Fruit Age and Growth Regulator Effects on the Quantity and Structure of the Epicuticular Wax of ‘Washington’ Navel Orange Fruit (original) (raw)
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Postharvest Biology and Technology, 2010
The effect of ethylene (2 μL L−1) on total and soft epicuticular wax content and wax morphology has been investigated in mature ‘Navelate’ (Citrus sinensis, L. Osbeck) oranges held under non-stressful environmental conditions (22 °C and constant high relative humidity (90–95% RH)). In addition, the objective of the study was to understand whether the ethylene-induced changes in epicuticular wax might participate in the beneficial effect of ethylene reducing non-chilling peel pitting, by modifying peel water, osmotic or turgor potential, or disease incidence caused by Penicillium digitatum (Pers.:Fr.) Sacc. Ethylene increased total and soft epicuticular wax content in ‘Navelate’ fruit and induced structural changes in surface wax that might be related to the formation of new waxes. Changes in epicuticular wax morphology, but not in its content, might be involved in the protective role of ethylene reducing non-chilling peel pitting, although the beneficial effect of the hormone is not relat
Journal of the American Society for Horticultural Science
Relationships among fruit age, epicuticular wax, weight loss, internal atmosphere composition, and respiration were investigated in mature ‘Washington’ navel orange fruit [Citrus sinensis (L.) Osbeck]. Fruit epicuticular wax, internal CO2, and internal C2H4 increased, whereas as the season advanced, weight loss during storage and respiration decreased. Concomitantly, fruit conductance to CO2 was reduced. GA3 (10 ppm) application prior to fruit color break reduced the increase in epicuticular wax and thereby delayed the decrease of CO2 conductance, resulting in less of an increase in internal CO2. GA3-treated fruit were not consistently different for other parameters evaluated. Chemical name used: lα,2β,4aα,4bβ,10β)-2,4a,7-trihydroxy-l-methyl-8-methylenegibb-3-ene-l,10-dicarboxylic acid l,4a-lactone (gibberellic acid).
Food Chemistry, 2014
Surface wax of mature Satsuma mandarin (Citrus unshiu) and 'Newhall' navel orange (Citrus sinensis) was analysed by crystal morphology, chemical composition, and gene expression levels. The epicuticular and total waxes of both citrus cultivars were mostly composed of aldehydes, alkanes, fatty acids and primary alcohols. The epicuticular wax accounted for 80% of the total wax in the Newhall fruits and was higher than that in the Satsuma fruits. Scanning electron microscopy showed that larger and more wax platelets were deposited on the surface of Newhall fruits than on the Satsuma fruits. Moreover, the expression levels of genes involved in the wax formation were consistent with the biochemical and crystal morphological analyses. These diversities of fruit wax between the two cultivars may contribute to the differences of fruit postharvest storage properties, which can provide important information for the production of synthetic wax for citrus fruits.
Postharvest Biology and Technology, 2013
Wax application plays an important role in prolonging fruit quality, and the addition of imazalil (IMZ) furthermore protects fruit against green mould caused by Penicillium digitatum. The objectives of this study were to evaluate green mould control and quality preservation effects of carnauba or polyethylene citrus coatings supplemented with IMZ, as well as the effect of synthetic or horsehair brush types used on sweet orange fruit. Single applications of IMZ at 3000 g mL −1 at rates of 0.6, 1.2 and 1.8 L t −1 resulted in residues that increased with increasing coating loads on navel oranges (1.31 to 3.32 g g −1) and Valencia oranges (3.22 to 6.00 g g −1). Coating with IMZ generally provided poorer curative control (≈14%) than protective control (≈58%), with less sporulation in treatments using horsehair (≈59%) than synthetic brushes (≈64%). More fruit weight and firmness losses were found in fruit treated with the polyethylene coating (≈1.18 and ≈0.93 ratios of treated vs. untreated, respectively) and lower in carnauba treated fruit (≈0.76 and ≈0.74 ratios, respectively). However, polyethylene coatings resulted in shinier fruit before (≈10.85 shine ratio) and after storage (11.60), whereas carnauba coatings resulted in lower shine ratios (≈7.45 and 10.15, respectively). Gas (CO 2) exchange ratios remained similar for both waxes (≈0.67). Higher polyethylene coating loads (1.8 L t −1) resulted in off-tastes similar to uncoated control fruit (≈2.21 rating on a 5-point scale) and higher than the rating for carnauba coated fruit (≈1.82) at this rate. Scanning electron micrographs showed an amorphous crystallised natural wax layer with uncovered stomatal pores on the surface of uncoated fruit. The thickness of the applied wax layer increased with increasing coating load. A single application of IMZ in wax provided good protective green mould control and sporulation inhibition, with differing effects on some fruit quality parameters due to coating and brush types.
international food research journal, 2014
The objective of this study is to assess the effects of wax coating concentrations and storage temperatures on the quality changes, both physically and nutritionally, of tangerine citrus (Citrus reticulata) var. Siam Banjar. Tangerine citrus var. Siam Banjar were coated with three different concentrations of wax emulsion (10, 12, and 15%) and stored at two different temperatures (5 and 25°C) at 85-90% RH. The observation in respect of the percentage weight loss, percentage decay incidence, fruit quality characteristics (titratable acidity, total soluble solids, and ascorbic acid), and sensory evaluation (colour, texture, odor, freshness, appearance, fruit firmness, taste, and overall acceptability) were recorded and evaluated at intervals of 5 days for 35 days of storage. The results showed that the combination of 12% wax coating and storage at 5°C was the most effective treatment in maintaining the quality of tangerine citrus var. Siam Banjar, which was significantly (p < 0.05) ...
