Journal of the Science of Food and Agriculture, Jul 6, 2017
BACKGROUND: Low temperature is often used to reduce metabolic processes and extend the storage of... more BACKGROUND: Low temperature is often used to reduce metabolic processes and extend the storage of fruit, however, in the case of avocado the temperature below 3 °C would often result in development of physiological disorders associated with chilling injury. The objective of this study was to investigate the ability of methyl jasmonate (MeJA) and methyl salicylate (MeSA) vapours to alleviate the chilling injury in 'Hass' avocado fruit kept at 2 °C for 21 d followed by 6-7 d shelf-life at 20 °C, simulating supply chain conditions. RESULTS: The incidence and severity of chilling injury was significantly reduced in MeJA and MeSA exposed fruit, especially at 100 µmol l-1. The mechanism involved improved membrane integrity via alteration of the fatty acids content and composition, down-regulation of LOX gene expression and reduced activity of lipoxygenase. CONCLUSION: Methyl jasmonate and methyl salicylate have the potential for being used with 'Hass' avocado fruit shipped at low temperature by reducing their susceptibility to chilling injury.
Highlights •Thyme oil and chitosan or Aloe vera coatings improved the antifungal activity against... more Highlights •Thyme oil and chitosan or Aloe vera coatings improved the antifungal activity against Colletotrichum gloeosporioides. •Thyme oil and chitosan coating effectively reduced the anthracnose incidence and severity. •Thyme oil and chitosan coating revealed higher PAL, POD, chitinase, β-1,3-glucanase, CAT and SOD.
Advancing persimmon ripening in South Africa has proved to be a worthwhile strategy to attain ear... more Advancing persimmon ripening in South Africa has proved to be a worthwhile strategy to attain early fruit that realise higher returns in the European market. This is currently achieved through use of the growth retardant paclobutrazol (PBZ) applied at a standard rate of 1.5 g per plant. However, even at this standard rate, PBZ results in excessive reduction in vegetative growth and decline in the fruit storage quality. The effect of lower PBZ application rates on fruit maturity and keeping quality, return bloom and vegetative growth was investigated over two seasons in ‘Triumph’ persimmon orchards at Simondium in the Western Cape Province of South Africa. The following treatments were evaluated: untreated control, 1.5 ml PBZ drench on 14 December 2009, 0.75 ml PBZ drench on 14 December 2009 and 17 February 2010, 0.75 ml PBZ drench on 14 December 2009 and 0.375 ml PBZ drench on 14 December 2009. In the second season (2010-2011), trees were left untreated as per current industry pract...
Avocados are a popular subtropical fruit of high economic importance and the European Union is th... more Avocados are a popular subtropical fruit of high economic importance and the European Union is the biggest importer of the bulk of the fruit coming from countries like South Africa, Chile and Israel. The fruit is highly nutritious being rich in vitamins A, B, C, minerals, potassium, phosphorus, magnesium, iron and antioxidants. The biggest challenge is that the fruit is highly susceptible to qualitative and quantitative postharvest losses. Successful maintenance of avocado fruit quality during the supply chain depends on many aspects including adequate orchard management practices, harvesting practices, packing operations, postharvest treatments, temperature management, transportation and storage conditions, and ripening at destination. Postharvest losses are mostly attributed to flesh softening, decay, physiological disorders and improper temperature management. Management of the supply chain is solely done to provide the fruit with the most favourable conditions to extend storage ...
The influence of the development stage and post-harvest handling on the microbial composition of ... more The influence of the development stage and post-harvest handling on the microbial composition of mango fruit plays a central role in fruit health. Hence, the composition of fungal and bacterial microbiota on the anthoplane, fructoplane, stems and stem-end pulp of mango during fruit development and post-harvest handling were determined using next-generation sequencing of the internal transcribed spacer and 16S rRNA regions. At full bloom, the inflorescence had the richest fungal and bacterial communities. The young developing fruit exhibited lower fungal richness and diversities in comparison to the intermediate and fully developed fruit stages on the fructoplane. At the post-harvest stage, lower fungal and bacterial diversities were observed following prochloraz treatment both on the fructoplane and stem-end pulp. Ascomycota (52.8%) and Basidiomycota (43.2%) were the most dominant fungal phyla, while Penicillium, Botryosphaeria, Alternaria and Mucor were detected as the known post-h...
