Postharvest Water Loss Research Articles

Epidermal and exodermal tissue structures are characteristic for the long shelf-life ‘Kárpia’ pepper cultivar

In this study two widely consumed Hungarian bell pepper cultivars ‘Ho’ and ‘Karpia’, were examined. Aims of the investigations were to describe the postharvest behaviour of the cultivars and assign associated traits to the largely different shelf-life that is well known for these cultivars. ‘Ho’ is a white fruit flesh cultivar with average postharvest storability, while ‘Karpia’ is of Capia type, with extended shelf-life. Postharvest water loss rates were measured, and differences between the cultivars were found. Interestingly, however, the longer shelf-life ‘Karpia’ fruits showed higher water loss rate. Bright field microscopy was used to study the tissue structure of the outer pericarp of pepper fruits to find explanation for the good storability of ‘Karpia’. Significantly more cell layers of the hypodermal collenchyma were found in ‘Karpia’, than in ‘Ho’. Thicker cell walls were also found in this tissue but also in the epidermis. Fluorescent imaging confirmed these observations and also supported dif...

Fruit cuticle lipid composition and fruit post‐harvest water loss in an advanced backcross generation of pepper (Capsicum sp.)

To understand the role of fruit cuticle lipid composition in fruit water loss, an advanced backcross population, the BC(2)F(2) , was created between the Capsicum annuum (PI1154) and the Capsicum chinense (USDA162), which have high and low post-harvest water loss rates, respectively. Besides dramatic differences in fruit water loss, preliminary studies also revealed that these parents exhibited significant differences in both the amount and composition of their fruit cuticle. Cuticle analysis of the BC(2)F(2) fruit revealed that although water loss rate was not strongly associated with the total surface wax amount, there were significant correlations between water loss rate and cuticle composition. We found a positive correlation between water loss rate and the amount of total triterpenoid plus sterol compounds, and negative correlations between water loss and the alkane to triterpenoid plus sterol ratio. We also report negative correlations between water loss rate and the proportion of both alkanes and aliphatics to total surface wax amount. For the first time, we report significant correlations between water loss and cutin monomer composition. We found positive associations of water loss rate with the total cutin, total C(16) monomers and 16-dihydroxy hexadecanoic acid. Our results support the hypothesis that simple straight-chain aliphatic cuticle constituents form more impermeable cuticular barriers than more complex isoprenoid-based compounds. These results shed new light on the biochemical basis for cuticle involvement in fruit water loss.

Leaf cuticular wax amount and crystal morphology regulate post-harvest water loss in mulberry (Morus species)

Mulberry leaves are the sole source of food for silkworms (Bombyx mori), and moisture content of the detached leaves fed to silkworms determines silkworm growth and cocoon yield. Since leaf dehydration in commercial sericulture is a serious problem, development of new methods that minimize post-harvest water loss are greatly needed. In the present study, variability in moisture retention capacity (MRC, measured as leaf relative water content after one to 5 h of air-drying) was examined by screening 290 diverse mulberry accessions and the relationship between MRC and leaf surface (cuticular) wax amount was determined. Leaf MRC varied significantly among accessions, and was found to correlate strongly with leaf wax amount. Scanning electron microscopic analysis indicated that leaves having crystalline surface waxes of increased facet size and density were associated with high MRC accessions. Leaf MRC at 5 h after harvest was not related to other parameters such as specific leaf weight, and stomatal frequency and index. This study suggests that mulberry accessions having elevated leaf surface wax amount and crystal size and density exhibit reduced leaf post-harvest water loss, and could provide the foundation for selective breeding of improved cultivars.

Influence of water and ABA supply on the ripening pattern of avocado ( Persea americana Mill.) fruit and the prediction of water content using Near Infrared Spectroscopy

Avocado fruit are highly variable, and even those graded for similar size and appearance do not behave in the same manner after harvest. This is particularly problematical for those involved in sales to the “ready-ripe” market. These operations are faced with a high variation in the rate of ripening within a consignment, causing logistical difficulties. Fruit water content (or its complement dry matter) has a major impact on-line ripening and has hence been used as the maturity marker in the South African avocado industry. Presently, fruit water content is destructively measured using a representative sample as an indicator of when to post-harvest. In order to investigate if fruit water content and/or abscisic acid triggers fruit ripening, water or ABA was infused into commercially mature, but non-ripe avocado fruit. The fruit ripening, mass, CO 2 and ethylene production patterns were determined over the ripening period. By infusing water through the pedicle, the variation in days to ripening was decreased without any effect on the number of days to ripening. ABA infusion hastened ripening but did not affect the variation in days to ripening. It is therefore suggested that the fruit water content at harvest forms the baseline condition from which the trigger for ripening is determined, while post-harvest water loss and ABA modulate and stimulate ripening, respectively. Furthermore, an equation was developed using Near Infrared Spectroscopy (NIRS) to measure mesocarp water content ( R 2 = 0.92, SE = 1.8% MC). It is postulated that on line sorting of fruit using NIRS, based on time to ripen, would result in consignments of fruit with less ripening variation, thereby solving the industry's logistical problem of fruit which have a wide spread of ripening being packed into one carton.

