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The aim of this work was to estimate shelf-life potential and understand quality characteristics of 'Golden Reinders' apples during ripening after storage under ultra low oxygen (ULO) atmosphere. Fruits, corresponding to two different maturity stages (147 and 155 dafb), were kept at 1 °C in ULO atmosphere (1 kPa O2: 1 kPa CO2) for seven months and subsequently kept at 1 °C in regular air for up to 28 days. Sub-batches were removed weekly and transferred to 20 °C, so that the shelf-life periods at room temperature were 28, 21, 14, 7, and 0 days. Fruit from both maturity stages showed firmness and soluble solids content (SSC) values above the minimum commercial requirements for this variety throughout the post-storage ripening period. However, only earlier harvested fruit maintained high levels of titratable acidity (TA). Production of aroma volatile compounds was low for shorter ripening periods, though it increased progressively as ripeness advanced. Principal component analysis showed the variables that positively influenced acceptability were: octyl acetate, hexyl octanoate, butyl propanoate, propyl pentanoate, and 6-methyl-5-hepten-2-one as aroma volatile compounds; SSC, TA, firmness, and epidermis colour (Hue) as physicochemical parameters; and sourness and sensory firmness as sensory attributes. From a general overview, the optimum shelf-life period for 'Golden Reinders' apples would be between 7 and 14 days for both maturity stages. [ABSTRACT FROM AUTHOR]

The production of aroma volatile compounds and standard quality attributes, in addition to lipoxygenase (LOX), hydroperoxide lyase (HPL), pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH) and alcohol o-acyltransferase (AAT) activities, were assessed during maturation of ‘Pink Lady®’ apples. Low production of aroma volatiles was observed in early harvested fruit, which gradually increased as ripeness approached. Hexyl acetate, hexyl 2-methylbutanoate, hexyl hexanoate, hexyl butanoate, 2-methylbutyl acetate and butyl acetate were prominent within the blend of volatiles produced by fruit throughout maturation. Multivariate analysis showed these compounds had the highest influence on differentiation of maturity stages, indicating that aroma volatile emission is an important factor for definition of fruit ripeness, which suggests production of these esters might be useful as an index of maturity. No large variations in AAT activity were found throughout the experimental period despite increasing ester emission, suggesting the enhancement of ester production by ‘Pink Lady®’ apples at ripening arises mainly from greater availability of substrates. Increased LOX activity was observed at later stages of fruit development, and the possible role of this enzyme activity on enhanced capacity for aroma volatile biosynthesis in more mature fruit is discussed. [Copyright &y& Elsevier]