Reduction of mycotoxin contamination level during soybean fermentation

This thesis deals with the reduction of mycotoxin contamination level during soybean fermentation (Thua-Nao). Beside this work, isolation, characterization, and ochratoxin A production ability of toxigenic fungi from French grapes were also study. Results of this latter part showed that Aspergillus carbonarius and Aspergillus niger are the most ochratoxin A producer in wine grape from France. Furthermore, Aspergillus japonicus can produce a little bit quantity of ochratoxin A in wine grape too. Regarding to the main part of the work, 23 isolates of Bacillus spp. were isolated from Thai Thua-Nao. An Aspergillus flavus aflatoxin producing strain was also isolated from Thua-Nao whereas an Aspergillus westerdijkiae was chosen as an OTA producing reference strain. The objectives were to find an efficient Bacillus strain for: Growth inhibition of Aspergillus flavus and Aspergillus westerdijkiae NRRL 3174. - Limitation of aflatoxin B1 production. ; - Mycotoxins, aflatoxin B1 and ochratoxin A detoxification. Among the results, Bacillus CM 21, which was identified later by ITS sequencing as Bacillus licheniformis, showed the highest ability on inhibition of growth of both Aspergillus strains and both of mycotoxins removal (decrease of 74% of AFB1 and 92.5% of OTA). Another Bacillus strain, MHS 13, inhibiting both Aspergillus growth and detoxifying 85% of AFB1 was identified as Bacillus subtilis. Finally, culture supernatant and cellular extract from both interested Bacillus strains were tested for aflatoxin B1 and ochratoxin A degradation ability in order to know their degradation mechanisms. Moreover, study on optimal condition for aflatoxin B1 and ochratoxin A degradation were also conducted. All results indicated that OTA was significantly degraded by culture supernatant from Bacillus licheniformis CM 21 (p lower than 0.0001) in OTalpha. The percentage of OTA degradation was 97.5% and the optimal activity of its culture supernatant was found at pH 7.0 and 37°C with 24 h culture incubation time and 2 h contact time. Moreover, OTA was also significantly degraded by culture supernatant from Bacillus subtilis MHS 13 (p lower than 0.0017) at pH 5.0 and 37°C with 48 h culture incubation time and 2 h contact time. The proposed degradation mechanism should be extracellular and carboxypeptidase A probably responsible for this degradation since no activity was found for the intracellular extract. However, AFB1 could be degraded by neither culture supernatant nor cellular extract from both of these microorganisms. Hence, the AFB1 detoxification mechanism may be due to non-enzymatic mechanism

Antigenotoxic Studies of Different Substances to Reduce the DNA Damage Induced by Aflatoxin B1 and Ochratoxin A

Mycotoxins are produced mainly by the mycelial structure of filamentous fungi, or more specifically, molds. These secondary metabolites are synthesized during the end of the exponential growth phase and appear to have no biochemical significance in fungal growth and development. The contamination of foods and feeds with mycotoxins is a significant problem for the adverse effects on humans, animals, and crops that result in illnesses and economic losses. The toxic effect of the ingestion of mycotoxins in humans and animals depends on a number of factors including intake levels, duration of exposure, toxin species, mechanisms of action, metabolism, and defense mechanisms. In general, the consumption of contaminated food and feed with mycotoxin induces to neurotoxic, immunosuppressive, teratogenic, mutagenic, and carcinogenic effect in humans and/or animals. The most significant mycotoxins in terms of public health and agronomic perspective include the aflatoxins, ochratoxin A (OTA), trichothecenes, fumonisins, patulin, and the ergot alkaloids. Due to the detrimental effects of these mycotoxins, several strategies have been developed in order to reduce the risk of exposure. These include the degradation, destruction, inactivation or removal of mycotoxins through chemical, physical and biological methods. However, the results obtained with these methods have not been optimal, because they may change the organoleptic characteristics and nutritional values of food. Another alternative strategy to prevent or reduce the toxic effects of mycotoxins is by applying antimutagenic agents. These substances act according to several extra- or intracellular mechanisms, their main goal being to avoid the interaction of mycotoxins with DNA; as a consequence of their action, these agents would inhibit mutagenesis and carcinogenesis. This article reviews the main strategies used to control AFB1 and ochratoxin A and contains an analysis of some antigenotoxic substances that reduce the DNA damage caused by these mycotoxins

