Quality of agricultural products becomes increasingly important to consumers, and hence to producers and retailers. Quality, however, is il! defined and perceived and evaluated differently by different individuals, or by groups of individuals. Based on problem decomposition, a working theory on quality of agricultural produce was developed. taking the variability in liking and evaluation of quality among humans into account. The realm of quality is decomposed into one part predominantly connected to intrinsic product properties, one part predominantly linked to consumer behaviour and appreciation, and one part predominantly linked to economic and market effects. The first item is covered by this study, the second part is the area of sensory, consumer science and psychology of man, and the last part is covered by market research and economics.Equally important to satisfy consumers with good quality produce while maintaining a competitive position in the market is modelling of quality behaviour. Proper and reliable simulation and prediction of food quality allows the optimisation of the production and distribution process. Based again on problem decomposition, a process-oriented modelling approach was developed, that uses all available information, not only that contained in experimental results, but also the knowledge of experts and theory. Based on both these theories and techniques and to prove their usefulness and added value, a number of models are developed and described covering the processes, intrinsic product properties and attributes that are important in postharvest technology (enzyme activity and denaturation, respiration and fermentation, chilling injury and free radical scavenging, firmness decay) and in the processing technology (effect of blanching on firmness and colour). For the distribution and logistics and to include some aspects of the psychology of food acceptance by consumers, the model of keeping quality is described which was developed by including some theoretical considerations into the ...