Non‐freezing points below zero induce low‐temperature breakdown of kiwifruit at harvest

To induce low‐temperature breakdown (LTB) at harvest, a post‐storage disorder of kiwifruit, kiwifruit were exposed to ?2 °C (a temperature determined to be above the freezing point), for 0 (control), 6, 12, 18, 24, 30, 36 and 42 h, followed by 5 days at 20 °C. Kiwifruit were also stored at ?0.5 °C for 16 and 24 weeks plus 5 days at 20 °C. LTB incidence and severity were measured on the cut surfaces following slicing at the upper, middle and lower parts of each fruit subjected to ?2 °C, whereas in stored fruit LTB incidence was measured following slicing at the middle part. Electrolyte leakage (ELL) was also determined. Exposure of fruit to ?2 °C resulted in induction of LTB incidence and severity, which increased with the duration of exposure, particularly, on the upper fruit part. Maximum ELL during exposure at ?2 °C for 36 h or during storage at ?0.5 °C for 16 weeks was as high as 50% of that of the frozen fruit. Fruit exposed to ?2 °C or stored at ?0.5 °C had similar LTB symptoms but both differed from those observed in frozen fruit. LTB of fruit stored at ?0.5 °C for 24 weeks was 27% and corresponded to LTB induced at harvest by exposure at ?2 °C for 24 h. The results of this study confirm that LTB is inducible by low but not freezing temperatures at harvest and therefore it might be considered as the physiological basis towards the development of an LTB incidence index for harvested kiwifruit. Copyright © 2006 Society of Chemical Industry     

Delayed harvest and cold storage period influence ethylene production,fruit firmness and quality of ‘Cripps Pink’ apple

The effects of harvest date and cold storage period on ethylene production, fruit firmness and quality of ‘Cripps Pink’ apple were investigated. Fruit were harvested from Perth Hills and Donnybrook (Western Australia) at commercial maturity (CM), 2, 4 and 6 weeks after CM prior to 0, 45, 90 and 135 days cold storage in 2003 and 2004. Delayed harvest significantly increased ethylene production, CIE values a* and C* at both locations in 2 years. Delayed harvest and extended cold storage period increased the internal ethylene production and reduced fruit firmness, soluble solids concentration: titratable acidity (SSC:TA) ratio and reduced CIE values L*, b*, h° during both years and locations. Fruit harvested 2 weeks after CM can be cold‐stored for 90 days with acceptable fruit quality. If the fruit is intended to be sold fresh immediately in local markets, the harvest can be delayed up to 6 weeks after CM to harness substantially improved fruit colour with acceptable fruit quality.     

Effect of delayed storage and continuous ethylene exposure on flesh reddening of ‘Royal Diamond’ plums

BACKGROUND: Flesh reddening has been described as one of the manifestations of plum fruits to low‐temperature storage for prolonged periods. The influence of factors such as ethylene and delayed storage has not been studied to date. In order to assess that, plum cv. ‘Royal Diamond’ fruits were (a) stored at 5 °C (control), (b) held at 20 °C for 2 days before storage at 5 °C (delayed storage) or (c) maintained at 5 °C under 15 µL L^?1 ethylene. Fruits were then transferred to 20 °C and ethylene, respiration, weight loss, firmness, soluble solids content, acidity, flesh reddening, anthocyanin accumulation and phenylalanine ammonia‐lyase (PAL) activity were determined. RESULTS: Delayed storage fruits showed more extensive flesh reddening than control fruits, with increased PAL activity and higher anthocyanin accumulation. Symptoms were expressed more markedly when fruits were stored at 5 °C in ethylene. CONCLUSION: Results indicated that the fruit ripening stage is a critical factor determining the susceptibility of ‘Royal Diamond’ plums to flesh reddening. Fruits continuously exposed to ethylene showed a dramatic increase in reddening, suggesting that ethylene contributes to the development of the disorder. Copyright © 2008 Society of Chemical Industry     

Changes in fatty acid composition and electrolyte leakage of ‘Hayward’ kiwifruit during storage at different temperatures

Exposure to low storage temperature induces changes in electrolyte leakage and fatty acids composition, in a way depending on the plant tissue. Those changes alter the response of the fruit to storage conditions. The influence of storage temperature on ripening, fatty acids composition and electrolyte leakage of ‘Hayward’ kiwifruit were investigated. Harvested fruit were stored at 0, 5, 10, 15 and 20 °C for 5, 12 and 17 days. Measurements of SSC, firmness, flesh colour, fatty acid composition and electrolyte leakage were performed during the experiment. Kiwifruit did not fully ripen during the 17 days storage at any temperature. The major fatty acid component in ‘Hayward’ kiwifruit consisted of linolenic, followed by oleic, palmitic, linoleic and stearic acid. Membrane permeability and unsaturated/saturated fatty acid ratio increased during storage in all treatments. The highest increase was during the first 5 days and at the lowest temperatures. The increase in unsaturated/saturated fatty acid ratio was caused mainly by a decrease in palmitic and an increase in oleic acids. Stearic, linoleic and linolenic acids had insignificant changes during storage. The main increase in electrolyte leakage and unsaturated/saturated fatty acid ratio occurred during the first storage days and at lower temperatures, probably as a response of the tissue to an adaptation to the new stress storage conditions.     