Avocados are a popular subtropical fruit of high economic importance, and the European Union is t... more Avocados are a popular subtropical fruit of high economic importance, and the European Union is the biggest importer of the bulk of the fruit coming from countries such as South Africa, Chile, and Israel. The fruit is highly nutritious, being rich in vitamins A, B, C, minerals, potassium, phosphorus, magnesium, iron, and antioxidants. The biggest challenge is that the fruit is highly susceptible to qualitative and quantitative postharvest losses. Successful maintenance of avocado fruit quality during the supply chain depends on many aspects, including adequate orchard management practices, harvesting practices, packing operations, postharvest treatments, temperature management, transportation and storage conditions, and ripening at destination. Postharvest losses are mostly attributed to flesh softening, decay, physiological disorders, and improper temperature management. Management of the supply chain is solely done to provide the fruit with the most favorable conditions to extend storage life, and retain quality and nutritional attributes of the fruit. The focus of this review is therefore to study the findings that have emanated from research done to retain overall avocado fruit quality and to reduce postharvest losses during the supply chain through the adoption of appropriate and novel postharvest technologies.
Thyme oil (TO) fumigation (96 ll l À1) to cv. Hass and Ryan avocados significantly reduced anthra... more Thyme oil (TO) fumigation (96 ll l À1) to cv. Hass and Ryan avocados significantly reduced anthracnose incidence compared to prochloraz and the untreated control. Also, enhanced activities of b-1,3-glucanase, chitinase were noted in both cultivars. TO fumigation induced the expression of both b-1,3-glucanase and chitinase genes in naturally infected fruit of both cultivars, during storage at 7 or 7.5 °C for up to 21 d and during subsequent simulated market shelf conditions at 20 °C for 5 d. However, the impact of TO fumigation on the b-1,3-glucanase gene expression was higher in both cultivars. Higher gene regulation and b-1,3-glucanase, chitinase activities were observed in cv. Ryan compared to Hass. Although TO fumigation significantly reduced anthracnose incidence in both naturally infected cultivars, the inhibitory effect was slightly higher in cv. Ryan than Hass. Thus, postharvest TO fumigation had positive effects on enhancing anthracnose disease resistance during storage and also gave a residual effect during the simulated shelf life.
Avocado fruit has high economic value; however, major post-harvest losses are encountered through... more Avocado fruit has high economic value; however, major post-harvest losses are encountered throughout the supply chain mostly due to anthracnose disease caused by the fungus Colletotrichum gloeosporioides. Increasing consumer concern regarding food safety and demand for organically produced fruits makes it necessary to search for natural environmentally friendly alternative products and processes for the fruit industry; particularly in disease control. Antifungal effects of Gum Arabic (GA) (10%), Aloe vera (AL) (2%), chitosan (CH) (1%) alone or in combination with thyme oil (1%) were investigated in vitro. CH þ thyme oil and AL þ thyme oil [1:1 or 3:1 v/v] showed fungicidal effects while AL, CH, GA and GA þ thyme oil [3:1 v/ v] showed fungistatic effects on mycelial growth of C. gloeosporioides in vitro. CH and AL coatings alone or in combination with thyme oil [3:1 v/v], either as preventative or curative treatments in comparison with commercial treatment (prochloraz, 0.05%) and untreated control were evaluated on incidence and severity (lesion diameter) of anthracnose in vivo. Preventative CH þ thyme oil treatments significantly reduced the severity of anthracnose (8.9 mm) compared to thyme oil (12.7 mm), AL þ TO (14.4 mm), CH (17.8 mm), AL (20.6 mm), PZ (18.3 mm) and untreated samples (34.8 mm). As curative method, the CH þ thyme oil combination also reduced the severity of anthracnose by at least 4 mm compared to the other treatments. The total phenols, polyphenol oxidase, phenylalanine ammonia-lyase, b-1,3-glucanase, chitinase, catalase and superoxide dismutase activities, firmness and flesh colour were also determined. Results showed an increase in peroxidase, phenylalanine ammonia-lyase, b-1,3-glucanase, chitinase, catalase and superoxide dismutase activities and total phenolics with reduced loss of firmness and flesh colour following CH þ thyme oil treatments. This investigation recommends CH þ thyme oil [3:1 v/v] combination treatment as a suitable alternative to the currently adopted prochloraz applications in controlling anthracnose disease in avocado fruit during storage.
