Browsing by Author "Terry, Leon A."
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Item Open Access 1-Methylcyclopropene (1-MCP) effects on natural disease resistance in stored sweetpotato(Wiley, 2018-03-06) Amoah, Robert S.; Terry, Leon A.BACKGROUND The potential of 1-methylcyclopropene (1-MCP) to maintain postharvest storage of sweetpotato was studied. In two separate experiments, the orange-fleshed sweetpotato cv. Covington was fumigated with 1-MCP (1.0 μL L-1, 24 h) and roots stored at 15 oC. During storage, samples were evaluated for the respiration rate, sprout growth, weight loss, incidence of decay and changes in dry matter. The roots were further assayed for the temporal changes in individual non-structural carbohydrates and phenolic compounds in the skin and flesh tissues of the proximal (stem end), middle, and distal (root end) regions. RESULTS 1-MCP treatment reduced root weight loss and decay but respiration rate and non-structural carbohydrates were not affected. No sprouting was recorded irrespective of the treatment. 1-MCP transiently suppressed the accumulation of individual phenolic compounds, especially in the middle and distal segments. This accentuated the proximal dominance of phenolic compounds. Isochlorogenic acid A and chlorogenic acid were the dominant phenolics in the skin and flesh tissues, respectively. CONCLUSION 1-MCP treatment may have anti-decay effect and reduce weight loss. Therefore, storage trials which involve the use of continuous ethylene supplementation to inhibit sprout growth may be combined with 1-MCP to alleviate ethylene-induced weight loss and decay in sweetpotato.Item Open Access 1-Methylcyclopropene maintains postharvest quality in Norwegian apple fruit(Sage, 2019-12-26) Falagán Sama, Natalia; Terry, Leon A.Norwegian fruit production is mostly destined for the local market and can suffer from poor-quality retention during storage. 1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene perception used to maintain the physical and functional quality of pome fruit. Extensive work has been carried out on the effect of 1-MCP on apples, but not on cultivars grown in Norway. In this work, the potential of 1-MCP application (0.625 ml l −1 for 24 h at 0 ± 1℃) for ripening control of the apple cultivars ‘Aroma’, ‘Red Gravenstein’, and ‘Summered’ was studied during 1 and 1.5 months of cold storage; both scenarios were followed by five days of shelf life. The application of 1-MCP reduced softening by an average of 12% in ‘Aroma’, ‘Red Gravenstein’, and ‘Summered’ apples when cold stored for both 1 and 1.5 months as compared to control. External colour remained similar to initial values in 1-MCP fruit when compared to control apples, which presented a significant skin darkening. This indicated a delay in the ripening process. 1-MCP treatment did not affect total soluble solids content. ‘Aroma’ samples treated with 1-MCP showed a low sucrose hydrolysis, indicating a slower ripening process. This work confirms that 1-MCP postharvest treatment shows great potential for maintenance of apple cvs. in Norway during cold storage and shelf life.Item Open Access Antiviral and quality effects of chemical elictors and Cucumber Mosaic Virus (CMV) infection on tomato plants and fruits(Cranfield University, 2012-05) Kalogirou, Maria; Terry, Leon A.; Varveri, ChristinaCucumber mosaic virus (CMV) has emerged as one of the most serious threats to tomato cultivation in Greece. In the present study the effects of Benzothiadiazoles (BTH) and pyraclostrobin against mechanically or aphid-transmitted CMV in tomato plants, of hybrid F1 Clodin, were investigated in greenhouse experiments. BTH was confirmed as capable of inducing systemic acquired resistance (SAR) in tomato seedlings against CMV, while pyraclostrobin was not. Responses to BTH application and/or CMV inoculation on Spanish tomato hybrid Delos (BTH, BTH+CMV, CMV treatments) were monitored during winter and spring season in Greece. In both seasons the SAR derived from BTH application suppressed CMV. BTH treatment presented increased plant growth, fruit size and marketable tomato yield compared to CMV and BTH+CMV treatments, whereas decreased compared to healthy control. CMV treatment caused the most severe stunting of tomato plants among the examined treatments and resulted in yield loss of marketable fruits, although the total fruit number was higher versus to other treatments. Cont/d.Item Open Access Avocado firmness monitoring with values obtained by means of laser doppler vibrometry(International Society for Horticultural Science, 2012-04-01) Terry, Leon A.; Landahl, SandraAvocado (Persea americana Mill.) ripeness is usually evaluated by destructive firmness assessment, yet quality is notorious for being heterogeneous within a consignment. This problem, which is especially true for imported avocado fruit, lends itself to searching for non-destructive methods for firmness evaluation. Firmness of objects can be analysed by impulse-response. This