title: Modelling of aflatoxin G1 reduction by kefir grain using response surface methodology.
abstract: Aflatoxin G1 (AFG1) is one of the main toxic contaminants in pistachio nuts and causes potential health hazards. Hence, AFG1 reduction is one of the main concerns in food safety. Kefir-grains contain symbiotic association of microorganisms well known for their aflatoxin decontamination effects. In this study, a central composite design (CCD) using response surface methodology (RSM) was applied to develop a model in order to predict AFG1 reduction in pistachio nuts by kefir-grain (already heated at 70 and 110°C). The independent variables were: toxin concentration (X1: 5, 10, 15, 20 and 25 ng/g), kefir-grain level (X2: 5, 10, 20, 10 and 25%), contact time (X3: 0, 2, 4, 6 and 8 h), and incubation temperature (X4: 20, 30, 40, 50 and 60°C). There was a significant reduction in AFG1 (p < 0.05) when pre-heat-treated kefir-grain used. The variables including X1, X3 and the interactions between X2-X4 as well as X3-X4 have significant effects on AFG1 reduction. The model provided a good prediction of AFG1 reduction under the assay conditions. Optimization was used to enhance the efficiency of kefir-grain on AFG1 reduction. The optimum conditions for the highest AFG1 reduction (96.8%) were predicted by the model as follows: toxin concentration = 20 ng/g, kefir-grain level = 10%, contact time = 6 h, and incubation temperature = 30°C which validated practically in six replications.
authors.affiliation: Bioprocess and Biodetection Laboratory (BBL), Department of Food Science, Engineering and Technology, University of Tehran, 31587-77871 Karaj, Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Ansari
authors.affiliation: Bioprocess and Biodetection Laboratory (BBL), Department of Food Science, Engineering and Technology, University of Tehran, 31587-77871 Karaj, Iran.
authors.forename: Faramarz
authors.initials: F
authors.lastname: Khodaiyan
authors.affiliation: Department of Food Science, Engineering and Technology, University of Tehran, 31587-77871 Karaj, Iran.
authors.forename: Karamatollah
authors.initials: K
authors.lastname: Rezaei
authors.affiliation: Department of Food Science and Technology, Standard Research Institute, 1745-139 Karaj, Iran.
authors.forename: Anosheh
authors.initials: A
authors.lastname: Rahmani
keywords: Aflatoxin G1; Kefir-grain; Optimization; Pistachio nut; Predictive modelling