Browsing by Author "Alamar, M. Carmen"
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Item Open Access Almost 25 years of chromatographic and spectroscopic analytical method development for petroleum hydrocarbons analysis in soil and sediment: State-of-the-art, progress and trends(Taylor & Francis, 2017-10-11) Douglas, Reward; Nawar, S.; Alamar, M. Carmen; Coulon, Frederic; Mouazen, Abdul M.This review provides a critical insight into the selection of chromatographic and spectroscopic techniques for semi-quantitative and quantitative detection of petroleum hydrocarbons in soil and sediment matrices. Advantages and limitations of both field screening and laboratory-based techniques are discussed and recent advances in chemometrics to extract maximum information from a sample by using the optimal pre-processing and data mining techniques are presented. An integrated analytical framework based on spectroscopic techniques integration and data fusion for the rapid measurement and detection of on-site petroleum hydrocarbons is proposed. Furthermore, factors influencing petroleum hydrocarbons analysis in contaminated samples are discussed and recommendations on how to reduce their influence provided.Item Open Access The application of a handheld mid-infrared spectrometry for rapid measurement of oil contamination in agricultural sites(Elsevier, 2019-02-07) Douglas, R. K.; Nawar, S.; Alamar, M. Carmen; Coulon, Frederic; Mouazen, A. M.Rapid analysis of oil-contaminated soils is important to facilitate risk assessment and remediation decision-making process. This study reports on the potential of a handheld mid-infrared (MIR) spectrometer for the prediction of total petroleum hydrocarbons (TPH), including aliphatic (alkanes) and polycyclic aromatic hydrocarbons (PAH) in limited number of fresh soil samples. Partial least squares regression (PLSR) and random forest (RF) modelling techniques were compared for the prediction of alkanes, PAH, and TPH concentrations in soil samples (n = 85) collected from three contaminated sites located in the Niger Delta, Southern Nigeria. Results revealed that prediction of RF models outperformed the PLSR with coefficient of determination (R2) values of 0.80, 0.79 and 0.72, residual prediction deviation (RPD) values of 2.35, 1.96, and 2.72, and root mean square error of prediction (RMSEP) values of 63.80, 83.0 and 65.88 mg kg−1 for TPH, alkanes, and PAH, respectively. Considering the limited dataset used in the independent validation (18 samples), accurate predictions were achieved with RF for PAH and TPH, while the prediction for alkanes was less accurate. Therefore, results suggest that RF calibration models can be used successfully to predict TPH and PAH using handheld MIR spectrophotometer under field measurement conditions.Item Open Access Application of novel technologies to reach net‐zero greenhouse gas emissions in the fresh pasteurised milk supply chain: A review(Wiley, 2022-12-21) Grandsir, Capucine; Falagán, Natalia; Alamar, M. CarmenThis review assesses the potential of three novel technologies (3-nitrooxypropanol, ultraviolet C light cold pasteurisation and biochar) to reduce the carbon footprint produced by the fresh milk supply chain at global level. In addition to the adoption of these technologies: (i) new policies should enhance the development and implementation of international standards to optimise the quality and safety of such technologies whilst facilitating their traceability; (ii) dairy firms and technology start-ups should benefit from worldwide emissions trading systems to limit technology implementation costs; and (iii) consumers could participate in the net-zero challenge by adopting easy-to-apply sustainable practices, thus reducing their milk carbon footprint.Item Open Access Assessing metal recovery opportunities through bioleaching from past metallurgical sites and waste deposits: UK case study(CISA Publisher, 2022-12-31) Tezyapar Kara, Ipek; Marsay, Niall; Huntington, Victoria; Coulon, Frederic; Alamar, M. Carmen; Capstick, Michael; Higson, Stuart; Buchanan, Andrew; Wagland, StuartRecovery of metals from former industrial areas (also called brownfields) and closed landfill sites, are critical for future sustainable development and reducing the environmental risks they