Continuous ethylene supplementation suppresses postharvest sprouting, but it can increase reducin... more Continuous ethylene supplementation suppresses postharvest sprouting, but it can increase reducing sugars, limiting its use as an alternative to chlorpropham for processing potatoes. To elucidate the mechanisms involved, tubers were treated after curing with or without the ethylene binding inhibitor 1-methylcyclopropene (1-MCP at 1 μL L − 1 for 24 h), and then stored in air or air supplemented with continuous ethylene (10 μL L − 1). Across three consecutive seasons, changes in tuber physiology were assessed alongside transcriptomic and metabolomic analysis. Exogenous ethylene alone consistently induced a respiratory rise and the accumulation of undesirable reducing sugars. The transient respiratory peak was preceded by the strong upregulation of two genes encoding 1-aminocyclopropane-1-carboxylate oxidase (ACO), typical of wound and stress induced ethylene production. Profiles of parenchymatic tissue highlighted that ethylene triggered abscisic acid (ABA) catabolism, evidenced by a steep fall in ABA levels and a transient rise in the catabolite phaseic acid, accompanied by upregulation of transcripts encoding an ABA 8ˊ-hydroxylase. Moreover, analysis of non-structural carbohydrate-related genes revealed that ethylene strongly downregulated the expression of the Kunitz-type invertase inhibitor, already known to be involved in cold-induced sweetening. All these ethylene-induced effects were negated by 1-MCP with one notable exception: 1-MCP enhanced the sprout suppressing effect of ethylene whilst preventing ethylene-induced sweetening. This study supports the conclusions that: i) tubers adapt to ethylene by regulating conserved pathways (e.g. ABA catabolism); ii) ethylene-induced sweetening acts independently from sprout suppression, and is similar to cold-induced sugar accumulation.
Health-promoting properties of fruit and vegetables, 2011
The identity and role of bioactives (organic acids, phenolics, flavonoids, organosulfur and organ... more The identity and role of bioactives (organic acids, phenolics, flavonoids, organosulfur and organoselenium compounds, fructans, and saponins), chemopreventive activity and bioavailability, effect of preharvest and postharvest continuum on onion, garlic, leek and shallot are discussed.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Increasing evidence suggests that anthocyanins, as natural antioxidants, exert anti-carcinogenic,... more Increasing evidence suggests that anthocyanins, as natural antioxidants, exert anti-carcinogenic, anti-inflammatory, vaso-protective and anti-obesity effects when tested in vitro or in vivo. Blackcurrant (Ribes nigrum L.) berries are a rich source of anthocyanins with concentrations up to 4-fold greater than that of other common fruits. However, there is a paucity of information on how blackcurrant anthocyanins change during ripening on the bush or during postharvest storage, which could lead to better selection of fruits with enhanced health-promoting properties. Accordingly, the present study describes the temporal changes in anthocyanins in different blackcurrant genotypes during the late stages of development or as a result of postharvest storage at different temperatures. In all cases, four major anthocyanins (viz. cyanidin-3-glucoside, cyanidin-3-rutinoside, delphinidin-3glucoside and delphinidin-3-rutinoside) were identified, accounting for over 80% of the total anthocyanin concentrations. Three different development stages (viz. early ripe (ER), fully ripe (FR) or over ripe (OR)) were chosen when fruit were at commercial maturity but presented different colorations. Anthocyanin concentration was nearly double in OR berries than ER, however the temporal changes during ripening were genotype-dependent, with some cultivars reaching maximum concentrations at the FR stage. During postharvest storage anthocyanin synthesis was observed in both ER and FR berries during storage, but ER berries never reached the concentrations of those harvested at FR stage. Storage temperature crucially affected anthocyanin concentrations in FR but not in ER berries. The results from this study may provide both growers and industry with additional information for maximising anthocyanin concentrations in blackcurrant berries.
Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can s... more Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can suppress sprouting while the ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) can also suppress sprout growth; yet, it is unknown how ethylene and 1-MCP elicit the same response. In this study, onions were treated with 10 μL L−1 ethylene or 1 μL L−1 1-MCP individually or in combination for 24 h at 20°C before or after curing (6 weeks) at 20°C or 28°C and then stored at 1°C. Following curing, a subset of these same onions was stored separately under continuous air or ethylene (10 μL L−1) at 1°C. Onions treated with ethylene and 1-MCP in combination after curing for 24 h had reduced sprout growth as compared with the control 25 weeks after harvest. Sprout growth following storage beyond 25 weeks was only reduced through continuous ethylene treatment. This observation was supported by a higher proportion of down-regulated genes characterized as being involved in photosynthesis, measur...
The aim of the present study was to determine if the enzyme Aspergillus niger prolyl endoprotease... more The aim of the present study was to determine if the enzyme Aspergillus niger prolyl endoprotease (ANPEP), which degrades the immunogenic proline-rich residues in gluten peptides, can be used in the development of new wheat products, suitable for gluten-sensitive (GS) individuals. We have carried out a double-blind, randomised, cross-over trial with two groups of adults; subjects, self-reporting benefits of adopting a gluten-free or low-gluten diet (GS, n 16) and a control non-GS group (n 12). For the trial, volunteers consumed four wheat breads: normal bread, bread treated with 0·8 or 1 % ANPEP and low-protein bread made from biscuit flour. Compared with controls, GS subjects had a favourable cardiovascular lipid profile – lower LDL (4·0 (sem 0·3) v. 2·8 (sem 0·2) mmol/l; P=0·008) and LDL:HDL ratio (3·2 (sem 0·4) v. 1·8 (sem 0·2); P=0·005) and modified haematological profile. The majority of the GS subjects followed a low-gluten lifestyle, which helps to reduce the gastrointestinal...
Investigation into the role of endogenous abscisic acid during ripening of imported avocado cv. H... more Investigation into the role of endogenous abscisic acid during ripening of imported avocado cv. Hass. Role of endogenous abscisic acid during ripening of imported avocado cv. Hass.
The American journal of clinical nutrition, Jan 5, 2017
Background: There are conflicting views in the literature as to whether vitamin D2 and vitamin D3... more Background: There are conflicting views in the literature as to whether vitamin D2 and vitamin D3 are equally effective in increasing and maintaining serum concentrations of 25-hydroxyvitamin D [25(OH)D], particularly at lower doses of vitamin D.Objectives: We aimed to investigate whether vitamin D2 or vitamin D3 fortified in juice or food, at a relatively low dose of 15 μg/d, was effective in increasing serum total 25(OH)D and to compare their respective efficacy in South Asian and white European women over the winter months within the setting of a large randomized controlled trial.Design: A randomized, double-blind, placebo-controlled food-fortification trial was conducted in healthy South Asian and white European women aged 20-64 y (n = 335; Surrey, United Kingdom) who consumed placebo, juice supplemented with 15 μg vitamin D2, biscuit supplemented with 15 μg vitamin D2, juice supplemented with 15 μg vitamin D3, or biscuit supplemented with 15 μg vitamin D3 daily for 12 wk. Serum...
The Journal of Horticultural Science and Biotechnology, 2014
ABSTRACT Long-term storage of potato (Solanum tuberosum L.) tubers provides year-round availabili... more ABSTRACT Long-term storage of potato (Solanum tuberosum L.) tubers provides year-round availability of the crop, but is limited by sprouting. Continuous exposure to ethylene during storage can prolong the storage-life of potato tubers by suppressing sprouting, yet there is little information on the effects of ethylene on a wide selection of common cultivars. Six different UK potato cultivars were stored at 6ºC for 30 weeks under continuous 10 μl l�1 ethylene treatment, under continuous air, or transferred from air to 10 μl l�1 ethylene at the first indication of sprouting, or vice versa. Fructose, glucose, and sucrose concentrations were determined in samples of tuber flesh and in potato skins. Texture and sprouting were measured after 30 weeks in cold storage. Ethylene applied at the first indication of sprouting was as effective at suppressing further sprouting in ‘Desiree’, ‘Sylvana’, and ‘Fianna’ as observed when ethylene was applied continuously and resulted in no additional ethylene-induced sugar accumulation. The texture data suggested that ethylene treatment had an indirect effect on tuber firmness through the inhibition of sprout growth only in ‘Sylvana’ potato tubers. The implications of these results are that the cost of ethylene application in cold-store rooms could be reduced by manipulating the timing of its application.
