Logistic regression analysis of factors influencing core breakdown in 'Conference' pears

Core breakdown of ‘Conference’ pears (Pyrus communis L.) is characterised by softening and browning of tissue near the core and is associated with the development of cavities. The disorder causes large economic losses of ‘Conference’ pears in Belgium, stored under controlled atmospheres. Factors that influence development of the disorder, CO2 and O2 concentration, the size and weight of the pear, the picking date and the storage temperature, were investigated. Multiple logistic regression was used to establish prediction and classification models for both internal browning and cavity development. Over-mature fruit was more susceptible to core breakdown during storage. It was also found that pears with a large weight had a higher probability of developing brownheart. R 2 values from 0.7 to 0.92 were obtained between the predicted and measured percentages of brownheart and cavities. The models classified up to 86% of the pears correctly. In a final analysis, the time sequence of the symptoms occurring during core breakdown disorder development was modelled with a generalized logits model. © 2000 Elsevier Science B.V. All rights reserved.