A newly developed rapid and convenient method was used for fractionation and analysis of fluorescent compounds (FCs) formed during lipid peroxidation in parsley (Petroselinum crispum Mill.) leaves. These lipofuscin-like FCs [which arise in vivo from reaction of malondialdehyde (MDA) with amino acids] were found to increase during the senescence of detached parsley leaves, following the commencement of chlorophyll degradation and proteolysis. However, accumulation of FCs in response to exogenous ethylene coincided with the onset of chlorophyll loss and proteolysis on day 2 and was accelerated markedly later. Unlike FC accumulation, levels of aldehydes and MDA in control leaves increased more drastically during senescence, but were not affected significantly by exogenous ethylene. The results suggest that the accumulation of FCs in detached parsley leaves exposed to exogenous ethylene is an early senescence-associated process.
Shimon Meir, Sonia Philosoph-Hadas, and Nehemia Aharoni
Amnon Lichter, Yohanan Zutahy, Tatiana Kaplunov, Nehemia Aharoni, and Susan Lurie
Grape (Vitis vinifera) storage requires stringent control of gray mold caused by Botrytis cinerea. The commercial practice is dependent on sulfur dioxide (SO2) as a fumigant, which is applied by various means with well-known advantages and disadvantages. Many alternative technologies were developed over the years, most of them with limited efficacy or applicability. Modified atmosphere of table grapes suffers from a narrow threshold between control of gray mold and damage to the berries and stems due to high level of carbon dioxide (CO2) within the film-enclosed package. We demonstrated in the past that dipping table grapes in ethanol after harvest has a very pronounced effect on prevention of decay. However, ethanol does not leave a protective residue within the grapes, so it is not expected to prevent latent infections from developing decay nests during prolonged storage. However, if grapes of cultivar Superior were treated with ethanol and then subjected to a modified atmosphere using plastic films (Xtend), we achieved an additive effect and observed persistent control of gray mold without injury to the grapes. The advantage of this plastic film was mainly in its water conductance, which prevented accumulation of free water that is often the limiting factor in modified atmosphere packaging. This combination results in greater decay control, which is a prerequisite for commercial applicability. If undesired aftertaste did develop within the fruit due to the modified atmosphere, 1 day of exposure to ambient air was sufficient to dissipate it.
Victor Rodov, Batia Horev, Yakov Vinokur, Azica Copel, Yair Aharoni, and Nehemia Aharoni
Modified-atmosphere (MA) packaging using bag-in-box Xtend® liners extended the postharvest life of nonnetted Charentais-type muskmelons (Cucumis melo L., Cantalupensis Group, cv. Luna) by delaying over-ripening: excessive softening, change of rind color, decreased soluble solids, and the development of postharvest pathogens. The most delayed fruit ripening was achieved by an atmosphere of 13-14 kPa CO2 and 7-10 kPa O2, even though ethylene concentrations were as much as 120 μL·L-1. Charentais fruit stored in this atmosphere at 6 to 7 °C maintained marketable quality for 12 days plus additional 3 days at 20 °C. In contrast, lifespan under commercial conditions in air did not exceed 3-5 days at 10 to 11 °C plus 3 days at 20 °C. The recommended MA was achieved by using the liners with low microperforation level (total perforation area 25 × 10-5 percent of the film surface), 8-9 fruit of total weight ≈5 kg per liner. MA packaging of Charentais melons makes possible their transportation from Israel to Europe by sea instead of air.
Shimon Meir, Sonia Philosoph-Hadas, Giora Zauberman, Yoram Fuchs, Miriam Akerman, and Nehemia Aharoni
Fluorescent products (lipofuscin-like compounds) of lipid peroxidation, which accumulate with age, were extracted from `Fuerte' avocado (Persea americana Mill.) peels during ripening. Fractionation and analysis of these fluorescent compounds (FCs) was carried out by an improved method, based on separation of FCs from-chlorophyll by Sep-Pak silica cartridges. A sharp rise in FCs content was found 2 days after harvest in avocado fruits stored at 22C, and ethylene enhanced this rise 3-fold on the 4th day. The accumulation of FCs preceded by at leasts days the onset of climacteric ethylene and respiration and by 2 days the decrease in fruit firmness. Moreover, a 6-foId increase in the FCs concentration occurred during 1 to 2 weeks of storage at SC, but the avocado fruits did not show any other detectable signs of ripening. These results suggest that lipid peroxidation may be regarded as one of the earliest detectable processes occurring during fruit ripening. Thus, an increase of FCs in peel may be employed as a horticultural characteristic for estimating initiation of ripening in avocado fruit.