Biochemical and physiological changes of star apple fruit (Chrysophyllum cainito) during different “on plant” maturation and ripening stages
蘋果果實在不同“掛樹期”成熟和成熟階段的生化和生理變化
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
A B S T R A C T
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.
本研究旨在測定星蘋果果實在“掛樹期”成熟和成熟過程中的呼吸速率、乙烯生成量、總還原糖、總酚類化合物、葉綠素、綠紫色品種的顏色和硬度，以幫助確定適宜收獲的成熟指數。時間到了。在紫色品種的成熟期，呼吸速率(rrco2)和乙烯產量顯著下降，但乙烯含量增加。三個階段中，總還原糖顯著增加，而總酚類化合物減少，皮膚總酚類含量比紙漿高。同樣地，在成熟過程中，皮膚中的葉綠素(a+b)和類胡蘿卜素減少，然而，類胡蘿卜素的減少與葉綠素的減少相比不那么顯著。總的來說，由于成熟，顏色由深變淺、變暗。在成熟過程中硬度也顯著降低，導致果實軟化。結果還表明，顏色和硬度是蘋果成熟的較好指標。結論星蘋果不具有更年期特征，其成熟和成熟過程與大多數非更年期果實相似。
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，采用靜態呼吸計法測定呼吸速率(RRco2)。(2000年)。將水果(200±10 g)放在2-L玻璃罐中，之前在所需溫度下平衡，并儲存在溫度控制室(5和10°C)和控制室溫度(20°C)中。對于每個溫度，關閉罐，在7個時間點0、1、2、3、4、5和6 h分析每個罐的氣體成分，以便在罐中氧氣耗盡和二氧化碳增加時僅選擇與有氧呼吸相關的數據。為了避免移除多個氣體樣品后罐內壓力發生變化，成分分析用空氣樣品通過分析儀(英國控制大氣有限公司型號ICA250)循環，并返回至試驗室。采樣時間為2分鐘。呼吸速率(RRco2)通過線性回歸擬合7個時間點的CO2累積數據計算，以毫摩爾/千克h co2表示，在保持期內消耗量不超過4%。每次呼吸速率測量使用三個罐子，并重復測量。
3. Ethylene production measurement
乙烯產量的測定方法與呼吸速率相同。使用ICA乙烯分析儀(型號ICA56，英國ICA)分析氣體樣品。乙烯產量通過乙烯產量曲線的線性回歸計算，并以nmol/kg h表示。對于每個乙烯測量，也使用三個罐，并重復測量。