technique utilizes recording of a vibration signature and interpretation of the resonant frequency. In this study a laser Doppler vibrometer (LDV) was used for non-contact recording. The aim of this study was to show the feasibility of using a LDV to monitor avocado firmness. In order to create avocado batches of different homogeneity, three groups were treated with and without ethylene, inside or outside a box. After day 0 a third of the fruit were transferred into boxes (325 L) to be treated with ethylene for 24 h. A third was kept in boxes untreated and another third was kept on open trays. Avocado fruit cultivar ‘Hass’ were ripened at 18°C and measured on days 0, 2, 3, 4 and 6. Individual fruit were impacted once and two LDV measurements were taken simultaneously at the stem-end and seed-end. This was repeated twice around the fruit. Force-deformation measurements in compression mode were performed by means of uniaxial testing (Instron model 5542) on two opposite sides (day 0 n=8, then n=24 i.e., 8 per treatment/d). Significant differences were found between firmness of avocados over time and across treatments. Firmness decreased exponentially as expected (304.1 to 2.1 N) over six days. The LDV results showed significant differences between days, treatments and laser-location. The resonant frequency of the fruit decreased linearly until day 4 and then decreased more slowly (1671 to 476 Hz). On average, the frequency found at the seed-end of the fruit was higher than the resonant frequency at the stem-end. This is thought to be due to the seed itself, which could influence the vibration pattern. Resonant frequencies showed good correlation to the logarithm of firmness (r=0.87) and therefore were shown capable of monitoring avocado firmness.Item Open Access Biochemical and textural ripeness assessment of avocado fruit from different origins(Ishs; 1999, 2010-10-06T00:00:00Z) Landahl, Sandra; Meyer, Marjolaine D.; Terry, Leon A.; Herppich, W. B.Stage of ripeness and quality of avocado is notoriously difficult to assess by conventional methods. Texture is a very important determinant of avocado fruit quality and can change radically during storage. The difficulties in determining avocado quality are related, in part, to the spatial heterogeneity of fruit characteristics during ripening. The aim of this study was to assess the discriminatory capabilities of physiochemical properties to determine ripeness of imported 'Hass' avocado fruit. Fruit were stored at 12°C and sampled at regular intervals. Using a previously unreported method, the texture of different slices from individual fruit was measured during ripening. Maximum load, elasticity and viscosity of fruit tissue were measured using a universal testing machine fitted with a 500N or 5N load cell. The same tissue slice was then further processed prior to subsequent quantification of non-structural carbohydrates (NSCs) and fatty acid methyl esters using standard high performance liquid chromatography coupled to evaporative light scattering detection and gas chromatography coupled to flame ionisation detection, respectively. Spatio-temporal differences in maximum load, elasticity, viscosity, NSCs and fatty acid composition were found in avocados from different origins. Results of measured texture and target analytes were used to differentiate avocado fruit into definable groups using partial least squares discriminant analysis.Item Open Access Biochemical profile of heritage and modern apple cultivars and application of machine learning methods to predict usage, age, and harvest season(American Chemical Society, 2017-06-02) Anastasiadi, Maria; Mohareb, Fady R.; Redfern, Sally P.; Berry, Mark; Simmonds, Monique; Terry, Leon A.The present study represents the first major attempt to characterise the biochemical profile in different tissues of a large selection of apple cultivars sourced from the UK’s National Fruit Collection comprising dessert, ornamental, cider and culinary apples. Furthermore, advanced Machine Learning methods were applied with the objective to identify whether the phenolic and sugar composition of an apple cultivar could be used as a biomarker fingerprint to differentiate between heritage and mainstream commercial cultivars as well as govern the separation among primary usage groups and harvest season. Prediction accuracy > 90% was achieved with Random Forest for all three models. The results highlighted the extraordinary phytochemical potency and unique profile of some heritage, cider and ornamental apple cultivars, especially in comparison to more mainstream apple cultivars. Therefore, these findings could guide future cultivar selection on the basis of health-promoting phytochemical content.Item Open Access Biology and management of freesia flower specking caused by Botrytis cinerea(Cranfield University, 2003) Darras, Anastasios I.; Joyce, Daryl C.; Terry, Leon A.There is no published research regarding postharvest infection of freesia