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Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study objective was to determine the effects of field application of hexanal on pre-harvest market attributes of orange (Citrus sinensis L.) fruits. The first factor was hexanal concentration (0.01, 0.02, 0.04% and controls – untreated fruits), the second factor consisted of time of hexanal application prior to fruit harvest (7, 21, 42 and 60 days to harvest) and the third factor was season (1st and 2nd season). Tested orange varieties were Early Valencia ('Msasa'), Jaffa and Late Valencia varieties. A fruit tree for each orange variety constituted a treatment for hexanal application and time of its application prior to fruit harvest. The results show that hexanal application at 0.01, 0.02 and 0.04% equally improved fruit marketable yields by increasing fruit firmness and number of marketable fruit of Early Valencia, Jaffa and Late Valencia varieties. Number of marketable fruit increased by 34.89%, 34.04% and 42.48% over the controls for Early Valencia, Jaffa and Late Valencia, respectively. Similarly, fruit firmness increased by 11.38, 11.03 and 11.92 N/mm2 over the control for Early Valencia, Jaffa and Late Valencia, respectively. It is recommended that farmers should treat Early Valencia, Jaffa and Late Valencia with hexanal at 0.01% in order to increase marketable yield and fruit quality. [ABSTRACT FROM AUTHOR]

Post-harvest loss negatively impacts food security, nutrition and economic stability of farmers, exporters, traders and consumers. Experiments were conducted to assess the effects of post-harvest techniques on the shelf life of Apple and Palmer mango cultivars under different storage conditions. Post-harvest losses of these fruit along the supply chain were also evaluated. A two-factors factorial experiment with six replications was used for each cultivar. Post-harvest techniques included dipping of fruit in hexanal solution (0.02% v/v), calcium chloride solution (2% w/v), smoke treatments and untreated fruit. The fruit were then stored at two different storage conditions namely: ambient temperature (28 ± 2°C) and cold storage (18 ± 2°C). Shelf life data was analyzed by using R-software. Mean separation was done by using Tukey Honestly Significant Difference at (p ≤ 0.05). Results showed that the major sites of post-harvest losses were at harvest, transport, wholesale and retail stages of supply chain. Furthermore, post-harvest treatments of fruit with hexanal and calcium chloride significantly increased shelf life and reduced disease incidences compared to untreated control and smoke-treated fruit. Cold storage significantly increased shelf life of mango fruit compared to ambient storage. Therefore, hexanal, calcium chloride and cold storage are recommended to extend fruit shelf life, maintain fruit firmness and to reduce disease incidences in mango fruit. [ABSTRACT FROM AUTHOR]

Maintaining the quality of perishable commodities during storage and transportation remains a challenge to the fruit and vegetable industry in many countries. In order to minimize post-harvest loss, a hexanal incorporated composite material (HICM) was created using hexanal, banana fibre, polymeric materials, and biopolymers. Efficacy of the HICM was tested on mango variety TEJC. Trials were conducted over two consecutive fruit seasons in 2016 and 2017. Six fruits were packed in corrugated cardboard cartons and eight cartons per treatment (with and without HICM) were stored at 13.5°C 2 °C and 92% relative humidity. Quality observations for each treatment were recorded at 7-day intervals for 28 days. Higher retention of fruit firmness and marketability were observed in fruits packed with the HICM with 50% of the fruit marketable after 21 days storage at 13.5 °C 2 °C (p <.05). Control fruits were not marketable at 21 days. Qualitative headspace gas chromatography molecular spectroscopy (GCMS) analyses were executed to determine the stability of released hexanal and the fate of hexanal when absorbed into fruit. Hexyl esters and hexanoate esters were observed in the headspace of HICM-treated fruits. Results from this study indicate that HICM treatment could be used along with low temperature storage to promote the marketability of TEJC mangoes. [ABSTRACT FROM AUTHOR]