Postharvest water loss induces marked changes in transcript profiling in skins of wine grape berries

A large-scale transcriptome analysis was conducted using an oligo-based microarray (14,562 probes) on skins of wine grape ( Vitis vinifera L.) berries dehydrated at different rates (slow, S and rapid, R) after harvest up to 10 and 30% of weight loss (WL). At 10% WL, a total of 84 and 68 probes were differentially expressed following S and R dehydration, respectively. At 30% WL, 309 and 262 differentially expressed probes were detected in S and R samples, respectively, indicating that grape berries are still reactive at advanced stages of postharvest dehydration. Bioinformatic analysis revealed that about 70% of the differentially expressed probes could be annotated and putative functions were assigned. Functional characterization highlighted that, independently of the rate and intensity of dehydration, differential expression occurred in particular for genes associated with general metabolism, regulatory processes, and responses to biotic and abiotic stimuli. A total of 16 (induced) and 10 (repressed) probes, common to all four dehydrated samples, were associated with hormone (ethylene) metabolism, transcription factors, carbohydrate and secondary (polyphenols) metabolism, transport and stress responses. Together with the total number of differentially expressed probes, enhancing the dehydration level from 10 to 30% WL also affected the distribution of genes within functional categories: this behaviour was observed in particular for R samples. A higher level of water stress in grapes appears to be associated with modification to the expression of genes mainly involved in hormone and sugar metabolism, and defence mechanisms. Besides the intensity of dehydration, a significant effect on gene expression was also associated with rate of water loss: an increase in the percentage incidence of differentially expressed probes was present for categories involved in defence and environmental stress when comparing R and S samples. The microarray data, validated by RT-PCR analyses, represent robust evidence for the marked effects of postharvest water loss on metabolic processes in fruit tissues.

Fruit size and stage of ripeness affect postharvest water loss in bell pepper fruit (Capsicum annuum L.)

AbstractQuality of bell peppers after harvest is largely influenced by water loss from the fruit. The objective of this study was to determine the effect of fruit fresh weight, size, and stage of ripeness on the rate of water loss and permeance to water vapor. Fruit diameter was correlated with fresh weight, and surface area was associated with fresh weight and diameter. Fruit surface area decreased logarithmically with increases in fruit size, with smaller fruit showing larger changes in surface area 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/fresh 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. Copyright © 2006 Society of Chemical Industry

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.

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.

Comparison of Stomatal Density and Postharvest Transpiration between Long- and Short-lived Cut Flower Genotypes of Antirrhinum majus L.

Evaluation of leaf stomatal numbers and postharvest water loss indicate these are important factors in Antirrhinum majus (snapdragon) cut flower postharvest longevity (PHL). Cut flowers with 9 days longer PHL had 53% fewer leaf stomata. Long PHL is associated with an early reduction in transpiration followed by low steady transpiration. Short-lived genotypes had a linear transpiration pattern over the period of PHL indicating poor stomatal control of water loss. Short-lived genotypes had 22% to 33% reductions in fourth quarter transpiration while long-lived genotypes had 2% to 8% reductions. In addition, short-lived genotypes had higher average fourth quarter cut flower weight losses compared to long-lived genotypes. Further investigation of stomatal numbers and functioning relative to PHL may provide breeders a rapid and nondestructive indirect selection method for PHL.

Extending shelf-life of peach and pear by using CMC from sugar beet pulp cellulose as a hydrophilic polymer in emulsions

