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 K.; Nawar, Said; 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 An overview of non-destructive technologies for postharvest quality assessment in horticultural crops(Taylor & Francis, 2025) O’Brien, Ciara; Alamar, M. CarmenArtificial intelligence and machine vision are increasingly popular within food supply chains for automated decision making in quality grading and disease identification. There are many types of data that these models can be trained on, and choosing which information is needed is a critical factor in minimising both food loss and cost, while maximising the impact on food quality. Non-destructive technologies give information about crop phenotypes (e.g. external colour, oil content, sweetness) without damaging the crop, allowing a greater and more representative proportion the stored food to be analysed. These non-destructive technologies use different methods to analyse the product, each with different intrinsic capabilities and limitations. Therefore, choosing which technology is most appropriate for each application is a complex and costly decision. This mini-review summarises the physical and chemical basis of how some popular non-destructive technologies function, and how these different methods give unique advantages and limitations. The most popular technologies summarised include Red-Green-Blue (RGB) imaging, visible and near-infrared spectroscopy, and vibrometry. We also review technologies that are growing in popularity, including X-ray imaging, ultraviolet spectroscopy, and magnetic resonance imaging.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, Reward K.; Nawar, Said; Alamar, M. Carmen; Coulon, Frederic; Mouazen, Abdul 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 Assuring potato tuber quality during storage: a future perspective(Frontiers Media, 2017-11-28) Alamar, M. Carmen; Tosetti, Roberta; Landahl, Sandra; Bermejo, Antonio; Terry, Leon A.Potatoes represent an important staple food crop across the planet. Yet, to maintain tuber quality and extend availability, there is a necessity to store tubers for long periods often using industrial-scale facilities. In this context, preserving potato quality is pivotal for the seed, fresh and processing sectors. The industry has always innovated and invested in improved post-harvest storage. However, the pace of technological change has and will continue to increase. For instance, more stringent legislation and changing consumer attitudes have driven renewed interest in creating alternative or complementary post-harvest treatments to traditional chemically reliant sprout suppression and disease control. Herein, the current knowledge on biochemical factors governing dormancy, the use of chlorpropham (CIPC) as well as existing and chemical alternatives, and the effects of pre- and post-harvest factors to assure potato tuber quality is reviewed. Additionally, the role of genomics as a future approach to potato quality improvement is discussed. Critically, and through a more industry targeted research, a better mechanistic understanding of how the pre-harvest environment influences tuber quality and the factors which govern dormancy transition should lead to a paradigm shift in how sustainable storage can be achieved.Item Open Access Biochemical and biomedical studies on African walnut (Tetracarpidium conophorum -Mull. Arg.) – a postharvest perspective(Cranfield University, 2015-10) Nkwonta, Chikere Godwin; Terry, Leon A.; Cellek, Selim; Alamar, M. CarmenAfrican Walnut (Tetracarpidium conophorum- Mull. Arg) is a perennial climbing shrub which grows mainly in the Western region of Africa. It is found mainly in Nigeria, Gambia, Sierra Leone, Gabon, Equatorial Guinea and Cameroon as well. The nuts are encased in pods which may contain between 2 to 5 nuts. The seed is enclosed in a hard shell-like case. The nuts are commonly processed by boiling or roasting and consumed as a snack or used as soup thickener. In ethnobotanical medicine, the nut extract is extensively used in decoctions for treatment and/or management of common and chronic ailments such as malaria, dysentery, high blood pressure, diabetes and cancer. The nuts are generally exposed to high temperatures (25 – 37 °C) and relative humidity (RH) which increases susceptibility to fungal contamination and nutrient degradation, hence, raising concerns over product quality and safety. Experiment simulating the common retail postharvest storage and processing practices was conducted to: (i) determine the effects on the fatty acid profile; (ii) assess the impact on the fungal population contaminating the nut shells at different maturity stages, and potential mycotoxigenic implications; (iii) evaluate the cytotoxicity of four extract of the nut on lung cancer (A549) cells; and finally (iv) assay the total phenolic content and profile potential individual phenolic components of the nut. Results indicated the presence of essential and non-essential fatty acids namely; palmitate, oleate, stearate, linoleate, arachidate and α-linolineate with α-linolineate being the most abundant (1.1 – 8.2 mg/g freeze-dry weight). Boiling and roasting generally improved the concentration of the fatty acids best when nuts are cold stored at 5 °C for maximum of 10 days. Potential mycotoxigenic species - Aspergillus section Nigri, Aspergillus flavus/Parasiticus, Fusarium spp. and Penicillium spp. - were frequently isolated from cultured shell pieces of stored nuts. When compared with unprocessed nuts, roasting completely prevented fungal contamination in shell pieces from nuts in the non-stored (NSN) group at early