International Journal of Molecular Sciences
The phytohormone abscisic acid (ABA) is a major regulator of fruit response to water stress, and may influence cuticle properties and wax layer composition during fruit ripening. This study investigates the effects of ABA on epicuticular wax metabolism regulation in a citrus fruit cultivar with low ABA levels, called Pinalate (Citrus sinensis L. Osbeck), and how this relationship is influenced by water stress after detachment. Harvested ABA-treated fruit were exposed to water stress by storing them at low (30–35%) relative humidity. The total epicuticular wax load rose after fruit detachment, which ABA application decreased earlier and more markedly during fruit-dehydrating storage. ABA treatment changed the abundance of the separated wax fractions and the contents of most individual components, which reveals dependence on the exposure to postharvest water stress and different trends depending on storage duration. A correlation analysis supported these responses, which mostly fitted...
Brazilian Archives of Biology and Technology, 2013
properties of wax apple. The wax apple trees were rubbing treated with 0, 20, 50 and 100 mgGA 3 /l under field conditions. The localized application (rubbing) of 50 mg GA 3 /l significantly increased the fruit set, fruit length and diameter, color development, weight and yield compared to the control. In addition, GA 3 treatments significantly reduced the fruit drop. With regard to the fruit quality, 50 mg/l GA 3 treatment increased the juice content, K + , TSS, total sugar and sugar acid ratio of wax apple fruits. In addition, higher vitamin C, phenol, flavonoid, anthocyanin, carotene content, PAL and antioxidant activities were recorded in the treated fruits. There was a positive correlation between the peel colour and TSS content and between the PAL activity and anthocyanin formation in the GA 3 -treated fruit. It was concluded that rubbing with 50 mg/L GA 3 at inflorescence developing point of phloem once a week from the tiny inflorescence bud until the flower opening resulted in better yield and quality of wax apple fruits and could be an effective technique to safe the environment from excessive spray.
The morphology of epicuticular wax and albedo cells of orange fruit in relation to albedo breakdown
Journal of Horticultural Science, 1994
Changes in the morphology of albedo cells of 'Leng' navel and 'Valencia' (Citrus sinensis (L.) Osbeck) orange fruit, in relation to fruit development and to the structural basis of albedo breakdown (creasing), were examined by scanning electron microscopy of frozenhydrated plant material. In albedo tissue sampled from fruit affected by albedo breakdown the fracture paths developed across cell layers in a radial direction, normal to the direction of the stress. The fracturing of albedo tissue was due predominantly to the separation of adjacent cells rather than the cleavage of individual cells, and was, therefore, characteristic of anisotropic tissue. Although separation of albedo cells was also observed in unaffected fruit, it was assumed that the number of cell separations did not exceed a critical threshold required to initiate fracture formation in the tissue. We suggest that changes in the cohesion of adjoining cells at the middle lamella predisposes the fruit to albedo breakdown. The rind of orange fruit was also examined by scanning electron microscopy to identify changes in the ultrastructure of the epicuticular wax of developing and mature fruit. The deposition of crystalline epicuticular wax was observed at an early stage of fruit development when albedo cells were beginning enlargement and differentiation. Although crystalline platelet structure was greater on the shaded side of fruit there were no apparent differences between affected and unaffected fruit in the morphology of the epicuticular wax on the shaded side of the rind.
Impact of changing wax type during storage on mandarin flavor and quality attributes
Acta Horticulturae, 2018
Mandarin (Citrus reticulata Blanco) packers sometimes apply a storage wax (SW) designed to limit water loss during the initial part of storage and then replace it with a higher shine pack wax (PW) prior to shipment of the fruit. Mandarins are prone to the development of off-flavors as a result of low internal oxygen levels following waxing and may lose flavor quality if the applied coating has insufficient permeability to oxygen. In order to better understand the impact of this waxing protocol on mandarin quality 'Tango' mandarins were harvested twice during the season and subjected to various combinations of SW and PW, with storage times up to seven weeks. Evaluations of visual and internal fruit quality, including flavor, were conducted at the end of each storage period. Flavor quality was worse after 4 weeks storage in fruit sequentially treated with both SW and PW in comparison to PW alone, although only for harvest 2 and the flavor differences among wax treatments were not significant after 7 weeks. Fruit receiving multiple wax applications were found to have more visual defects than fruit receiving SW or PW alone, mainly in the form of peel pitting and browning. 'Tango' and 'W. Murcott' mandarins in the second year of the study developed far less rind injury in any of the treatments than had been observed in the initial year, indicating that the impact of applying multiple waxes is likely dependent on the initial condition of the fruit. No flavor differences were found among the wax treatments in year 2. Inclusion of gibberellin into the wax had no clear impact on peel injury. Multiple wax applications have the potential to damage both mandarin appearance and sensory quality and care should be taken to minimize mechanical impacts on the packing line and optimize the gas exchange characteristics of the coatings used.
Activity of salts incorporated in wax in controlling postharvest diseases of citrus fruit
Postharvest Biology and Technology, 2012
The role of some salts applied in combination with wax on the development of postharvest rots was examined on 'Tarocco' and 'Valencia late' oranges and 'Comune' Clementines. Sodium carbonate and bicarbonate, potassium carbonate and bicarbonate, ammonium bicarbonate, and potassium sorbate, at 6% concentration (w/v), in combination with a commercial wax, were evaluated for their activity against naturally occurring postharvest decay. Fruit were stored for one month at 4 • C ('Tarocco' and 'Valencia late' oranges) or 6 • C ('Comune' Clementine), followed by one week of shelf life at 20 ± 2 • C and high RH.