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Volume 2 Number 1 & 2 2008 
CONTENTS AND ABSTRACTS
Number 1
Lijun Wang, Shaohua Li (China) Role of Salicylic Acid in Postharvest Physiology (pp 1-5)
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ABSTRACT
Invited Mini-Review: Salicylic acid (SA) belongs to a group of phenolic compounds widely distributed in plants and is now considered as a hormonal substance, playing an important role in plant physiology. SA has become more and more important in postharvest storage of fruit. Pre-harvest treatments with SA reduced lesion diameters on fruit caused by fungi, and induce β-1,3-glucanase, phenylalanine ammonia-lyase (PAL) and peroxidase (POD) activities during storage. SA shows direct fungitoxicity on fungi and significantly inhibits fungal growth and spore germination of the pathogen in vitro. SA can delay the ripening of fruit, probably through inhibition of ethylene biosynthesis or action. During postharvest ripening and softening of some fruit, the levels of SA in fruit tissues decline, lipoxygenase (LOX) activity increases, and this is associated with climacteric ethylene release. SA treatment maintains greater firmness, reduces chilling injury indices, and delays membrane lipid peroxidation in fruit during cold storage. The effect of SA on alleviating chilling injury of peaches during cold storage may be attributed to its ability to induce antioxidant systems and heat shock proteins or HSPs. Exogenous application of SA or methyl-salicylic acid may also induce the expression of many defense genes during fruit storage. Pre-storage or preharvest application of SA may provide a useful means of controlling post-harvest decays and extending fruit postharvest life during storage.
María Victoria Agüero, Alejandra G. Ponce, María R. Moreira, Sara I. Roura (Argentina) Plastic Mulch Improves Microbial Quality and Shelf Life of Cold Stored Butter Lettuce (Lactuca sativa var. Lores) (pp 6-13)
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Original Research Paper: Differences in soil management during crop cultivation (plastic mulch or bare soil) are likely to influence microflora behavior during the post-harvest of the product. The evolution of native microflora and sensory quality analysis were assayed during cold storage of butter lettuce (Lactuca sativa var. Lores) from greenhouse cultivation using mulch and bare soil. All parameters analyzed were measured in three different zones of the complete lettuce head named as the external (outer leaves), middle (mid leaves) and internal (inner leaves) zones. The lettuce cultivation method had impact on the initial counts as well as on microbial evolution during refrigerated storage, playing a singular role on the sensorial quality and shelf life of each lettuce. The higher initial counts in mulch lettuce could be explained by the microclimate generated by the plastic mulch around the plant. While bacterial increment was observed from the beginning of the storage in the three zones of bare soil lettuce, cold storage had a bacteriostatic or bactericidal effect on mulch lettuce. Through OVQ indexes a significant higher shelf life was observed in mulch lettuce.
Gabriela Antmann, Claudia Lareo, Gastón Ares, Patricia Lema (Uruguay) Influence of Temperature on Respiration Rate of Shiitake Mushrooms under Air and 15% O2 (pp 14-16)
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ABSTRACT
Short Communication: Modified atmosphere packaging could be a useful technique for extending the shelf life of shiitake mushrooms (Lentinus edodes). The design of modified atmosphere packaging requires information about the produce’s respiration rate. In this work, the influence of temperature on O2 consumption and CO2 production rate of shiitake mushrooms under air and 15% O2 were studied. Respiration rate values of shiitake mushrooms under air were higher (105.4 mL CO2 kg-1 h-1 at 5°C) than those encountered in the literature for other mushroom species, suggesting that they might be particularly perishable. The respiration quotient was independent of both temperature and gas composition within the range of those variables that were tested, and near to one in all cases. Mushrooms showed a significantly lower respiration rate under 15% O2 than under air at 1, 5 and 10°C. On the other hand, calculated activation energies were equivalent to Q10 values of approximately 3 between 5 and 15°C.
Guimin Tang, Yanqing Feng, Wenqian Zhang, Tingting Qian, Xiyan Yu (China) Alcohol Acetyltransferase Activity, Ethylene Production and Aroma Formation of Muskmelon during Fruit Development (pp 17-21)
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ABSTRACT
Original Research Paper: Muskmelon (Cucumis melo L.) varieties differ in a range of physical and chemical attributes. Aroma is one of the most important factors determining fruit quality and consumer preference. Volatile esters, a major class of compounds contributing to the aroma of muskmelon fruit, are synthesized by alcohol acyl-transferases (AATs). We demonstrate here that volatile aldehydes are most abundant in unripe ‘Shannong Golden1’ fruit, a climacteric muskmelon but volatile esters are the major components of ripe fruit. In contrast, both ripe and unripe ‘Sweet Delight’ fruit, a non-climacteric muskmelon, had an abundance of volatile aldehydes. Unripe ‘Takami’ fruit, another climacteric muskmelon, had an abundance of alcohols and aldehydes whereas ripe fruit of this cultivar had an abundance of esters and aldehydes. Ripe ‘Takami’ fruit produced ethylene at an intermediate concentration relative to that of ‘Shannong Golden1’ and ‘Sweet Delight’. Interestingly, the levels of AAT of all three cultivars mirrored ethylene concentrations and again were highest in ripe ‘Shannong Golden1’ fruit and lowest in ‘Sweet Delight’ fruit. These data suggest that the volatiles differ between fruit types and higher ethylene concentrations result in higher volatile ester concentrations in muskmelon. Furthermore, AAT activity appears to be positively correlated with volatile esters produced during muskmelon ripening and thus may play an important role in aroma formation.