Two formulations of bees wax-based edible coatings with added anti-ripening and antifungal compounds, C5 (hexanal and cinnamon bark oil) and C6 (cinnamon bark oil only), were developed and tested on mangoes stored at low temperature (13.5 °C ± 2 °C) for quality attributes including internal CO2 accumulation and marketability. The particle size distribution of the waxes and the surface morphology of the coating were also assessed. Our results demonstrate a low rate of disease incidence with higher marketability in wax-treated fruits after two weeks of storage at the low temperature compared to untreated controls (p < .05). Internal CO2 accumulation in the wax-coated mangoes was high compared to un-waxed controls indicating the formation of a semi-permeable coating around the fruit. No significant differences (p < .05) in other quality parameters such as fruit colour, fruit firmness, and pH were observed in wax-treated fruits compared to controls. However, significantly higher (p < .05) fruit acidity with lower total soluble solid content was observed in wax-coated fruits after one week of storage indicating a delay in the ripening process. No off-flavours were reported for the wax-coated fruits by the sensory panellists. [ABSTRACT FROM AUTHOR]

Generally, limequat (Citrofortunella floridana J.W.Ingram & H.E.Moore) fruits have a relatively short shelf life at supermarket display temperatures (17-22oC). In some cases, shelf life can be as short as four days, after which surface discolouration becomes evident, along with shrivelling, and in many instances, the development of post-harvest diseases. Therefore, for maintenance of marketable quality, these three factors must be controlled. Pre-harvest treatments are known to positively affect the post-harvest quality of many commodities. Among these, treatment with hexanal has resulted in improved post-harvest quality maintenance because of its retarding effect on enzyme-driven cellular degradation. This study was conducted to observe the effect of pre-harvest treatments with hexanal on the length of the shelf life and the postharvest quality of limequat fruits. Pre-harvest spray applications of 2% and 4% EFF (Enhanced Freshness Formulation), containing hexanal as the active ingredient, were made at weekly and biweekly intervals 30-days before the expected date of harvest. Pre-harvest spray treatments of EFF at 2% and 4% to trees of limequat resulted in the delay in the rate of colour change from green to yellow by an average of 7 days and 14 days, respectively, in harvested mature fruit. Senescent changes and other signs of deterioration including surface discolouration as brown patches, appeared on the fruit only after full colour change from green to yellow had occurred. Pre-harvest treatment also resulted in a reduction in the incidence of post-harvest diseases by up to 21 days during storage at 17-19oC / 90-95% RH. Thus, pre-harvest spray application had a marked effect on appearance by delaying both yellowing and shrivelling of the fruit, and consequently on marketability since appearance is one of the main factors determining acceptability in the marketplace. [ABSTRACT FROM AUTHOR]

