Chlorophyll fluorescence as a tool to evaluate the ripening of 'Golden' papaya fruit

Fruit classification based on one or more physical or physiological attributes is important to improve quality during storage and marketing. Our objectives were to evaluate changes in chlorophyll fluorescence of papaya fruit (Carica papaya L. cv. Golden) at different ripeness stages and during the ripening to determine if this non-destructive technique might assist the evaluation of fruit ripeness. Maximal (F-m), minimal (F-o), variable (F-v), variable: maximal (F-v/F-m) and maximal:minimal (F-m/F-o) chlorophyll fluorescence, fruit firmness, and skin color (H) were evaluated at three ripeness stages and during the ripening of papaya fruit. Simple and multiple empirical regressions assessed the relationships among all measured parameters. The three ripeness stages were differentiated using the chlorophyll fluorescence parameters. All chlorophyll fluorescence parameters declined with the progress of fruit ripening, where F-m and F-o showed the best correlation with changes in skin color and fruit firmness. This suggests a relationship between the fluorescence and the level of papaya fruit senescence. Chlorophyll fluorescence decline was probably due to chlorophyll degradation and also to the degree of chloroplast membrane injury due to fruit ripeness and senescence. Chlorophyll fluorescence associated with chloroplast function, declined in parallel with the decline of other quality characteristics during papaya fruit ripening. The use of a single parameter to determine the overall quality of papaya fruit may be unreliable, and the chlorophyll fluorescence technique may be a helpful, complementary, non-destructive technology that can be combined with other quality measurement techniques. (C) 2004 Elsevier B.V. All rights reserved.