posed. In this study, the feasibility of using bioleaching for resource recovery of raw and secondary raw materials from a former metallurgical site and deposit (PMSD) located in the UK was investigated. Determination of the physicochemical parameters (conductivity, pH, moisture and ash content) that can affect bioleaching performance along with metal content analysis were carried out. Field measurement were also carried out using a portable X-ray fluorescence (pXRF) spectrometer as a rapid measurement tool and compared with the induced coupled mass spectrometry (ICP-MS) results. Fe (469,700 mg/kg), Ca (25,900 mg/kg) and Zn (14,600 mg/kg) were the most dominant elements present in the samples followed by Mn (8,600 mg/kg), Si (3,000 mg/kg) and Pb (2,400 mg/kg). The pXRF results demonstrated minimal variance (<10%) from the ICP-MS results. The preliminary assessment of bioleaching using Acidithiobacillus ferrooxidans at 5% pulp density with 22 g/L energy source and 10% (v/v) inoculum at pH 1.5 showed that 100% of Ti and Cu, 32% of Zn and 24% of Mn was recovered from the sample material, highlighting opportunities for the recovery of such metals through bioleaching processes.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 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 Embargo Cultivar differences in the hormonal crosstalk regulating apple fruit development and ripening: Relationship with flavour components and postharvest susceptibility to Penicillium expansum(Elsevier, 2023-08-17) Fernández-Cancelo, Pablo; Echeverria, Gemma; Teixidó, Neus; Alamar, M. Carmen; Giné-Bordonaba, JordiThe hormonal interplay during the on-tree development and ripening of three apple cultivars with known differences in their postharvest ripening patterns was studied, at the biochemical and targeted gene expression level, along with characterizing the changes in main sugars, acids, phenylpropanoids and volatile organic compounds (VOCs). Our findings suggest that in ‘Royal Gala’ and ‘Opal®’ apples, a peak in indole 3-acetic acid (IAA) seems necessary to activate ethylene metabolism, being its intensity proportional to the ethylene production. The interplay between IAA and ethylene appears to be mediated by MdARF5, responsible for activating the expression of MdACS3 and triggering ethylene metabolism. On the other hand, the lack of ethylene production observed in ‘Granny Smith’ apples was likely related to the absence of an IAA peak and possibly caused by the over activation of IAA conjugation mechanisms leading to a greater accumulation of IAA inactive conjugates such as indole-3-acetyl-aspartate (IAAsp). Abscisic acid (ABA) accumulation was only observed in cultivars with the ability to accumulate sucrose and produce ethylene, suggesting a possible crosstalk among those hormones and sucrose in orchestrating apple on-tree ripening. While differences in hormone levels among cultivars led to noticeable differences in some specific VOCs, no evident associations were found between hormone changes and the accumulation or degradation of monosaccharides, organic acids or phenolic compounds during fruit development and ripening. Likewise, no clear relationship was found between the fruit susceptibility to blue mould and hormonal levels yet certain specific biochemical compounds (i.e., procyanidins and sucrose) could be acting as a source of resistance or susceptibility, respectively, to blue mould development. Overall, understanding the cultivar specific hormonal regulation of apple on-tree ripening provides valuable insights to optimize fruit quality at the time of harvest as well as to develop strategies for improved postharvest management.