Limequat (Citrofortunella floridana J.W.Ingram & H.E.Moore), unlike many tropical fruits, is produced year-round in Trinidad and Tobago and there are periods where other seasonally available varieties of limes, for example, the West Indian variety, are in greater demand than the limequat, resulting in glut supplies and high losses in the field. Limequat has been known to produce in excess of 250,000 fruits per hectare and during periods of low demand, much of these fruits go to waste. Retention time of the fruit on the tree is usually around 35 days, after full colour change from green to yellow. Due to its soft texture, the fruit bruises very easily leading to high post-harvest losses and loss of earnings to farmers. This study was conducted to determine the effects of pre-harvest treatments with enhanced freshness formulation (EFF), applied at different concentrations and different application intervals, on retention time of the fruit on the tree and time to colour change of the fruit as an indicator of onset of senescence. Trials conducted showed that pre-harvest biweekly applications of EFF at four percent was more effective in delaying the onset of colour change of the limequat fruits than EFF application at two per cent. It was observed that application of two per cent EFF bi-weekly for four weeks gave a greater reduction in the average number of fruits showing full colour change after treatment when compared to weekly application. Results of the study indicated that application of four percent EFF at bi-weekly spray intervals for one month significantly reduced the rate of colour change of limequats on the trees. Weekly applications of two percent EFF gave the best retention times on the tree, in excess of 99 days, after treatment. Thus, treatment with EFF reduced pre-harvest losses and increased the time for which marketable quality of fruits was maintained. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of hexanal on the post-harvest shelf life and quality of papaya (Carica papaya L.) in two agro-ecological zones (AEZs II and IV) among small-holder farmers in Kenya. Hexanal was tested at two concentrations, 1% and 2%, and applied as a dip for 2.5 minutes or 5 minutes on mature green Solo Sunrise and Mountain papaya cultivars. Water was used as control. The experiment was done in a randomized complete block design with three replications; means were compared by Analysis of Variance using GenStat Version 15. Untreated papaya fruits lasted for 9 days whereas papaya fruits dipped in 2% hexanal for 5 minutes lasted for 15 days with ethylene and respiratory peaks delayed by three days (p < 0.05). These hexanal-dipped fruits lost up to 19% of their cumulative physiological weight (p < 0.05) after the entire storage period of 15 days, whereas controls lost up to 35% of their physiological weight over the same period, and were firmer in texture by 37.4% (p < 0.05). Titratable acidity in papaya fruits gradually decreased with time during the ripening period with no significant difference between the treated and the untreated fruits (p <0.05). Total soluble solids, however, increased as the fruit ripened and then declined with no significant differences between the treatments (p <0.05). Dipping the papaya fruits in hexanal had no effect on beta-carotene content but decreased the rate of vitamin C decline with fruit ripening (p < 0.05). The results of this study indicate that the use of hexanal could be a novel and viable option for reducing post-harvest losses of papaya (Carica papaya L.) in Africa, benefitting small-scale farmers as well as large-scale farmers and traders through improved post-harvest maintenance of quality and longer shelf life. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the efficacy of hexanal applied either as pre-harvest spray or post-harvest dip in enhancing the shelf life of banana var. Grand Nain. The study was done in Meru County (high potential zone) and Machakos County (low potential zone) of Kenya. Two hexanal concentrations (2% and 3%) were sprayed either once (at 30 days) or twice (at 30 days and 15 days) before harvest. Observations of how long the fruits stayed on the tree between the treated and untreated ones, was based on the duration taken for 20% of the fruits per bunch to ripen. Once ripe, the fruits were harvested and analysed. For the post-harvest dip treatment, fruits harvested at the mature green stage were dipped in 2% hexanal, 3% hexanal, or water (control) for 2.5 minutes or 5 minutes. The fruits were allowed to ripen at ambient room conditions (25 ± 1oC and RH 60 ± 5%). Physiological and physico-chemical parameters associated with fruit ripening were evaluated at 3-day intervals. An interaction between zone of production and mode of application had a significant effect (p <0.05) on fruit retention. Hexanal applied twice as a spray significantly (p < 0.05) improved fruit retention by 12 days and 18 days in Machakos and Meru Counties, respectively. Post-harvest dip treatments enhanced fruit shelf life by 9 days (5- minute dip) and 6 days (2.5-minute dip) compared to 6 days for bananas sprayed twice. Respiration rate, ethylene production, and fruit softening were significantly (p < 0.05) delayed by hexanal treatment. Progression of other ripeningrelated changes including increases in total titratable acidity, 0Brix, and vitamin C were slower in fruits treated with hexanal. Overall, these findings indicate that hexanal applied either as a pre-harvest spray (30 days and 15 days before harvest) or a post-harvest dip (5 minutes) has the potential to enhance banana shelf life besides improving fruit retention on the tree by 12-18 days when applied as pre-harvest spray. [ABSTRACT FROM AUTHOR]