maturity stage, while boiling significantly reduced the level of contamination to about 58 % (P < 0.05). Simulating open market conditions caused 100% fungal contamination in all boiled samples and roasted samples at early maturity. Mycotoxin analysis using Yeast Extract agar (YES) and High Performance Liquid Chromatography (HPLC) - Fluorescence detector (FLD) showed that Aflatoxins - G1 (AFG1), B1 (AFB1), G2 (AFG2), and B2 (AFB2) were produced by 20 isolates with both AFG1 and AFB1 being predominant at concentration ranges 4 – 32,200 and 4 – 22,700 ng/g plug weight, respectively. No Ochratoxin A (OTA) was detected. Phenolic component analysis indicated unprocessed (20.79 ± 1.0 mg gallic acid equivalent per gram freeze-dry weight – GAE/g FDW) samples showed the highest value for total phenolics while both boiling (9.90 ± 1.8 mg GAE/g FDW), and roasting (9.32 ± 2.7 mg GAE/g FDW) reduced the amount by more than 50 % when compared with unprocessed. Potential individual phenolic compounds were unambiguously separated using high performance liquid chromatography – diode array detector (HPLC-DAD). There were no differences between chromatograms of defatted and non-defatted unprocessed, roasted and boiled samples. Cytotoxicity evaluation showed no decrease in cell densities in plates treated with extracts from unprocessed nuts at all concentrations. Diethyl ether-ethyl acetate (10 µg/mL) and n-butanol (1000 and 500 µg/mL) extracts of roasted nuts as well as dichloromethane and water (1, 10 µg/mL) of boiled nuts caused a non-significant decrease of < 10 % in cell densities when compared with the phosphate buffered saline-media control. However, all extracts showed no cytotoxic effect on the A549 cells African walnut is basically produced at subsistence level in Nigeria, but considering the presence of desirable fatty acid profile and phenolic compounds, need for increased industrial scale production is herein recommended. Although fungal attack and potential mycotoxin risk on the nut may be high, retail processing by roasting has prospects to greatly accentuate the risk. Cold storage of the nut may help to improve the shelf life although it may not be cost effective for local farmers in Nigeria and Africa, however, it provides opportunity for export business. Although the nut extracts showed no cytotoxic effect on A549 lung cancer cell lines, there is need to investigate further to confirm it non-cytotoxicity activity on other cancer lines and normal cell lines.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 Open Access Cultivar differences in the hormonal crosstalk regulating apple fruit development and ripening: Relationship with flavour components and postharvest susceptibility to Penicillium expansum(Elsevier, 2023-11-01) 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 Data "Underlying data set for Collings et al 2025_Impact of growing temperature on spear and root carbohydrate content and the effects on postharvest asparagus tip breakdown incidence"(Cranfield University, 2025-01-13) Collings, Emma R.; Alamar, M. Carmen; Terry, LeonTip breakdown has been identified as the main issue causing deterioration in asparagus quality during storage; however, the underlying mechanisms responsible for its development are unknown. Previous work showed higher incidence of tip breakdown occurring later in the season, when growing temperature is higher. To further our understanding and identify potential biomarkers of this physiological disorder, spears from two growing conditions (cooler vs. warmer), were harvested through the season to assess tip breakdown incidence, and quality attributes (asparagine and non-structural carbohydrates) during storage. Rapid growth due to warmer temperatures (up to 45°C) resulted in spears with lower sugar content and higher incidence of tip breakdown compared to cooler conditions. Asparagine slowly increased through the season (7 to 11 mg g-1 DW) with no differences between growing condition suggesting it is not a biomarker for tip breakdown. Pre-season spears (warm temperature only) had double the amount of sugar compared to early-season spears, with no incidence of tip breakdown despite an extended storage period (up to 18 days at 7°C). Sugar concentrations in roots were similar between growing conditions and between pre- and early-season despite clear differences in spear sugar content. These results showed a strong positive link between cooler growing conditions, high spear sugar content and low susceptibility to tip breakdown which was not reflected in root sugar concentrations.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 R.; Alamar, M. Carmen; Cools, Katherine; Ordaz-Ortiz, José Juan; 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 Effect of growing temperature on root carbohydrate content and postharvest asparagus tip breakdown(Wiley, 2025-12-31) Collings, Emma R.; Alamar, M. Carmen; Terry, Leon A.BACKGROUND Tip breakdown has been identified as the main issue causing deterioration in asparagus quality during storage; however, the underlying mechanisms responsible for its development are unknown. Previous work showed higher incidence of tip breakdown occurring later in the season, when growing temperature was higher. Spears from two growing conditions (cooler vs warmer) were harvested throughout the season to assess tip breakdown incidence and quality attributes (asparagine and non‐structural carbohydrates) during storage, with the aim of enhancing understanding and identifying potential biomarkers of this physiological disorder. Root samples were also collected just after harvest to determine if storage root carbohydrate content was