Journal of Agricultural and Food Chemistry, Nov 1, 2010
Reducing the current U.K. curing temperature from 28 to 20 °C would help to reduce energy costs; ... more Reducing the current U.K. curing temperature from 28 to 20 °C would help to reduce energy costs; however, onion skin appearance and consumer acceptability may be detrimentally affected. The aim of this study was to elucidate the compounds responsible for the difference in color between brown and red onions cured at 20 and 28 °C by monitoring dynamic biochemical changes in the skin at set intervals during curing and after storage from two years' data. Sugar concentrations appeared to play no role in the difference in onion skin appearance when cured at different temperatures. Using regression, principal component, and partial least-squares discriminant analyses, the decrease in skin H° after the curing of brown onion cultivars at 28 °C was linked to a decrease in individual flavonol concentrations, possibly due to their oxidation at higher temperatures into brown pigmented compounds. Red onion cultivars cured at lower temperatures and for a shorter curing period had higher concentrations of individual anthocyanins as well as a darker skin color. Skin water content was reduced significantly in only the first 6 days of curing. Taken together, this suggests that current U.K. curing practice could be carried out at a lower temperature (20 °C) and/or for a shorter duration, resulting in reduced curing costs and possibly improved skin appearance.
Controlled atmosphere storage (CA) is used to increase the storage life of onions; however detrim... more Controlled atmosphere storage (CA) is used to increase the storage life of onions; however detrimental effects on the shelf-life have been reported. The effect of the transition between CA (5 kPa CO 2 , 3 kPa O 2) and air (and vice versa) on onion cvs. Renate, Carlos and SS1 in terms of the respiration rate, sprout growth, dry weight, firmness, pungency, total soluble solids, abscisic acid concentration and non-structural carbohydrate composition was assessed. Removal of bulbs from CA storage resulted in an immediate increase in the respiration rate (measured in air), which then reverted to a lower rate following subsequent storage under air conditions for 21 days. In some cultivars, this could be sufficient to trigger the onset of sprouting and thus account for the detrimental effect of CA storage on shelf-life. Delaying the start of CA storage of onions cv. SS1 for 21 days was as effective in suppressing sprout growth as CA storage for 42 days. Further investigation into the use of CA storage in this manner with relation to the optimum time to begin CA conditions could decrease the cost of CA storage without compromising storage life. Abscisic acid concentration has been associated with storage life of onions. There was a significant decrease in the bulb ABA concentration between the time of harvest and the beginning of storage. This is likely to be due to the effects of curing and suggests that current curing practices are having a detrimental effect on storage potential.
Atmospheric pressure cold plasma has the potential to modify biological chemistry and modulate ph... more Atmospheric pressure cold plasma has the potential to modify biological chemistry and modulate physical surface properties. Wheat flour was treated by low levels of cold plasma (air, 15V and 20V) for 60 or 120s. There was no change in the total aerobic bacterial count or total mould count as a result of treatment. Treatment did not impact the concentration of total non-starch lipids, or non-polar and glycolipids. However, treatment did reduce total free fatty acids and phospholipids and was dose dependent. Oxidation markers (hydroperoxide value and head space n-hexanal) increased with treatment time and voltage, which confirmed the acceleration of lipid oxidation. Total proteins were not significantly influenced by treatment although there was a trend towards higher molecular weight fractions which indicated protein oxidation and treated flour did produce a stronger dough. This study confirms the potential of cold plasma as a tool to modify flour functionality.
