Two hundred to three hundred milligrams of food material taken from a previously homogenized sample was mixed with 860 ml of extraction buffer (10 mM TriseOH, 150 mM NaCl, 2 mM EDTA and 1% w/v sodium dodecyl sulfate), 100 ml of guanidine hydrochloride (5 M) and 40 ml of proteinase K (20 mg/ml), then incubated at 65 Covernight.