Biocontrol Potential of Antagonistic Yeasts on In Vitro and In Vivo Aspergillus Growth and Its AFB1 Production.

Aspergillus flavus is a major aflatoxin B1, posing significant health concerns to humans, crops, and producer fungi. Due to the undesirable consequences of the usage of synthetic fungicides, biological control using yeasts has gained more attention. In this study, eight isolates of epiphytic yeasts belonging to Moesziomyces sp., Meyerozyma sp. and Metschnikowia sp., which have been identified as antagonists, were isolated from different plants, including grapes, blueberries, hawthorns, hoskiran, beans and grape leaf. While volatile organic compounds (VOCs) produced by Moesziomyces bullatus DN-FY, Metschnikowia aff. pulcherrima DN-MP and Metschnikowia aff. pulcherrima 32-AMM reduced in vitro A. flavus mycelial growth and sporulation, only VOCs produced by Metschnikowia aff. fructicola 1-UDM were found to be effective at reducing in vitro AFB1 production. All yeasts reduced the mycelial growth of A. flavus by 76-91%, while AFB1 production reduced to 1.26-10.15 ng/g and the control plates' growth was 1773 ng/g. The most effective yeast, Metschnikowia aff. Pulcherrima DN-HS, reduced Aspergillus flavus growth and aflatoxin B1 production on hazelnuts. The AFB1 content on hazelnuts reduced to 333.01 ng/g from 536.74 ng/g. To our knowledge, this is the first report of yeasts isolated from plants being tested as potential biological control agents to reduce AFB1 production on hazelnuts.

A conceptual framework for the collection of food products in a Total Diet Study.

A total diet study (TDS) provides representative and realistic data for assessing the dietary intake of chemicals, such as contaminants and residues, and nutrients, at a population level. Reproducing the diet through collection of customarily consumed foods and their preparation as habitually eaten is crucial to ensure representativeness, i.e., all relevant foods are included and all potential dietary sources of the substances investigated are captured. Having this in mind, a conceptual framework for building a relevant food-shopping list was developed as a research task in the European Union's 7th Framework Program project, 'Total Diet Study Exposure' (TDS-Exposure), aimed at standardising methods for food sampling, analyses, exposure assessment calculations and modelling, priority foods, and selection of chemical contaminants. A stepwise approach following the knowledge translation (KT) model for concept analysis is proposed to set up a general protocol for the collection of food products in a TDS in terms of steps (characterisation of the food list, development of the food-shopping list, food products collection) and pillars (background documentation, procedures, and tools). A simple model for structuring the information in a way to support the implementation of the process, by presenting relevant datasets, forms to store inherent information, and folders to record the results is also proposed. Reproducibility of the process and possibility to exploit the gathered information are two main features of such a system for future applications.

Lab-on-a-chip based biosensor for the real-time detection of aflatoxin.

Polymers were synthesized and utilized for aflatoxin detection coupled with a novel lab-on-a-chip biosensor: MiSens and high performance liquid chromatography (HPLC). Non-imprinted polymers (NIPs) were preferred to be designed and used due to the toxic nature of aflatoxin template and also to avoid difficult clean-up protocols. Towards an innovative miniaturized automated system, a novel biochip has been designed that consists of 6 working electrodes (1mm diameter) with shared reference and counter electrodes. The aflatoxin detection has been achieved by a competition immunoassay that has been performed using the new biochips and the automated MiSens electrochemical biosensor device. For the assay, aflatoxin antibody has been captured on the Protein A immobilized electrode. Subsequently the sample and the enzyme-aflatoxin conjugate mixture has been injected to the electrode surfaces. The final injection of the enzyme substrate results in an amperometric signal. The sensor assays for aflatoxin B1 (AFB1) in different matrices were also performed using enzyme link immunosorbent assay (ELISA) and HPLC for confirmation. High recovery was successfully achieved in spiked wheat samples using NIP coupled HPLC and NIP coupled MiSens biosensor [2ppb of aflatoxin was determined as 1.86ppb (93% recovery), 1.73ppb (86.5% recovery), 1.96ppb (98% recovery) and 1.88ppb (94.0% recovery) for immunoaffinity column (IAC)-HPLC, NIP-HPLC, Supel™ Tox SPE Cartridges (SUP)-HPLC and NIP-MiSens, respectively]. Aflatoxin detection in fig samples were also investigated with MiSens biosensor and the results were compared with HPLC method. The new biosensor allows real-time and on-site detection of AFB1 in foods with a rapid, sensitive, fully automated and miniaturized system and expected to have an immense economic impact for food industry.

TDS exposure project: relevance of the total diet study approach for different groups of substances.

A method to validate the relevance of the Total Diet Study (TDS) approach for different types of substances is described. As a first step, a list of >2800 chemicals classified into eight main groups of relevance for food safety (natural components, environmental contaminants, substances intentionally added to foods, residues, naturally occurring contaminants, process contaminants, contaminants from packaging and food contact materials, other substances) has been established. The appropriateness of the TDS approach for the different substance groups has then been considered with regard to the three essential principles of a TDS: representativeness of the whole diet, pooling of foods and food analyzed as consumed. Four criteria were considered for that purpose (i) the substance has to be present in a significant part of the diet or predominantly present in specific food groups, (ii) a robust analytical method has to be available to determine it in potential contributors to the dietary exposure of the population, and (iii) the dilution impact of pooling and (iv) the impact of everyday food preparation methods on the concentration of the substance are assessed. For most of the substances the TDS approach appeared to be relevant and any precautions to be taken are outlined.