Fruit Water Loss Research Articles

The relationship between water loss, lipid content, membrane integrity and LOX activity in ripe pepper fruit after storage

Ten pepper genotypes with wide variation in rate of water loss after storage were examined in relationship to their membrane lipid content, loss of membrane integrity (electrolyte leakage) and lipoxygenase activity. Pepper genotypes susceptible to high rates of water loss, membrane ion leakage and lipoxygenase activity were found to have correspondingly low amounts of total lipids, total phospholipids and phospholipids classes. The fatty acids determined were also low in amounts except linoleic acid which was high in genotypes susceptible to high rates of water loss. Genotypes with low water loss rates had high amounts of all lipids with the exception of linoleic acid. The high amount of linoleic acid in high water loss genotypes suggests either a rapid biosynthesis of this fatty acid or a slower rate of its catabolism. Correlations between total membrane lipids and rate of water loss (−0.79), electrolyte leakage (−0.89), lipoxygenase (−0.87) were negative and significant. The total phospholipids, phospholipids classes and the fatty acids followed similar trends to total lipids in relation to the other parameters. The high negative correlation between membrane lipids and lipoxygenase activity strengthened the suggestion of the involvement of lipoxygenase activity in lipid peroxidation. Lipoxygenase-catalyzed oxidation of membrane lipids can cause membrane damage, loss of membrane integrity, and interaction of membrane components with highly reactive oxidation products resulting in membrane ion leakage and accelerated water loss in stored peppers.

Influence of cultivar and harvest method on postharvest storage quality of pepper ( Capsicum annuum L.) fruit

The principal physiological factors that negatively impact pepper fruit during shipment and storage and subsequent marketing are water loss and chilling injury. The current study evaluated the effect of harvest methodology on postharvest water loss from sweet bell pepper fruit and the potential relationship between water loss and chilling injury in cold-stored fruit. The influence of cultivar, epicuticular wax, and AOX gene expression on water loss and chilling injury were examined. Our results demonstrated that the degree of water loss in pepper fruit is subject to effects of genotype and pre- and postharvest environments as evidenced by year to year variation in fruit storage attributes. A comparison of pepper fruit harvest methods, wherein peduncles were either torn or cut, showed that harvest method had little effect on percent water loss. Observations on fruit water loss in relation to fruit size suggested that fruit cuticles are the primary barrier to water loss. A clear relationship between epicuticular wax content and fruit water loss was not evident. Cultivars varied in their susceptibility to chilling injury and fruit water loss was positively correlated with the severity of chilling injury. No correlation was found between endogenous AOX transcript levels and cultivar-specific susceptibility to chilling injury. The results illustrate the difficulty of identifying indices correlated with water loss that could be used to develop or identify cultivars with improved storability. We did, however, find that there are significant differences in storage attributes of pepper cultivars and that routine screening for water loss and chilling injury are advantageous for selection of cultivars most suitable for cold-storage.

FRUIT SIZE AND STAGE OF RIPENESS AFFECT POSTHARVEST WATER LOSS IN BELL PEPPER FRUIT (CAPSICUM ANNUUM L.)

Fruit water loss significantly affects the quality of bell peppers. The objective of this study was to determine the effect of fruit weight, size, and stage of ripeness on the rate of water loss and permeance to water vapor. Fruit surface area/weight ratio decreased logarithmically with increases in fruit size, with smaller fruit showing larger changes in the ratio than larger fruit. Mean water loss rate for individual fruit and permeance to water vapor declined with increases in fruit size and as fruit ripeness progressed. Fruit surface area/weight ratio and rate of water loss were both highest in immature fruit and showed no differences between mature green and red fruit. In mature fruit, permeance to water vapor for the skin and calyx were 29 μmol·m–2·s–1·kPa–1 and 398 μmol·m–2·s–1·kPa–1, respectively. About 26% of the water loss in mature fruit occurred through the calyx. There was a decline in firmness, water loss rate, and permeance to water vapor of the fruit with increasing fruit water loss during storage.