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 Evaluation of vis-NIR reflectance spectroscopy sensitivity to weathering for enhanced assessment of oil contaminated soils(Elsevier, 2018-02-19) Douglas, Reward K.; Newar, S; Cipullo, Sabrina; Alamar, M. Carmen; Coulon, Frederic; Mouazen, A. M.This study investigated the sensitivity of visible near-infrared spectroscopy (vis-NIR) to discriminate between fresh and weathered oil contaminated soils. The performance of random forest (RF) and partial least squares regression (PLSR) for the estimation of total petroleum hydrocarbon (TPH) throughout the time was also explored. Soil samples (n = 13) with 5 different textures of sandy loam, sandy clay loam, clay loam, sandy clay and clay were collected from 10 different locations across the Cranfield University's Research Farm (UK). A series of soil mesocosms was then set up where each soil sample was spiked with 10 ml of Alaskan crude oil (equivalent to 8450 mg/kg), allowed to equilibrate for 48 h (T2 d) and further kept at room temperature (21 °C). Soils scanning was carried out before spiking (control TC) and then after 2 days (T2 d) and months 4 (T4 m), 8 (T8 m), 12 (T12 m), 16 (T16 m), 20 (T20 m), 24 (T24 m), whereas gas chromatography mass spectroscopy (GC–MS) analysis was performed on T2 d, T4 m, T12 m, T16 m, T20 m, and T24 m. Soil scanning was done simultaneously using an AgroSpec spectrometer (305 to 2200 nm) (tec5 Technology for Spectroscopy, Germany) and Analytical Spectral Device (ASD) spectrometer (350 to 2500 nm) (ASDI, USA) to assess and compare their sensitivity and response against GC–MS data. Principle component analysis (PCA) showed that ASD performed better than tec5 for discriminating weathered versus fresh oil contaminated soil samples. The prediction results proved that RF models outperformed PLSR and resulted in coefficient of determination (R2) of 0.92, ratio of prediction deviation (RPD) of 3.79, and root mean square error of prediction (RMSEP) of 108.56 mg/kg. Overall, the results demonstrate that vis–NIR is a promising tool for rapid site investigation of weathered oil contamination in soils and for TPH monitoring without the need of collecting soil samples and lengthy hydrocarbon extraction for further quantification analysis.Item Open Access Fructans redistribution prior to sprouting in stored onion bulbs is a potential marker for dormancy break(Elsevier, 2018-12-18) Ohanenye, Ikenna Christian; Alamar, M. Carmen; Thompson, Andrew J.; Terry, Leon A.Continuous supply of high quality onion bulbs to meet year-round demand is dependent on maintaining dormancy and bulb quality during storage. Sprouting impacts negatively on the storage quality of onion bulbs. Ethylene supplementation has previously been revealed to inhibit sprout growth in stored onion bulbs. Fructans content, especially those at higher degree of polymerisation (DP), are reported to positively correlate with delayed sprouting. However, little is known about the impact of pre-harvest irrigation regimes on fructans accumulation and redistribution in relation to onion bulb dormancy and quality in store. Across two seasons, onion plants of cultivars ‘Red Baron’ and ‘Sherpa’ were subjected to full irrigation (FI) (100% replenishment of crop evapotranspiration) or deficit irrigation (DI) (50% of FI treatment) from bulb initiation to harvest. Bulbs were harvested at full maturity and stored at 1 °C for five months. Bulbs were treated with or without 1-MCP (1 μL L−1) for 24 h before storage under continuous ethylene supplementation (10 μL L−1) or air. DI had no effect on dormancy-break, sprout emergence, total fructans content and total sugar content. In contrast, ethylene delayed sprout emergence and suppressed sprout growth; added 1-MCP enhanced this effect. The concentration of DP3-8 fructans were higher in top and bottom sections compared to the baseplate. Before sprout emergence, fructans of DPs 7–8 were no longer present in the top and bottom wedges, while they accumulated in the baseplate; irrespective of pre- or postharvest treatments. This redistribution of fructans within the bulb suggested a transition in dormancy state and could be used as a predictive marker for sprouting in stored onion bulbs.Item Open Access Implementation of spectroscopy as a rapid measurement tool (RMT) to inform risk assessment at petroleum contaminated sites in the Niger Delta, Nigeria.