Dr. Leon A. Terry, Head of Plant Science Laboratory, Cranfield University, UK (l.a.terry@cranfield.ac.uk), February 2009.
Apples still represent one of the most important fresh produce types within the fresh fruit and vegetable category. Standard quality control for apple fruit is usually based on setting a numerical lower limit for firmness, soluble solids content, starch pattern index, colour and mass. All these factors affect quality but are commonly measured using rather rudimentary equipment which is known to have some flaws. This said, recent published research has shown that apple firmness is the most important factor in determining consumer acceptance of apples (Harker et al., 2008). Soluble solids content and acidity also play a role in defining consumer preference within specific cultivars. Mealiness is a negative attribute. There has been a positive trend towards consumers choosing to purchase firm/crisp apples, whilst a small proportion still value softer and more aromatic cultivars; these being inherently more challenging to store. However, is the consumer driving the selection of firmer varieties or is it availability (i.e. what they are presented with) and/or standardisation/consistency? Apple quality (the product) is only one aspect which governs consumer choice; price, promotion, place and packaging (the 5 P’s) are also important. In addition, availability is also key. This has been increased through cold storage, ethylene control/suppression and controlled atmosphere storage such that consumers are often faced with fruit from both hemispheres. Consumers thus have to choose (consciously or not) between short to long-term stored fruit (Varela et al., 2008). However, the notion that longer stored produce are less fresh and thus inferior does not always stand true. Time is only one factor which governs postharvest quality. The storage conditions, postharvest treatments and handling are the defining criteria which ultimately affect quality.
Significant advances in postharvest technology have reduced wastage and maintained quality, yet extension of storage life and thus availability of a consistent product are still primary concerns. Since the first work by Kidd and West after The First World War on developing CA storage to the recent advances in usage of the ethylene binding inhibitor 1-methylcyclopropene (1-MCP) it could be argued that many of the fundamental challenges faced today by the apple industry have changed little in the last 90 years. A report by the now defunct British Government’s Department for Scientific and Industrial Research in 1930 (Food Investigation Report No. 38: J. Baker) stated that for apples ‘the most important losses are caused by over-ripeness, fungal rotting, bitter pit and internal breakdown, freezing and development of scald; Jonathan spot and brown heart are also found. Bitter pit and internal breakdown are most common in certain varieties, but all varieties are liable to suffer from fungal rotting. A survey of the present knowledge with regard to each of these abnormalities is given, with suggested remedies, but it is emphasised that in many cases more work is required before marked improvement may be expected.’
References:
- Harker, F.R. et al. (2008). Eating quality standards for apples based on consumer preferences. Postharvest Biology and Technology, pp. 50, 70-78.
- Varela, P., Salvador, A. and Fiszman, S. (2008). Shelf-life estimation of ‘Fuji’ apples. Postharvest Biology and Technology, pp. 50, 64-69.