Postharvest Changes in Sugar, Organic Acid, Glutamic Acid and Antioxidant Contents in Tomato Fruit Grown under Salinity Stress

The postharvest changes in taste-related compositions (sugar, organic acid and glutamicacid) and antioxidants (ascorbic acid, lycopene and β-carotene) in tomato fruit grown under salinity stress were examined. Salinity stress was applied by adding nutrients (N, P, K, Ca and Mg) of the same ratios as those in the control solution (EC =1.6 dS m-1), until the EC reached by 4.0 dS m-1. Fruits were harvested at a breaker stage (when blossom-end turned red), and then they were stored under the conditions of 20°C, 50-60% of relative humidity in a darkroom. The sugar, organic acid, glutamic acid and ascorbic acid contents on a fresh weight basis of salinity-stressed fruit were higher than those of control fruit throughout the storage. In addition, the results of dry weight basis suggested that the changes in chemical composition during storage in salinity-stressed fruit cannot be induced only by the concentration effect with fruit water loss, but also by the net accumulations. Furthermore, proline content as an indicator of salinity damage was increased in salinity-stressed fruit during storage. These results suggest that postharvest changes in rhemiral composition are influenced by the salinity-effects before harvest.

Characterization of Physiological and Biochemical Factors Associated with Postharvest Water Loss in Ripe Pepper Fruit during Storage

Fruit of pepper (Capsicum annuum L.) is hollow by nature, which limits its water reservoir capacity, and as such, small amounts of water loss result in loss of freshness and firmness, which reduce fruit quality, shelf life, and market value. In order to understand the basis for water loss from fruit, 10 pepper accessions with wide variation in water loss rate were used to study physiological and biochemical factors associated with postharvest water loss in ripe pepper fruit during storage. Postharvest water loss rate in ripe pepper fruit stored at 20 °C, and 85% relative humidity, was found to be associated with cell membrane ion leakage, lipoxygenase activity, and total cuticular wax amount. Total cuticular wax amounts were highest in the high-water-loss pepper fruit, and lowest in the low-water-loss fruit. However, total cuticle amount (isolated enzymatically and quantified gravimetrically), total cutin monomer amount, and the amount of individual cutin monomer and wax constituents (determined using gas chromatography mass spectrometry) indicated no direct association with postharvest water loss rates. Fruit fresh weight, pericarp weight, pericarp surface area, pericarp thickness, initial water content, and dry matter were highly associated with each other, but less so with water loss rate. Fruit of accessions displaying high fruit water loss rate matured and ripened earlier than fruit of accessions displaying low-water-loss rate. Cell membrane ion leakage and lipoxygenase activity were higher after storage than immediately after harvest. Pepper fruit total cuticle wax amount, lipoxygenase activity, and cell membrane ion leakage were directly related to postharvest water loss rate in pepper fruit during storage.

Water Diffusivity and Color of Cactus Pear Fruits (Opuntia Ficus Indica) Subjected to Osmotic Dehydration

This paper details the results of a series of tests whose main purpose was to determinate how osmotic drying influences both water loss and color retention in cactus pear fruits. The dehydration process was performed using a 32 experimental design which involved three different sugar concentration levels (40, 50, and 608Brix) and three different temperatures (25, 40, and 558C). A product/solution ratio of 1/15, cactus pear cylindrical slices 5 mm thick, and ten-hour immersion time spans were used for all the experiments. Modeling of the drying curves was done with Fick's second law and Page's equation, which were used to calculate water effective diffusivity (De), drying constant (k), and the b values respectively. The color parameters (L*, a*, b*) of the samples were measured before and after each test to evaluate total color change (ΔE). An analysis of variance (ANOVA) revealed that water diffusivity and Page's parameter b were affected by temperature and sugar concentration while the drying constant (k) was independent of the drying conditions. The total color change was affected only by the temperature. De and b values varied from 4.06×10−11 to 2.95×10−10 m2/s, and from 0.453 to 0.861 respectively. The best color retention was obtained at 25°C independent of the sugar concentration.