Continuous ethylene supplementation suppresses postharvest sprouting, but it can increase reducin... more Continuous ethylene supplementation suppresses postharvest sprouting, but it can increase reducing sugars, limiting its use as an alternative to chlorpropham for processing potatoes. To elucidate the mechanisms involved, tubers were treated after curing with or without the ethylene binding inhibitor 1-methylcyclopropene (1-MCP at 1 μL L − 1 for 24 h), and then stored in air or air supplemented with continuous ethylene (10 μL L − 1). Across three consecutive seasons, changes in tuber physiology were assessed alongside transcriptomic and metabolomic analysis. Exogenous ethylene alone consistently induced a respiratory rise and the accumulation of undesirable reducing sugars. The transient respiratory peak was preceded by the strong upregulation of two genes encoding 1-aminocyclopropane-1-carboxylate oxidase (ACO), typical of wound and stress induced ethylene production. Profiles of parenchymatic tissue highlighted that ethylene triggered abscisic acid (ABA) catabolism, evidenced by a steep fall in ABA levels and a transient rise in the catabolite phaseic acid, accompanied by upregulation of transcripts encoding an ABA 8ˊ-hydroxylase. Moreover, analysis of non-structural carbohydrate-related genes revealed that ethylene strongly downregulated the expression of the Kunitz-type invertase inhibitor, already known to be involved in cold-induced sweetening. All these ethylene-induced effects were negated by 1-MCP with one notable exception: 1-MCP enhanced the sprout suppressing effect of ethylene whilst preventing ethylene-induced sweetening. This study supports the conclusions that: i) tubers adapt to ethylene by regulating conserved pathways (e.g. ABA catabolism); ii) ethylene-induced sweetening acts independently from sprout suppression, and is similar to cold-induced sugar accumulation.
Health-promoting properties of fruit and vegetables, 2011
The identity and role of bioactives (organic acids, phenolics, flavonoids, organosulfur and organ... more The identity and role of bioactives (organic acids, phenolics, flavonoids, organosulfur and organoselenium compounds, fructans, and saponins), chemopreventive activity and bioavailability, effect of preharvest and postharvest continuum on onion, garlic, leek and shallot are discussed.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Increasing evidence suggests that anthocyanins, as natural antioxidants, exert anti-carcinogenic,... more Increasing evidence suggests that anthocyanins, as natural antioxidants, exert anti-carcinogenic, anti-inflammatory, vaso-protective and anti-obesity effects when tested in vitro or in vivo. Blackcurrant (Ribes nigrum L.) berries are a rich source of anthocyanins with concentrations up to 4-fold greater than that of other common fruits. However, there is a paucity of information on how blackcurrant anthocyanins change during ripening on the bush or during postharvest storage, which could lead to better selection of fruits with enhanced health-promoting properties. Accordingly, the present study describes the temporal changes in anthocyanins in different blackcurrant genotypes during the late stages of development or as a result of postharvest storage at different temperatures. In all cases, four major anthocyanins (viz. cyanidin-3-glucoside, cyanidin-3-rutinoside, delphinidin-3glucoside and delphinidin-3-rutinoside) were identified, accounting for over 80% of the total anthocyanin concentrations. Three different development stages (viz. early ripe (ER), fully ripe (FR) or over ripe (OR)) were chosen when fruit were at commercial maturity but presented different colorations. Anthocyanin concentration was nearly double in OR berries than ER, however the temporal changes during ripening were genotype-dependent, with some cultivars reaching maximum concentrations at the FR stage. During postharvest storage anthocyanin synthesis was observed in both ER and FR berries during storage, but ER berries never reached the concentrations of those harvested at FR stage. Storage temperature crucially affected anthocyanin concentrations in FR but not in ER berries. The results from this study may provide both growers and industry with additional information for maximising anthocyanin concentrations in blackcurrant berries.
Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can s... more Onion (Allium cepa) is regarded as a nonclimacteric vegetable. In onions, however, ethylene can suppress sprouting while the ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) can also suppress sprout growth; yet, it is unknown how ethylene and 1-MCP elicit the same response. In this study, onions were treated with 10 μL L−1 ethylene or 1 μL L−1 1-MCP individually or in combination for 24 h at 20°C before or after curing (6 weeks) at 20°C or 28°C and then stored at 1°C. Following curing, a subset of these same onions was stored separately under continuous air or ethylene (10 μL L−1) at 1°C. Onions treated with ethylene and 1-MCP in combination after curing for 24 h had reduced sprout growth as compared with the control 25 weeks after harvest. Sprout growth following storage beyond 25 weeks was only reduced through continuous ethylene treatment. This observation was supported by a higher proportion of down-regulated genes characterized as being involved in photosynthesis, measur...
The aim of the present study was to determine if the enzyme Aspergillus niger prolyl endoprotease... more The aim of the present study was to determine if the enzyme Aspergillus niger prolyl endoprotease (ANPEP), which degrades the immunogenic proline-rich residues in gluten peptides, can be used in the development of new wheat products, suitable for gluten-sensitive (GS) individuals. We have carried out a double-blind, randomised, cross-over trial with two groups of adults; subjects, self-reporting benefits of adopting a gluten-free or low-gluten diet (GS, n 16) and a control non-GS group (n 12). For the trial, volunteers consumed four wheat breads: normal bread, bread treated with 0·8 or 1 % ANPEP and low-protein bread made from biscuit flour. Compared with controls, GS subjects had a favourable cardiovascular lipid profile – lower LDL (4·0 (sem 0·3) v. 2·8 (sem 0·2) mmol/l; P=0·008) and LDL:HDL ratio (3·2 (sem 0·4) v. 1·8 (sem 0·2); P=0·005) and modified haematological profile. The majority of the GS subjects followed a low-gluten lifestyle, which helps to reduce the gastrointestinal...
Investigation into the role of endogenous abscisic acid during ripening of imported avocado cv. H... more Investigation into the role of endogenous abscisic acid during ripening of imported avocado cv. Hass. Role of endogenous abscisic acid during ripening of imported avocado cv. Hass.
The American journal of clinical nutrition, Jan 5, 2017
Background: There are conflicting views in the literature as to whether vitamin D2 and vitamin D3... more Background: There are conflicting views in the literature as to whether vitamin D2 and vitamin D3 are equally effective in increasing and maintaining serum concentrations of 25-hydroxyvitamin D [25(OH)D], particularly at lower doses of vitamin D.Objectives: We aimed to investigate whether vitamin D2 or vitamin D3 fortified in juice or food, at a relatively low dose of 15 μg/d, was effective in increasing serum total 25(OH)D and to compare their respective efficacy in South Asian and white European women over the winter months within the setting of a large randomized controlled trial.Design: A randomized, double-blind, placebo-controlled food-fortification trial was conducted in healthy South Asian and white European women aged 20-64 y (n = 335; Surrey, United Kingdom) who consumed placebo, juice supplemented with 15 μg vitamin D2, biscuit supplemented with 15 μg vitamin D2, juice supplemented with 15 μg vitamin D3, or biscuit supplemented with 15 μg vitamin D3 daily for 12 wk. Serum...
The Journal of Horticultural Science and Biotechnology, 2014
ABSTRACT Long-term storage of potato (Solanum tuberosum L.) tubers provides year-round availabili... more ABSTRACT Long-term storage of potato (Solanum tuberosum L.) tubers provides year-round availability of the crop, but is limited by sprouting. Continuous exposure to ethylene during storage can prolong the storage-life of potato tubers by suppressing sprouting, yet there is little information on the effects of ethylene on a wide selection of common cultivars. Six different UK potato cultivars were stored at 6ºC for 30 weeks under continuous 10 μl l�1 ethylene treatment, under continuous air, or transferred from air to 10 μl l�1 ethylene at the first indication of sprouting, or vice versa. Fructose, glucose, and sucrose concentrations were determined in samples of tuber flesh and in potato skins. Texture and sprouting were measured after 30 weeks in cold storage. Ethylene applied at the first indication of sprouting was as effective at suppressing further sprouting in ‘Desiree’, ‘Sylvana’, and ‘Fianna’ as observed when ethylene was applied continuously and resulted in no additional ethylene-induced sugar accumulation. The texture data suggested that ethylene treatment had an indirect effect on tuber firmness through the inhibition of sprout growth only in ‘Sylvana’ potato tubers. The implications of these results are that the cost of ethylene application in cold-store rooms could be reduced by manipulating the timing of its application.