Papaya (Caria papaya L.) cv. Red lady is used as ripened fresh fruit as well as in the unripe state in many processed products. Therefore, for uses other than fresh fruit consumption, maintenance of fruit in the unripe state is extremely important for viable commercial applications. The application of 2% enhanced freshness formulation (EFF) with hexanal as the main active ingredient, has been shown to delay the onset of ripening in several subtropical fruits. This investigation was done to determine its effect on ripening and senescence in papaya fruits. Trials were conducted using 2% EFF applied as a preharvest spray and as a post-harvest dip alone or in combination with the pre-harvest spray. Pre-harvest treatments were applied at two week intervals beginning 30-days before expected harvest maturity. For post-harvest treatments, fruits were completely immersed in the dip solution for ten minutes and allowed to air dry at room temperature before storage. Fruits on trees sprayed pre-harvest with 2% EFF developed first colour stripe approximately 75 days after second spraying while fruits on trees sprayed with the control solution developed first colour stripe 15 days after application of the second spray. This was as expected since the pre-harvest applications were timed to be begin within 30 days of expected harvest. Thus, pre-harvest treatment with 2% EFF resulted in a 60 day delay in the onset of ripening in fruits on treated trees. Fruits were harvested on development of the first colour stripe, indicative of the onset of ripening. Following the delayed onset of ripening, fruits harvested from trees sprayed pre-harvest with 2% EFF ripened to full colour change in 15-18 days during storage at 20-22oC / 90-95% RH. Fruits harvested from trees sprayed with the control solution ripened to full colour change in 8-10 days when stored under the same conditions. At full colour change, fruits from trees treated pre-harvest with 2% EFF had a lower incidence of post-harvest diseases than fruits from control trees. The application of 2% EFF as a preharvest treatment and as a postharvest dip can be used to increase the time to onset of ripening of papaya fruit in the field, delay the development of full colour change in fruits after harvest, maintain postharvest quality of fruits during storage at 20-22oC / 90-95% RH and reduce the incidence of post-harvest diseases. [ABSTRACT FROM AUTHOR]

A laboratory study was undertaken to determine the effects of a nano-emulsion carrying hexanal, an enhanced freshness formulation (EFF), as a post-harvest dip technology to minimize the post-harvest losses and to extend the shelf life of bananas. The banana fruits were harvested at three maturities (95%, 85%, and 75%), dipped or not dipped in the EFF, and studied under both ambient and reduced temperature storage conditions. During the experiments, the fruit's physical, physiological, and biochemical parameters were periodically evaluated. The treated fruit had lower physiological loss of weight and higher firmness throughout the study period, regardless of maturity level at the start. Treated fruit had higher total soluble solids and total sugars, and less acidity indicating improved fruit quality during storage, in addition to an extended shelf life. High resolution imaging using scanning electron microscopy showed that EFF-treated fruit exhibited well maintained structural lenticels on the fruit skin and deposition of starch granules in the fruit pulp, regardless of maturity level at the start. Overall, the results clearly indicated that the EFF-treated banana fruit were delayed in the ripening process and had an extended shelf life of up to six days in ambient conditions and nine days in cold storage conditions. Post-harvest dipping using hexanal formulation is a potential technology that could be adopted in pack houses for domestic and export markets. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

'Honeycrisp' (Malus domestica Borkh.), a premium applecultivar, is highly susceptible to bitter pit and decline in quality during long-term storage. In order to enhance the quality, an aqueous composition containing hexanal was applied as a preharvest spray. The effects of hexanal were assessed on the treated fruit and compared with HarvistaTM (a sprayable 1-Methylcyclopropene based commercial formulation) applied and control fruit under both cold (2.5 °C; four months) and cold after room temperature storage (20 °C; 14 days) conditions. Color, firmness, and total soluble solids (TSS) did not show a significant change in response to any treatment at harvest, while abscisic acid (ABA) significantly reduced and tryptophan increased in response to hexanal, compared to HarvistaTM and control. The treatment effects on quality traits were observed during storage. Both hexanal and HarvistaTM sprayed apples had higher TSS under both cold and room temperature storage. In addition, both sprays enhanced firmness at room temperature storage. However, the effects of sprays on other quality traits showed a different pattern. Apples sprayed with hexanal had lower phospholipase D enzyme (PLD) activity, lower incidence of bitter pit, and decreased expression of MdPLDα1 compared to HarvistaTM and control. On the other hand, HarvistaTM treated fruit produced lower ethylene. Both sprays decreased the expression of MdPLDα4, MdCaM2, MdCaM4 and MdCML18 genes. Generally, PLD alpha has a direct role in promoting fruit senescence, whereas the calcium senor proteins (CaM/CMLs) may involve in fruit ripening process via calcium and ethylene interactions. Therefore, improved postharvest qualities, including the lower incidence of bitter pit in hexanal treated 'Honeycrisp', may be associated with lower membrane damage due to lower PLD enzyme activity and decreased expression of MdPLDα1 and MdPLDα4 genes throughout the storage period. [ABSTRACT FROM AUTHOR]