(2018-04) Douglas, Kokah Douglas B.; Alamar, M. CarmenThe recent developments and applications of rapid measurement tools (RMT) such as visible near-infrared (vis-NR) spectroscopy can provide ‘fit for purpose’ and cost effective data for informing risk assessment and managing oil-contaminated sites. Infrared spectroscopy discriminates between chemical compounds by detecting the specific vibrational frequencies of molecular bonds, producing a unique infrared ‘spectral signal’ thereby enhancing its identification and quantification applying chemometrics. The aim of the research was therefore to assess the potential of vis-NIR and mid-infrared (MIR) diffuse reflectance spectroscopy (DRS) techniques as RMT to inform risk decision support for remediation of petroleum contaminated sites. The objectives of the study were to: critically review chromatographic and spectroscopic methods for petroleum hydrocarbon analysis in soils; evaluate vis-NIR sensitivity to detect hydrocarbon concentration differences throughout weathering; predict TPH, PAH and alkanes concentrations in contaminated soils using vis-NIR and MIR DRS coupled with regression techniques. The study further evaluated which spectroscopy technique (vis-NIR or MIR); and which modelling method (RF or PLSR) performs best. In this study, a series of 13 soil mesocosms was set up where each soil sample collected was spiked with 10 ml of Alaskan crude oil and allowed to equilibrate at room temperature for 48 h before analysis. The mesocosms were incubated for two years at roomntemperature in the dark. Soils scanning and gas chromatography coupled to mass spectrometry (GC-MS) analysis were carried out at T0, 4, 12, 16, 20 and 24 months. Prior to scanning, soil samples were air-dried at room temperature (21oC) to reduce the effect of moisture. The soil scanning was done simultaneously using an AgroSpec spectrometer with a spectral range of 305 to 2200 nm (tec5 Technology for Spectroscopy, Germany) and Analytical Spectral Devices LabSpec2500 spectrometer (ASD Inc, USA) with a spectral range of 305 to 2500 nm to assess and compare the sensitivity and response of the two instruments to weathering and hydrocarbon composition change overtime against GC-MS data. Partial least squares (PLS) and random forest (RF) regression models showed that ASD LabSpec2500 performed better than tec5 which may be attributed to the shorter wavelength spectra range of the tec5 spectrometer and therefore not detecting all significant hydrocarbon signals (e.g., 2207, 2220, 2240 and 2460 nm). The sensitivity of the two spectral devices to weathering and REWARD K. DOUGLAS Cranfield University PhD Thesis, 2018 hydrocarbon composition change was, however, comparable; and the predicted concentrations were also comparable to the hydrocarbons concentrations determined by GC-MS. The results (coefficient of determination, R²=0.9; ratio of prediction deviation, RPD=3.79 and root mean square error of prediction, RMSEP=108.56 mg/kg) demonstrate that visible-near infrared diffuse reflectance spectroscopy (vis-NIR DRS) is a proven tool for rapid site investigation and monitoring without the need of collecting soil samples and lengthy hydrocarbon extraction for further analysis..To this end, 85 soil samples collected from three crude oil spill sites in the Niger Delta, Nigeria. Prior to spectral measurement, soil physiochemical properties such as pH, total organic carbon and textural analysis were carried out. Soil samples were scanned (field-moist) and assessed using ASD LabSpec2500 (wavelength 350-2500 nm) and MIR data was acquired with Agilent 4300 handheld Fourier transform infrared (FTIR) spectrometer (Agilent Technologies, Santa Clara, CA, United States) with a spectral range of 4000- 650 cmˉ¹. Specifically, detailed analysis of the hydrocarbon content including total petroleum hydrocarbons (TPH), aliphatic and aromatic hydrocarbon fractions were determined and quantified by GC-MS, vis-NIR and MIR DRS. MIR over-performed vis-NIR with RF modelling method performing better than PLSR in predicting TPH, PAH and alkanes. However, PLSR-vis-NIR produced slightly better results than PLSR- MIR in predicting TPH and alkanes. Overall, vis-NIR (wavelength 350-2500 nm) laboratory-scale study yields better TPH prediction than the field-scale study. The minimised moisture content may have improved the results, as laboratory-scale samples were air-dried. Based on the results, MIR spectroscopy coupled with RF is recommended for the analysis of hydrocarbon contaminated soil. Finally, spectroscopy approach was proposed as RMT for contaminated soil investigation and risk prioritisation.Item Open Access Improving the tea withering process using ethylene or UV-C(American Chemical Society, 2021-11-05) Collings, Emma