flowers by Botrytis cinerea. Although, infection problems have concerned freesia growers and wholesalers in recent years. The overall objectives of this study were firstly to evaluate the factors affecting B. cinerea postharvest disease establishment and secondly to evaluate a range of novel potential treatments to reduce postharvest freesia infection. These treatment options include plant activators such as acibenzolar-S-methyl and methyl jasmonate and biotic (Aureobasidium pullulans) and abiotic (UV-C irradiation) biological/elicitors agents. Research was undertaken in an attempt to explain the variation in B. cinerea incidence on cut freesia flowers as noted by the UK importer Zwetsloots & Sons Ltd. in 2000. Higher monthly rejections of freesia flower stems throughout 2000 due to B. cinerea infection were recorded during spring (April-May), early summer (June) and autumn (October). Comparatively higher proportions of rejected freesia stems were associated with glasshouse temperatures ranging from 13-17°C. In the presence of B. cinerea inoculum on freesia petal surface, temperature was not a limiting factor for disease establishment. Incubation of artificially inoculated freesia flowers at 12°C resulted in overall higher disease severity and lesion numbers compared to flowers incubated at 5 or 20°C. In contrast, relative humidity was the most important factor for postharvest infection by B. cinerea. Elicitor based strategies for IPM using the potent activator acibenzolar provided limited protection of freesia flowers against B. cinerea when applied postharvest. Acibenzolar significantly reduced disease severity, lesion numbers and lesion diameters compared to the untreated control when applied at 0.15 g A. 1. U1. Methyl jasmonate (MeJA) applied as gas, pulse and spray generally suppressed B. cinerea disease on cut freesia flowers. Disease severity, lesion numbers and lesion diameters of flowers gassed with 0.1 μL MeJA L"' were reduced by 56,43 and 37%, respectively compared to untreated control flowers. Gaseous MeJA treated freesia flowers at 0.1 μL L"1 increased PPO activity by 57% compared to untreated controls 24h after MeJA treatment. After 36h of incubation at 20°C, disease severity, lesion numbers and lesion diameters of gaseous MeJA treated flowers were reduced by 68,56 and 50%, respectively, compared to the untreated controls. However, PAL activity in MeJA treated freesia flowers did not decrease significantly over time compared to untreated control 12h post-inoculation and thereafter. These findings suggest that MeJA treatment might suppress the action of PAL in the phenylpropanoid pathway and consequently block SA production. UV-C irradiation might be used in an integrated postharvest disease management program for freesia flowers. UV-C irradiation after artificial inoculation resulted in markedly reduced B. cinerea disease severity scores and lesion numbers. In detail, UV-C irradiation of cut freesia flowers with 0.5,1,2.5 and 5 kJ m''` reduced disease severity by up to 44,70,74 and 59% and lesion numbers by up to 37,62,68 and 60%, respectively. UV-C irradiation at 1 kJ M-2 before artificial inoculation slightly reduced disease severity and lesion numbers possibly by inducing defence responses. However, the limited disease suppression suggested that apparently B. cinerea could overcome the UV-C induced effect. The effect of preharvest treatments on freesia crops with acibenzolar was investigated in glasshouse trials in view to suppress postharvest B. cinerea infection via SAR induction. Acibenzolar was effective in selected treatments and conditions. Disease pressure varied over the 3 years and over varieties tested. However, it was unclear whether acibenzolar induced systemic and/or local defence responses. The latter was supported by biochemical investigations in 2001 which suggested that acibenzolar did not induce PAL activity. In contrast, preharvest MeJA treatment resulted in markedly systemic protection of treated flowers compared to untreated ones. MeJA efficacy was dependent on variety and on postharvest incubation temperatures. Disease severity, lesion numbers and lesion diameters on MeJA treated freesia var. `Dukaat' flowers incubated at 20°C were reduced by 56,61, and 49% compared to controls, respectively. Also, disease severity, lesion numbers and lesion diameters on MeJA treated `Cote d'Azur' flowers incubated at 20°C were reduced by 36,26, and 49% compared to controls, respectively.Item Open Access Biomarkers of postharvest resilience: unveiling the role of abscisic acid in table grapes during cold storage(Frontiers, 2023-09-29) Navarro-Calderón, Ángela; Falagán, Natalia; Terry, Leon A.; Alamar, M. CarmenTable grapes are considered non-climacteric fruit, not showing a rapid increase in respiration rate and ethylene production during ripening. Previous research has suggested that abscisic acid (ABA) may have a more crucial role in grape postharvest behaviour. This study aimed to identify biomarkers