Effects of high hydrostatic pressure sterilization on texture of yellow peach in pouch with different shapes

Yellow peach in pouches (YPP) is one of the most popular canned fruits in the world, and the texture properties of canned fruit products are important to influence consumers' acceptability However, the textural deterioration often occurred during conventional heat processing. Therefore, there is an urgent need to search for a novel processing technique which has a less detrimental effect on the texture of canned fruit products. High hydrostatic pressure (HHP) technology is one of the alternatives to conventional thermal pasteurization for food, it has the paramount promising applications to satisfy consumer demand for high quality and safe canned fruit products with its advantages to inactivate microorganisms but have minimal sensory changes to the product. In recent years, some authors have studied that HHP was effective in maintaining the texture of fresh-cut fruits, but limited studies evaluated the effect of HHP on the texture of canned fruit during storage. In this study, under the premise of guaranteeing yellow peach in pouch sterile, the effects of high hydrostatic pressure on the texture of yellow peach in pouch with different shapes were evaluated. The inactivation condition is determined by measuring the total aerobic bacteria, yeasts and molds firstly. The texture of yellow peach in pouch (YPP) with different shapes sterilized by high hydrostatic pressure was investigated by determining hardness, syrup viscosity and microscopic structure of YPP, and the results were compared with those from heat (90°C, 20 min) sterilized YPP. The results of inactivation showed that all the microorganisms were completely inactivated by HHP at 600 MPa and 5 min. However, in order to eliminate the time difference compared with heat treatment, and based on the previous studies, 600 MPa and 20 minutes was chosen as the condition of textural research. The results of textural changes indicated that the hardness of different shapes of YPP treated by HHP is 2.8 times (striped), 3.1 times (diced), 2.9 times (blocky) harder than heat-treated ones respectively. The hardness degradation kinetics of YYP indicated that the drop rate of the hardness of YYP treated by HHP is lager and the half-time is shorter than heat-treated ones both during low temperature storage and room temperature storage. Nevertheless, due to the higher initial hardness of YYP treated by HHP, in comparison to the thermal treatment, the residual texture (hardness) was always higher during consumption. Meanwhile, the texture-related indicators of HHP-treated YYP were superior to that of heat-treated YYP. The lowest syrup viscosity and the best cell structure of YPP with blocky flesh processed by HHP were obtained. Furthermore, these textural qualities of YPP stored at (4±1)°C were better than those stored at (25±1)°C. Among the three different shapes of flesh, whether YPP were stored at (4±1)°C or at (25±1)°C, the highest flesh hardness and the lowest syrup viscosity of YYP with blocky flesh were obtained, and the best cell structure was retained during storage, so blocky is the best shape in processing YPP. Based on the study of textural changes of YYP with different shapes of flesh during storage, it can be concluded that, compare with thermal processing, HHP can better preserve the texture of YYP, and blocky flesh is among the best shape of YYP in maintaining the texture. These results can provide reference for industrial production of HHP processed YPP, and HHP is paramount promising in displacing the thermal sterilization in canned food industry.