associated with a predisposition to tip breakdown. RESULTS Rapid growth due to warmer temperatures (up to 45 °C) resulted in spears with lower sugar content and higher incidence of tip breakdown in comparison with cooler conditions. Asparagine slowly increased through the season (7 to 11 mg g−1 DW) with no differences between growing conditions, suggesting that it is not a biomarker for tip breakdown. Pre‐season spears (warm temperature only) had double the amount of sugar in comparison with early season spears, with no incidence of tip breakdown despite an extended storage period (up to 18 days at 7 °C). Sugar concentration in roots was similar between growing conditions and between pre‐ and early season despite clear differences in spear sugar content. CONCLUSION These results showed a strong positive link between cooler growing conditions, high spear sugar content, and low susceptibility to tip breakdown, which was not reflected in root sugar concentrations. However, further research is needed to understand the molecular mechanisms responsible for tip breakdown.Item Open Access Elucidating the impact of environmental factors on the growth of Colletotrichum coccodes strains isolated from potato tubers in Great Britain(Elsevier, 2024-10-01) Sanzo-Miró, Marta; Medina, Angel; Terry, Leon A.; Alamar, M. CarmenBlack dot and silver scurf caused by Colletotrichum coccodes and Helminthosporium solani, respectively, are tuber blemish diseases affecting quality in the fresh and pre-pack potato industry. In the last 20 years, the importance of high-quality tuber appearance has increased considerably due to the growing demand for washed and pre-packed potatoes in the UK. Changing climate characterised by rising temperatures and wetter summers is a threat as this will favour the development of pathogens such as C. coccodes in the soil increasing the risk of food spoilage. Moreover, both diseases can develop not only in the field but also after harvest, with postharvest storage temperatures being a crucial factor in controlling fungal growth. Furthermore, anecdotal evidence showed differences on the aggressiveness of black dot depending on its origin (i.e. England and Scotland) on potato tubers. Silver scurf and black dot are difficult to differentiate as they present similar phenotypes characterised by silvery lesions making it challenging for managers to take the necessary corrective action during storage. Hence, the aim of this study was to give a general insight into the ecological conditions affecting the establishment of the causal agent of potato black dot in the field, and black dot and silver scurf during the supply chain. Therefore, in vitro experiments were designed to study the growth rate and lag times simulating both scenarios respectively: on soil extract agar (SEA) media at different temperatures (4, 11, 15 °C) and matric potentials (control [unmodified] and − 1.4 MPa [modified]); and on natural potato dextrose agar (NPDA) for different temperatures (4, 11, 15 and 20 °C) at 99 % relative humidity (RH) for 25 days. When simulating the field environment, drier conditions (matric potential = −1.4 MPa) reduced fungal growth for both isolates by 0.1 cm day−1 at the temperature of 15 °C, suggesting temperature as the main limiting factor for the growth of C. coccodes in the soil. The causal agent of black dot exhibited a faster growth rate under retailer-like conditions (i.e., 15 °C) compared to H. solani. Understanding the environmental influence on both the pathogen and the crop is vital for proper disease management to help reduce food loss and waste.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, Said; Cipullo, Sabrina; Alamar, M. Carmen; Coulon, Frederic; Mouazen, Abdul 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 Impact of controlled atmosphere scheduling on strawberry and imported avocado fruit(Elsevier, 2017-09-01) Alamar, M. Carmen; Collings, Emma R.; Cools, Katherine; Terry, Leon A.British grown strawberry cv. Sonata and Chilean avocado cv. Hass were exposed to controlled atmospheres (CA) of 15 kPa CO2 + 5 kPa O2 (5 °C) and 10 kPa CO2 + 5 kPa O2 (5 or 20 °C), respectively, at early, middle or late stages during postharvest storage of avocados and at early and middle stages for strawberries. Real-time respiration rate (RR) was measured during CA storage and regular fruit sampling carried out to assess disease severity, objective colour, ethylene production and firmness. The automated in situ set-up used allowed continuous recordings of real-time respiration measurements without disruption to the CA environment. Cold stored strawberry fruit treated for 2.5 d with CA midway through the storage period were firmer and maintained a more vibrant colour despite bursts of increased RR. Furthermore, just 2.5 d of CA was sufficient to extend the shelf-life of strawberries (based on disease incidence) by a further 3 d, as compared to control. Irrespective of timing, RR of avocado stored at 20 °C was reduced while under CA environment; and early CA exposure maintained firmness yet increased the incidence of internal discolouration 7 d after removal from CA. At 5 °C, avocado skin colour and internal discolouration were positively affected by the mid CA treatment. These results are discussed in the context of the targeted use of CA, compared to control, for extending shelf-life, and reducing waste of these two different fruit produces. Furthermore, reducing the length of time required for CA application, which has not previously been explored in avocado or strawberries, would potentially be more energy efficient/cost effective.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.