of postharvest resilience and flavour life of imported table grapes. An experiment was designed to determine i) the role of ABA and catabolites on grape berry senescence; ii) the spatial distribution of these hormones within the grape berry, and iii) the effect of 1-MCP and storage temperature on its postharvest quality. Hence, the use of an ethylene inhibitor, 1-methylcyclopropane (1-MCP), during table grape storage was investigated. Table grapes (Vitis vinifera L.) cv. ‘Krissy’ were subjected to i) control (untreated); and ii) 1-MCP (1 µL L-1; 12 hours; 15°C) and stored under two scenarios: i) 15 days at 0.5°C, followed by five days at 5.5°C to simulate shelf-life; and ii) 20 days at 5.5°C to simulate a higher storage temperature followed by shelf-life. Physiological (i.e. mould incidence, skin colour, firmness, respiration rate) and biochemical analysis (i.e. individual sugars, organic acids, abscisic acid and catabolites) were performed. Grapes subjected to 5.5°C showed significantly higher mould incidence at the end of the shelf-life compared to 0.5°C storage temperature (12.6% vs. 3.1%). Also, and for the first time, the spatial distribution of ABA during the senescence of table grapes was profiled; the distal section had three times more ABA and metabolites than the proximal. We demonstrated that senescence processes were initiated after a significant increase in respiration rate (from 1 to 2.8 mL CO2 kg-1 h-1), and that ABA could be considered a biomarker for table grapes senescence, since an ABA peak preceded the increase in respiration rate, mould incidence, organic acids, and sucrose hydrolysis during postharvest storage; and coincided with a decrease in berry firmness. These findings are of significant importance for the industry as understanding how ABA regulates both senescence processes and quality changes during postharvest cold storage of tables grapes can improve the consistency and reduce waste and consumer complaints.Item Open Access Characterization of industrial onion wastes (Allium cepa L.): dietary fibre and bioactive compounds.(2011-03-31T00:00:00Z) Benítez, Vanesa; Mollá, Esperanza; Martín-Cabrejas, María A.; Aguilera, Yolanda; López-Andréu, Francisco J.; Cools, Katherine; Terry, Leon A.; Esteban, Rosa M.The food industry produces a large amount of onion wastes, making it necessary to search for possible ways for their utilization. One way could be to use these onion wastes as a natural source of high-value functional ingredients, since onion are rich in several groups of compounds, which have perceived benefits to human health. The objective of this work is to gain knowledge of any differences between the different onion wastes obtained from industry and non-commercial bulbs to use them as food ingredients rich in specific compounds. The results showed that brown skin and top-bottom could be potentially used as functional ingredient rich in dietary fibre, mainly in insoluble fraction, and in total phenolics and flavonoids, with high antioxidant activity. Moreover, brown skin showed a high concentration of quercetin aglycone and calcium, and top-bottom showed high concentration of minerals. Outer scales could be used as source of flavonols, with good antioxidant activity and content of dietary fibre. However, inner scales could be an interesting source of fructans and alk(en)yl cystein sulphoxides. In addition, discarded onions (cvs Recas and Figueres) could be used as a good source of dietary fibre, and cv Recas also as a source of phenolics compounds.Item Open Access Continuous exposure to ethylene differentially affects senescence in receptacle and achene tissues in strawberry fruit(Frontiers, 2020-03-12) Tosetti, Roberta; Elmi, Fardusa; Pradas, Inmaculada; Cools, Katherine; Terry, Leon A.Strawberry shelf life is limited, and little is known about the postharvest regulation of senescence in different fruit tissues. Strawberry is classified as a non-climacteric fruit, yet it is known that ethylene affects strawberry ripening. Here the effects of continuous exogenous ethylene (50 µl l−1) were investigated in cold stored strawberry (5°C). The physiological and biochemical responses of ripe strawberry were evaluated across 6 days, together with hormonal profiles of the whole fruit and individual tissues (achenes and receptacle). Continuous exposure to ethylene induced as a first response an accumulation of abscisic acid (ABA) in the receptacle tissue, followed by an increase in CO2 production. Ethylene also elicited sucrose hydrolysis and malic acid catabolism, with the major effect seen after 4 days of ethylene exposure. Additionally, accumulation of phenolics (epicatechin and chlorogenic acid) were also observed in ethylene treated strawberry. Achenes did not exhibit a response to ethylene, yet catabolism of both ABA and auxins increased by two thirds during air storage. In contrast, ethylene induced ABA accumulation in the receptacle tissue without ABA catabolism being affected. This hormonal