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Additives analysis plays important role in food quality control and has a great impact on public health. Therefore, rapid detection of these compounds in food samples is important in food safety. In this study, reduced graphene oxide /Fe 3 O 4 nanocomposite (rG -Fe 3 O 4 -NC) was synthesized in the presence of sour lemon peel extract as a reducer and stabilizer agent in aqueous solution. For the first time multivariate optimization based on rotatable central composite design (RCCD) coupled with response surface methodology (RSM) was used to optimize effective experimental variables for fabrication of electrode. An experimental design has been used to examine and optimize the impacts of diverse experimental parameters like the pH and concentration of the nanocomposite in rG -Fe 3 O 4 -NC. The optimal conditions were pH: 6 and the concentration of the nanocomposite: 8%. The synthesized nanocomposites were characterized by TEM and XRD techniques. The rGO modified carbon paste electrode (rG-Fe3O4-NC/CPE) was used as a highly sensitive electrochemical sensor for the detection of vanillin. Interference of vitamin B 2, methionine, valine, glycine and KBR, KCl and glucose were checked in the presence of 25 µM vanillin at surface of rG -Fe 3 O 4 -NC/CPE with acceptable error 5%. Results confirmed that 500 - folde of above compounds have not any important interference in monitoring process of 25 µM vanillin. The vanillin sensor showed linear range between 01 nM – 250 μM and a low detection limit of 0.3 nM. Finally, the rG -Fe 3 O 4 - NC/CPE was successfully used for determining vanillin in food samples.Therefore, this sensor can be used in food industry to the online determination of vanillin in flavored milks and ice cream. [ABSTRACT FROM AUTHOR]

Introduction: Many microorganisms like fungi, bacteria and yeasts, have a natural ability to produce vitamins included vitamin B2 or riboflavin. In this regard, the present study was performed to isolation and screening for riboflavin producing yeasts from various sources of soil, leaf and fruits. Materials and methods: samples of leaf, soil and fruits were prepared for the presence of yeasts and by its ability to produce riboflavin. After purification and enrichment of samples, in order to assay riboflavin production, spectrometry, thin layer chromatography and high performance liquid chromatography were used. Finally, the best selected isolate was identified using conventional morphological, biochemical and molecular techniques. Results: In this study, 26 yeast strains were isolated from environmental samples, that 6 isolates showed the ability to produce riboflavin. Identification results of the best selected isolate by biochemical and phenotypic characteristics revealed that this isolate is related to Clavispora lusitaniae and considering isolation of it from nectarine, has named it Clavispora lusitaniae strain N3 (Gene accession no: JQ586258 ). Discussion and conclusion: Although only one of the six producing strains was studied and identified, observation of ability to produce among 23% of strains showed necessity for further investigation. And according to the result of absence of viewing report about production by investigated strain, it can be said that Iran has potentiality for isolation of yeasts and is capable of producing riboflavin. [ABSTRACT FROM AUTHOR]