A study of rapid senescence of detached litchi: roles of water loss and calcium

Cultivar performance of litchi (Litchi chinensis Sonn.) and roles of water loss and calcium in postharvest fruit senescence were studied. Desiccation and membrane breakdown were accelerated once litchi fruit were detached from the tree. Membrane breakdown began from the inner part (mesocarp) of the pericarp within 2 days after harvest (DAH) and within 5 DAH in the sclerenchyma exocarp cells. Membrane breakdown was not yet observed at 5 DAH in the epidermis cells, where a very high calcium concentration was revealed by X-ray microanalysis. Transfusion of water to the fruit through the stalk slowed fruit water loss and browning within 4 DAH, but the treated fruit tended to rot from the internal and deteriorated entirely by 6 DAH. There was no difference in response to transfusions of water and calcium chloride (18 mmol/l) solution. Among the five tested cultivars, ‘Nuomici’ had the shortest shelf-life, while ‘Guiwei’ had the longest. Desiccation rates of these cultivars were not consistent with their fruit deterioration rate. Concentration of structural calcium in the pericarp was negatively correlated to fruit deterioration rate and membrane leakage. The results suggest that calcium in structural form may influence fruit senescence through its role in tolerance to desiccation and in maintenance of membrane integrity. Preharvest spray of calcium chloride (40 mmol/l) at different stages of fruit development failed to increase structural calcium in the pericarp and was ineffective in slowing fruit senescence.

DYNAMIC OPTIMIZATION USING NEURAL NETWORKS AND GENETIC ALGORITHMS FOR TOMATO COOL STORAGE TO MINIMIZE WATER LOSS

In this study, dynamic optimization of heat treatment for reducing the water loss in fruit during storage wasinvestigated using intelligent approaches. Over a temperature range from 15.C to 40.C, the control process was divided intol steps (l = 6). The dynamic change in the rate of water loss as affected by temperature was first identified using neuralnetworks, and then the optimal combination of the lstep setpoints for temperature that minimized the rate of water loss wassearched for through simulation of the identified model using genetic algorithms. Two types of optimal values, a singleapplication of heat stress and a double application of heat stress, were obtained under the range of 15.C < T < 40.C. Thelength of each step was 24 h. The former treatment is useful for shortterm storage, and the latter is useful for comparativelylongterm storage. With the single heat treatment, the temperature first rises to the highest level (40.C), which is maintainedover a period of 24 h, and then suddenly drops to the lowest level (15.C). In particular, the sudden drop in temperature fromthe highest level to the lowest level provided lower values of the rate of water loss than maintaining the temperature constantlyat the lowest level throughout the control process. These results suggest that application of heat stress to fruit is effective inmaintaining freshness of fruit during storage.

Responses of strawberry fruit to 1-Methylcyclopropene (1-MCP) and ethylene

1-Methylcyclopropene (1-MCP), a competitive inhibitorof ethylene action, binds to the ethylene receptor toregulate tissue responses to ethylene. In this work,we investigated the effects of 1-MCP and exogenousethylene on ripening, respiration rate, ionicconductivity and peroxidase activity in strawberryfruit. Strawberry fruit can ripen without exogenousethylene treatment, but exogenous ethylene inducessecondary ripening processes. Results indicated thatstimulation of respiration by ethylene wasdose-dependent. Fruit colour development and softeningwere slightly accelerated by ethylene, but changes insoluble solid content were not. 1-MCP may/may notaffect the respiratory rise induced by exogenousethylene dependent on fruit maturity. Cycloheximide(CHI) reduced the ethylene-induced respiratoryincrease. Combinations of 1-MCP and CHI reducedrespiration more than CHI alone. 1-MCP and CHI did notinfluence the primary respiratory change in nonethylene-treated fruit. This indicates that ethyleneinduced respiratory increase may involve an ethylenereceptor in early harvested fruit, but not in laterharvested fruit. Exogenous ethylene stimulatedrespiration by regulating new respiratory enzyme(s)synthesis in strawberry fruit. Ethylene induced anionic leakage increase, and this was positivelycorrelated to fruit water loss and peroxidaseactivity. These results suggest that non-climactericfruit, such as strawberry, may have different ethylenereceptor(s) and/or ethylene receptor(s) may havedifferent regulatory functions. It may be thesecondary effect of ethylene to stimulate respirationin strawberry. Non-climacteric fruit ripening may berelated to the development of active oxygen species(AOS) induced by postharvest stress.