disequilibrium in response to ethylene between the two tissues was maintained during storage, and therefore might be the precursor for the following biochemical variations reported during storageItem Open Access Cultivar and tissue-specific changes of abscisic acid, its catabolites and individual sugars during postharvest handling of flat peaches (Prunus persica cv. platycarpa)(Elsevier, 2021-08-20) García-Pastor, María E.; Falagán, Natalia; Giné-Bordonaba, Jordi; Wójcik, Dorota A.; Terry, Leon A.; Alamar, M. CarmenThe role of abscisic acid (ABA) during postharvest ripening of peaches remains unclear. This study aimed to investigate the temporal and tissue-specific changes in ABA, and ABA catabolites, of two flat peach cultivars, ‘Plane Sun’ and ‘Platibell’, during the stone fruit supply chain. The relationship between ABA catabolism, ethylene production, individual sugar changes and fruit firmness was also studied. We found that flat peaches can produce and metabolise ABA during postharvest ripening, and that this is cultivar and tissue dependent. Our results demonstrated that a burst in ABA concentration preceded that of ethylene production in ‘Plane Sun’ fruit, suggesting cross-talk between the two hormones. ABA and ethylene were both negatively correlated with fruit firmness, whilst sugar content, especially glucose, was only correlated with ABA. In conclusion, ABA may trigger ethylene production changes while also affecting sugar metabolism leading to fruit softening and over-ripening associated processes during stone fruit postharvest handling.Item Open Access Design and construction of a flexible laboratory-scale mixing apparatus for continuous ethylene supplementation of fresh produce(Elsevier, 2017-03-17) Amoah, Robert S.; Landahl, Sandra; Terry, Leon A.The design and construction of a laboratory-scale apparatus for generating variable concentrations and flow rates of exogenous ethylene for fresh produce supplementation during storage trials is described. A stock of compressed ethylene in nitrogen (5000 μl l−1) was blended into a continuous flow stream of air and diluted to the desired concentrations. The ethylene and air flow rates were controlled with calibrated mass flow control valves. An empirical mathematical model was derived for real-time variation of both the mixed concentration and flow rate during continuous flow. Validation of the model was performed using fresh sweet potato as a case study where a steady continuous ethylene concentration of 10 μl l−1 was achieved for three months. The bespoke system offers easy-to-manage ethylene supplementation for research.Item Open Access Detection of internal defects in onion bulbs by means of single-point and scanning laser Doppler vibrometry(Elsevier, 2022-08-05) Landahl, Sandra; Terry, Leon A.The number of onion consignments which are rejected or downgraded due to the incidence of internal defects is a continuing problem for wholesalers and growers. Defects may only be up to 4% incidence level, but result in the entire lot being lost for sale. Destructive quality control testing causes waste, so that there is a need for alternative non-invasive assessment. The aim of the current research was to demonstrate whether internal defects could be detected using Laser Doppler vibrometry (LDV). Several trials, with different types of sensors and levels of onion defect severity were conducted. Both scanning and single-point LDV were employed in order to develop a suitable measurement method to evaluate onion defects. It was necessary to measure resonant frequency at the neck or equator of the bulbs in order to segregate neck rot (Botrytis allii) or bacterial rot, respectively, but LDV could not differentiate sprouting and double hearted bulbs from sound onions. In conclusion, it was possible to non-destructively identify onion bulbs with only a 5% area affected with neck rot (visible after cutting). It would be necessary to calibrate for different onion cultivars and origins, if the technique is to be implemented on a commercial sorting line.Item Open Access Development of a Botrytis specific immunosensor: towards using PCR species identification(Cranfield University, 2014-01) Binder, Michael; Terry, Leon A.; Tothill, Ibtisam E.Botrytis species affect over 300 host plants in all climate areas of the world, at both pre and post-harvest stages, leading to significant losses in agricultural produce. Therefore, the development of a rapid, sensitive and reliable method to assess the pathogen load of infected crops can help to prescribe an effective curing regime. Growers would then have the ability to predict and manage the full storage potential of their crops and thus provide an effective disease control and reduce post-harvest losses. A highly sensitive electrochemical immunosensor based on a screen-printed gold electrode (SPGE) with onboard carbon counter and silver / silver chloride (Ag/AgCl) pseudo-reference electrode was developed in this work for the detection