R.; Alamar, M. Carmen; Bogaerts Márquez, Maria; Kourmpetli, Sofia; Kevei, Zoltan; Thompson, Andrew J.; Mohareb, Fady; Terry, Leon A.Using a combination of biochemical, transcriptomic, and physiological analyses, we elucidated the mechanisms of physical and chemical withering of tea shoots subjected to UV-C and ethylene treatments. UV-C irradiation (15 kJ m–2) initiated oxidation of catechins into theaflavins, increasing theaflavin-3-monogallate and theaflavin digallate by 5- and 13.2–4.4-fold, respectively, at the end of withering. Concomitantly, a rapid change to brown/red, an increase in electrolyte leakage, and the upregulation of peroxidases (viz. Px2, Px4, and Px6) and polyphenol oxidases (PPO-1) occurred. Exogenous ethylene significantly increased the metabolic rate (40%) and moisture loss (30%) compared to control during simulated withering (12 h at 25 °C) and upregulated transcripts associated with responses to dehydration and abiotic stress, such as those in the ethylene signaling pathway (viz. EIN4-like, EIN3-FBox1, and ERFs). Incorporating ethylene during withering could shorten the tea manufacturing process, while UV-C could enhance the accumulation of flavor-related compounds.Item Open Access An integrated approach to control and manage potato black dot disease: a review(Springer, 2023-09-15) Sanzo-Miró, Marta; Simms, Daniel M.; Rezwan, Faisal I.; Terry, Leon A.; Alamar, M. CarmenPotato black dot is a foliar and tuber blemish disease that has become an increasingly economic problem in recent years. Black dot is caused by the fungus Colletotrichum coccodes and is characterised by silver/brown lesions on the tuber skin leading to lower aesthetic quality of potatoes destined for the pre-pack market. Given the consumers’ growing demand for washed and pre-packed potatoes, skin blemish diseases (such as black dot and silver scurf), once considered of minor importance, are now serious challenges for the fresh potato industry. The management of C. coccodes is far from satisfactory at either pre- or postharvest stages: firstly, the disease symptoms have not been consistently described on potato plant foliage; and secondly, black dot disease is often confounded with other tuber blemishes during postharvest storage. Good field managing practices in combination with improved postharvest strategies and an accurate detection support tool can be a useful integrated approach to manage potato black dot disease. This review aims to evaluate and critically discuss different novel approaches for better management and detection of potato black dot disease.Item Open Access Investigating the involvement of ABA, ABA catabolites and cytokinins in the susceptibility of ‘Nules Clementine’ mandarin to rind breakdown disorder(Wiley, 2019-02-14) Magwaza, Lembe Samukelo; Alamar, M. Carmen; Tesfay, Samson Zeray; Mditshwa, Asandas; Opara, Umezuruike Linus; Terry, Leon A.Abstract BACKGROUND Nules Clementine’ mandarin was used to investigate the potential involvement of endogenous plant hormones in mediating the citrus fruit susceptibility to rind breakdown disorder (RBD). The effect of light exposure (viz. canopy position and bagging treatments) on the endogenous concentration of ABA, 7’hydroxy‐abscisic acid (7‐OH‐ABA), ABA‐glucose ester (ABA‐GE) and dihydrophaseic acid (DPA), and t‐zeatin was tested using four preharvest treatments: outside, outside bagged, inside and inside bagged. Phytohormones concentration was evaluated during 9 weeks of postharvest storage at 8 °C. RESULTS The shaded fruit inside the canopy had the highest RBD score (0.88) at the end of postharvest storage, while sun‐exposed fruit had the lowest score (0.12). Before storage, ABA concentration was lowest (462.8 μg kg‐1) for inside fruit, and highest in outside bagged fruit (680.5 μg kg‐1). Although ABA concentration suddenly increased from the third week, reaching a maximum concentration of 580 μg kg‐1 at week 6 in fruit from inside position, it generally reduced 1.6‐fold ranging from 240.52 to 480.65 μg kg‐1 throughout storage. The increase of 7‐OH‐ABA was more prominent in fruit from inside canopy. Overall, the concentration of ABA‐GE increased 3‐fold with storage time. DPA concentration of bagged fruit from inside canopy position was significantly higher compared to outside fruit. The lower