Chapter 19 - Safety concerns on biological contaminations in fermented foods: Special focus on fungi and mycotoxins

International audienceThere are rising concerns regarding the consumption of fermented foods regarding their safety to microbial contaminations from fermenting consortium and food processing materials. On the other hand, there has been a dramatic increase in demand for safe foods and the major concerns are not just associated with the methods of food production, but also with all stages across the supply chain. Mycotoxins, produced by some groups of fungi, are known to impact on significant economic loss. Their presence in foods at levels above regulatory limits brings about adverse effects on sustainable food supply, posing health risks to humans and animals, as well as limitations on international trade. Mycotoxins such as aflatoxins, ochratoxin A, fumonisins, deoxynivalenol and citrinin are the majorly identified in the etiology of food safety concerns causing numerous food-borne diseases. This chapter discusses fungi-mycotoxin contaminations in different fermented food products, highlights the major components influencing the microbial safety of fermented foods (including lack of proper processing and handling, and poor storage conditions which could trigger the production of these naturally occurring toxic compounds) as well as their impacts on economic and human health. From the various studies reviewed, mycotoxins were mainly detected in soy-based (tempeh, doenjang, soy sauce, meju, miso and shoyu) and rice-based (Red yeast rice and sake) fermented food products. Hence, there is a need for the integration of mycotoxin mitigation actions to safeguard the quality of raw materials used in food fermentation and to ensure the consumption of safe and healthy foods