Mango is a highly preferred seasonal tropical fruit with a maximum shelf-life of five to seven days. Hexanal is a plant volatile compound assayed in green tissues and showing significance in enhancing storage life and fruit quality attributes by preserving membrane integrity. This experiment explored the effect of the pre-harvest application of an aqueous hexanal composition (active ingredient: 0.02% hexanal) in altering the post-harvest storage behavior of four mango cultivars. The pre-harvest application of the hexanal formulation to the fruit surface twice before the harvest date drastically slowed down the physiological loss in weight by 70% to 80%, and reduced the ethylene evolution rate by two to three folds, respectively. The pre-harvest hexanal formulation spray combined with post-harvest cold storage prominently improved the storage life along with the total soluble solids, total sugars, ascorbic acid and carotenoid content compared to untreated fruits stored in ambient conditions. Though ripening coincides with the increased activity of enzymes, the hexanal formulation spray acts predominantly in bringing down the activities of fruit softening enzymes viz. pectinmethlyesterase (43%) and polygalacturonases (37%), and antioxidant enzymes viz. peroxidase (67%) and catalase (45%), respectively. [ABSTRACT FROM AUTHOR]

Apples (Malus domestica Borkh) are prone to preharvest fruit drop, which is more pronounced in 'Honeycrisp'. Hexanal is known to improve fruit retention in several economically important crops. The effects of hexanal on the fruit retention of 'Honeycrisp' apples were assessed using physiological, biochemical, and transcriptomic approaches. Fruit retention and fruit firmness were significantly improved by hexanal, while sugars and fresh weight did not show a significant change in response to hexanal treatment. At commercial maturity, abscisic acid and melatonin levels were significantly lower in the treated fruit abscission zone (FAZ) compared to control. At this stage, a total of 726 differentially expressed genes (DEGs) were identified between treated and control FAZ. Functional classification of the DEGs showed that hexanal downregulated ethylene biosynthesis genes, such as S-adenosylmethionine synthase (SAM2) and 1-aminocyclopropane-1-carboxylic acid oxidases (ACO3, ACO4, and ACO4-like), while it upregulated the receptor genes ETR2 and ERS1. Genes related to ABA biosynthesis (FDPS and CLE25) were also downregulated. On the contrary, key genes involved in gibberellic acid biosynthesis (GA20OX-like and KO) were upregulated. Further, hexanal downregulated the expression of genes related to cell wall degrading enzymes, such as polygalacturonase (PG1), glucanases (endo-β-1,4-glucanase), and expansins (EXPA1-like, EXPA6, EXPA8, EXPA10-like, EXPA16-like). Our findings reveal that hexanal reduced the sensitivity of FAZ cells to ethylene and ABA. Simultaneously, hexanal maintained the cell wall integrity of FAZ cells by regulating genes involved in cell wall modifications. Thus, delayed fruit abscission by hexanal is most likely achieved by minimizing ABA through an ethylene-dependent mechanism. [ABSTRACT FROM AUTHOR]

Highlights: [•] Quality of greenhouse tomato can be enhanced by preharvest application of hexanal-containing aqueous formulations and enhanced freshness formulation. [•] Postharvest dips in “enhanced freshness formulation” are also effective in enhancing shelf life of tomatoes. [•] Increased firmness, red colour, ascorbic acid levels, etc., are features observed in tomatoes treated with “enhanced freshness formulation” indicative of better quality. [Copyright &y& Elsevier]