Peach and pear were treated with different compositions of emulsions to extend shelf-life of fruits and to preserve the fruit quality. Paraffin wax, beeswax and soybean oil; carboxymethyl cellulose (CMC) with degree of substitution of 0.6670; Emulgin PE, triethanolamine, oleic acid and sodium oleate were used as hydrophobic phases, hydrophilic polymer and emulsifying agents in the coatings of peach and pear, respectively. The CMC obtained by etherification of the sugar beet pulp cellulose was used as a hydrophilic polymer. To investigate the post-harvest water loss of peach and pear, fruits were observed during storage while being subjected to dehydrating conditions in storage chamber at 25 °C and 75% relative humidity level. The changes in weight, pH, soluble solids, titratable acidity and ascorbic acid of the coated samples with storage time were measured at regular intervals throughout the storage period to evaluate the effect of storage period on fruit quality. The modified drying models describing the storage time dependence of weight loss were fitted to the experimental data and the model parameters in equations were determined by multiple regression analysis. Some of the coatings decreased the soluble solids, titratable acidity and ascorbic acid losses in comparison to the uncoated peaches and pears. The coating of peach and pear surfaces with emulsions containing CMC from sugar beet pulp cellulose as a hydrophilic polymer extended the shelf-lives of peach and pear to 12 and 16 days, respectively. It was found that a combination using beeswax as hydrophobic phase, triethanolamine and oleic acid as emulsifying agent, CMC as hydrophilic polymer and the emulsion containing soybean oil as hydrophobic phase, sodium oleate as emulsifying agent, CMC as hydrophilic polymers were suitable for the coating of peaches and pears, respectively.

Effect of postharvest water loss on ‘Hayward’ kiwifruit water status

To investigate the effect of postharvest water loss on ‘Hayward’ kiwifruit (Actinidia deliciosa C.F. Liang and A.R. Ferguson var. deliciosa) water status, fruit were observed over 14 days after harvest while being subjected to dehydrating conditions in chambers ventilated at 1 l min−1 with dry air (∼10% relative humidity, 20°C). Techniques for monitoring the change in internal aqueous characteristics involved serial magnetic resonance (MR) imaging and traditional measures of fruit water status: water content, relative water content (RWC), tissue water potential, and juice osmotic potential. Fruit fresh weight decreased by 8–10% of the initial weight over the trial period. This was accompanied by decreased water content, RWC and water potential. The rate of decrease in fresh weight, water content and RWC slowed with time. Measurements from serial MR images revealed fruit volume also decreased. This was attributable to shrinkage along the stem–calyx axis (6–9% reduction) rather than across the fruit diameter (1–3% reduction). Relaxation measurements (spin–lattice (T1) and spin–spin (T2)) indicated that there were significant differences between the localised aqueous environments of the core, inner pericarp and outer pericarp, and that the water content (proton density) differed across the fruit. However, despite the marked changes in the fruit's tissue water content, RWC, water potential and juice osmotic potential during dehydration, no significant change was observed in any of the MR measurements during the course of this study. Comparison of the relaxation measurements with those from other imaging studies suggested this observation was not unusual.

Use of nitric oxide to reduce postharvest water loss from horticultural produce

SummaryEleven types of fruit and vegetables and five types of flowers were held in an atmosphere containing a range of concentrations of nitric oxide (NO) gas in nitrogen for 2 h then stored for 24 h in air at 20°C and 60% r.h. Each type of produce was weighed before treatment, and after 24 h, and the rate of water loss calculated. Treatment with NO was found to result in 20% less water loss than in produce stored in air.

Postharvest Water Loss and Storage Quality of Nine Pepper (Capsicum) Cultivars

Nine pepper cultivars (Capsicum annuum L.) representing five pepper types were studied to determine water-loss rates, flaccidity, color, and disease development when stored at 8,14, or 20C for 14 days. Water-loss rate was markedly higher at 14C than at 8C, and was somewhat lower at 20C than at 14C. There were significant differences in water-loss rates between pepper cultivar with `NuMex R Naky', `NuMex Conquistador', and `New Mexico 6-4' (New Mexican-type peppers) having the highest water-loss rates. Flaccidity followed a pattern similar to water loss at each storage temperature, suggesting a direct relationship. Color development was cultivar- and package-dependent, and ratings increased with temperature. Placing pepper fruit in perforated polyethylene packages reduced water-loss rates 20 times or more, so that water loss no longer limited postharvest storage. Packaging also eliminated flaccidity and reduced color development across cultivars at 14 and 20C. Packaged fruit, however, developed diseases that limited postharvest longevity.

Relationships between Postharvest Water Loss and Physical Properties of Pepper Fruit (Capsicum annuum L.)

Physical characteristics [initial water content, surface area, surface area: volume (SA: V) ratio, cuticle weight, epicuticular wax content, and surface morphology] were examined to determine relationships between physical properties and water-loss `rate in pepper fruits. `Keystone', `NuMex R Naky', and `Santa Fe Grande' peppers, differing in physical characteristics, were stored at 8, 14, or 20C. Water-loss rate increased linearly with storage time at each temperature and was different for each cultivar. Water-loss rate was positively correlated with initial water content at 14 and 20C, SA: V ratio at all temperatures, and cuticle thickness at 14 and 20C. Water-loss rate was negatively correlated with surface area and epicuticular wax content at all temperatures. Stomata were absent on the fruit surface, and epicuticular wax was amorphous for each cultivar.