Rosaria Cornacchia, Maria Luisa Amodio, Raffaella Rinaldi, Giancarlo Colelli (Italy) Effect of 1-Methylcyclopropene and Controlled Atmosphere on Storage of Kiwifruits (pp 22-25)
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ABSTRACT
Original Research Paper: ‘Hayward’ kiwifruits were treated with 0.5 μL/L of 1-methylcyclopropene (1-MCP) for 24 hours at 0°C, and then stored either in air or in controlled atmosphere (CA) with 3 kPa O2 + 5 kPa CO2 at 0°C. Initially, and after 13, 20, 28, 36, 41, and 55 days of storage, respiration rate, firmness, soluble solids content (SSC), and titratable acidity (TA) were measured in order to assess fruit ripening. Both 1-MCP and controlled atmosphere resulted in effective firmness retention compared to untreated control fruit held in air, although throughout the experiment, fruit treated with 1-MCP presented only 17% higher firmness than untreated fruit, while firmness of kiwifruit stored in CA resulted 40% higher compared to fruit stored in air. Treatments showed no synergistic effect during the first 4 weeks of storage, while fruit pre-treated with 1-MCP and stored in CA presented significantly higher firmness compared to all other treatments starting from the fifth week of storage. Treatment under 1-MCP and CA significantly affected SSC but not TA, and weight loss. Pre-reatment with 1-MCP did not affect respiration rate.
Athanasios Koukounaras, Anastasia L. Lagopodi, Kamer Cetiz, Evangelos Sfakiotakis (Greece) The Effect of Post-storage Hot Water Dipping on Control of Botrytis cinerea Rot and on Preservation of Quality of ‘Hayward’ Kiwifruit (pp 26-31)
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Original Research Paper: The effectiveness of hot water dipping treatments applied after storage to control Botrytis cinerea rot and preserve quality of kiwifruit during shelf life was evaluated in ‘Hayward’ kiwifruit artificially inoculated with the fungus 6 h before heat treatment. Post storage hot water dipping treatment, applied at 50°C, 55°C, or 60°C for 1.5 or 3 min inhibited growthof B. cinerea completely at the stem end of kiwifruit. Treatments at 55°C and 60°C for 1.5 min resulted in extension of shelf life and preservation of fruit quality after storage. This beneficial effect was expressed by maintenance of fruit quality attributes, specifically flesh firmness, soluble solid concentration, citric acid content, color, vitamin C, and antioxidant content during a storage period of 8 days at 20°C and high relative humidity (>90%). These results suggest that hot water dipping at 55°C for 1.5 min provides an effective, non-chemical method to extend storability by protecting from B. cinerea, and preserving the quality of ‘Hayward’ kiwifruit during market circulation. Number 2
Maria Vargas, Clara Pastor, Ana Albors, Amparo Chiralt, Chelo González-Martínez (Spain) Development of Edible Coatings for Fresh Fruits and Vegetables: Possibilities and Limitations (pp 32-40)
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Invited Mini-Review: The development of edible coatings to extend the shelf-life of fresh fruits and vegetables has been one of the most important goals of the post harvest industry. Thus, in the last decade, research efforts have resulted in edible coatings based on biodegradable biopolymers (proteins and polysaccharides) that at the same time allow the reutilization of some by-products of the food industry. Generally, these hydrocolloids are used as a support matrix since they show excellent film-forming ability, good mechanical properties and selective permeability to gases. However, due to their poor water vapour barrier properties, they have to be combined with lipid compounds in order to obtain composite edible coatings with the desired functional characteristics. Moreover, edible coatings for fruits and vegetables can be especially designed to incorporate and/or controlled release antioxidants, vitamins, nutraceuticals, prebiotics and antimicrobial agents. This work reviews the composition and main properties of formulations and commercial applications available at present, as well as their main effects on the quality and shelf-life of fruit and vegetables during storage.
