Comparative Effects of Soft Freezing and Ozone in Preserving the Freshness of Fresh Pork

As a new technology, soft freezing is a new concept proposed in the refrigeration industry in recent years. It can freeze food at-7 ℃, and the frozen food is easy to cut off in a short time for processing. In order to provide evidence for improving the quality of food stored in a refrigerator under soft freezing conditions, a comparative analysis of the changes in pH, total bacterial count, total volatile base nitrogen(TVB-N), the freshness indicator K-value and sensory evaluation was carried out on fresh pork stored in three low-temperature environments, soft freezing at-7 ℃ plus ozone(Ⅰ), soft freezing at-7 ℃(Ⅱ) and-18 ℃ freezing(Ⅲ). The results showed that pork freshness was maintained at the first level over the storage period of 21 d under soft freezing conditions, and at the second level up to 35 d, supporting the use of soft freezing in households. The first grade of freshness was prolonged to 45 d by combined use of soft freezing and ozone treatment through reducing the pH and total bacterial count, and the color was preserved better than under-18 ℃ freezing condition. Thus the combination of soft freezing and ozone has potential for commercial application.