Abstract:The chicken wings were fried with palm oil. Changes of fatty acids and amino acids in the chicken wings after frying and aroma compounds in the fried chicken wings were analyzed. The totals of fatty acid contents and amino acid contents in the muscles of the chicken wings after frying were both increased. In particular, the ratios of the essential amino acids to total amino acids (EAA /TAA) and the essential amino acids to non-essential amino acids (EAA/NEAA) became higher and reached 43.23%和76.16%, respectively, suggesting the meat nutritive indices were increased. Solvent assisted flavor evaporation combined with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) with frequency detection were utilized to analyze the aroma-active compounds in meat of the fried chicken wings. GC-MS identified 79 compounds while GC-O identified 51 odor-active compounds. The odor activity values (OAV) for those with higher detection frequencies in the GC-O analysis were calculated, of which 25 compounds with OAVs≥1 were considered to be the key aroma compounds in the fried chicken wings. They included dimethyl disulfide, 2-methyl-3-furanthiol, methional, bis(2-methyl-3-furyl)disulfide, 2-methyl-pyrazine, 2,5-dimethyl-pyrazine, 2,3,5-trimethyl-pyrazine, 3-ethyl-2,5-dimethyl-pyrazine, 2-ethyl-3,5-dimethyl-pyrazine, 2-pentylfuran, 2-methylbutanal, octanal, (E)-2-heptenal, nonanal, decanal, (E)-2-nonenal, (E)-2-decenal, benzeneacetaldehyde, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, etc. The research results can provide references for chicken cooking and processing and chicken flavorings preparation.

Abstract:In order to study the optimal enzymatic hydrolysis process for preparing thermal reaction bovine bone flavoring, bovine bone extract (BBE) was used as raw material, and compound enzyme was selected. The effects of enzymatic hydrolysis temperature, enzymatic hydrolysis time, compound enzyme addition amount and compound enzyme addition ratio on the degree of hydrolysis of enzymatic hydrolysate and the sensory score of thermal reaction bovine bone flavoring prepared by Maillard reaction of enzymatic hydrolysate with sugar and amino acid were investigated by single factor and response surface test. The mass ratio of free amino acid was determined by high performance liquid chromatography (HPLC), and the mass ratio of key odor compounds of thermal reaction bovine bone flavoring prepared before and after enzymatic hydrolysis of BBE was analyzed by comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry (GC×GC-O-MS). The results showed that the better enzymatic hydrolysis process of BBE was enzymatic hydrolysis temperature of 50°C, enzymatic hydrolysis time of 4 h, enzyme addition amount of 1250 U/g, and the ratio of compound flavor protease to compound protease was 1: 1. Under this condition, the sensory score was 8.24. Compared with BBE, the mass ratio of 15 free amino acids in the enzymatic hydrolysate increased significantly. The odor profile and taste profile of BBE and enzymatic hydrolysate were measured by electronic nose and electronic tongue. It was found that the nitrogen oxide odor characteristics of enzymatic hydrolysate were enhanced, and the umami, richness and salty taste characteristics of enzymatic hydrolysate were more obvious. The key odor compounds of thermal reaction bovine bone flavoring prepared by BBE and enzymatic hydrolysate were analyzed by solid phase microextraction (SPME) combined with GC×GC-O-MS. A total of 164 volatile odor compounds were identified, including 27 aldehydes, 30 ketones, 12 alcohols, 16 acids, 7 sulfur-containing compounds, 10 esters, 18 pyrazines, 10 furans, 6 thiazoles, 4 thiophenes and 24 other compounds. Through gas chromatography-olfactometry (GC-O) analysis, 74 odor-active compounds were detected. There were 22 key odor compounds with odor activity value (OAV) greater than 1. The most important key odor compounds in the thermal reaction bovine bone flavoring prepared by BBE and enzymatic hydrolysate were bis(2-methyl-3-furanyl) disulfide (OAV was 13078 and 8052, respectively). Compared with the thermal reaction bovine bone flavoring prepared by BBE, 5 new key odor compounds (E,E)-2,4-decadienal, 2-methyl-3-furanthiol, methyl furfuryl disulfide, S-methyl thiohexanoate and β-caryophyllene appeared in the thermal reaction bovine bone flavoring prepared by enzymatic hydrolysate. The purpose of this study was to provide a theoretical basis for the enzymatic hydrolysis process in the industrial production of thermal reaction bovine bone flavoring.

Abstract:As a common food component, fat could interact with cow’s milk allergens, and thereby affecting the extraction effect and detection accuracy of allergens. However, research on degreasing methods for allergens in high-fat complex matrices was rarely reported. Chocolates containing cow’s milk allergens were used to simulate the high-fat complex matrix and decreased by n-hexane, isopropanol, ethyl acetate and lipase. The degreasing rate and protein loss rate were determined, the changes of protein structure, particle size, fat distribution and microstructure were compared, and the concentration of major milk allergens extracted from simulated matrix before and after degreasing were determined by indirect ELISA. The results showed that the sample treated with n-hexane had the highest degreasing rate (87.87%), and the lowest protein loss rate (6.86%). Degreasing would change the spatial structure of proteins, with the overall structure changing from compact to loose, and there is no obvious change in protein in the n-hexane and ethyl acetate treatment groups. The particle size of decreased slightly after degreasing, but the isopropanol treatment caused the protein to aggregate into larger particles, and the particle size increased from 297.9 nm to 445.1 nm. After degreasing by n-hexane and ethyl acetate, the fat distribution in simulated matrix was more uniform and the fat droplets became smaller. The microstructure of the simulated matrix changed from a dense and smooth clump to an incompact and porous structure, while the isopropanol and lipase groups still showed partial agglomeration. The indirect ELISA results showed that the extraction rate of casein in the ethyl acetate group increased by 61.53%, and the concentrations of α-lactalbumin and β-lactoglobulin were highest in the n-hexane group, which were 0.73 mg·mL-1 and 1.89 mg·mL-1, respectively. N-hexane degreasing treatments can significantly improve the extraction effect of cow’s milk allergens in high-fat complex matrices, hoping that the results can provide reference for the accurate detection of allergens in high-fat complex matrix foods.

Abstract:Volatile sulfur-containing compounds (VSCs) have the characteristics of strong aromas and low thresholds, which have important impacts on the flavor of baijiu, wine and other foods. In order to fully understand the distribution differences of VSCs in baijiu, solid phase microextraction (SPME) combined with comprehensive two-dimensional gas chromatography-sulfur chemiluminescence detection was used to analyze the VSCs in the six samples both qualitatively and quantitatively. The differences of VSCs in 6 kinds of Wuling soy sauce aroma-type baijiu samples were investigated using principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA), and hierarchical cluster analysis (HCA). The results demonstrated that there were significant differences in the VSCs contents of the six kinds of soy sauce aroma-type baijiu. Excellent separation of the six samples could be achieved by OPLS-DA. Based on the variable projection importance greater than 1, 14 VSCs were screened out as the different components from the analysis results to distinguish the flavor characteristics of different Wuling samples. The results of HCA showed that the six kinds of soy sauce aroma-type samples could be divided into two categories according to the type and content of VSCs. This study aims to enrich the research on the flavor of baijiu and provide a suggestion for the classification of baijiu grades.