Application Of Nisin And Other Preservatives In Extending The Shelf-life Of Fresh Mutton Meat

Mutton meat, as a popular food in China, has been consumed for a long time. In recent decades, the consumption of small vacuum-packaged fresh meat has grown rapidly. However, one of the main problems facing the fresh lamb meat product is a short shelf-life and fast spoilage. The purpose of this study was how to use food-grade preservatives to improve the shelf-life of fresh mutton meat packaged.It was seen that the main microflora causing the spoilage of fresh mutton meat consisted of 3 gram-positive bacilli with spore (about 30% of the micro flora), 1 gram-positive coccus (about 2% of the whole microflora), 3 gram-negative spirilla (about 63% of the whole microflora), and 1 gram-negative bacillus (about 5% of the whole microflora).Potassium sorbate, EDTA and nisin were used as preservatives to inhibit the growth of the main strains representative for the spoilage of fresh lamb meat. It was found that 0.25%o potassium sorbate produced a positive inhibition against short G+ spore bacillus with a concentration less than 5xl04cfu/ml. A concentration less than \%o potassium sorbate hardly exerted a complete control towards short G- plump bacillus having a population density of 5x104cfu/ml. It was proved that use of l% potassium sorbute never controlled the growth of G+ coccus, G~ spirilla and enterobacter with a population density of 104cfu/ml.1mmol EDTA completely controlled the growth of G+ short spore bacillus and G+ coccus whose cell density was 5xl04cfu/ml. A level of lmmol EDTA showed a limited inhibition against the growth of G- spirilla with a population density of 105 cfu/ml. However, a level of 10mmol EDTA completely controlled the growth of the G- spiral bacteria having a population density of 105cfu/ml. lOmmol EDTA produced a very significant control towards the growth of G" plump short bacillus with 105cfu/ml. 20mmol EDTA showed a remarkable inhibition against the enterobacter with a population density of 105cfu/ml.Different concentrations of nisin including 25mg/mL, 50mg/mL, 75mg/mL and 100mg/mL were used as bio-preservative to examine its effects against the growth of allstrains leading to the spoilage of fresh mutton meat. It was seen that there was a big difference in nisin's concentrations in inhibiting the spoiling bacteria. Generally speaking, as more as 75mg/mL of nisin significantly inhibited the growth of G+ short spore bacillus, G-plump short bacillus, enterobacter, G'spiral bacteria and G+ coccus having a population density of 105cfu/ml. The growth of G+ short spore bacillus with a population density of 105cfu/ml was almost controlled in the presence of 75mg/mL nisin.Different combined preservatives including potassium sorbate, EDTA and nisin, based on the information from individual preservatives, were tested for their inhibitions against all the strains spoiling fresh mutton meat. The compound preservative consisting of Nisin(25mg/mL)-EDTA(20mmol)-potassium sorbate(l %) showed the most strong inhibition against the growth of the bacteria causing the spoilage of fresh mutton meat. Furthermore, this preservator was employed to improve the quality of small vacuum-packaged mutton meat. A 28-d shelf life of fresh mutton meat was maintained. Compared to controlling samples, an extended shelf life of 5 to 7 days was produced if the combined preservative was used to practice.