Aflatoxin binding efficiency of Saccharomyces cerevisiae mannoprotein in contaminated pistachio nuts

Mannoprotein (mannan), an important cell wall component of Saccharomyces cerevisiae, is a bioactive glycoprotein that has aflatoxin binding effect. In this study, mannan from the cell wall of Saccharomyces cerevisiae was extracted and lyophilized. Aflatoxin binding assay of mannan in water/methanol were spiked with 0.5 μl. Aflatoxin standard solution showed that aflatoxin binding and mannan concentration had a positive correlation (p < 0.05). To evaluate the binding efficacy of mannan on aflatoxin content in pistachio, the contaminated pistachio kernels were soaked in mannan solution (25 and 50 mg/ml). Highest binding percent (84.40 ± 0.20% for aflatoxin B1) was seen in higher concentration of mannan. An increasing trend was observed by contact time (5, 15, 30, 60,120, 180 min); furthermore, there were 80% aflatoxin binding occurrence in the first 5 min contact time. The aflatoxin binding efficacy of mannan incorporated in gelatin -based coating on pistachio showed that the gelatin/mannan (3.5:1.5) coating can bind 83.49 ± 0.17% aflatoxin in contaminated pistachio. Since aflatoxin contamination of nuts such as pistachio is a critical defect in quality of control and safety guarantee, elimination/reduction of aflatoxin content attracted more attentions. According the results of this study, mannan alone or in corporation with gelatin -based coating has a potential application to reduce aflatoxin level in contaminated pistachio.