Chilling injury development of ‘Tahitian’ lime, ‘Emperor’ mandarin, ‘Marsh’ grapefruit and ‘Valencia’ orange

The effect of varying levels of ethylene on the chilling injury (CI) development and the changes in the levels of putrescine, squalene and α-farnesene of ‘Tahitian’ lime (Citrus latifolia Tanaka), ‘Emperor’ mandarin (Citrus reticulata Blanco), ‘Marsh’ grapefruit (Citrus paradisi Macf) and ‘Valencia’ orange (Citrus sinensis L Osbeck) stored at 0°C was investigated. It was found that different citrus fruits stored at 0°C had varying sensitivity to CI, and that low levels of exogenous ethyiene induced earlier and more severe CI in all citrus fiuits. The levels of endogenous putrescine, squalene and α-farnesene varied between fruit, and was affected by the time of exposure at 0°C and the presence of ethylene. The patterns of change indicate that loss of squalene coupled with loss of α-farnesene could be involved in induction of CI.     

An investigation of ripening and handling strategies for early season kiwifruit (Actinidia deliciosa cv Hayward)

The proportion of the world's population that cannot get enough food to eat is increasing. Research has led to methods of increasing yields in ‘good’ soils with heavy inputs of fertilisers and other agrochemicals. But millions of people have to rely on food grown with few inputs on soils that are difficult to manage and present severe nutritional problems. There is a pressing need to devise sustainable systems of production that increase yields for these people. The problems that need to be overcome and the opportunities for advance are examined. Innovative agronomic practices are being developed that show promise of success. Quantitative models for soil and plant processes have also been developed and should be applied, to a greater extent than at present, in assessing possible practices in a given area, and in adapting practices to suit conditions. In addition there are a range of new techniques for measuring soil conditions and plant characteristics which should greatly facilitate progress. New methods of supplying crops with nutrients and water have led to spectacular improvements in the production of many horticultural crops in the Western world. Improvements in quality and the introduction of new products have been especially notable. They have enriched the lives of the consumer and created wealth for the producer. Pollution of the environment occurs almost everywhere. It has contributed to the economic decline of some of the earliest industrial areas of the world. Methods of overcoming the chemical constraints to plant growth on polluted and disturbed soils have been devised and have played a major part in improving the appearance of some of these former industrial areas and enabling them to attract modern industries and to enjoy new prosperity. Forest decline brought about by atmospheric pollution is becoming very serious in Western Europe and the USA. So far the only practical remedy involves the application of selected nutrients chosen on the basis of site characteristics.     

Chlorine dioxide treatment decreases respiration and ethylene synthesis in fresh‐cut ‘Hami’ melon fruit

The effects of chlorine dioxide (ClO₂) on respiration and ethylene synthesis of fresh‐cut melon fruit and the possible mechanisms involved were investigated. Fresh‐cut ‘Hami’ melon fruit fumigated with gas ClO₂ in sealed container for 12 h and then stored at 5 °C with 95% relative humidity (RH) for 19 days. Results showed that fruit treated with ClO₂ resulted in lower rates of the total respiration, alternative pathway respiration, cytochrome pathway respiration and ethylene production. Furthermore, the expressions of ethylene biosynthesis‐related genes, including CmACS2, CmACO1 and CmACO3 were reduced by ClO₂ treatment. Taken together, it is suggested that ClO₂ treatment might be an effective way to delay ripening of fresh‐cut ‘Hami’ melon, partially due to the reduced respiration and ethylene biosynthesis.     

不同贮藏温度及时间对黄瓜果实冷害发生的影响

为了研究不同贮藏温度及贮藏时间对黄瓜果实冷害的影响规律,对0～20℃的贮藏温度下,在贮藏时间15d内的黄瓜果实的细胞膜电解质渗透率进行了系统测试。结果表明:黄瓜冷害的发生与贮藏温度及处理时间有关,而电解质渗透率的变化能很好地体现不同贮藏温度及时间下,黄瓜细胞组织受损程度及与冷害发生的关系。研究发现,0℃下的渗透率最高,渗透率变化最为明显,渗透率增量最大。表明贮藏温度越低,电解质渗透率变化越明显,出现跃变的时间越早,则黄瓜冷害发生得越早;随着贮藏时间的延长,细胞膜电解质渗透率随之增加,冷害随之加重。同时,适当的变温处理可以有效地缓解和抑制冷害的发生,延长贮藏期。     

