| Pork cured with sweet soybean paste was a traditional meat product in China. After dry-salt, traditional pork cured with sweet soybean paste was fermented with microorganism coming from sweet soybean paste, then dried under natural environment. The processing period of traditional pork cured with sweet soybean paste processing was long, however wet salting, fermentation and drying technology could shorten the processing time. This studies about pork cured with sweet soybean paste were focused on safty, sanitary, preservation and quality control. The aspect of its flavor compounds was studied very little. Analysis of volatile flavor components of pork cured with sweet soybean paste could not only prevent the product of bad flavor, but also take a consult of improving flavor and production technique.Using pork and sweet soybean paste as the main materials, flavor additive, curing and drying conditions were optimized in this experiment. At the same time, changes of physicochemical indices during processing were studied. Furthermore this study had analyzed the volatile flavor components of porks cured with sweet soybean paste coming from different processing technology and its raw material with HS-SPME-GC-MS. The main conclusions were as follow.1. The processing technology of traditional pork cured with sweet soybean paste was cleanout, cure, brush sweet soybean paste and dryness. The preserving composition was sweet soybean paste10%, sodium chloride 4%, sugar 1%, zanthoxylum 0.3% and wine 0.5%.Changes of physicochemical indices of traditional pork cured with sweet soybean paste during processing: (1) Change of pH values: the pH values of muscle was floated around 5.8. The pH values of fat reduced from 6.70 to 5.89. (2) Change of water content: the change of water content presented obvious fall. (3) Change of fat content: the fat content of fat raised slowly, but muscle was almost unchanged. (4) Change of protein content: the protein content of muscle ascended, whereas the fat's was unchanged. (5) Change of sodium chloride content: the sodium chloride content went up sharply during curing. The sodium chloride content of muscle increased gradually during drying, whereas the fat's was below 1%. (6) Change of peroxide value: the POV was low when curing and brushing sweet soybean paste, then raised obviously in prophase of drying and was unchanged during the anaphase of drying. (7) Change of acid value: the AV was went up from 0.85 mg (KOH) / g to 2.14 mg (KOH) / g during processing. (8) Change of propyldialdehyde content: the propyldialdehyde content kept steady in curing, however it moved up slowly after curing.2. The processing technology of unfermentation pork cured with sweet soybean paste was cleanout, cure, dryness and packaging. The preserving composition was sweet soybean paste 10%, sodium chloride 3%, sugar 1%, zanthoxylum 0.3%, wine 0.5%, sodium nitrite 0.013%, sodium isoascorbate 0.07%, multiple phosphate 0.1%.The processing technology of fermentative pork cured with sweet soybean paste was cleanout, cure, fermentation, dryness and packaging. The preserving composition was sweet soybean paste 10%, sodium chloride 3%, sugar 1%, zanthoxylum 0.3%, wine 0.5%, sodium nitrite 0.013%, sodium isoascorbate 0.07%, multiple phosphate 0.1%, starter 2%.Changes of physicochemical indices of new technics product during processing: (1) Changes of pH values: the pH values of fat from unfermentative product reduced quickly in the prophase of curing, however it decreased slowly during the anaphase of curing and drying. The pH values of muscle from unfermentative product ascended at first, then fell. The pH values of fat and the muscle in curing from fermentative product were siminar to unfermentative product, but the pH values of muscle in fermentation decreased sharply and the trend of change lessened on the process of drying. (2) Changes of water content: the change of water content of unfermentative product presented obvious fall, thereinto it fell dramatically during drying and the prophase of curing. Fermentative product went through the loss of water in curing, a improvement on fermentation and volatilization during drying. (3) Changes of fat content: the fat content of fat raised slowly, but the muscle's was floated around 3.00%. (4) Changes of protein content: the protein content of muscle ascended, whereas the fat's was between 2.26% and 2.98%. (5) Changes of sodium chloride content: the sodium chloride content showed a trend of rise. (6) Changes of peroxide value: the POV ascended steadily during processing. (7) Changes of acid value: the AV showed a tendency of rise. (8) Changes of propyldialdehyde content: the change of propyldialdehyde content to new technics product was siminar to traditional product, but the value was lower.3. The GC/MS method was: Shimadzu GCMS-QP2010 (Shimadzu, Japan.) was equipped with a capillary column: DB-5ms and a quadrupole mass filter. The volatile flavor compounds in pork cured with sweet soybean paste and its raw materials were isolated by solid phase microextraction at 60℃for 30min with the fiber of 75μm CAR/PDMS, then desorption in injection port of GC at 250℃for 5min. The split ratio was 15:1. The oven temperature was held at 40℃for 5 min and increase from 40℃to 120℃at the rate of 4℃min-1, from 120℃to 250℃at the rate of 12℃min-1, and the final temperature was maintained for 10min. The flow rate of helium, the carrier gas, was 1 mL min-1. The temperature of injector was 250℃; the ion source temperature and interfacetemperature were 230℃and 250℃, respectively. Other conditions were as follows: ionization energy, 70 eV; mass range 35-500 amu; and scanning rate 0.5 scans's-1.4. 226 species of volatile flavor compounds were identified from pork cured with sweet soybean paste and its raw material with HS-SPME-GC-MS. There were 49 alcohols, 27 aldehydes, 13 acids, 15 ketones, 27 esters, 38 hydrocarbons, 50 oxygen-, nitrogen- and sulfur-containing compounds, 1 aether, 6 others during those compounds.Sweet soybean paste owned the most of volatile flavor compounds, fermentative product was second, traditional product was third, nonfermentative product was fourth and the last is raw pork..The main aroma compounds of Sweet soybean paste were Butanal, 3-methyl-; Butanal, 2-methyl-; Furfural; 2-Furancarboxaldehyde,5-methyl-; Benzaldehyde; Benzeneacetaldehyde; 2,3-Butanediol; 1-Butanol, 3-methyl-; 2-Furanmethanol; 2-Octen-l-ol; Ketone,2-furyl methyl; 2H-Pyran-2-one, 3-acetyl-4-hydroxy-6-methyl-; Ethyl acetate and Acetic acid. The main aroma compounds of pork cured with sweet soybean paste were Butanal, 3-methyl-; Butanal, 2-methyl-; Hexanal; Heptanal; Octanal; nonanal; Linalyl alcohol;2-Octen-1-ol; 1-Butanol, 3-methyl-; Piperitone; Ethyl acetate; Acetic acid and .bata.-Myrcene.5. In conclution, the fermentative pork cured with sweet soybean paste was best. |
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