595 The Cuticular Membrane: A Critical Factor in Rain-induced Cracking of Sweet Cherry Fruit

Morphological and physical characteristics of the cuticular membrane (CM) of selected cultivars of sweet cherry (Prunus avium L.) fruit were studied relative to rain-induced cracking. Two characteristics of the CM may be determinants in rain-induced fruit cracking. The surface morphology and chemistry determine surface wettability and water retention, and the morphology and physicochemical characteristics its water permeability. The fruit epidermis as well as the guard cell walls adjacent to the outer vestibule and stomatal pore are covered by a thin lipoidal CM. Stomata were present at a frequency of 0.1 to 2 per mm2 depending on cultivar and fruit surface position. However, most appeared nonfunctional with many pores partially or completely occluded with wax-like material. There was no evidence of water (containing fluorescein or AgNO3) penetration into stomatal pores following surface application or submerging fruit for short periods. There was stomatal pore penetration when submerged fruit were infiltrated by reduced pressure in the presence of 0.1% L-77. Preferential sorption of AgNO3 and fluorescein by cuticular ledges and guard cells was noted. The epicuticular wax (ECW) had no significant fine-structure. The CM was isolated enzymatically (cellulase/pectinase) and found to be 1 to 2 μm thick with an area weight of 1.2 to 2.3 g·m–2, of which 25% to 40% was chloroform/methanol (1: 1by vol.) soluble. Fractionation of the chloroform/methanol fraction indicated the presence of four groups of nonpolar constituents. The fruit surface was moderately difficult to wet, forming contact angles of 85% to 105%, and with an estimated critical surface tension in the range of 16-24 mN·m–1. Fruit water loss (transpiration) and uptake on submersion was followed and found to be complex. Transpiration increased with an increase in temperature, and both rate of transpiration and water uptake increased after removal of the epicuticular and cuticular waxes. Pathways of water uptake and the significance of our findings to rain-induced fruit cracking will be discussed.

Transpiration rates in eggplant fruit as affected by fruit and calyx size

Fruit transpiration was measured on eggplants of a wide range of sizes. The separate contributions of the skin and calyx to whole-fruit (skin plus calyx) transpiration were determined. The calyx was the main route for fruit water loss, accounting for at least 60% of fruit transpiration. Fruit transpiration rate declined as eggplants increased in size. This decline in fruit transpiration was due to both a reduction in the portion of the fruit covered by the calyx and a reduction in the surface area/mass ratio of the fruit as they increased in size. The calyx covered 95 and 10% of fruit surface area in a 5 and 550 g fruit, respectively. The high rate of water loss through the calyx indicates that postharvest treatments intended to reduce water loss from the calyx may be beneficial in extending shelf life in eggplant fruit.

Effect of preharvest bagging on fruit calcium levels, and storage and ripening characteristics of ‘Sensation’ mangoes

Mango fruit may be bagged during their development on the tree in order to reduce disease incidence and skin blemish. However, the influence of fruit bagging on calcium accumulation and their storage and ripening characteristics has not been reported. ‘Sensation’ mango fruit were bagged with commercially available plastic or paper bags 7 weeks before normal harvest. No significant differences in calcium concentrations between bagged (plastic or paper) and unbagged fruit were recorded for either skin or flesh tissue. Plastic bags resulted in increased fruit water (weight) loss after harvest. Softening and colouring of fruit which had been bagged with plastic were both hastened. Paper bags had no apparent influence, compared with unbagged control fruit, on weight loss or ripening characteristics of ‘Sensation’ mango fruit.

Improvement of the postharvest keeping quality and colour development of bell pepper (cv. ‘Maor’) by packaging with polyethylene bags at a reduced temperature

The keeping quality of red bell pepper (Capsicum annuum) is relatively low, since the fruits are sensitive to low temperature (< 7 °C), rot development and water loss. The effect of packaging red bell pepper fruits in various kinds of polyethylene bags, having various percentages of perforation (0.064 – 0.42%), was examined as a means of reducing water loss in fruits stored at the usual storage temperature (7–8 °C) and at 3 °C. In addition, prestorage holding of fruits for two-three days at various temperatures, combined with polyethylene-bag packaging was examined as a means of improving fruit colour development. Several beneficial effects were found: (1) polyethylene-bag packaging reduced water loss by 40–50% in fruits stored for two weeks at 7.5 °C and an additional three days at 17 °C, thereby resulting in maintenance of fruit quality; (2) packaging did not significantly increase rot development in the stored fruits during either storage or shelf-life; (3) polyethylene-bags enabled bell peppers to be stored at a reduced temperature (3 °C) without the appearance of chilling injury symptoms; (4) prestorage holding of peppers packed in perforated bags for two days at 25 °C, resulted in full red colour development at the end of their 12 days storage period, without loss of their firmness and quality.

