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Treatment with 1-methylcyclopropene (1-MCP), an ethylene inhibitor, considera­bly prolongs the storage and shelf life of apples, and diminishes the occurrence of some physiological diseases, such as scald. Various fruit quality parameters define fruit acceptance by consumers, while some also determine the storability of fruits, including firmness, acidity and internal ethylene concentration. The aroma of apples is regarded as one of the most important quality parameters. Many factors influence the aroma profile, with ethylene having a key role in the biosynthesis of flavour com­pounds. 1-MCP is an inhibitor of ethylene synthesis and is now widely used. We tested apples of the three main cultivars grown in Slovenia ('Idared', 'Jonagold' and 'Golden Delicious') following their treatment with 1 ^l l-1 1-MCP at +1 °C, with 6 months of storage under standard ultra-low oxygen storage conditions (1.2% O2, 1.5% CO2). The fruits were analysed for firmness and ground colour, with headspace analy­ses of the aroma compounds, before and after storage. Compared with the control fruits, 1 -MCP-treated apples had significantly improved firmness and colour parame­ters (L*, a*, b*), but showed strong inhibition of total aroma production. Among the aroma compounds, the esters were most severely suppressed by the treatment with 1 - MCP, with the exception of 2-methylethyl acetate. In general, 1-MCP positively af­fected most of the quality parameters (fruit firmness, ground colour, acidity), but greatly suppressed the synthesis of the aroma volatiles.
Colour is traditionally one of the important appearance features of all fruit for consumers in deciding to buy them. Colour is therefore important in the postharvest supply chain. But where does that colour of fruit come from? Clearly the period of growing and the circumstances during growth are important for developing this im­portant feature. During several seasons (2007-2009), the skin colour of individual apples of dif­ferent cultivars ('Braeburn', 'Fuji', 'Gala', 'Golden Delicious') were measured using a Minolta CR-400 chromameter during the last 40-60 days before (commercial) har­vest. By including the biological variation between individual apples in the analyses and applying non linear indexed regression analysis based on process oriented mod­els, explained parts were obtained for the a*-value, all exceeding 90%. The estimated rate constants for the colouration process were remarkably similar for all cultivars (except 'Fuji') and growing conditions. That would indicate that the process of colouration is really reflecting the degradation of chlorophyll and not the production of red or yellow coloured blush (anthocyanins). The expected effect of growing conditions (fertilization and crop level, hail net or not, sunny side or shady side of the tree) did change the mechanism nor the kinetic parameter values but could all be attributed to the minimal obtainable skin colour (asymptotic values of the logis­tic model). This type of information from the production period may constitute an important link to postharvest supply chain management.
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