Study On The Characteristic Chromatogram Of Amino Acids And Identification Of Production Technology In Soy Sauce

As soy sauce is an important condiment in people's daily life, national and occupation standards were promulgated at 2000. In GB18186-2000 fermented soy sauce and SB 10336-2000 blended soy sauce, the definitions and technical requirements were set,further more the proportion of blended soy sauce in fermented soy sauce cannot be less than 50% and the former one must not be labeled with the latter one. But the blended soy sauce seems to disappear overnight wholly into the labels of fermented soy sauce due to the unceasingly-spread counterfeited products with the lack of regulatory standards of manufacturing and quality test.Aiming to acquire amino acid by the acid hydrolysis, basic hydrolysis and other extract methods of sauce and bean pulp, the characteristic chromatogram of amino acids was obtained by pre-column derivatization and RP-HPLC. The paper studied the species, quantities, and portions of the amino acids. Some conclusions are as following:1. Amino acids were determined by OPA-FMOC pre-column derivatization and RP-HPLC. The derivatization was accomplished by an auto-injector online; The derivatives were separated on a Hypersil AA (125 mm×4.6 mm I.D. and 5μm particle size) and the signals were detected with a programmable fluorospectrophotometer detector. Mobile phase A was 10 mmol·L^-1 pH 7.2 sodium phosphate buffer (PB) , and mobile phase B was PB + methanol + acetonitrile (50 + 35 + 15) (v + v + v). The elution program was 100% A with 0% B at the start (0 minute), and 0% A with 100% B at the end (25 minute) of the program. The 22 amino acids were separated satisfactorily in 25 minutes with R > 1.5 under above conditions. The lowest limit of detection were between 0.2 to 1.0 pmol. The linear correlation coefficients of 22 amino acids were between 0.982 and 0.999 in the range of 5.0 to 250 nmol·mL^-1 of each amino acid injected. The coefficients of variation of retention time and peak area of 22 amino acids were 0.05⁰.50% and 0.7².9%.2. The ratio of arginine and tyrosine is low in fermented soy sauce, separately 3.0% and 1.0%; and by contrast 9.1% and 3.8% in acid hydrolyzed vegetable protein seasoning. This can be one of the references to identify the two kinds of sauce: the larger ratio they cover, the more possible acid hydrolyzed vegetable protein seasoning is added. 3. Fermented soy sauce and blended soy sauce can be identified by measuring tryptophan and ornithine: tryptophan and ornithine exist in fermented sauce by basic hydrolysis and their ratio is stable while they do not exist in acid hydrolyzed vegetable protein seasoning. This can be one of the references to judge the two kinds of sauce: the smaller ratio they cover, the more possible acid hydrolyzed vegetable protein seasoning is added.4. Fermented soy sauce contains more peptides while no peptides are in acid hydrolyzed vegetable protein seasoning. Compared the HAA with the FAA, it can be found that the contents of aspartic acid ,glycine,histidine,arginine,proline are much higher than its equivalent ones in free amino acids, in which aspartic acid,histidine and arginine are separately 49.8%,53.6% and 34.0% higher. Thus this comparison can also be one of the references: the lowerer contents of aspartic acid,histidine and arginine, the more possible acid hydrolyzed vegetable protein seasoning is added.