ISHS Acta Horticulturae 465: IV International Peach Symposium
DEVELOPMENT OF AN OBJECTIVE AND NON-DESTRUCTIVE HARVEST MATURITY INDEX FOR PEACHES AND NECTARINES |
| Authors: | L.E. Luchsinger, C.S. Walsh |
| Keywords: | Prunus persica, fruit ripening, color, ethylene, firmness, quality |
| Abstract:
The objectives of this study were to develop an objective and non-destructive harvest maturity index based on ground color for peaches [Prunus persica (L.) Batsch] and nectarines (P. persica var. Nectarina), and to evaluate statistical models to predict the maturity stage measured as ethylene evolution rate (EER). After fruit set, peach cv. Redhaven et Elegant Lady, and nectarine cv. July et August Red fruit were tagged in order to follow maturation and ripening on the tree. Before, during and after commercial harvest, 48 fruit of similar diameter and tree position were harvested every 2–4 days. EER (at 20°C), fresh weight, ground and cover color (L*, a*, b*, C* and Hue value) were measured on all 48 fruit. Firmness at several fruit points, TSS, pH, TA and TSS/TA ratio were measured only on 24 fruit, and the rest were held for up to 7 days at 20°C as a ripening period to measure all the parameters mentioned above. Pearson correlation coefficients were determined between variables to explore possible relations with the log of the EER (maturity index). The Stepwise procedure was used for model building. The log of the EER was used as the dependent variable. To test the validity of criteria used in the model and significance of coefficients of independent variables the Regression Procedure of SAS was performed. The models used to predict EER produced varying results depending on the cultivar, but the best fit was found with a quadratic model for ground color a* value (harvest index) with an R2 = 0.69, and fruit firmness (R2 = 0.71). It was also found that fruit softening varies according to the point of measurement in the fruit. | |
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