Applying prior knowledge to model batch keeping-quality of cucumber batches

Keeping-quality of individual cucumbers is limited by the green colour; the keeping-quality of batches of cucumbers is limited by the time it takes before 5% of the cucumbers in the batch reach a predefined colour limit. From literature concerning the synthesis and degradation of chlorophyll and a published colour model (Schouten, Tijskens and Van Kooten 2002) it is known that colour behaviour of individual cucumbers depends on the concentration of protochlorophyllide (Pchl), at harvest. Here a model for the synthesis and degradation of Pchl is proposed for individual cucumbers, assuming that light conditions during growth are a major factor for Pchl synthesis. Subsequently, this individual Pchl model is expanded to a batch model that describes the variation in the Pchl concentration by assuming that differences between cucumbers of the same batch are primarily caused by differences in light conditions during growth. Pchl data were obtained from colour data from six batches from three cultivars (‘Volcan’, ‘Beluga’ and ‘Borja’) over two growing seasons. Pchl data were gathered per batch and compared with the proposed batch model. The variation in the Pchl concentration per batch could be described satisfactorily in terms of the parameters of the proposed Pchl batch model: batch maturity, batch variation (due to differences in light conditions during growth on a batch level) and a cultivar-dependent factor. Estimating this cultivar-dependent factor for new cultivars could be a tool for cucumber-breeding companies to obtain cultivars with an increased keeping-qualit