Export opportunities to the European market exist for out-of-season persimmon fruit. Thus early f... more Export opportunities to the European market exist for out-of-season persimmon fruit. Thus early fruit (April) sell at a much higher price than late (mid-May to June) fruit. The South African persimmon industry has adopted the use of the plant growth regulator paclobutrazol (PBZ) at a standard rate of 1.5 g per plant to advance harvest maturity. However, at this application rate, PBZ results in stunted growth and a decline in fruit keeping quality. The aim of this research was to investigate the effect of lower PBZ application rates on fruit maturity and fruit keeping quality as well as vegetative growth. The experiment was conducted in 'Triumph' persimmon orchards at Simondium in the Western Cape Province of South Africa. Treatments included an untreated control, 1.5 ml PBZ soil drench on 14 December 2009, 0.75 ml PBZ drench on 14 December 2009 and 17 February 2010, 0.75 ml PBZ drench on 14 December 2009 and 0.375 ml PBZ drench on 14 December 2009. In the second season, trees were left untreated as per current industry practise. In the first season, all the PBZ treatments advanced harvest maturity regardless of rate. The effect of the highest PBZ application rates (1.5 ml PBZ drench and 0.75 ml PBZ drench twice) on harvest maturity carried through to the subsequent season. On average, PBZ decreased fruit firmness and increased the percentage soft fruit at the end of the shelf-life period in the first season. In the subsequent season, firmness at harvest decreased while the percentage soft fruit at the end of the shelf life period increased linearly with increasing PBZ application rate.
Journal of the Science of Food and Agriculture, Jul 6, 2017
BACKGROUND: Low temperature is often used to reduce metabolic processes and extend the storage of... more BACKGROUND: Low temperature is often used to reduce metabolic processes and extend the storage of fruit, however, in the case of avocado the temperature below 3 °C would often result in development of physiological disorders associated with chilling injury. The objective of this study was to investigate the ability of methyl jasmonate (MeJA) and methyl salicylate (MeSA) vapours to alleviate the chilling injury in 'Hass' avocado fruit kept at 2 °C for 21 d followed by 6-7 d shelf-life at 20 °C, simulating supply chain conditions. RESULTS: The incidence and severity of chilling injury was significantly reduced in MeJA and MeSA exposed fruit, especially at 100 µmol l-1. The mechanism involved improved membrane integrity via alteration of the fatty acids content and composition, down-regulation of LOX gene expression and reduced activity of lipoxygenase. CONCLUSION: Methyl jasmonate and methyl salicylate have the potential for being used with 'Hass' avocado fruit shipped at low temperature by reducing their susceptibility to chilling injury.
Highlights •Thyme oil and chitosan or Aloe vera coatings improved the antifungal activity against... more Highlights •Thyme oil and chitosan or Aloe vera coatings improved the antifungal activity against Colletotrichum gloeosporioides. •Thyme oil and chitosan coating effectively reduced the anthracnose incidence and severity. •Thyme oil and chitosan coating revealed higher PAL, POD, chitinase, β-1,3-glucanase, CAT and SOD.
