| Chicken soup is one of the traditional chicken products in our country. It is often stewed with low temperature and long time. It is difficult to standardize and industrialize, because of processing time-consuming, less chicken extractables, and fuzzy of formation mechanism in flavor quality. In this paper, study on the effect of three extraction methods(water, Na Cl and papain) on the dissolution of chicken protein,researching the changes of taste substances in chicken soup after thermal reaction. To provide a reference for the industrial production of chicken soup.(1)The influence of different extraction methods on the dissolution of chicken protein. The contents of soluble protein(SB) and free amino acids(FAA) showed an upward trend first and then decreased with the increase of temperature in water-extract of chicken. The content of highest protein was 58.96 mg/g at 10℃, the content of FAA reached a maximum 228.281 mg/100 g at 30℃. The extraction rate of chicken SB showed an upward trend first and then decreased with the increase of solid-liquid ratio,it reached a maximum 22.84%, when solid-liquid ratio was 1:2.The contents of SB and FAA increased gradually with the addition of Na Cl increased, reaching a maximum when addition was 1%, 3.42 mg/g and 232.62 mg/100 g respectively.The contents of SB and FAA increased gradually with the addition of acetic acid increased, reaching a maximum when addition was 0.3%, 46.35 mg/g and 189.650mg/100 g respectively.With the increase of enzymatic temperature, nitrogen recovery rate(NR), the degree of hydrolysis(DH), the content of protein(CP) and polypeptide showed an upward trend and then decreased, all of these indexes got the highest value at 55℃,21.03%, 7.42%, 59.77 mg/g and 0.639 mg/m L respectively. With the increase of enzymatic time, NR, DH, CP and polypeptide showed an upward trend, all of these indexes got the highest value at 120 min, 22.25%, 7.40%, 59.33 mg/g and 0.636 mg/m L respectively. With the increase of enzyme addition, NR, DH, CP and polypeptide showed an increasing trend, all of these indexes got the highest value at 0.16%, 22.63%,8.38%, 56.65 mg/g and 0.662 mg/m L respectively.(2)The influence of thermal reaction on free amino acids in chicken soup. The contents of total free amino acids(TAA) and taste amino acids showed a downward trend first and then increased(p<0.05) with the addition of glucose increased between0% to 4% in enzymatic chicken soup. The content of TAA minimized to 952.229mg/100 m L. The contents of bitter amino acids(BAA), sweet amino acids(SAA) and umami amino acids(UAA) got minimums,463.306 mg/100 m L, 204.847 mg/100 m L,133.870 mg/100 m L respectively.With the time of thermal reaction increased under general pressure conditions, the content of taste amino acids increased in Na Cl extract of chicken after thermal reaction,enzymatic chicken soup showed the same trend, while water extract of chicken got a opposite result. With the increase of heating time,the content of taste amino acids showed a downward trend first and then increased in three kinds of thermal-reaction chicken soup which was made under high pressure conditions.The highest value got at20 min under high pressure, 50.192 mg/100 m L, 966.556 mg/100 m L, 55.380 mg/100 m L respectively.(3)The influence of thermal reaction on volatile flavor substances in chicken soup.There were 52 kinds of volatile compounds detected in control group(0%), the content was 462.86 ng/100 m L. There were 50 to 56 kinds of volatile compounds in enzymatic chicken soup, after glucose added, the content was in range of 800.04 ng/100 m L to2102.00 ng/100 m L, when addition of glucose was 1%, the content reached a maximum.There were 44 to 63, 51 to 62 and 48 to 55 kinds of volatile compounds examined respectively in enzymatic chicken soup, thermal-reaction chicken soup made by Na Cl extract and water-extract got from chicken. The contents of volatile compounds were got maximums, 3525.20 ng/100 m L, 2909.64 ng/100 m L and 1278.24 ng/100 m L respectively.(4)The influence of macroporous resins on the debittering of enzymatic chicken soup. The XDA-200 used in enzymatic chicken soup selectively absorbed BAA, which was the strongest of the four kinds of macroporous resins(XDA-200、AB-8、D3520、HPD400A). The content of BAA was 222.876 mg/100 m L, accounted for 53.35%, after debittered. The content of SAA was 114.393 mg/100 m L, accounted for 27.38%. The content of UAA was 80.532 mg/100 m L, accounted for 19.28%. Compared to the control group, there were a lot of volatile compounds lost in enzymatic chicken soup after debittered by four kinds of macroporous resins. The species reduced from 63 to therange of 32 to 37, and the contents decreased from 3525.20 ng/100 m L to the range of107.63 ng/100 m L to 385.93 ng/100 m L.(5)The comparative study of thermal-reaction chicken soup with the traditional chicken soup. The thermal-reaction chicken soup include enzymatic chicken soup,thermal- reaction chicken soup made by Na Cl extract and water-extract got from chicken, and debittering chicken soup. The contents of FAA was 996.212 mg/100 m L,155.737 mg/100 m L, 149.680 mg/100 m L and 441.202 mg/100 m L respectively in four kinds of thermal-reaction chicken soup. It’s higher than traditional chicken soup(45.726mg/100 m L). The content of BAA was 13.256 mg/100 m L in traditional chicken soup,accounted for 34.91%. The content and ratio of BAA was so close in thermal-reaction chicken soup, which made by Na Cl extract and water-extract got from chicken, 44.519mg/100 m L accounted for 37.69%, and 42.844 mg/100 m L accounted for 37.80%. The content of BAA was higher in enzymatic chicken soup, it was 577.404 mg/100 m L accounted for 68.54%. The content of BAA decreased to 160.549 mg/100 m L accounted for 49.79%, after the enzymatic chicken soup was debittered.There were in range of 36 to 39 volatile compounds detected in traditional chicken soup and thermal-reaction chicken soup. The content decreased in turn: enzymatic chicken soup, debittering chicken soup, thermal-reaction chicken soup made by water-extract, thermal-reaction chicken soup made by Na Cl extract. The volatile compounds in thermal-reaction chicken soup and traditional soup were analyzed by principal component analysis. Screening for volatile compounds were more contributed to chicken soup, as followed:(E)-2-Octenal, 2,4-Decadienal,(2E,6Z)-Nonadienal,(E)-2-Nonena, 2-Dodecenal, trans-2-Octen-1-ol, 2-Pentylfuran,(E)-Hept-2-enal,(2E,4E)-Hepta-2,4-dienal,trans-2-Decenal,Hexanal,trans-2-Hexenal,(E,E)-2,4-Nonadien al. Comprehensive ranking showed that enzymatic chicken soup got the highest score,thermal-reaction chicken soup made by Na Cl extract and water-extract followed,traditional chicken soup was minimum. |
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