC50 as an evaluation index:In the DPPH assay, 1mL MRPs'effects equaled with 0.28mg tea polyphenols or 0.32mg TBHQ; In superoxide anion scavenging assay,1mL MRPs'effects equaled with 2.66mg tea polyphenols or 3.52mg TBHQ; In ABTS assay,1mL MRPs' effects equaled with 0.09mg of tea polyphenols or 0.20mg TBHQ. It believed that MRPs have good antioxidant activity. (1mL MRPs need 0.11g Parabramis pekinensis fish meal preparation).(6) In vitro ACE inhibitory activity experiment, the results obtained from the inhibition of ACE were notable, and within a certain degree in a concentration-dependent relationship. When the MRPs were added 10μl, the inhibition ratio was highest of 57.53%. If continued increasing of concentration, the inhibition was hardly change.In the antioxidant activity and in vitro ACE inhibitory activity experiments, MRPs all showed a good inhibitory effects, and within a certain degree in a concentration-dependent relationship. The inhibition ratio was increased with the increasing of MRPs'concentration. The mechanisms for the antioxidant activity and ACE inhibitory activity were not yet known. It could be thought that some lower molecular volatile compounds could provide hydrogen might have effects in antioxidation. On the other hand, melanoidins had antioxidant capacity and antioxidant activity might come from metal chelating properties..