and quantification of Botrytis species. The sensor utilised a direct sandwich enzyme-linked immunosorbent assay (ELISA) format with a monoclonal antibody against Botrytis immobilised on the gold working electrode. Two immobilisation strategies were investigated for the capture antibody, and these included adsorption and covalent immobilisation after self-assembled monolayer formation with 3-dithiodipropionic acid (DTDPA). A polyclonal antibody conjugated to the electroactive enzyme horseradish peroxidase (HRP) was then applied for signal generation. Electrochemical measurements were conducted using 3,3’, 5,5’-tetramethylbenzidine dihydrochloride / hydrogen peroxide (TMB/H2O2) as the enzyme substrate system at a potential of -200 mV. The developed biosensor was capable of detecting latent Botrytis infections 24 h post inoculation with a linear range from 150 to 0.05 μg fungal mycelium ml-1 and a limit of detection (LOD) as low as 16 ng ml-1 for covalent immobilisation and 58 ng ml-1 for adsorption, respectively. Benchmarked against the commercially available Botrytis ELISA kits, the optimised immuno-electrochemical biosensor showed strong correlation of the quantified samples (R2=0.998) ... [cont.].Item Open Access Development of a disposable pyruvate biosensor to determine pungency in onions (Allium cepa L.)(Elsevier, 2006-05-15) Abayomi, Louise Anike; Terry, Leon A.; White, S. F.; Warner, P. J.A disposable prototype pyruvate biosensor was constructed using pyruvate oxidase immobilised on mediated meldolas blue electrodes to determine pungency in onions (Allium cepa L.). The optimum operating potential was +150 mV (versus Ag/AgCl). A strong correlation between the biosensor response and untreated onion juice of known pyruvate concentration 2–12 μmol/g fresh weight (FW) was demonstrated. The biosensor was able to differentiate between low and high pungency onions. The detection limit using 1 unit of pyruvate oxidase was 1–2 μmol/g FW. Optimum concentrations of co-factors TPP, FAD and MgSO4 comprising the enzyme cocktail were determined as being 0.04, 0.1 and 30 mM, respectively.Item Open Access Discovering biomarkers of postharvest resilience and flavour life in imported citrus and table grapes.(Cranfield University, 2022-02) Navarro-Calderon, Angela; Alamar, M. Carmen; Terry, Leon A.Clementines and table grapes, which are the main fruit crops consumed in the UK after bananas and apples, are considered non-climacteric fruit, not showing an increase in respiration rate and ethylene production during ripening. Previous research has suggested that a different ripening hormone, abscisic acid (ABA), has a more crucial role in the ripening of this kind of produce. The study presented herein aimed to identify biomarkers of postharvest resilience and flavour life of imported clementines and table grapes. For these studies two experiments were designed with the common objectives of determining: 1) the pre- or postharvest factors influencing the postharvest produce quality – both physiological and biochemical, and 2) the role of ABA and ABA catabolites on fruit senescence. The main findings from these studies were that the canopy position of clementines significantly affected fruit postharvest quality and hormonal content. Fruit located on the inside canopy showed higher RR and lower sugar content than outside fruit at the end of postharvest storage, resulting in a shorter shelf- life. At the same time, inside fruit showed a higher content of ABA and ABA catabolites than outside fruit, coinciding with a lower consumer preference score for external appearance, aroma and flavour. This is the first study that determined the ABA and ABA catabolite contents in the pulp of clementines from different canopy positions during senescence, and related this to consumer acceptance. The use of an ethylene inhibitor, 1-methylcyclopropane (1-MCP), during the postharvest storage of table grapes was investigated. The treatment did not have a positive effect on their postharvest quality; in fact, grapes were significantly affected by mould incidence at the end of the shelf-life. The hormonal content in different berry sections was also evaluated; the distal section, which showed a higher mould incidence than the proximal, had three times more ABA and ABA catabolites than the proximal section. This is the first time that the spatial distribution of ABA during the senescence of table grapes was profiled. Despite being different products, similar novel results were observed for both clementines and table grapes. This study indicated that senescence processes in these non-climacteric produce was initiated after a significant increase in RR, and that ABA could be considered a biomarker for clementines and table grapes senescence since an ABA peak during postharvest storage preceded an increase in RR, mould incidence, organic acids, and sucrose hydrolysis. This coincided with a decrease in berry firmness. These findings are of significant importance for