高静压杀菌对不同形状果块的黄桃罐头质地的影响

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

    • 摘要: 该文在保证黄桃罐头无菌的前提下,研究了高静压杀菌技术对不同形状果块的黄桃罐头质地的影响。首先通过测定不同的高静压条件下黄桃罐头细菌总数、霉菌和酵母数的变化,并结合热杀菌时间,确定出质地研究的杀菌条件为600 MPa/20 min。再将不同形状果块的黄桃罐头在600 MPa下处理20 min后,以90℃,20 min热杀菌的黄桃罐头为对照,通过测定2种杀菌方式前后及低温和常温贮藏过程中不同形状果块的黄桃罐头果肉硬度、汤汁黏度及果肉细胞结构的变化,得出了高静压杀菌结合低温贮藏技术在罐头质地保持方面的优越性。研究结果表明:高静压杀菌的3种形状果块的罐头果肉硬度分别为热杀菌的2.8倍(“条状”),3.1倍(“丁状”)和2.9倍(“块状”),高静压杀菌后“块状”黄桃罐头汤汁黏度较小,果肉细胞结构较完整;且高静压杀菌后低温贮藏(4±1)℃的黄桃罐头质地品质均优于常温贮藏(25±1)℃。在3种形状果块的黄桃罐头中,无论是低温贮藏(4±1)℃还是常温贮藏(25±1)℃,“块状”的黄桃罐头其果肉硬度最大,汤汁黏度最小,细胞结构破坏程度最小,是最适宜的黄桃罐头加工形状。研究结果为高静压技术取代热杀菌应用于黄桃罐头的加工提供了理论依据。

       

      Abstract: 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℃, 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)℃ were better than those stored at (25±1)℃. Among the three different shapes of flesh, whether YPP were stored at (4±1)℃ or at (25±1)℃, 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.

       

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