Irrigation Regimes Affect Fruit Soluble Solids Concentration and Rate of Water Loss of `O'Henry' Peaches

The effect of irrigation management strategies on the quality and storage performance of `O'Henry' peaches [Prunus persica (L.) Batsch] was studied for two seasons. The deficit irrigation treatment induced a higher fruit soluble solids concentration and lower fruit weight. The excess irrigation treatment, compared to the optimum treatment, increased the rate of fruit water loss without altering fruit quality and storage performance. Scanning electron microscope observations indicated a higher density of trichomes on fruit from the deficit and optimum irrigation treatments than from the excess irrigation treatment. Light microscopy studies indicated that fruit from deficit and optimum irrigation had a continuous and much thicker cuticle than fruit from the excess irrigation treatment. These differences in exodermis structure may explain the high percentage of water loss from fruit from the excess irrigation treatment compared to the deficit and optimum irrigation treatments.

Effect of pre- and post-harvest water stress on the potential for fruit quality defects in avocado (Persea americanaMill.)

Physiological and pathological disorders of avocado fruit are a limitation to export sales. The influence of pre-harvest water stress on post-harvest quality was studied using a long-term irrigation trial, i.e., re-wetting in the root zone when soil water tensions reached 35 kPa, 55 kPa and 80 kPa. Fruit quality from two harvest dates was expressed in terms of the browning enzyme polyphenol oxidase (PPO). The effect of post-harvest fruit moisture loss on pathological and physiological disorders was investigated using increased humidity in the storage container to minimize fruit water loss. Pre-harvest water stress played a role in determining post-harvest browning potential. Fruit calcium concentration changes were also affected. For early (autumn) harvested fruit, highest PPO activity was found in the 80 kPa (most stress) irrigation treatment and lowest in the 55 kPa (intermediate stress) treatment for both stored and unstored fruit. Stored fruit had higher PPO values than unstored fruit. Winter harveste...

Sources of Photosynthate for Fruit Growth in ‘Bing’ Sweet Cherry

Abstract Source–sink relationships in sweet cherry were altered by girdling limbs both above and below fruiting spurs. Spurs isolated by girdling both above and below had lower total fruit weight per spur and lower weight per fruit then those above or below girdles. Fruit number per spur was not altered, but soluble solids and fruit color were lower in fruits from isolated spurs than fruit from spurs either above or below girdles. Fruit on spurs above girdles were generally highest in soluble solids and fruit color. These factors indicate fruit on isolated spurs also were delayed in maturity. Spurs below girdles were unaffected by girdling. Girdling had no effect on spur leaf net photosynthesis, stomatal conductance, or fruit water loss rate. The results indicate that spur leaves alone do not have the capacity to support fruit growth in sweet cherry and must, therefore, be supplemented by photosynthates from other sources.

Relationship of Netted Muskmelon Fruit Water Loss to Postharvest Storage Life

Abstract ‘Magnum 45’ muskmelon fruit, (Cucumis melo L. var. reticulatus Ser.) either shrink-film-wrapped to maintain a water-saturated microatmosphere or non wrapped, were stored in 4°C, 85-95% RH, and were sampled at 10-day intervals for 40 days postharvest. Fruits maintained in a water-saturated microatmosphere via shrinkwrap exhibited no significant change in percentage of dry weight, firmness, soluble sugars, β-carotene, or a loss of membrane integrity throughout 40 days storage. Shrink-wrap fruit had a 1% reduction in fresh weight, and a decline in appearance rating and surface browning by 40 days postharvest but were generally rated as excellent to good salable quality. Unwrapped fruit maintained in 85-95% RH exhibited progressive decline in appearance, surface browning, percentage of dry weight, soluble sugars, mesocarp firmness, and loss of membrane integrity. No change was observed in β-carotene. Non wrapped fruit had a 5.7% reduction in fresh weight within 20 days postharvest and were generally rated as fair to poor salable quality. Mesocarp membrane integrity during postharvest storage was highly dependent on percentage of fresh weight loss over time for both shrink-film-wrapped and non wrapped muskmelon fruit.