the industry. Understanding how ABA regulates senescence processes and the quality changes taking place during postharvest cold storage of clementines and tables grapes improves the consistency in fruit quality and reduces waste and consumer complaints. Although clear beneficial findings have been identified, the results of this study were limited by time, resources, climatic conditions, and other factors. Therefore, recommendations for future work are: to perform molecular studies on genes regulating the ABA pathway from field to postharvest storage; to investigate the crosstalk between ABA, ethylene, and sucrose from ripening to senescence; and to further investigate the use of shade nets and harvesting by canopy position on fruit quality consistency and consumer acceptance.Item Open Access Discrete ex situ and continuous in situ real-time respiration rate measurements of fresh produce using a novel automated dynamic approach(International Society for Horticultural Science (ISHS), 2018-04-04) Collings, Emma; Alamar, M. Carmen; Cools, Katherine; Ordaz-Ortiz, J. J.; Terry, Leon A.Fresh produce respiration rate is a useful indicator of metabolic state often used in postharvest research to determine physiological differences between factors. Static (no flow) and dynamic (constant flow) measurements are two types of methods that exist for determining respiration rate in fresh produce. Implementation of an automated real-time respiration method, using a dynamic measurement, for measuring respiration rates of fresh produce in discrete (ex situ) and continuous (in situ) set-ups has been established. Discrete methods were performed on fresh (green) black pepper within 3 L hermetically sealed containers with constant flow rates of 400 mL min-1 and 1 L min-1, respectively. Continuous respiration measurements were also obtained in situ for fresh black pepper stored under air (1.8 L min-1) at 5°C, and avocado fruit stored under air and controlled atmosphere environment (ca. 10 kPa CO2 and 10 kPa O2; 400 mL min-1), at 20°C. In addition, simultaneous automated recordings of O2 and CO2 enabled accurate respiratory quotient (RQ) values to be determined for avocado throughout storage. Application of the continuous dynamic in situ measurements can also provide a more realistic assessment of physiological change / behaviour under real-world storage conditions. In this paper, we discuss the application of both discrete and continuous dynamic methods as powerful research techniques for measuring respiration rate in postharvest research.Item Open Access Discrimination of Allium headspace volatiles affected by variations in genotype growing environment and storage using an electronic noses(2003) Abbey, Lord; Joyce, Daryl C.; Terry, Leon A.Alliums are valued mainly for their unique organosulphur-derived flavours and aromas. Traditional sensory and analytical determinations of Allium quality are constrained by high cost, technical difficulties and, time and human limitations. This thesis investigates the potential for use of relatively novel electronic nose (E-nose) technology for Allium discrimination. Chapters 3, 4 (Sections 4.1 to 4.3), 5 (Sections 5.1 and 5.2) and Appendices II and III inclusive have been published or submitted for publication. Consequently, Chapters in this thesis are presented in the form of papers. The E-nose AromaScan LabStation A32/8S (Osmetech Pic., UK) consists of 32 conducting polymer miniature sensors. Adsorbed odour molecules alter the electric conduction mechanism of the sensor polymer. The response is measured as proportional (%) change in sensor resistance ratio (%dR/R). The E-nose discriminated Allium types (Chapter 3), varieties of spring onion grown with or without sulphur addition and a single variety of spring onion grown under different levels of sulphur, nitrogen, water-deficit stress and soil type (Chapter 4). Bulb onion affected by nitrogen, sulphur and soil type and diced onion sealed in polyethylene bags stored at 4°C for 9 days were also discriminated by the E-nose (Chapter 5). A descriptive model for the direction of E-nose sensor polymer response to Allium headspace volatiles affected by genotypic differences and edaphic variables was outlined in Section 6.2. Principal Component Analyses (PCA) of E-nose data sets output accounted for >75% to nearly 100% of variations in the Alliums. The variations in Allium genotype differentially affected the E-nose sensor conductivity following headspace volatiles interaction with sensor polymer element. Classification of data sets output showed greater (Mahalanobis distance statistic, D² >3.0) sensitivity of spring onion cvs Guardsman and Fragrance to S fertilisation while the headspace volatiles characteristics of cvs Winter Over and Paris Silverskin were not significantly (D²<3.0) altered by S. The headspace volatiles of onion bulb cv. Sprinters also responded to S fertilisation (D²>3.0) and thus, increased %dR/R. Overall, N-fertilised onion cv. Sprinters reduced E-nose sensor conductivity leading to an increase in %dR/R. Increases in water-deficit stress i.e. > -0. 