Effect of Ultra High Pressure Combined with Partial Freezing on the Storage Quality of Chicken Soup

Traditional high-temperature sterilization of chicken soup can easily lead to adverse effects on product quality and result in a short storage period, which fails to meet the demands for modern convenience and nutritional consumption. In this study, ultra high pressure combined with partial freezing multi-fence technology was applied to preserve chicken soup, aiming to extend its storage period, reduce nutritional loss, and enhance overall quality. The quality of chicken soup was compared and analyzed using pasteurization, high temperature and high pressure treatment, as well as ultra high pressure (400 MPa for 15 min) combined with partial freezing (−2.5 ℃) storage. Freshness indicators (total bacterial count, fat oxidation, protein oxidation), flavor-related parameters (soluble protein content, free amino acid content, inosine acid content, volatile substances), sensory evaluation scores were used to investigate the effects of these three sterilization methods combined with partial freezing technology on the storage stability and freshness of chicken soup. Furthermore, the impact of ultra high pressure combined with partial freezing technology on changes in the quality attributes of chicken soup during storage was explored. Results demonstrated that the group treated with ultra high pressure combined with partial freezing exhibited favorable microbial load values (with a total colony count only at 2.11 log CFU/mL) after being stored for 100 days. Malondialdehyde (MDA) values differed among the three groups subjected to different treatment methods: Higher MDA levels were observed in the high temperature and high pressure group compared to both pasteurization group and ultra high pressure group. Consistently lower MDA values were found in the ultra high pressure group throughout storage stages when compared against other two groups. The soluble protein content in the ultra high pressure group remained consistently higher at 5.22 mg/mL than that in other two groups. Additionally, the ultra high pressure group exhibited significantly higher levels of flavor substances (phenylalanine, proline, inosine, octanaldehyde, 2-heptanone, 2-amylfuran) compared to the other two groups. These findings demonstrate that the combination of ultra high pressure and partial freezing is more effective than traditional heat treatment in minimizing nutrient loss, preserving sensory quality of chicken soup, and extending shelf life.