| This paper explored the preservation effect of fresh-cut lotus root by treating the ozone water, as for replacing sulfate chemical preservation method. The microorganisms were isolated and identified from the swollen bag of vacuum packaged fresh-cut lotus root, the solubility and the stability was investigated, exploring the preservation effect by ozone water, and compared with traditional sulfite chemical preservation method. This study will provide a reference for other similar products by using ozone water. The main results were as follows:1.Swollen bag of vacuum packaged fresh-cut lotus root was taken to be the materials, by isolating and purifying, then eighteen strains were found, including eight strains of bacteria, three strains of lactic acid bacteria and seven strains of yeast. After doing back inoculation tests, two microbial bacteria and three yeast can cause bulging bags of fresh-cut lotus root. Based on morphological features, physiological features and biochemical features, combined with the VITEK 2 Compact results defined these five kinds of bacteria were Enterobacter cloacae,Bacillus cereus,C. Guilliermondii,C. Famate and C. Iusitaniae;2.Using ozone water generator consisted of ozone generators and water circuit water to generate ozone water, its’ relevant property were measured at 14 ℃, the results showed that: the ozone water concetrations were 0.7 mg/L, 1.2 mg/L, 1.7 mg/L when the ozone generator turned on at 20 min, 50 min and 70 min. Half life of ozonated water was30 min. With different concentrations(0.7 mg/L,1.2 mg/L,1.7 mg/L) and treatment time(2min,5 min,10 min) on five kinds of microorganisms from the package swollen fresh-cut lotus root in the methods suspension quantitative germicidal test,the results showed that the higher concentration of ozone water and the longer precessing time treating the microorganisms, the higher sterilizing rate. Under the conditions of treatment time 5 min,more than 97.00% bactericidal rate to five strains can be achieved at the concentration of ozonated water 1.2mg/L respectively;3.Three different coneentrations of ozone water(0.7 mg/L,1.2 mg/L and l.7 mg/L)were used to treat the fresh-cut lotus root for 5min that were stored at three storage temperatures(4 ℃,14 ℃ and 24 ℃) respectively, the investigation of quality and microbiological index of fresh-cut lotus root by ozone treatment was showed that 1.2mg/L ozone water can inhibit polyphenol oxidase activity, reduce respiration rate, weight loss and total number of colonies, maintain hardness and soluble solids content, but this treatment still caused a degree of browning. Futhermore, under 14 ℃and 24 ℃storage conditions, it promoted browning and deterioration of lotus root;4.Using seven kinds of color agent combined treatment with ozone water to filter the appropriate color fixative, by determining weight loss, browning. Calcium chloride(0.15 % to 0.20 %, 0.25 %), Sodium chloride(0.3 %, 0.5 %, 1.0 %) and phytic acid(0.1 %, 0.2 %, 0.3 %) in combination with 1.2mg/L ozone water treatment respectively,its effect of preservatoin were better. so choosing these three kinds of three concentration of color fixative to doing orthogonal test, a comprehensive analysis of the variance and range was showed the optimum combination treatment was 0.2 % Ca Cl2+ 0.5 % Na Cl+0.2 % PA;5.Though the compared preservation effect of ozone water combined color fixative(0.2 % phytic acid +0.2 % sodium chlorid+0.5 % calcium chloride) treatment with 0.1%sodium bisulfite treated fresh-cut lotus root, the results showed that the treatment more effectively inhibited the lotus’ s PPO activity and browning degree, maintained a higher hardness and soluble solids, reduced the weight loss, the total plate count and respiration,extended the storage duration of fresh-cut lotsus root to 20 days at 4 ℃, and can become a new green preservative of fresh-cut root, replaced sodium bisulfite effectively. |
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