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来源: Racquel S. Williams, Noureddine Benkeblia  发布日期: 2019-06-05  访问量: 37

标签: 星苹果、采后、呼吸、ICA250、SCS250、ICA56、SCS56

Biochemical and physiological changes of star apple fruit (Chrysophyllum cainito) during different “on plant” maturation and ripening stages

Racquel S. Williamsa, Noureddine Benkebliaa,b,⁎

a Crop Science Laboratory, Department of Life Sciences, The University of the West Indies, Mona Campus, Kingston 7, Jamaica
b Tree and Aromatic Crops Laboratory, The Biotechnology Centre, The University of the West Indies, Mona Campus, Kingston 7, Jamaica

This study aimed to determine the respiration rate, ethylene production, total reducing sugars, total phenolic compounds, chlorophylls, color and firmness of green and purple varieties of star apple fruit (Chrysophyllum cainito) during “on-plant” maturation and ripening in order to contribute determining a ripening index for appropriate harvesting time. Respiration rate (RRCO2) and ethylene production decreased significantly during ripening, although an increase in ethylene was noted at mature stage of the purple variety. Total reducing sugars increased significantly during the three stages, while total phenolic compounds decreased, and skin showed higher level of total phenolics compared to pulp. Similarly, chlorophylls (a+b) and carotenoids in skin decreased during ripening, however, the decrease in carotenoids was less significant compared to the decrease of chlorophylls. Overall, color changed from darker to lighter and duller due to ripening. Firmness also decreased significantly during ripening causing softening of the fruit. Results also showed that color and firmness might be considered as a good ripening index for star apple. Conclusively, star apple does not seem to have a climacteric pattern, and its behavior during maturation and ripening was similar to most of non-climacteric fruits.


2.2. Respiration rate (RRCO2) measurement
The respiration rates (RRCO2) were determined using a static respirometer method as described by Benkeblia et al. (2000). Fruits (200 ± 10 g) were placed in 2-L glass jars previously equilibrated at the required temperature and stored in temperature-controlled rooms (5 and 10 °C) and controlled room temperature (20 °C). For each temperature, jars were closed, and the gas composition of each jar analyzed at seven-time points 0, 1, 2, 3, 4, 5, and 6 h to be able to select only those data associated with aerobic respiration as oxygen is depleted in the jar and CO2 increases. To also avoid changes in pressure in the jars that can occur following the removal of multiple gas samples, the air sample for composition analysis was circulated through the analyzer (model ICA250, International Controlled Atmosphere Ltd Instrument Division, Kent, UK) and back to the chamber. The sampling duration was 2 min. Respiration rates (RRCO2) were calculated by fitting CO2 accumulation data for the seven-time points with a linear regression and expressed as mmol/kg h CO2 and depletion did not exceed 4% during the holding period. For each respiration rate measurement, three jars were used, and measurements were duplicated.

如Benkeblia等人所述,采用静态呼吸计法测定呼吸速率(RRco2)。(2000年)。将水果(200±10 g)放在2-L玻璃罐中,之前在所需温度下平衡,并储存在温度控制室(5和10°C)和控制室温度(20°C)中。对于每个温度,关闭罐,在7个时间点0、1、2、3、4、5和6 h分析每个罐的气体成分,以便在罐中氧气耗尽和二氧化碳增加时仅选择与有氧呼吸相关的数据。为了避免移除多个气体样品后罐内压力发生变化,成分分析用空气样品通过分析(英国国际控制大气有限公司型号ICA250)循环,并返回至试验室。采样时间为2分钟。呼吸速率(RRco2)通过线性回归拟合7个时间点的CO2累积数据计算,以毫摩尔/千克h co2表示,在保持期内消耗量不超过4%。每次呼吸速率测量使用三个罐子,并重复测量。

3. Ethylene production measurement
乙烯产量的测定方法与呼吸速率相同。使用ICA乙烯分析仪(型号ICA56,英国ICA)分析气体样品。乙烯产量通过乙烯产量曲线的线性回归计算,并以nmol/kg h表示。对于每个乙烯测量,也使用三个罐,并重复测量。