Texture difference and storage characteristics evaluation based on texture profile analysis in kiwifruits

 Abstract:【Objective】The texture analyzer has been widely used in the study on texture characteristics of various fruits and vegetables, especially some fruits with post-ripening habit, which have obvious flesh texture changes during softening. The quantitative analysis can be realized by accurately trans- forming the complex and abstract taste of fruits into specific indexes that can reflect the properties of fruit texture, such as hardness, cohesiveness, resilience, adhesiveness and gumminess. The objective of this study was to compare the postharvest texture characteristics and storage properties among different kiwifruit cultivars so as to provide reference for the study on kiwifruit texture, storage and preservation.【Methods】The fruits of Xuxiang, Jinli, White and Sweet White were used as the test materials. Enough fruits were collected at commercial harvesting period and stored at two different temperatures (25 °Cand 4 °C). The fruits stored at 25 °C were tested every 3 days, and the fruits stored at 4 °C were tested every 7 days. Six fruits were randomly sampled for texture profile analysis for each variety, respectively. Flesh texture properties including hardness, adhesiveness, cohesiveness, springiness, chewiness and resilience were measured by the texture analyzer (CT3-25K), using TA/100 probe. The parameters were set as follows: the pre- test and post- test speeds were 2 mm · s- 1 and the mid- test speed was 1 mm · s- 1, within 5 seconds interval between two compressions. The trigger force was 5 g and the target value was 5 mm. The data processing and analysis and picture drawing were carried out using Excel 2019 and SPSS 19 software.【Results】During both 25 °C and 4 °C storage, the overall change trend of texture pa- rameters of four kiwifruit varieties were basically consistent. Among them, the TPA hardness, springi- ness, cohesiveness, chewiness and resilience of kiwifruits decreased, and the adhesiveness increased. At harvest period, the hardness, springiness, cohesiveness, chewiness and resilience of Xuxiang and Jinli were significantly higher than those of White and Sweet White. All the texture parameters of the four ki- wifruit varieties changed dramatically in the early storage at 25 °C and the change of hardness was the most obvious. Within 6 days of storage, the hardness of Xuxiang, Jinli, White and Sweet White de- creased by 60.06%, 90.30%, 22.48% and 17.11%, respectively. At the end of storage, the hardness, adhesiveness, springiness and chewiness of White and Sweet White were significantly higher than those of Xuxiang and Jinli. In general, the changes of the texture parameters of White and Sweet White were relatively smooth, especially in the later stage of storage, and the adhesiveness of the two varieties was always large. At 4 °C, the hardness of White and Sweet White increased slightly after one week of stor- age and then decreased, and the changes of texture parameters of Xuxiang and Jinli tended to be gentle after 5 weeks of storage. At the end of softening, compared with 25 °C, the hardness of Xuxiang and Jinli increased by 27.03% and 44.73%, the springiness increased by 12.42% and 17.11%, the chewiness in- creased by 1.26 times and 1.40 times, separately, while the hardness, springiness and chewiness of White and Sweet White did not significantly increase. The low temperature condition at 4 °C was more favorable for the storage of Xuxiang and Jinli, which effectively improved the springiness and chewi- ness of kiwifruit in the later stage of storage. Correlation analysis showed that there was a significant correlation between texture parameters with four kiwifruit varieties: TPA hardness, cohesiveness, spring- iness, chewiness, and resilience were significantly and positively correlated, but there was mostly nega- tive correlation between the adhesiveness and other texture parameters. In addition, most of the storage indexes of White and Sweet White were close to 0, which indicated that their textures were more stable, and they had the best storage potential under 25 °C conditions. By PCA analysis, two principal compo- nents were extracted from 6 TPA texture indexes, and cumulative variance contribution rate was 92.08%. The two principal components could be used to distinguish these four kiwifruit varieties.【Conclusion】The TPA hardness, adhesiveness, springiness, cohesiveness, chewiness and resilience could be used as the main indexes for the evaluation on the kiwifruit texture. Flesh texture of four kiwifruit vari- eties was different during storage, and most of the TPA texture parameters showed significant and posi- tive correlations. During 25 °C storage, the texture parameters of White and Sweet White changed very slowly, they were more resistant to storage, and Xuxiang was more resistant to storage at 4 °C. The TPA hardness, chewiness and adhesiveness were the important texture parameters to distinguish White and Sweet White from Xuxiang and Jinli.