Aqueous compositions of hexanal, an inhibitor of phospholipase D, has been shown to enhance the shelf life and quality of fruits and vegetables. In the present study, sweet bell pepper fruit were exposed to hexanal vapor and its effect on quality attributes, shelf-life, and antioxidant enzyme activities were evaluated during storage at 7 day intervals for 21 d. Peppers subjected to hexanal vapor treatments (0.005, 0.01, and 0.02%, w/w) showed a significant (p < 0.05) delay in ripening process and preservation of postharvest qualities than untreated peppers, even at 21 d of storage. Treated fruit were characterized by increased firmness, a reduction in physiological water loss and lower electrical conductivity than control fruit, which indicated better membrane preservation. These treatments also resulted in an increase in the levels of antioxidant enzyme activities, specifically that of superoxide dismutase, catalase, glutathione reductase and guaiacol peroxidase. Evidences from the present study indicate that postharvest hexanal vapor treatment at optimal levels can effectively enhance the quality and shelf life of sweet bell peppers. [ABSTRACT FROM AUTHOR]

Field experiments were conducted to study the response of mango (var. Alphonso and Banganapalli) to pre-harvest sprays of a nano-emulsion of hexanal (Enhanced Freshness Formulation) in extending retention and shelf-life of fruits. Hexanal, a naturally occurring plant derived compound is known to inhibit phospholipase-D and facilitates extension of shelf-life of fruits during storage. Pre-harvest sprays of EFF (1.6 mM) on 30 and 15 days before harvest were done and the observations on fruit retention, incidence of post-harvest diseases and net fruit yield were recorded. After harvest, the fruits were kept under ambient (25 ± 2 °C; 70–75% RH) and cold (14 ± 2 °C; 85–90% RH) storage conditions and the physiological and biochemical parameters were measured regularly till the end of the shelf-life. The data clearly indicated that pre-harvest sprays of EFF significantly reduced the post-harvest diseases such as anthracnose, stem end rot and other infestations which minimized the post-harvest losses while increasing the net fruit yield by 4–5 kg per tree. The sprayed trees retained the fruits in the tree by 3–4 weeks longer than control. Further, the fruits harvested from the sprayed trees remained fresh for a longer period of time under both ambient (24–25 days) and cold (36–40 days) storage conditions in comparison to their respective controls (16–18 days; 20–22 days). The physiological loss in weight was registered lower while other quality attributes such as firmness, total sugars, acidity of treated fruits were higher than their respective controls regardless of storage conditions. Overall, the results suggested that pre-harvest sprays of EFF assisted in retention fruits for 3–4 weeks longer in the orchard itself besides extending shelf-life under storage conditions without the loss of quality of fruits. [ABSTRACT FROM AUTHOR]

• Hexanal formulation increased the fruit retention in Honeycrisp apples. • Pre-harvest spraying of Honeycrisp apples reduced the incidence and progression of bitter pit. • Hexanal reduced the phospholipase D enzyme activity and ethylene evolution. • Hexanal application helps retain the integrity of the cell wall. 'Honeycrisp' is a popular apple variety among consumers due to its desirable flavour and characteristic texture. However, this variety is highly prone to pre-harvest fruit drop, bitter pit and decline in quality during long-term storage. This research investigated the effects of hexanal as a formulation (named by us as Enhanced Freshness Formulation -EFF) on fruit retention and post-harvest shelf-life in 'Honeycrisp' apples. Hexanal is a known inhibitor of phospholipase D (PLD). Our results indicated that hexanal application reduced PLD enzyme activity from 30 days post-harvest to the end of the storage period compared to the other treatments. Ethylene production was reduced with hexanal treatment from 0 to 90 days post-harvest. An increase in total soluble solids and a decrease in physiological loss in weight was observed with hexanal application. A significantly lower occurrence of progression and severity of bitter pit was observed, while incidence of bitter was reduced by 70 %. Further electron micrographs revealed that hexanal treated apples had higher structural integrity overall. Our results reveal that application of hexanal can reduce bitter pit incidence in Honeycrisp apples, while increasing the post-harvets storage. [ABSTRACT FROM AUTHOR]