ABA‐GE and higher DPA concentration in inside bagged fruit throughout storage also coincided with higher RBD. CONCLUSION The strong positive correlations between 7‐OH‐ABA, DPA and RBD incidence demonstrated that these ABA catabolites could be used as biomarkers for fruit susceptibility to the disorder.Item Open Access A member of the TERMINAL FLOWER1/CENTRORADIALIS gene family controls sprout growth in potato tubers(Oxford University Press, 2018-11-03) Morris, Wayne L.; Alamar, M. Carmen; Lopez-Cobollo, Rosa M.; Castillo Cañete, Javier; Bennett, Mark; van der Kaay, Jeroen; Stevens, Jennifer; Sharma, Sanjeev Kumar; McLean, Karen; Thompson, Andrew J.; Terry, Leon A.; Turnbull, Colin G. N.; Bryan, Glenn J.; Taylor, Mark A.Potato tuber bud dormancy break followed by premature sprouting is a major commercial problem which results in quality losses and decreased tuber marketability. An approach to controlling premature tuber sprouting is to develop potato cultivars with a longer dormancy period and/or reduced rate of sprout growth. Our recent studies using a potato diploid population have identified several quantitative trait loci (QTLs) that are associated with tuber sprout growth. In the current study, we aim to characterize a candidate gene associated with one of the largest effect QTLs for rapid tuber sprout growth on potato chromosome 3. Underlying this QTL is a gene encoding a TERMINAL FLOWER 1/CENTRORADIALIS homologue (PGSC0003DMG400014322). Here, we use a transgenic approach to manipulate the expression level of the CEN family member in a potato tetraploid genotype (cv. Désirée). We demonstrate a clear effect of manipulation of StCEN expression, with decreased expression levels associated with an increased rate of sprout growth, and overexpressing lines showing a lower rate of sprout growth than controls. Associated with different levels of StCEN expression were different levels of abscisic acid and cytokinins, implying a role in controlling the levels of plant growth regulators in the apical meristem.Item Open Access Minimising food waste: a call for multidisciplinary research(Wiley, 2017-09-30) Alamar, M. Carmen; Falagán, Natalia; Aktas, Emel; Terry, Leon A.Food losses and waste has always been a significant global problem for mankind, and one which has become increasingly recognised as such by policy makers, food producers, processors, retailers, and consumers. It is however an emotive subject whereby the extent, accuracy, and resolution of available data on postharvest loss and waste is questionable such that key performance indicators on waste can be misinformed. The nature and extent of food waste differs amongst developed economies, economies in transition, and developing economies. Whilst most emphasis has been put on increasing future crop production, far less resource has been and is still channelled towards enabling both established and innovative food preservation technologies to reduce food waste while maintaining safety and quality. Reducing food loss and waste is a more tractable problem than increasing production in the short to medium term, as its solution is not directly limited, for instance, by available land and water resources. Here we argue the need for a paradigm shift of current funding strategies and research programmes which will encourage the development, implementation, and translation of collective biological, engineering, and management solutions to better preserve and utilise food. Such cross disciplinary thinking across global supply chains is an essential element in the pursuit of sustainable food and nutritional security. The implementation of allied technological and management solutions is reliant on there being sufficient skilled human capital and resource. There is currently a lack of robust postharvest research networks outside of the developed world, and insufficient global funding mechanisms which can support such interdisciplinary collaborations. There is thus a collective need for schemes which encourage inter-supply chain research, knowledge exchange and capacity building to reduce food losses and waste.Item Open Access New insights into the effects of ethylene on ABA catabolism, sweetening and dormancy in stored potato tubers(Elsevier, 2020-12-08) Tosetti, R.; Waters, Amanda; Chope, Gemma A.; Cools, K.; Alamar, M. Carmen; McWilliam, S.; Thompson, Andrew J.; Terry, Leon A.