Advancing persimmon ripening in South Africa has proved to be a worthwhile strategy to attain ear... more Advancing persimmon ripening in South Africa has proved to be a worthwhile strategy to attain early fruit that realise higher returns in the European market. This is currently achieved through use of the growth retardant paclobutrazol (PBZ) applied at a standard rate of 1.5 g per plant. However, even at this standard rate, PBZ results in excessive reduction in vegetative growth and decline in the fruit storage quality. The effect of lower PBZ application rates on fruit maturity and keeping quality, return bloom and vegetative growth was investigated over two seasons in ‘Triumph’ persimmon orchards at Simondium in the Western Cape Province of South Africa. The following treatments were evaluated: untreated control, 1.5 ml PBZ drench on 14 December 2009, 0.75 ml PBZ drench on 14 December 2009 and 17 February 2010, 0.75 ml PBZ drench on 14 December 2009 and 0.375 ml PBZ drench on 14 December 2009. In the second season (2010-2011), trees were left untreated as per current industry pract...
Avocados are a popular subtropical fruit of high economic importance and the European Union is th... more Avocados are a popular subtropical fruit of high economic importance and the European Union is the biggest importer of the bulk of the fruit coming from countries like South Africa, Chile and Israel. The fruit is highly nutritious being rich in vitamins A, B, C, minerals, potassium, phosphorus, magnesium, iron and antioxidants. The biggest challenge is that the fruit is highly susceptible to qualitative and quantitative postharvest losses. Successful maintenance of avocado fruit quality during the supply chain depends on many aspects including adequate orchard management practices, harvesting practices, packing operations, postharvest treatments, temperature management, transportation and storage conditions, and ripening at destination. Postharvest losses are mostly attributed to flesh softening, decay, physiological disorders and improper temperature management. Management of the supply chain is solely done to provide the fruit with the most favourable conditions to extend storage ...
The influence of the development stage and post-harvest handling on the microbial composition of ... more The influence of the development stage and post-harvest handling on the microbial composition of mango fruit plays a central role in fruit health. Hence, the composition of fungal and bacterial microbiota on the anthoplane, fructoplane, stems and stem-end pulp of mango during fruit development and post-harvest handling were determined using next-generation sequencing of the internal transcribed spacer and 16S rRNA regions. At full bloom, the inflorescence had the richest fungal and bacterial communities. The young developing fruit exhibited lower fungal richness and diversities in comparison to the intermediate and fully developed fruit stages on the fructoplane. At the post-harvest stage, lower fungal and bacterial diversities were observed following prochloraz treatment both on the fructoplane and stem-end pulp. Ascomycota (52.8%) and Basidiomycota (43.2%) were the most dominant fungal phyla, while Penicillium, Botryosphaeria, Alternaria and Mucor were detected as the known post-h...
Avocados are a popular subtropical fruit of high economic importance, and the European Union is t... more Avocados are a popular subtropical fruit of high economic importance, and the European Union is the biggest importer of the bulk of the fruit coming from countries such as South Africa, Chile, and Israel. The fruit is highly nutritious, being rich in vitamins A, B, C, minerals, potassium, phosphorus, magnesium, iron, and antioxidants. The biggest challenge is that the fruit is highly susceptible to qualitative and quantitative postharvest losses. Successful maintenance of avocado fruit quality during the supply chain depends on many aspects, including adequate orchard management practices, harvesting practices, packing operations, postharvest treatments, temperature management, transportation and storage conditions, and ripening at destination. Postharvest losses are mostly attributed to flesh softening, decay, physiological disorders, and improper temperature management. Management of the supply chain is solely done to provide the fruit with the most favorable conditions to extend storage life, and retain quality and nutritional attributes of the fruit. The focus of this review is therefore to study the findings that have emanated from research done to retain overall avocado fruit quality and to reduce postharvest losses during the supply chain through the adoption of appropriate and novel postharvest technologies.
Thyme oil (TO) fumigation (96 ll l À1) to cv. Hass and Ryan avocados significantly reduced anthra... more Thyme oil (TO) fumigation (96 ll l À1) to cv. Hass and Ryan avocados significantly reduced anthracnose incidence compared to prochloraz and the untreated control. Also, enhanced activities of b-1,3-glucanase, chitinase were noted in both cultivars. TO fumigation induced the expression of both b-1,3-glucanase and chitinase genes in naturally infected fruit of both cultivars, during storage at 7 or 7.5 °C for up to 21 d and during subsequent simulated market shelf conditions at 20 °C for 5 d. However, the impact of TO fumigation on the b-1,3-glucanase gene expression was higher in both cultivars. Higher gene regulation and b-1,3-glucanase, chitinase activities were observed in cv. Ryan compared to Hass. Although TO fumigation significantly reduced anthracnose incidence in both naturally infected cultivars, the inhibitory effect was slightly higher in cv. Ryan than Hass. Thus, postharvest TO fumigation had positive effects on enhancing anthracnose disease resistance during storage and also gave a residual effect during the simulated shelf life.
