Browsing by Author "Kiaitsi, Elisavet"

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    Fusarium graminearum in stored wheat: use of CO2 production to quantify dry matter losses and relate this to relative risks of Zearalenone contamination under interacting environmental conditions
    (MDPI, 2018-02-17) Garcia-Cela, Esther; Kiaitsi, Elisavet; Sulyok, Michael; Medina-Vayá, Ángel; Magan, Naresh
    Zearalenone (ZEN) contamination from Fusarium graminearum colonization is particularly important in food and feed wheat, especially during post-harvest storage with legislative limits for both food and feed grain. Indicators of the relative risk from exceeding these limits would be useful. We examined the effect of different water activities (aw; 0.95–0.90) and temperature (10–25 °C) in naturally contaminated and irradiated wheat grain, both inoculated with F. graminearum and stored for 15 days on (a) respiration rate; (b) dry matter losses (DML); (c) ZEN production and (d) relationship between DML and ZEN contamination relative to the EU legislative limits. Gas Chromatography was used to measure the temporal respiration rates and the total accumulated CO2 production. There was an increase in temporal CO2 production rates in wetter and warmer conditions in all treatments, with the highest respiration in the 25 °C × 0.95 aw treatments + F. graminearum inoculation. This was reflected in the total accumulated CO2 in the treatments. The maximum DMLs were in the 0.95 aw/20–25 °C treatments and at 10 °C/0.95 aw. The DMLs were modelled to produce contour maps of the environmental conditions resulting in maximum/minimum losses. Contamination with ZEN/ZEN-related compounds were quantified. Maximum production was at 25 °C/0.95–0.93 aw and 20 °C/0.95 aw. ZEN contamination levels plotted against DMLs for all the treatments showed that at ca. <1.0% DML, there was a low risk of ZEN contamination exceeding EU legislative limits, while at >1.0% DML, the risk was high. This type of data is important in building a database for the development of a post-harvest decision support system for relative risks of different mycotoxins.
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    Influence of storage environment on maize grain: CO2 production, dry matter losses and aflatoxins contamination
    (Taylor and Francis, 2019-01-14) Garcia-Cela, Esther; Kiaitsi, Elisavet; Sulyok, M.; Krska, R.; Medina-Vayá, Ángel; Petit Damico, I.; Magan, Naresh
    Poor storage of cereals, such as maize can lead to both nutritional losses and mycotoxin contamination. The aim of this study was to examine the respiration of maize either naturally contaminated or inoculated with Aspergillus flavus to examine whether this might be an early and sensitive indicator of aflatoxin (AF) contamination and relative storability risk. We thus examined the relationship between different interacting storage environmental conditions (0.80–0.99 water activity (aw) and 15–35°C) in naturally contaminated and irradiated maize grain + A. flavus on relative respiration rates (R), dry matter losses (DMLs) and aflatoxin B1 and B2 (AFB1-B2) contamination. Temporal respiration and total CO2 production were analysed by GC-TCD, and results used to calculate the DMLs due to colonisation. AFs contamination was quantified at the end of the storage period by HPLC MS/MS. The highest respiration rates occurred at 0.95 aw and 30–35°C representing between 0.5% and 18% DMLs. Optimum AFs contamination was at the same aw at 30°C. Highest AFs contamination occurred in maize colonised only by A. flavus. A significant positive correlation between % DMLs and AFB1 contamination was obtained (r = 0.866, p < 0.001) in the irradiated maize treatments inoculated with A. flavus. In naturally contaminated maize + A. flavus inoculum loss of only 0.56% DML resulted in AFB1 contamination levels exceeding the EU legislative limits for food. This suggests that there is a very low threshold tolerance during storage of maize to minimise AFB1 contamination. This data can be used to develop models that can be effectively used in enhancing management for storage of maize to minimise risks of mycotoxin contamination.
