Texture changes of different apple varieties during storage

Abstract:【Objective】Texture analyzer is the instrument for the objective evaluation of the quality of food by the determination of physical properties. The application of texture analysis can not only characterize the fruit quality, but also can predict the storage period of the fruits. Fruit texture characteristics is one of the important physical properties of apple fruits. In particular, the hardness, brittleness, chewing characteristic, fruit quality are considered as important intrinsic quality characteristics of apple can better distinguish different varieties of apple, or determine the fruit taste. Texture changes are the most significant changes in fruit development and storage, and it is an important indicator of quality evaluation in the process of fruit ripenning and storage. The objective was to tudy the changes of texture properties during storage, and to investigate the optimum evaluation parameters for fruit texture.【Methods】The fruits of‘Gala'‘Jonagold'‘Tsugaru'and‘Fuji'were used as the test materials, textural properties of the flesh of the fruits were investigated by two different textural analysis(texture profile analysis(TPA) and puncture test) during storage, and meanwhile the correlation among the texture parameters were analyzed.The fruits were harvested when the fruits were ripe. The fruit were placed in the room with temperature control. The room temperature was 20±1 degree, relative humidity 90%-95%. The fruits were sampled for TPA test and puncture test on 0、5、10、15、20、25 d, respectively.5 fruits were randomly sampled for TPA test and 5 fruits for puncture test for each variety, respectively. Food analyzer(Technology Corporation Food)TMS-PRO was use for TPA test, using the 75 mm garden column probe. The test speed was60 mm·min-1, the initial force 2N, the flesh deformation 10%. Determination of the parameters were used for flesh hardness, adhesion, cohesion, elasticity, recovery, chewing characteristics. The whole fruit puncture method was used for puncture test. The test probe diameter was 10 mm, the test speed was60 mm·min-1, the puncture depth 10 mm. The parameters were obtained from the flesh hardness, modulus maximum, maximum hardness puncture displacement, peel hardness, peel work, flesh work. These paramaters were automatically calculated by software.【Results】The results showed that, there were some differences in fruit texture among‘Tsugaru'‘Fuji'‘Gala'and‘Jonagold'. Flesh firmness, peel hardness,flesh firmness, maximum modulus of puncture of‘Gala'were higher than those of the other three varieties. The difference among the other three varieties was not obvious. The trend of the changes of flesh firmness, chewiness, resilience, cohesiveness, springiness, peel hardness, flesh firmness, maximum modulus,maximum hardness displacement peel puncture work consistently decreased, but there was a slight difference in the changing trend. Flesh firmness and chewiness of TPA test and peel hardness, flesh firmness,maximum modulus, peel work, flesh work of puncture test of texture index of‘Gala'and‘Jonagold'decreased the more rapidly during storage. On the contrary, these seven texture index of‘Tsugaru'and‘Fuji'decreased relatively lowly. The resilience, cohesiveness, springiness, maximum hardness displacement of the four varieties changed gently. The displacement of the maximum hardness of peel toughness of‘Gala'decreased rapidly and that of,‘Jonagold'‘Tsugaru'and‘Fuji'appeared at different levels. Correlation analysis indicated that there were very significantly positive correlations between flesh firmness,chewiness, springiness, cohesiveness, resilience of TPA test and peel hardness, maximum modulus, maximum hardness displacement, peel puncture work, flesh work besides maximum hardness displacement of puncture test.【Conclusion】There were differences in texture in four apple varieties during storage and there were signification correlations between the textural parameters of TPA and puncture value. In summary, the peel hardness, flesh hardness of‘Gala'was significantly higher than those of‘Jonagold'‘Tsugaru'and‘Fuji'. In post harvest, the texture parameters of‘Fuji'changed slowly, while‘Gala'changed more rapidly during the storage. The Flesh firmness, resilience of TPA test, and peel hardness,maximum modulus and flesh firmness of puncture could be used as the main indexes for the evaluation of the fruit texture.