Studies On Microorganism, Physical And Chemical Properties Chang Regulations During Storage And Preservation Techniques

The cured meat products with its color and luster,aroma,flavor and special shape is like by the consumer deeply; But the our national cured meat products can not realize industrialization production due to its thick processing, no hot sterilizing craft, and Limiting produce and circulation by microorganism spoilage .In this thesis, Changs regulation of organoleptic properties , physical and chemical properties and microflora in saltied duck under different storage condition were studied, Isolation and identification of mostly spoilage bacteria, the effect of four preservatives to different spoilage bacteria , Confirming the best concentration by orthogonal experiment were studied too , Discussing possibility of low temperature and the microwave second sterilization and preservatives application to salted duck.The results indicated:1. Original physical and chemical parameter and total bacterial counts of salted duck: pH 6.67, TVB-N9.64, Aw 0.93, TBARS0.4518, total bacterial counts 1.06×104cfu/g.Indicating that the Physical and Chemical properties of the salted duck causes microorganism corruption easily, The higher TBARS value(0.4518) elucidating severe fatty oxidization of the salted duck in baking the stage, And the higher beginning total bacterial counts is main reason for of the salted duck shorter shelf life.2. The different packaging and storage temperature to its pH value, TVB-N value and total bacterial counts has remarkable influence, different ways of Packaging is the main factor of TBARS value, Experiment temperature influences unremarkablely to the vacuum-packed salted duck TBARS value, The main Corruption characteristics of The salted duck packed by preservative film are the pollution of the fungi to cause inferior organoleptic properties and the fatty oxidization and rancidness, and shelf life is only 3-7 days. To the salted duck vacuum-packed, The spoilage microorganism makes use of protein to produce various off-odour amic compounds, slime productiong,gas productiong and ferment to produce acid, were the main characteristics Of inferior salted duck, the shelf life of salted duck vacuum-packed is 14 days in 7°C, 7 days in 25°C.3. Composition of original microflora in salted duck: the predominant spoilage bacteria:lactic acid bacteria (LAB) (41.20%),pseudomonas (38.29%), enterobacteriaceae(16.78%)and micrococcus and staphylococcus (3.08%) are minor, In addition , there are bacillus (0.20%) and Brochothrix thermosphacta (0.12%). The Spoilage microflora of the salted duck took on different chang regulation under different storage temperature condition and packing the way.4. By incubation and morphology characteristics of bacteria and some physiology and biochemistry experimentation , making sure category and genus of bacterium isolated from diffenent me- dium. The results indicated: Lactic acid bacteria(LAB ):Lactobacillus plantarurn, lactobacillus curvatus, Lactobacillus sake, Lactobacillus xylosus, Lactobacillus fructosus. Micrococcus and Staphylococcus: Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus sci-uri, Staphylococcus camosus, Staphylococcus xylosus, Micrococcus luteus; Pseudomonas: Pseudomonas putida, Pseudomonas alcaligenes; Enterobacteriaceae:Enterobacter cloacae, Enterococcus faecalis, Enterococcus saccharolyticus, Enterococcus avium; Bacillus: Bacillus subtilis, Bacillus cereus, Bacillus fastidious.5. The single factor antiseptics bacteriostasis experiment indicated: four kinds of antiseptics (potassium sorbate ,NaL ,Nisin,EDTA-2Na) had different levels effect of bacteriostasis to themain spoilage bacteria in salted duck. An orthogonal experiment design was Used to find the optimum proportion of 4 kinds of antiseptics ,This optimum proportion was:0.01% Nisin,2% NaL,0.3%potassium sorbate,0.3% EDTA-2Na,The results of orthogonal experiment showed :there were cooperation effect of bacteriostasis among four antiseptics.6. By different sterilization ways ,time and organoleptic characteristics observation ,confirming the optimum condition was that sterilization temperature was 65°C～70°C, times was 15 min ,it could reduce greatly Original bacterial counts ,at the same time, and kept organoleptic quality of salted duck. The research also discovered that thermo-sterilization was better than microwave-sterilization for higher fat content product of salted duck, Due tofat melt, bigger water evaporation lose, the organoleptic quality descendding Seriously under microwave heating.7. Application experiment of synthetical preservation technology showed that total bacterial counts of the salted duck products which were sterilized secondly and treated by copulate preservatives was under 10~4 level in 7°C,25°C after 32 days, 15 days.Therefore,the shelf life of products treated could be prolonged 1 month.