Studies On Ultra High Pressure Sterilization Of Packaging Pickled Mustard Tubers

Ultra high pressure technology has been used in the food industry for a couple of years. The quality of high pressure sterilized products is usually superior to conventionally heat sterilized products, this applies particularly to texture, colour, flavour and retention of nutrients. Mustard Tuber is our nation's mainly pickled vegetables and one of three pickled vegetables in the world. Packaging pickled mustard tuber has become the popular form in the market, however, is always harassed by the problem of bag inflation. There is little paper that studied the application of ultra high pressure sterilization on pickled vegetables. Effects of ultra high sterilization on packaging pickled mustard tubers were studied, and these are results:1. Effects of ultra high pressure treatments on the microflora of packaging pickled mustard tubers were studied. Three groups of single-facktor experiments and a group of orthogonal experiments were carried on. We found that the best sterilization processes is high pressure treatment at 300 MPa for 20 min that can effectively prevent inflation.2. Six groups of treatment including control group, high pressure process, heat process, high pressure process and heat process with preservatives, pressure process with heat process beforehand on packaging pickled mustard tubers were studied. Mustard tuber treated with pressure has a better sensory evaluation, and the heat group affected flavour. Brittleness of mustard tuber decreased with the prolonging of shelf time, the control group was the worst, the group with preservatives and pressure process with heat process beforehand were nearly not affected(P<0.05). Protein content increased after being treated, the group treated with high pressure has the most marked effect, increased as much as 10%. Amino acid contents of mustard tuber increased after being treated, no significant effect was discovered within the high pressure group and heat group. Heat process decreased the content of nitrite in a significant way.3. Synergistic effect of heat and pressure treatment was studied. The best sterilization process was heated at 70℃for 7 min, then treated at 200 MPa for 20 min. Analysis of variance found that sterilization temperature and pressure significantly affected the results (P<0.05).4. The microbial reason for inflation was studied. Eight bacillises, two yeasts and two molds were isolated from packaging mustard tubers. It showed that two yeasts were the reason for inflation bags in counterevidence experiments. Yeast A was found be alert to temperature, but be tolerant to pressure, and Yeast B had just reversed results. Synergistic effect of heat and pressure was considered to be controlling inflation from happening the most effective and economical way.