Nisin extraction capacity of aqueous ethanol and methanol from a 2.5% preparation

Nisin is a widely used antimicrobial preservative whose efficacy is compromised by interaction with food components when applied to food matrices hence, encapsulation may overcome this problem. The objective of this research was to study parameters for concentrating nisin from a 2.5% preparation using 10–100% aqueous ethanol and methanol at 1–15 mg solids/mL solvent (MSMS). The extraction yield was the highest at an intermediate alcohol concentration (80% methanol or 50% ethanol) corresponding to intermediate polarity, while a poorer extraction was observed at higher MSMS. The higher alcohol concentration also enabled improved removal of impurities such as protein. The highest purification factor (PF) was observed at 1 MSMS in 90% methanol (PF = 5.3, 91.0% yield) or 2 MSMS in 70% ethanol (PF = 5.5, 84.7% yield). The recommended conditions (2 MSMS in 70% ethanol) were further used to prepare a powdered product 4.4 times more concentrated by spray drying. The concentrated product may be used for encapsulation of the antimicrobial in capsules or films/coatings.