Investigation on β-D-glucan extraction methods from Pleurotus ostreatus mycelium and its capability to adsorb aflatoxin M1 in milk

Abstract

Milk and dairy products constitute a critical component of the human diet, particularly for children. Nevertheless, the presence of aflatoxins, such as aflatoxin M₁ (AFM₁), within milk is highly undesirable due to their associated health risks. It is imperative to employ safe methodologies to reduce or eliminate aflatoxins from milk exceeding permissible standards. A promising novel approach involves the utilization of organic absorbent compounds. Structural β-D-glucan, a constituent of the fungal cell wall of organisms like the oyster mushroom (Pleurotus ostreatus), emerges as a potential organic adsorbent. This study encompassed the collection, drying, and pulverization of mycelial biomass cultivated in a laboratory setting. Diverse extraction techniques, including hot water, acid, and hot alkali treatments or ultrasonic pretreatment, were applied to isolate polysaccharide compounds, including β-D-glucan, from the fungal mycelium cell wall. The β-D-glucan content yielded by each extraction method was quantified using the Megazyme Assay Kit. Results indicated that the hot alkali method demonstrated superior β-D-glucan extraction efficiency at 77.54% compared to alternative approaches. To assess the AFM₁ adsorption capacity of extracted β-D-glucan, a specific quantity (2.5 mg/ml) was added to milk which was artificially contaminated with varying AFM₁ concentrations. Subsequently, adsorption efficiency was determined via High-Performance Liquid Chromatography (HPLC). Findings revealed that the addition of extracted β-D-glucan resulted in the adsorption of up to 100%, 70%, and 58% of AFM₁ content within contaminated milk at concentrations of 35, 75, and 120 ng/L, respectively, within 10, 20, and 40 min. These research outcomes introduce a secure and organic adsorbent capable of removing or reducing AFM₁ in contaminated milk, thereby fostering public health confidence. Moreover, β-D-glucan not only lacks the adverse effects associated with chemical compounds but also offers potential additional benefits when retained within the milk.