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.Item Open Access Non-destructive methods for mango ripening prediction: Visible and near-infrared spectroscopy (visNIRS) and laser Doppler vibrometry (LDV)(Elsevier, 2024-03-16) O’Brien, C.; Falagán, Natalia; Kourmpetli, Sofia; Landahl, Sandra; Terry, Leon A.; Alamar, M. CarmenWith up to 19% of mango fruit being lost during ripening, the need for non-destructive technologies to predict internal physiochemical traits is paramount. This study compared two non-destructive technologies, visible and near-infrared spectroscopy (visNIRS) and laser Doppler vibrometry (LDV), for predicting the ripeness of mango fruit in two cultivars, ‘Kent’ and ‘Keitt’. An internal quality index (IQI) in ‘Kent’ was predicted using visNIRS (RP2 = 0.729, RMSEP = 0.532) using partial least squares regression, which gave a single measure for ripeness incorporating firmness, sweetness, and pulp colour. This model was improved by using the sum of the individual sugar contents (glucose, sucrose, and fructose) over the conventional total soluble solids (TSS) measure. LDV provided poor predictions of firmness (R2 < 0.5) in both ‘Kent’ and ‘Keitt’ using least squares regression line. The resonant frequency, as measured by LDV, decreased linearly with time, while firmness quantified destructively (quasi-static) showed an exponential decrease, suggesting the vibrational and destructive firmness measure distinct characteristics, which would contribute to poor model performance. These results showed that LDV is not suitable for assessing mango ripening. While visNIRS models have been successful at predicting quality traits, our results suggested that using individual sugar content in place of TSS can improve the prediction of ripening. This understanding of the strengths and limitations of both visNIRS and LDV, and how they relate to destructive quality measurements, can be used to improve postharvest management practices whilst reducing commercial losses in the mango industry.Item Open Access Oxalic acid preharvest treatment improves colour and quality of seedless table grape ‘Magenta’ upregulating on-vine ABA metabolism and relative VvNCED1 gene expression and the antioxidant system in berries(Frontiers, 2021-11-01) García-Pastor, María E.; Giménez, María J.; Serna-Escolano, Vicente; Guillén, Fabián; Valero, Daniel; Serrano, María; García-Martínez, Santiago; Terry, Leon A.; Alamar, M. Carmen; Zapata, Pedro J.The effect of oxalic acid (OA) in determining poorly coloured table grape quality remains relatively unknown. Some red cultivars, such as seedless table grape ‘Magenta’ are characterised by a poor berry colour, an attribute highly demanded by the consumer. The aim of this research was to elucidate the effect of a preharvest OA treatment (5 mM) on berry colour and quality of table grape by investigating its role in berry development, on-vine ripening, and postharvest senescence. We found that OA significantly increased abscisic acid (ABA) and ABA glucose ester (ABA–GE) content in treated berries. This increase was mediated by changes in the ABA biosynthetic pathway, specifically by the upregulation of the 9-cis-epoxycarotenoid dioxygenase (VvNCED1) gene. The accumulation of ABA in treated berries resulted in colour improvement and a higher individual and total anthocyanins content at harvest compared with control; whereas at harvest, OA-treated table grapes showed a significantly lower glucose and fructose content and a higher content of tartaric, ascorbic, and succinic acids. Furthermore, antioxidant enzyme activity was increased during berry development in OA-treated berries. On the other hand, those berries treated with OA showed a delay in loss of firmness and colour during cold storage, as well as less susceptibility to postharvest decay incidence. This effect of OA delaying the senescence process was also related to enzymatic antioxidant system stimulation. For the first time, the role of OA on increasing quality, mainly colour, in table grapes was elucidated, highlighting that this treatment upregulated ABA metabolism, relative VvNCED1 gene expression and antioxidant system, delaying postharvest berry senescence.