Abstract:

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.

Key words: soft freezing, ozone, pork, freshness preservation, freshness