Réduction du niveau de mycotoxines dans la fermentation du soja

This thesis deals with the reduction of mycotoxin contamination level during soybean fermentation (Thua-Nao). Beside this work, isolation, characterization, and ochratoxin A production ability of toxigenic fungi from French grapes were also study. Results of this latter part showed that Aspergillus carbonarius and Aspergillus niger are the most ochratoxin A producer in wine grape from France. Furthermore, Aspergillus japonicus can produce a little bit quantity of ochratoxin A in wine grape too. Regarding to the main part of the work, 23 isolates of Bacillus spp. were isolated from Thai Thua-Nao. An Aspergillus flavus aflatoxin producing strain was also isolated from Thua-Nao whereas an Aspergillus westerdijkiae was chosen as an OTA producing reference strain. The objectives were to find an efficient Bacillus strain for: Growth inhibition of Aspergillus flavus and Aspergillus westerdijkiae NRRL 3174. - Limitation of aflatoxin B1 production. ; - Mycotoxins, aflatoxin B1 and ochratoxin A detoxification. Among the results, Bacillus CM 21, which was identified later by ITS sequencing as Bacillus licheniformis, showed the highest ability on inhibition of growth of both Aspergillus strains and both of mycotoxins removal (decrease of 74% of AFB1 and 92.5% of OTA). Another Bacillus strain, MHS 13, inhibiting both Aspergillus growth and detoxifying 85% of AFB1 was identified as Bacillus subtilis. Finally, culture supernatant and cellular extract from both interested Bacillus strains were tested for aflatoxin B1 and ochratoxin A degradation ability in order to know their degradation mechanisms. Moreover, study on optimal condition for aflatoxin B1 and ochratoxin A degradation were also conducted. All results indicated that OTA was significantly degraded by culture supernatant from Bacillus licheniformis CM 21 (p < 0.0001) in OTalpha. The percentage of OTA degradation was 97.5% and the optimal activity of its culture supernatant was found at pH 7.0 and 37C with 24 h culture incubation time and 2 h contact time. Moreover, OTA was also significantly degraded by culture supernatant from Bacillus subtilis MHS 13 (p <0.0017) at pH 5.0 and 37C with 48 h culture incubation time and 2 h contact time. The proposed degradation mechanism should be extracellular and carboxypeptidase A probably responsible for this degradation since no activity was found for the intracellular extract. However, AFB1 could be degraded by neither culture supernatant nor cellular extract from both of these microorganisms. Hence, the AFB1 detoxification mechanism may be due to non-enzymatic mechanism.Cette étude traite de la réduction du niveau de contamination en mycotoxines pendant la fermentation du soja (produit alimentaire thaïlandais appelé Thua-Nao). En marge de ce travail, l'isolement et la caractérisation de la capacité à produire de l'ochratoxine A a été évaluée chez des champignons toxinogènes isolés de raisins français destinés à la vinification. Les résultats de cette partie ont montré que Aspergillus carbonarius et Aspergillus niger sont les champignons les plus producteurs en France. Cependant, Aspergillus japonicus peut aussi être à l'origine de faibles quantités d'ochratoxine A au niveau des raisins. En ce qui concerne la principale partie de ce travail, 23 isolats de Bacillus spp. ont été obtenus à partir de Thua-Nao thaïlandais. Une souche d'Aspergillus flavus productrice d'aflatoxine a aussi été isolée de Thua-Nao tandis qu'une souche d'Aspergillus westerdijkiae (ex ochraceus) a été choisie comme référence d'Aspergillus producteur d'OTA. Les objectifs étaient de trouver des souches de Bacillus efficaces pour: - inhiber la croissance d'Aspergillus flavus et Aspergillus westerdijkiae NRRL 3174 ; - limiter la production d'aflatoxine B1 ; - détoxifier le milieu en diminuant la teneur en mycotoxines : aflatoxine B1 (AFB1) et Ochratoxine A (OTA). Parmi les résultats principaux, Bacillus CM 21, ensuite identifiée comme Bacillus licheniformis par séquençage des ITS, a montré la meilleure capacité à inhiber la croissance des 2 souches d'Aspergillus ainsi que la meilleure capacité détoxifiante (diminution de 74% d'AFB1 et 92.5% d'OTA). Une autre souche de Bacillus, MHS 13, capable à la fois d'inhiber la croissance des 2 souches d'Aspergillus et de diminuer de 85% la teneur en AFB1 a été identifiée comme Bacillus subtilis.Finalement, le surnageant de culture et l'extrait cellulaire des 2 souches de Bacillus ont été testés pour la dégradation de l'AFB1 et de l'OTA afin de mieux comprendre les mécanismes de la détoxification. Les conditions optimales de la dégradation ont aussi été étudiées. Les résultats montrent que l'OTA était significativement degradée par le surnageant de Bacillus licheniformis CM 21 (p inférieur à 0.0001) en OTalpha. Le pourcentage de dégradation d'OTA a été de 97.5% et les conditions optimales d'activités étaient : pH 7.0, 37C, 24 h de croissance de la bactérie et 2 heures d'incubation avec la solution d'OTA. De même, l'OTA a été degradée à 69% par le surnageant de Bacillus subtilis MHS 13 (p inférieur à 0.0017) à pH 5.0, 37C, 48 h de croissance de la bactérie et 2 heures d'incubation avec la solution d'OTA. Le mécanisme de dégradation proposé est donc la présence d'une carboxypeptidase A extracellulaire. En effet, le contenu intracellulaire des 2 bactéries n'a montré aucune activité détoxifiante.Par ailleurs l'AFB1 n'a été dégradée ni par le surnageant de culture, ni par le contenu extracellulaire des 2 bactéries. On peut donc supposer que le mécanisme de détoxification pour l'AFB1 n'est pas de nature enzymatique .TOULOUSE-ENSAT-Documentation (315552324) / SudocSudocFranceF

Modernizing traditional fermented foods for a more sustainable and diverse food system