Effect of cold‐shock treatment on chilling injury in mango (Mangifera indica L. cv. ‘Wacheng’) fruit

To investigate how cold shock may affect chilling injury in mango fruit (Mangifera indica L. cv. ‘Wacheng’), the fruit were treated for 3, 4 or 5 h at 0 °C, or treated for 8, 10 or 12 h at 4 °C, respectively, then transferred to 20 °C for 20 h prior to being stored at 2 °C, 85–95% RH. The chilling injury index of mango treated at 0 °C for 4 h was 59.7% lower than that of the control fruit directly stored at 2 °C, 85–95% RH. Some attributes were assayed in the fruit treated at 0 °C for 4 h. Ion leakage of the cold‐shock fruit at 0 °C for 4 h was 16% or 10% lower than that of the control on day 9 or day 12 of storage, respectively. Malondialdehyde content of the cold‐shocked fruit was 70% or 50% lower than that of the control on day 6 or day 12 of storage at 2 °C, respectively. Activities of catalase, ascorbate peroxidase, and contents of glutathione and phenolic compounds in the fruit during storage were all markedly enhanced by the cold‐shock treatment, whereas activities of superoxide dismutase, glutathione reductase and content of ascorbic acid in the mango were slightly influenced by the cold‐shock treatment. These results suggest that cold‐shock treatment may hold promise as an alternative approach to reduce chilling injury in mango fruit during cold storage. Copyright © 2006 Society of Chemical Industry     

Increased ethylene biosynthesis elevates incidence of chilling injury in cold‐stored ‘Amber Jewel’ Japanese plum (Prunus salicina Lindl.) during fruit ripening

Mature ‘Amber Jewel’ Japanese plum fruit were stored at 0 or 5 °C for 3 and 6 weeks to investigate their effects on ethylene (C₂H₄) biosynthesis during ripening at ambient temperature in the development of chilling injury (CI) and fruit quality. CI (internal breakdown and browning) and fruit softening were higher during ripening, in the fruit stored at 5 °C than 0 °C, irrespective of storage period (SP). C₂H₄ production and activities of 1‐aminocyclopropane‐1‐carboxylic acid synthase (ACS) and 1‐aminocyclopropane‐1‐carboxylic acid oxidase (ACO) enzymes, and 1‐aminocyclopropane‐1‐carboxylic acid (ACC) content were higher during ripening in fruit stored at 5 °C than 0 °C. The fruit stored at 5 °C also exhibited higher respiration rate and higher soluble solids concentration/titratable acidity ratio. In conclusion, increase in storage temperature and SP elevates the activities of ACS and ACO enzymes and consequently C₂H₄ production which leads to the development of CI in plum fruit with advancement of ripening.     

ACC oxidase activation by cold storage on ‘Passe-Crassane’ pears: effect of calcium treatment

Ethylene biosynthesis and respiration in untreated and in calcium-treated Passe-Crassane pear fruits during cold storage and during ripening at 20°C after removal from storage at 2°C was studied. Results suggest that the increase in ACC oxidase activity along with free-ACC availability for enzyme action is the most important limiting factor in the capacity of these fruits to produce ethylene and to ripen. A chilling period of at least 30 days was shown to be required for inducing the climacteric increase in ethylene biosynthesis. Calcium treatment partially prevented ethylene production and retarded the onset of the climacteric process in Passe-Crassane fruits. The role that calcium plays in preventing cellular wall and membrane degradation is probably responsible for this delaying effect on the ripening process of this pear cultivar. © 1998 SCI.     

Preconditioning treatment maintains taste characteristic perception of ripe ‘September Sun’ peach following cold storage

Preconditioning is a thermal treatment that consists in maintaining stone fruits immediately after harvest and prior to cold storage at 20 °C for 24–48 h in special chambers aimed to extend fruit market life reducing chilling injury symptoms. This work investigates whether preconditioned ‘September Sun’ peaches had better eating quality than control fruit. Commercially harvested peaches were preconditioned and transferred to cold storage for 12, 26 and 40 days and evaluated for sensory characteristic perception after a ripening period at 20 °C. Acceptability of preconditioned fruit was higher than control fruit during this 40‐day cold‐storage period. Preconditioned and control fruit were also segregated into two clusters by PCA analysis; preconditioned fruit clustered together and show association to acceptability, sweetness and juiciness, while the second cluster was associated with flesh texture, acidity and aroma, suggesting the positive effect of preconditioning on final fruit quality. Preconditioned fruit maintained their sensory characteristics longer than control fruit during this 40‐day cold‐storage period.