Acetaldehyde is produced in fruit of pear (Pyrus communis L.) and can stimulate ripening. The action of selective inhibitors indicates that acetaldehyde operates independently of ethylene.
Abbreviations: AA, acetaldehyde; RQ, respiratory quotient; TSS, total soluble solids content. Supported by grant no. 1-900-85 from BARD, the U.S.-Israel Binational Agricultural Research and Development Fund. Contribution from the Agr. Res
relation to disorder incidence. At harvest and under aerobic storage conditions, apples usually have low acetaldehyde and ethanol concentrations, as well as low pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities ( Pesis, 2005 ). Both
A new method for analyzing acetaldehyde concentration in apple (Malus domestica Borkh.) tissues was used to measure its accumulation in senescing fruits. Initially low levels (1 µg/g fresh weight) increased as the fruits ripened, but only at advanced senescence did they reach relatively high levels (14 µg/g fresh weight). Acetaldehyde did not accumulate in advance of tissue disorganization. Watercored ‘Delicious’ apple tissue accumulated significantly more acetaldehyde than tissue of non-watercored fruits during storage, but watercore breakdown did not result. There was no consistent difference in acetaldehyde levels of ethephon-treated and non-treated ‘McIntosh’ apples after long-term storage, although the ethephon-treated fruits developed more senescent breakdown. However, the acetaldehyde level in fruits after breakdown occurred was about 20% higher than that in corresponding sound fruit. Acetaldehyde accumulation appeared to be a consequence of tissue disorganization rather than a cause of senescent breakdown in the fruits.
‘Sultanina’ and ‘Perlette’ grapes (Vitis vinifera L.), with initially low sugar concentrations (13% to 14% total soluble solids content; TSS) and high acidity received postharvest application of 0.2% to 0.9% acetaldehyde vapors for 24 hr. This treatment increased TSS, decreased acidity of the juice, and enhanced the sensory preference by judges in a test panel. However, the response was limited to early picked fruit with low TSS and high acidity and the treatment damaged the berries of ‘Sultanina’ grapes and left some off-flavor. The levels of acetaldehyde and ethanol in the juice were positively correlated with the amount of applied acetaldehyde, the level of ethanol being 20 times higher than that of acetaldehyde. After 4 days of shelf life, the levels of both acetaldehyde and ethanol declined in the juice.
Decay of apples (Malus sylvestris Mill.) inoculated with Penicillium expansum was controlled by acetaldehyde vapor concentrations (v/v) of 0.5% for 180 min, 1% for 120 min, 2% for 60 min, and 3% for 30 min. The above treatments did not produce lenticel or skin injury. Fumigated conidia did not germinate in 21 days at 21°C on artificial media and failed to induce decay in stem-punctured apples. The pathogen could not be re-isolated from fumigated inoculated punctures, however, the pathogen was obtained from inoculated punctures not exposed to acetaldehyde vapor. Fungicidal action of acetaldehyde vapor was a function of concentration and exposure period. Objectional off-flavors were not detected in fumigated apples, although appreciable amounts of acetaldehyde vapor were absorbed.
disruption and lead to increased levels of acetaldehyde, ethanol, ethyl acetate, and ethyl lactate, which confer undesirable aromas to the fruit ( Kader, 2003b ). In an attempt to reduce the risks caused by CAs with high levels of CO 2 , other gases have been
Exposure to acetaldehyde (M) vapors that produced tissue levels of 0.02% AA (w/w) stimulated ripening of `Hayward' kiwifruit (Actinidia deliciosa L.) much more effectively than exposure to ethanol vapors that produced tissue levels of 0.18% ethanol. Tissue levels of 0.02% and 0.18% ethanol stimulated ripening, while the ripening rate of tissue with 0.04% was similar to the controls. Ethylene and CO production from M-treated tissues were, respectively, 23 times and 60% higher than from control tissues. AA induced a rapid softening that was localized in the core tissue and rendered the fruit unmarketable for 7 days after treatment.
The content of acetaldehyde (AA) and ethanol (EtOH) increases in ripening climacteric fruit. Application of EtOH inhibits tomato (Lycopersicon esculentum) fruit ripening without affecting subsequent quality, and AA enhances organoleptic quality. AA inhibited ripening of mature-green tomato discs (MGTD) at about 30% conc of EtOH. The relationship between EtOH and AA inhibition of tomato fruit ripening is unclear. The inter-conversion of AA and EtOH is catalyzed by alcohol dehydrogenase (ADH) which is inhibited by 4-methylpyrazole (4-MP). No adverse physiological effects upon ripening were observed in MGTD receiving 20 μL of 4.0 mM 4-MP. Treating MGTD with 0.5 to 4.0 mM 4-MP in concert with AA (≤2.0 μL/g FW) or EtOH (≤8 μL/g FW) was not deleterious to ripening. A rapid, efficient method for the analysis of tissue AA and EtOH was linear (r2 = 0.97) for discs spiked with 0 to 45 μL EtOH. No temporal (0 to 42 h) changes in tissue AA and EtOH were detected in MGTD receiving 2.0 mM 4-MP. MGTD treated with 2.0 mM 4-MP and 8 μL/g FW EtOH had a 360-fold increase in AA after 6 days of ripening, but had no differences on EtOH conc. These conditions maximally inhibited ripening as determined by lycopene content.
Mechanically harvested fruits of A-5344 and ‘Earlibelle’ strawberry (Fragaria × ananassa Duch.) were stored at 24°C for 72 and 120 hours in atmospheres containing acetaldehyde (Aa) with and without prior dipping in 0 to 1.5% acetaldehyde solutions. Aa atmospheres and a combination of atmospheres and dips were most effective in maintaining visual color, freedom from browning, and product acceptability of machine harvested strawberries for processing. Fruit stored in atmospheres containing Aa vapor increased in acidity by 72 hours.