Study On Optimization And Fresh - Keeping Technology Of Cantonese - Style

Cantonese stewed pork is used as the experimental material in this thesis. On the basis of traditional cooking methods, it’s combined with candied processing technolog y. We use the sensory score in the orthogonal design test in order to gain the optimal production process. Count of spoilage by selective medium in the cantonese stewed p ork and isolation and identification of them.investigate the initial bacteria of cantonese stewed pork and its change rule. We choose six spices from the stewed material form ulations to study the inhibitory properties of the major spoilage bacteria in cantonese s tewed pork. By exploring the interaction between inhibition of spices, we choose four kinds of natural preservatives which are clove, licorice, cinnamon and nisin. In order t o finalize the fonmulation of complex natural preservative, we use regression test desig n which evaluated by TVB-N. Comparison of pasteurization, irradiation, high temperatu re and pressure these two sterilization treatment after the stewed pork samples for the total number of bacteria and the sensory index sterilization conditions of the stewed po rk had been determined. The main conclusions of this thesis are as follows:(l)The optimal portfolio of cantonese crisp type pickled pork is A2B1C2D4,namely the candied time is8h, candied temperature is4℃, stewed time is15min, stewed te mperature is100℃. Four factors have different effects on the sensory index, candied time, stewed time and stewed temperature are significant, candied temperature is not si gnificant. It had obvious difference between optimization pocess and traditional process. It found that the cantonese stewed pork of optimization pocess can obviously improve the production rate, water content and fat content, in which the production rate increa sed from59.26%to90.81%, the water content increases from32.09g/100g to43.14g/1OOg, the fat content was increased from7.59g/100g to10.68g/100g, so as to improve t he quality of the products.(2) Eleven strains dominant microorganisms of the stewed pork were isolated and preliminary identified. Including two strains of Lactococcu lactis, three strains of Lacto bacillus.sp and Enterobacter aerogenes, micrococcus.sp, Bacillus stearothermophilus, sta phylococcus.sp, Saccharomycodes and Aspergillums each one strain. The initial microflo ra of vacuum packaging cantonese stewed pork at low temperature:lactic aeid bacteria (67.07%), enterobacteriaceae (18.29%) and Bacillus.sp(12.20%).(3)Effective inhibition of six kinds of spices were found based on single factor e xperiments.The extraction of clove was strongly inhibited, it had wide antimicrobial spe ctrum, MIC were less than3.125mg/mL.The extraction of licorice against Lactococcu l actis and Lactobacillus.sp were strongly inhibited. The extraction of cassia against Baci llus.sp, Lactococcu lactis and Saccharomycod.es were strongly inhibited. The extraction of Chinese prickly ash, fennel and star anise had inhibitory effect on some bacteria, b ut is not strong. The extraction of clove and licorice is significantly on the interactivit y inhibition of Bacillus stearothermophilus, Lactococcus lactis and Enterobacter aeroge nes, not significantly on the interactivity inhibition of Lactobacillus.sp and Saccharomy codes.(4) The data model of regression design has high fitting degree and small coeffici ent of variation, it showed that antistaling agent mixed model has significant effects o n the TVB-N, with a high degree of statistical significance. Four kinds of natural pre servatives inhibiting effect relationship:the extraction of clove> the extraction of licor ice> Nisin> the extraction of cassia. The extraction of clove and licorice, the extract ion of clove and Nisin, the extraction of licorice and Nisin are significantly on the int eractivity inhibition, with a high degree of statistical significance. The extraction of cas sia not statistical significantly on the interactivity inhibition. Through the derivation of the model equations, the optimal ratio:corresponding to the extraction of clove is66.05mg/mL, the extraction of licorice is65.80mg/mL, the extraction of licorice is65.80m g/mL, the extraction of cassia is44.69mg/mL and Nisin is0.03mg/mL. Comparison of physicochemical indexes, the shelf life of treatment group is14d longer than the blan k group. The shelf life of the samples stored at (4±1)℃is7d longer than the samples stored at (25±1)℃. The cold condition and addition of compound natural preservativ es is beneficial to prolong the shelf life of stewed pork.(5) Comparing the cantonese stewed pork of sensory evaluation and microbial cha nges by three sterilization method we can see:Pasteurized method can prolong the she If life of cantonese pickled pork about6d,4kGy irradiation method can prolong the sh elf life of cantonese pickled pork about100d,6kGy irradiation method can prolong th e shelf life of cantonese pickled pork about80d, Autoclave sterilization method can pr olong the shelf life of cantonese pickled pork about120d.6kGy irradiation method ha s an obvious effect on the sample color significantly, which turning color orange. So t hat it is not suitable as two sterilization method. The autoclave sterilization method ha s a great influence on texture of the crisp stewed pork, so that it is not suitable as t wo sterilization method. Combined with sensory indicators and microbial indicators, the best sterilization technology is the irradiation dose of4kGy,dose rate of14Gy/min. W ith irradiation sterilization stewed pork can maintain quality, the shelf life is about100d.