Journal of Agricultural and Food Chemistry, Nov 1, 2010
Reducing the current U.K. curing temperature from 28 to 20 °C would help to reduce energy costs; ... more Reducing the current U.K. curing temperature from 28 to 20 °C would help to reduce energy costs; however, onion skin appearance and consumer acceptability may be detrimentally affected. The aim of this study was to elucidate the compounds responsible for the difference in color between brown and red onions cured at 20 and 28 °C by monitoring dynamic biochemical changes in the skin at set intervals during curing and after storage from two years' data. Sugar concentrations appeared to play no role in the difference in onion skin appearance when cured at different temperatures. Using regression, principal component, and partial least-squares discriminant analyses, the decrease in skin H° after the curing of brown onion cultivars at 28 °C was linked to a decrease in individual flavonol concentrations, possibly due to their oxidation at higher temperatures into brown pigmented compounds. Red onion cultivars cured at lower temperatures and for a shorter curing period had higher concentrations of individual anthocyanins as well as a darker skin color. Skin water content was reduced significantly in only the first 6 days of curing. Taken together, this suggests that current U.K. curing practice could be carried out at a lower temperature (20 °C) and/or for a shorter duration, resulting in reduced curing costs and possibly improved skin appearance.
Controlled atmosphere storage (CA) is used to increase the storage life of onions; however detrim... more Controlled atmosphere storage (CA) is used to increase the storage life of onions; however detrimental effects on the shelf-life have been reported. The effect of the transition between CA (5 kPa CO 2 , 3 kPa O 2) and air (and vice versa) on onion cvs. Renate, Carlos and SS1 in terms of the respiration rate, sprout growth, dry weight, firmness, pungency, total soluble solids, abscisic acid concentration and non-structural carbohydrate composition was assessed. Removal of bulbs from CA storage resulted in an immediate increase in the respiration rate (measured in air), which then reverted to a lower rate following subsequent storage under air conditions for 21 days. In some cultivars, this could be sufficient to trigger the onset of sprouting and thus account for the detrimental effect of CA storage on shelf-life. Delaying the start of CA storage of onions cv. SS1 for 21 days was as effective in suppressing sprout growth as CA storage for 42 days. Further investigation into the use of CA storage in this manner with relation to the optimum time to begin CA conditions could decrease the cost of CA storage without compromising storage life. Abscisic acid concentration has been associated with storage life of onions. There was a significant decrease in the bulb ABA concentration between the time of harvest and the beginning of storage. This is likely to be due to the effects of curing and suggests that current curing practices are having a detrimental effect on storage potential.
Atmospheric pressure cold plasma has the potential to modify biological chemistry and modulate ph... more Atmospheric pressure cold plasma has the potential to modify biological chemistry and modulate physical surface properties. Wheat flour was treated by low levels of cold plasma (air, 15V and 20V) for 60 or 120s. There was no change in the total aerobic bacterial count or total mould count as a result of treatment. Treatment did not impact the concentration of total non-starch lipids, or non-polar and glycolipids. However, treatment did reduce total free fatty acids and phospholipids and was dose dependent. Oxidation markers (hydroperoxide value and head space n-hexanal) increased with treatment time and voltage, which confirmed the acceleration of lipid oxidation. Total proteins were not significantly influenced by treatment although there was a trend towards higher molecular weight fractions which indicated protein oxidation and treated flour did produce a stronger dough. This study confirms the potential of cold plasma as a tool to modify flour functionality.
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