Loss of Gloss: A Fresh Look at Freshness

Freshness provides the appeal for the consumer to purchase a particular horticultural produce, being a combination of size, colour, shape, flesh firmness, turgescence without wilting. This implies that the produce has been picked only a short while ago and has not suffered any decay during harvest, transport or storage. Post-harvest approaches aim to main these parameters of fruit quality, summarized under the term “freshness”. However, the definition of “freshness” is difficult and can hence vary from the point of view, farmer, processing industry, retailer or consumer, i.e. not only where esthetic appearance is of importance. Glossiness is a relatively new parameter in this approach to parametrize freshness. Older equipment was stationary, struggled with curved surfaces and biological material, as glossmeters originate from paint surveys on metal, e.g. cars, and might not work on a plant surface. Despite these technical shortcomings, the strive is for non-destructive, instant, fast and real-time methods, allowing a vast number of specimen to be investigated in-situ in the field, on a ship, in a carton or on the shelf. This chapter provides an update of assessing glossiness based on these requirements and glossy fruits such as cherry, aubergine, banana, pomegranate, plum and cucumber. Opto-electronic portable and reasonably -priced sensor work is presented. The results are discussed with respect to the physiological barrier (wax composition and crystallization) for water loss and shrivel, handling and polishing the fruit as well as the underlying molecular mechanisms using cucumber as example.