The increasing use of 1-methylcyclopropene (1-MCP) to extend the commercial life of fruit constitutes an attractive way of improving packing house competitiveness. This compound prevents the effects of ethylene in a wide range of fruit and vegetables. However, despite the extensive literature relating to this action on ethylene, little is known about its other physiological effects. In this work, pears (Pyrus malus L cv Blanquilla) were treated with 100 ppb 1-MCP immediately after harvest and stored in air for 5 months. Differences in oxidative stress and in antioxidant potential between controls and 1-MCP-treated fruits were established, determining the changes in the levels of hydrogen peroxide, ascorbate content and ionic leakage during storage. Activities of the H 2 O 2 -generating enzyme superoxide dismutase (EC 1.15.11) and the H 2 O 2 -scavenging enzymes catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11) and unspecific peroxidase (EC 1.11.1.7) were also determined. 1-MCP-treated fruits exhibited lower levels of hydrogen peroxide, ascorbate and lower ionic leakage during storage. In accordance with this result, 1-MCP-treated fruits also exhibited higher enzymatic antioxidant potential. These results challenge the hypothesis that the beneficial effects of 1-MCP on ripening were not exclusively due to its action on ethylene but also to an increase in antioxidant potential in pear.

The main goal of our study was to see whether an artificial olfactory system can be used as a nondestructive instrument to measure fruit maturity. In order to make an objective comparison, samples measured with our electronic nose prototype were later characterized using fruit quality techniques. The cultivars chosen for the study were peaches, nectarines, apples, and pears. With peaches and nectarines, a PCA analysis on the electronic nose measurements helped to guess optimal harvest dates that were in good agreement with the ones obtained with fruit quality techniques. A good correlation between sensor signals and some fruit quality indicators was also found. With pears, the study addressed the possibility of classifying samples regarding their ripeness state after different cold storage and shelf-life periods. A PCA analysis showed good separation between samples measured after a shelf-life period of seven days and samples with four or less days. Finally, the electronic nose monitored the shelf-life ripening of apples. A good correlation between electronic nose signals and firmness, starch index, and acidity parameters was found. These results prove that electronic noses have the potential of becoming a reliable instrument to assess fruit ripeness.

Està subjecte a una llicència de Reconeixement-NoComercial-SenseObraDerivada 4.

Effects of regulated deficit irrigation (RDI) on the quality of a mid-late maturing peach (Prunus persica L Batsch cv Andross) were determined at commercial harvest as well as 1 week before (early pick-up) and after 1 week of cold storage. Respiration and ethylene evolution were measured during 96 h on fruits sampled at early pick-up and at harvest. Fruits from a well-watered irrigation treatment (Control) were compared with a treatment of RDI during stage II of fruit growth (RDI-SII) and with RDI applied postharvest (RDI-PH). A fourth treatment received a combination of deficit irrigation applied during stage II and postharvest (RDI-SII-PH). Higher soluble solids content (SSC) amd SSC/titratable acidity (TA) ratio for RDI-SII were already noted at early pick-up and these differences were enhanced after cold storage (RDI fruits having higher SSC, lower TA and higher SSC/TA ratio than Control fruits). This improvement in quality (high SSC/TA ratio) was also correlated with a more reddish colouration in the fruit skin. Moreover, ethylene production indicated different behaviour of the physiological evolution for fruits from the different treatments.

Starking Delicious apples were cold-stored in semicommercial chambers in normal atmosphere and in different controlled atmospheres in which oxygen and carbon dioxide were held at 1%, 2%, and 3% for 3, 5, and 7 months. After storage, fruit was kept at ambient temperature (20 degrees C) for 1, 5, and 10 days. The volatile emission was collected and analyzed. After all storage periods and conditions, the total aromatic volatile emission was higher than at commercial harvest. The highest emission of volatile components was obtained after 5 months of storage, in which controlled-atmosphere conditions gave a lower concentration than normal cold storage. Esters were the main volatiles detected (>98%). Acetate ester concentrations after all storage periods assayed were higher at 3% and 2% O(2)/CO(2). The components that contributed most to the characteristic aroma of Starking Delicious were ethyl 2-methylbutyrate, ethyl butyrate, and ethyl hexanoate. Their concentrations were higher after 5 months of storage and also during poststorage at ambient temperature (20 degrees C).