International audienceTraditional fermented foods are products belonging to the World Heritage that are often obtained in a more sustainable way than other foods. Over the past decades, traditional food systems evolved to globalized networks of regulated trade. However, for safety, sensorial, and nutritional issues, the way they are produced has to be modernized with a better control of the fermentation step (eg starter cultures vs spontaneous fermentation). Innovations should follow economic, and eco-friendly approaches to improve their safety and quality, creating a good balance among history, culture, and advanced biotechnologies.The production of some traditional fermented foods is well defined through Protected Geographical Indications whereas other products arousing keen interest of big companies or for which traditional processes are not able to fulfil quality and safety requirements might be endangered. A danger concerns the loss of “typicity” (all the characteristics/features/typical qualities that make a food peculiar/distinctive) through the use of uniform standardized processes and commercial starter cultures.The main objective of this special issue is to analyse traditional fermented foods, considering their opportunities, such as the sustainable way of production which can be widespread to improve the carbon balance of our food system

The Effectiveness of Durian Peel as a Multi-Mycotoxin Adsorbent

Durian peel (DP) is an agricultural waste that is widely used in dyes and for organic and inorganic pollutant adsorption. In this study, durian peel was acid-treated to enhance its mycotoxin adsorption efficacy. The acid-treated durian peel (ATDP) was assessed for simultaneous adsorption of aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON), and fumonisin B1 (FB1). The structure of the ATDP was also characterized by SEM&ndash;EDS, FT&ndash;IR, a zetasizer, and a surface-area analyzer. The results indicated that ATDP exhibited the highest mycotoxin adsorption towards AFB1 (98.4%), ZEA (98.4%), and OTA (97.3%), followed by FB1 (86.1%) and DON (2.0%). The pH significantly affected OTA and FB1 adsorption, whereas AFB1 and ZEA adsorption was not affected. Toxin adsorption by ATDP was dose-dependent and increased exponentially as the ATDP dosage increased. The maximum adsorption capacity (Qmax), determined at pH 3 and pH 7, was 40.7 and 41.6 mmol kg&minus;1 for AFB1, 15.4 and 17.3 mmol kg&minus;1 for ZEA, 46.6 and 0.6 mmol kg&minus;1 for OTA, and 28.9 and 0.1 mmol kg&minus;1 for FB1, respectively. Interestingly, ATDP reduced the bioaccessibility of these mycotoxins after gastrointestinal digestion using an in vitro, validated, static model. The ATDP showed a more porous structure, with a larger surface area and a surface charge modification. These structural changes following acid treatment may explain the higher efficacy of ATDP in adsorbing mycotoxins. Hence, ATDP can be considered as a promising waste material for mycotoxin biosorption

The Effectiveness of Durian Peel as a Multi-Mycotoxin Adsorbent

Durian peel (DP) is an agricultural waste that is widely used in dyes and for organic and inorganic pollutant adsorption. In this study, durian peel was acid-treated to enhance its mycotoxin adsorption efficacy. The acid-treated durian peel (ATDP) was assessed for simultaneous adsorption of aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON), and fumonisin B1 (FB1). The structure of the ATDP was also characterized by SEM–EDS, FT–IR, a zetasizer, and a surface-area analyzer. The results indicated that ATDP exhibited the highest mycotoxin adsorption towards AFB1 (98.4%), ZEA (98.4%), and OTA (97.3%), followed by FB1 (86.1%) and DON (2.0%). The pH significantly affected OTA and FB1 adsorption, whereas AFB1 and ZEA adsorption was not affected. Toxin adsorption by ATDP was dose-dependent and increased exponentially as the ATDP dosage increased. The maximum adsorption capacity (Qmax), determined at pH 3 and pH 7, was 40.7 and 41.6 mmol kg−1 for AFB1, 15.4 and 17.3 mmol kg−1 for ZEA, 46.6 and 0.6 mmol kg−1 for OTA, and 28.9 and 0.1 mmol kg−1 for FB1, respectively. Interestingly, ATDP reduced the bioaccessibility of these mycotoxins after gastrointestinal digestion using an in vitro, validated, static model. The ATDP showed a more porous structure, with a larger surface area and a surface charge modification. These structural changes following acid treatment may explain the higher efficacy of ATDP in adsorbing mycotoxins. Hence, ATDP can be considered as a promising waste material for mycotoxin biosorptio