Jorge M. Fonseca, James W. Rushing (USA) Application of Ultraviolet Light during Postharvest Handling of Produce: Limitations and Possibilities (pp 41-46)
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Invited Mini-Review: The use of ultraviolet (UV) light for improving the quality and safety of whole and fresh-cut fruits and vegetables is reviewed. Ultraviolet-C (UV-C) is non-ionizing radiation that does not penetrate beyond surfaces and is generally regarded as a contact germicide. However, UV-C may induce resistance to various stress factors in tissue via hormesis (initiation of a positive reaction by a low dose of radiation). In some studies, UV-C light treatments have shown potential for controlling various post harvest fungal diseases, an effect often accompanied by delay of senescence. More recent studies suggest that UV-C can alter nutritional composition of some fruits and vegetables, revealing its potential as a tool to develop fresh functional products. Treatments that include UV-C in combination with other sanitizing agents appear to be particularly effective in reducing populations of human pathogens, but little is known about the effects of hurdle sanitizing systems on other aspects of the product’s quality including nutrient content. Although it is well known than plants respond to UV-A and UV-B, examination of these wavelengths for postharvest applications has been scarce. Overall, UV is a promising technology for postharvest disease control and microbial population reduction in some operations; provided that economically feasible means of irradiating fruits and vegetables on a large scale are identified.
Jocelyn R. Eason, Ed R. Morgan, Garry K. Burge (New Zealand) Practical and Genetic Solutions for Quality Sandersonia aurantiaca Flowers (pp 47-55)
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Invited Mini-Review: This review introduces the reader to a cut flower that has been developed from a wild-grown South African native plant. New Zealand’s growers, breeders, production and postharvest researchers have optimised cultivation, harvest and postharvest care of Sandersonia aurantiaca so that cut flowers can be exported to northern hemisphere destinations for maximum returns (in their out-of-season production window).Sandersoniais a lileaceous cut flower comprising bright orange lantern-like flowers on wiry stems that also hold bright green lancolate leaves. There is only one species in the Sandersonia genus, and breeding initiatives have been undertaken to increase the genetic diversity of the crop in order to expand flower colour and form. This review will show that plant production, postharvest management and an ongoing breeding programme are all essential for success of sandersonia in the future market place. It will also review recent molecular research, showing how our understanding of the metabolic processes that influence the rate of flower senescence has advanced.
Asghar Ebrahimzadeh (Spain/Iran), Silvia Jiménez (Spain), Jaime Teixeira da Silva, Shigeru Satoh (Japan), María Teresa Lao (Spain) Postharvest Physiology of Cut Carnation Flowers (pp 56-71)
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ABSTRACT
Invited Review: The most important challenge for postharvest researchers is to slow the processes controlling flower death to enable cut flowers with longest vase life and best quality to reach distant markets. Senescence of carnation is normally characterized by a climacteric-like pattern of ethylene production in which a surge in ethylene production is followed by a decline. Therefore, ethylene sensitivity is an important determinant in flower longevity of carnations. Nevertheless, postharvest losses in this flower result mainly from exposure to unfavourable conditions that accelerate ethylene production or render the flower more sensitive to ethylene, therefore careful postharvest handling is essential to maximise vase life and maintain flower quality. Pre-treatment of carnations with sugars and anti-ethylene agents such silver thiosulfate (STS) and 1-methylcyclopropene (1-MCP) result in a desirable increase in postharvest longevity. Floral preservatives that contain a proper amount of sucrose and different anti-ethylene products (inhibitors of ethylene biosynthesis or action) not only delay petal senescence and decrease tissues’ sensitivity to ethylene, but also significantly improve qualitative or aesthetic characteristics of cut carnations. As cut flowers are often exposed to ethylene in the postharvest shipping and marketing environment, it would be useful to develop cultivars that are insensitive or less sensitive to ethylene. Carnations have now been genetically modified through the addition of a mutation of the ethylene binding site which makes them insensitive to ethylene. The breeding of cultivars with genetically superior vase life appears to be a very efficient approach for satisfying the consumer’s quality expectations.
Shukadev Mangaraj, Tridib Kumar Goswami (India) Respiration Rate Modelling of Royal Delicious Apple at Different Storage Temperatures (pp 72-80)
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Original Research Paper: Temperature is the most important factor that controls the rate of respiration of fruits and vegetables. Several experiments were conducted at different storage temperatures to generate respiration data using a closed system method for respiration measurement. Two different models based on regression analysis and enzyme kinetics were developed. In the model based on enzyme kinetics the Arrhenius equation was proposed for predicting the respiration rates of Royal Delicious apple as a function of O2 and CO2 concentrations and storage temperature. In the enzyme kinetics model, the dependence of respiration rate on O2 and CO2 was found to follow an uncompetitive inhibition. The regression coefficient values were used for the prediction of respiration rates using regression model. The enzyme kinetic model parameters, calculated from the respiration rate at different O2 and CO2 concentrations were used to fit the Arrhenius equation against different storage temperatures. The activation energy and respiration pre-exponential factor were used to predict the model parameters of enzyme kinetics at any storage temperature between 0-30°C. The developed models were verified for goodness of fit at 12°C and found to be in close agreement with the experimentally estimated respiration rates. |