80 MPa soil water potential, SWP generally reduced separation between E-nose data set clusters for clay versus sandy loam soils from D² = 43.2 for -0.01 MPa SWP to D² = 6.2 for -1.19 MPa. Headspace volatiles of onions grown in the glasshouse clay increased %dR/R compared to reduced %dR/R values for both glasshouse and field sandy loam soils. The E-nose detected gradual changes in headspace volatiles of diced onion wrapped in polyethylene bags stored at 4°C for 9 days. The changes in headspace volatiles reduced %dR/R values while data set cluster separations with reference to day 0 for each sampling time increased from D² = 3.6, 5.8 and 7.0 on days 3, 6 and 9, respectively. The results suggested that Allium quality can be assessed with ease along production, postharvest and marketing chains compared to traditional destructive methods. Linear correlations for E-nose data sets versus Allium pungency determinants (pyruvic acid and lachrymatory potency), total soluble solids and dry-matter were poor. The thesis discusses the commercial significance of the result and its implication for the development of E-nose sensor tailored for Alliums. This would promote application and use of E-nose technology in the Allium industry, germplasm evaluation, and discrimination of agronomic variables and possibly, monitoring spoilage pathogens during storage. The effects of nitrogen, sulphur, water-deficit stress and soil type and their interactions have given new insight into agronomic inputs on growth and microbial load (Chapters 4.3, 5.1 and Appendix III).Item Open Access Disposable pyruvate biosensors for routine assessment of onion flavour(Cranfield University, 2007-04) Abayomi, Louise Anike; Terry, Leon A.The UK-grown onion sector shows strong potential for growth through new product development as consumers become increasingly aware of the health and dietary benefits of fresh onion consumption. Prospects for the production of new, more palatable sweet onions will be boosted by the development of improved grower diagnostics for flavour standardisation. Growers require simple-to-use on-farm diagnostics to assure flavour quality. The introduction of pungency tests has led to increased mild onion sales, however currently tests are out-sourced and as a result costly. Through this Defra- (Department for Agriculture Food and Rural Affairs) sponsored research project (HL0164), hand-held biosensor technology, adapted from the medical sector, has been developed for improved and lower cost pungency and sweetness analysis in onions. Cont/d.Item Open Access Effect of controlling ethylene on ripening of avocado cv. hass fruit(Cranfield University, 2010-05) Meyer, Marjolaine D.; Terry, Leon A.Rigorous control of ethylene inside storage atmosphere is cardinal to maintain quality of climacteric fruit, including avocado cv. Hass. This can be achieved using the ethylene action inhibitor, 1-methylcyclopropene (1-MCP). The recent development of a novel palladium (Pd)-based ethylene scavenger, e+® Ethylene Remover, provides a new opportunity to delay avocado fruit ripening. A new method was developed to sequentially extract and quantify both lipids and sugars from the same avocado mesocarp tissue sample. Extraction by homogenization with hexane yielded slightly less oil than the standard Soxhlet technique whilst the fatty acid profiles of the oil extracts were similar. Extraction of the resulting filter residue with methanol (62.5%, v/v) better recovered sucrose, perseitol and mannoheptulose as compared to ethanol (80%, v/v). The new method has a shorter extraction time, lower extraction temperature and requires less solvent. Presence of e+® Ethylene Remover in storage atmosphere removed all ethylene and accordingly delayed the ripening of avocado cv. Hass stored at low temperature. 1-MCP also inhibited ripening, yet, unlike e+® Ethylene Remover it impaired subsequent ripening. It was possible to slow down the ripening rate after the climacteric has been induced by removing ethylene below 1 μL L-1 in presence of e+® Ethylene Remover, and the scavenger was effective in combination with modified atmosphere packaging (MAP). Blocking ethylene action or removing ethylene did very slightly affect the fatty acid composition of the mesocarp oil. Depending on the origin and maturity of the fruit, 1-MCP and e+® Ethylene Remover better maintained seven-carbon sugars concentrations in mesocarp. Results support the view that mannoheptulose and perseitol could be important features of the avocado ripening process but more research is necessary to elucidate their exact function. Mesocarp abscisic acid (ABA) was quantified using a newly developed LC-ESIMS/ MS method. ABA increased as fruit ripened but appeared to be at least partly regulated by ethylene. Whether ABA influences the ethylene-associated ripening in avocado cv. Hass remains to be determined in future.