Standard Methods HiVeg™ Agar w/ Tween 80 and Lecithin

Principle and Interpretation

This medium is prepared by using HiVeg hydrolysate in place of Casein enzymic hydrolysate which makes the medium free of BSE/TSE risks. Standard Methods HiVeg Agar with Tween 80 and Lecithin is the modification of Standard Methods Agar with Tween 80 and Lecithin which is formulated as per APHA (1) for the enumeration of microorganisms from flat and nonporous surfaces. For the intended purpose the plates of this medium should be prepared carefully to ensure the presence of meniscus of agar extending above the top of the poured plate. HiVeg hydrolysate provides amino acids while yeast extract supplies vitamin B complex and dextrose serves as an energy source. Polysorbate 80 and lecithin act as neutralizers to inactivate the residual disinfectants from where the samples are collected (2, 3). Lecithin inactivates quaternary ammonium compounds whereas polysorbate 80 neutralizes formalin, phenolic disinfectants, hexachlorophene etc.