| Summary: | 碩士 === 國立宜蘭大學 === 食品科學系碩士班 === 106 === Maillard reaction is one of the central pathways to produce meat flavor, and sulfur-containing compounds of Maillard reaction products show a great influence on aroma. The peptide molecular weight from 1,000-5,000 Da in Maillard reaction products called Maillard peptide does not have a strong taste but it can produce an enhanced effect on flavor.
The protein content of sake lees was comprised for 78.79% of dry basis. In this study, hydrolyzing sake lees by two-stage enzyme then using sake lees enzymatic hydrolysate which had the most amount peptides of molecular weight 1,000－5,000 Da to with xylose, thiamine, and glutathione or cysteine through Maillard reaction prepared meaty flavor. Evaluate the degree of hydrolysis (DH), molecular weight distribution, volatile compounds from Maillard reaction products and sensory evaluation to investigate the relation between enzyme hydrolysis, Maillard peptide, the composition of volatile compounds and sensory evaluation among Maillard reaction products.
First, sake lees were hydrolyzed 1-7 hours by Alcalase, the DH of sake lees hydrolyzed was 22.42% until 5 hours and the molecular weight distribution of hydrolysates the part of 1,000-5,000 Da had the highest ratio was 85.03%. The product hydrolyzed for 5 hours by Alcalase furthermore hydrolyzed for 1－4 hours by Flavourzyme. The DH which Flavourzyme hydrolyzed 2 hours was increased to 29.03%. However, the proportion of 1,000－5,000 Da peptides decreased in time by gel permeation chromatography column analyzing. Hydrolysate (A5F2; S) with Flavourzyme for 2 hours, add xylose (X) and then add thiamine (T) or cysteine (C) or glutathione (G), respectively or mix. In the Maillard reaction, seven kinds of Maillard reaction products such as SX, SXT, SXTC, SXTG, SXGC, SXTGC and XTGC were prepared.
In the consumer sensory evaluation, the Maillard reaction products XTGC and SXTGC had higher consumer acceptability than that of the other products, and SXTGC which adding A5F2 had the best consumer preference. In the descriptive analysis, the odor descriptive contribution of SXTGC had sweetness (jar*), brothy, chicken, fish soup and vegetable etc. odor characteristics which were consumers liking. And Maillard reaction products SXTGC had the most content of Maillard peptides, its overall flavor intensity and meat odor intensity were just about alright.
There are 58 volatile compounds were identified in Maillard reaction products, including furans, aliphatic S compounds, S-substituted furans, thiophenes, aldehydes, alcohols and esters etc. When reactants without thiamine, the products didn't have related compounds from thiamine degradation; without glutathione, some kinds of S-substituted furan in products reduced; while the most important reactant was cysteine, it affected the formation of most sulfur-containing compounds; finally, without cysteine and glutathione, sulfur-containing compounds couldn't be generated. Therefore, SXTGC showed the most amount of sulfur-containing compounds which associated with meaty aroma. Because of the higher content of 2-Methyl-3-furanthiol and 2-Acetyl-3-methylthiophene, SXTGC also had fish and vegetable odor characteristic in addition to meaty odor. Compared with the descriptive analysis of sensory evaluation, the odor of identified volatile compounds of SXTGC could match with the odor descriptions that brothy, chicken, fish soup, seafood, vegetable etc.
In summary, compounds formation in Maillard reaction were been affected by the different precursor, it causes the differences in the molecular weight distribution and composition of volatile compounds. And there is a certain relation between sensory evaluation, the contents of Maillard peptide and odor descriptions of volatile compounds identified by GC-MS.
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