Avocado fruit has high economic value; however, major post-harvest losses are encountered through... more Avocado fruit has high economic value; however, major post-harvest losses are encountered throughout the supply chain mostly due to anthracnose disease caused by the fungus Colletotrichum gloeosporioides. Increasing consumer concern regarding food safety and demand for organically produced fruits makes it necessary to search for natural environmentally friendly alternative products and processes for the fruit industry; particularly in disease control. Antifungal effects of Gum Arabic (GA) (10%), Aloe vera (AL) (2%), chitosan (CH) (1%) alone or in combination with thyme oil (1%) were investigated in vitro. CH þ thyme oil and AL þ thyme oil [1:1 or 3:1 v/v] showed fungicidal effects while AL, CH, GA and GA þ thyme oil [3:1 v/ v] showed fungistatic effects on mycelial growth of C. gloeosporioides in vitro. CH and AL coatings alone or in combination with thyme oil [3:1 v/v], either as preventative or curative treatments in comparison with commercial treatment (prochloraz, 0.05%) and untreated control were evaluated on incidence and severity (lesion diameter) of anthracnose in vivo. Preventative CH þ thyme oil treatments significantly reduced the severity of anthracnose (8.9 mm) compared to thyme oil (12.7 mm), AL þ TO (14.4 mm), CH (17.8 mm), AL (20.6 mm), PZ (18.3 mm) and untreated samples (34.8 mm). As curative method, the CH þ thyme oil combination also reduced the severity of anthracnose by at least 4 mm compared to the other treatments. The total phenols, polyphenol oxidase, phenylalanine ammonia-lyase, b-1,3-glucanase, chitinase, catalase and superoxide dismutase activities, firmness and flesh colour were also determined. Results showed an increase in peroxidase, phenylalanine ammonia-lyase, b-1,3-glucanase, chitinase, catalase and superoxide dismutase activities and total phenolics with reduced loss of firmness and flesh colour following CH þ thyme oil treatments. This investigation recommends CH þ thyme oil [3:1 v/v] combination treatment as a suitable alternative to the currently adopted prochloraz applications in controlling anthracnose disease in avocado fruit during storage.
Export opportunities to the European market exist for out-of-season persimmon fruit. Thus early f... more Export opportunities to the European market exist for out-of-season persimmon fruit. Thus early fruit (April) sell at a much higher price than late (mid-May to June) fruit. The South African persimmon industry has adopted the use of the plant growth regulator paclobutrazol (PBZ) at a standard rate of 1.5 g per plant to advance harvest maturity. However, at this application rate, PBZ results in stunted growth and a decline in fruit keeping quality. The aim of this research was to investigate the effect of lower PBZ application rates on fruit maturity and fruit keeping quality as well as vegetative growth. The experiment was conducted in 'Triumph' persimmon orchards at Simondium in the Western Cape Province of South Africa. Treatments included an untreated control, 1.5 ml PBZ soil drench on 14 December 2009, 0.75 ml PBZ drench on 14 December 2009 and 17 February 2010, 0.75 ml PBZ drench on 14 December 2009 and 0.375 ml PBZ drench on 14 December 2009. In the second season, trees were left untreated as per current industry practise. In the first season, all the PBZ treatments advanced harvest maturity regardless of rate. The effect of the highest PBZ application rates (1.5 ml PBZ drench and 0.75 ml PBZ drench twice) on harvest maturity carried through to the subsequent season. On average, PBZ decreased fruit firmness and increased the percentage soft fruit at the end of the shelf-life period in the first season. In the subsequent season, firmness at harvest decreased while the percentage soft fruit at the end of the shelf life period increased linearly with increasing PBZ application rate.
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