Predicting keeping quality of batches of cucumber fruit based on a physiological mechanism

• Published in: Postharvest biology and technology Vol. 26; no. 2; pp. 209 - 220
• Main Authors: Schouten, Rob E, Tijskens, L.M.M, van Kooten, Olaf
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier B.V 01.09.2002; Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chlorophyll; Colour; Economic plant physiology; Food industries; Fructification, ripening. Postharvest physiology; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Generic; Growth and development; Non-destructive; Protochlorophyllide; Spoilage; Lot; Midi Pyrénées; France; Europe; Protochlorophyllide; Chlorophyll; Non-destructive; Spoilage; Generic; Colour; Fruit; Cucurbitaceae; Shelf life; Processing quality; Cucumis sativus; Forecast model; Metabolism; Degradation; Postharvest physiology; Non destructive method; Keeping quality; Vegetable crop; Photosynthetic pigment; Dicotyledones; Quality; Angiospermae; Spermatophyta; Intraspecific comparison; Measurement method; Cucumber; Cultivar
• ISSN: 0925-5214; 1873-2356
• DOI: 10.1016/S0925-5214(02)00017-0

The keeping quality for a cucumber, defined as the time the colour remains acceptable to the consumer, depends on the state of the chlorophyll metabolism. By building a physiological model of the chlorophyll metabolism for cucumbers and using colour data from cucumbers stored at 12, 20 and 28 °C, the parameters of the model were estimated with time and temperature simultaneously as explaining variables. Colour data were expressed as ratios of the separate intensities of the red, green and blue (RGB) values from a 3CCD digital camera, namely blue/red (B/R) and blue/green (B/G). The explained variance obtained was more than 93%. The model structure is generic in nature and describes the postharvest colour behaviour in time and temperature for cucumbers, irrespective of growing conditions and cultivar. For six batches, from three cultvars over two growing seasons, the batch keeping quality, i.e. the time that 95% of all cucumbers in a batch had an acceptable colour, was obtained at 20 °C. A batch was defined as all cucumbers from one grower, one cultivar and one harvest. It is shown that, for batches grown in the spring season, high (colour) keeping quality related to high resistance against bacterial spoilage. Model parameters were estimated using either B/R or B/G colour data. Comparing the model parameters, it was deduced that the average initial colour measurement, expressed as the ratio of the red and green intensities (R/G), would be indicative for the batch keeping quality. It was possible to predict batch keeping quality, on the basis of initial colour measurements only, with a percentage variance accounted for R 2 adj of 94%. As the basis of the batch keeping quality predictions is a generic model, it might be possible to predict batch keeping quality for many other products which have green colour as the limiting quality attribute.