Analysis of free and esterified ergosterol in tomato products

A new extraction and chromatographic procedure to quantify free and esterif ied ergosterol in tomato products was devised. The extraction solution was composed of a dichloromethane/methanol mixture in a 2:1 (v/v) ratio. This e xtraction solvent allowed for higher ergosterol recovery from tomato produc ts (an average of 25% more) compared to hexane, which is frequently employe d for ergosterol extraction. Both free and esterified ergosterol were deter mined by HPLC reverse-phase chromatography employing a Nova-Pall C-18 colum n (300 x 3.9 mm), filled with 4 mm average particle size and a guard column of the same material. The elution was performed at a now rate of I ml min- l with a linear gradient of solvent A (methanol/water, 80:20, v/v) and solv ent B (dichloromethane). The gradient, starting at sample injection, was fr om 0 to 50% B for 20 min for the free ergosterol analysis and additional 15 min at 50% B to analyze the ergosterol esters. This technique has proven t o be more sensitive for ergosterol determination than other reported chroma tographic procedures. Moreover, ergosterol esters, extracted from various f ungal sources, separated well and were easily quantified.