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    Interacting environmental stress factors affects targeted metabolomic profiles in stored natural wheat and that inoculated with F. graminearum
    (MDPI, 2018-01-29) Garcia Cela, Esther; Kiaitsi, Elisavet; Medina-Vayá, Ángel; Sulyok, Michael; Krska, Rudolf; Magan, Naresh
    Changes in environmental stress impact on secondary metabolite (SM) production profiles. Few studies have examined targeted SM production patterns in relation to interacting environmental conditions in stored cereals. The objectives were to examine the effect of water activity (aw; 0.95–0.90) x temperature (10–25 °C) on SM production on naturally contaminated stored wheat and that inoculated with Fusarium graminearum. Samples were analysed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) on (a) total number of known SMs, (b) their concentrations and (c) changes under environmental stress. 24 Fusarium metabolites were quantified. Interestingly, statistical differences (ChisSq., p < 0.001) were observed in the number of SMs produced under different sets of interacting environmental conditions. The dominant metabolites in natural stored grain were deoxynivalenol (DON) and nivalenol (NIV) followed by a range of enniatins (A, A1, B, B1), apicidin and DON-3-glucoside at 10 °C. Increasing temperature promoted the biosynthesis of other SMs such as aurofusarin, moniliformin, zearalenone (ZEN) and their derivatives. Natural wheat + F. graminearum inoculation resulted in a significant increase in the number of metabolites produced (ChisSq., p < 0.001). For ZEN and its derivatives, more was produced under cooler storage conditions. Fusarin C was enhanced in contrast to that for the enniatin group. The relative ratios of certain groups of targeted SM changed with environmental stress. Both temperature and aw affected the amounts of metabolites present, especially of DON and ZEN. This study suggests that the dominant SMs produced in stored temperate cereals are the mycotoxins for which legislation exists. However, there are changes in the ratios of key metabolites which could influence the relative contamination with individual compounds. Thus, in the future, under more extreme environmental stresses, different dominant SMs may be formed which could make present legislation out of step with the future contamination which might occur.
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    Physiological and biochemical changes in potato stocks with different susceptibility to blackheart disorder
    (Cranfield University, 2015-03) Kiaitsi, Elisavet; Terry, Leon A.
    Blackheart (BH) is a non-pathogenic internal physiological disorder induced in potato tubers during storage. It is usually associated with oxygen (O2) depletion and/or carbon dioxide (CO2) accumulation. BH symptoms are characterized by a dark brown to black discoloration in the central portion of the tuber tissues. It is believed that phenolic compounds are related to tuber tissue discoloration and development of BH. In recent years, this disorder has been a particular problem for the UK fresh and packed potato industry and to date there is still no true understanding of the causal factors that govern BH susceptibility in stored potato tubers. Accordingly, the aim of this project was to elucidate the physiological and metabolomic mechanisms involved in potato blackheart disorder and to have a better understanding of the factors which contribute to BH development in order to alleviate this problem for the UK fresh potato industry. ...[cont.]
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    Susceptibility to blackheart disorder in potato tubers is influenced by sugar and phenolic profile
    (Elsevier, 2019-12-23) Kiaitsi, Elisavet; Tosetti, Roberta; Terry, Leon A
    Blackheart (BH) is a physiological disorder of potato tubers in which internal tissue becomes discoloured during storage. The development of BH has been previously linked with general phenolic accumulation. In this study, five potato stocks cv. Maris Piper with different susceptibility to BH were selected across two consecutive seasons, whereupon targeted analysis of sugar and individual phenolic compounds in two tuber sections (flesh and heart) was conducted after storage at 1.5 °C or after one week at 15 °C. The most susceptible stock to BH had the highest accumulation of reducing sugars, while crypto- and neo-chlorogenic acids (chlorogenic acid isomers) were more abundant in flesh tissue of non-susceptible stocks. It is postulated that these metabolites may represent putative pre-symptomatic predictive biomarkers of stock susceptibility to BH.
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    Unveiling the effect of interacting forecasted abiotic factors on growth and Aflatoxin B1 production kinetics by Aspergillus flavus
    (Elsevier, 2020-05-30) Garcia-Cela, Esther; Verheecke-Vaessen, Carol; Gutierrez-Pozo, Maria; Kiaitsi, Elisavet; Gasperini, Alessandra M.; Magan, Naresh; Medina, Angel
    The aim was to decipher the temporal impact of key interacting climate change (CC) abiotic factors of temperature (30 vs 37 °C), water activity (aw; 0.985 vs 0.930) and CO2 exposure (400 vs 1000 ppm) on (a) growth of Aspergillus flavus and effects on (b) gene expression of a structural (aflD) and key regulatory gene (aflR) involved in aflatoxin B1 (AFB1) biosynthesis and (c) AFB1 production on a yeast extract sucrose medium over a period of 10 days. A. flavus grew and produced AFB1 very early with toxin detected after only 48 h. Both growth and toxin production were significantly impacted by the interacting abiotic factors. The relative expression of the aflD gene was significantly influenced by temperature; aflR gene expression was mainly modulated by time. However, no clear relationship was observed for both genes with AFB1 production over the experimental time frame. The optimum temperature for AFB1 production was 30 °C. Maximum AFB1 production occurred between days 4–8. Exposure to higher CO2 conditions simulating forecasted CC conditions resulted in the amount of AFB1 produced in elevated temperature (37 °C) being higher than with the optimum temperature (30 °C) showing a potential for increased risk for human/animal health due to higher accumulation of this toxin.