ROUTINE LIMULUS AMEBOCYTE LYSATE (LAL) TEST FOR ENDOTOXIN DETERMINATION IN MILK USING A TOXINOMETER ET-201

A rapid method of performing the Limulus amoebocyte lysate (LAL) test in milk is proposed using the Toxinometer ET-201. This instrument meas ured the increase in turbidity due to the interaction between the endo toxins of the Gram-negative bacteria and the LAL reagent, monitored th e ratio R(t) of the sequential to the initial transmission at 12 s int ervals and quantified endotoxins by determination of the reaction time T(r) required to obtain a 5% decrease in R(t). There was a good corre lation between the toxinometrically determined endotoxin concentration s and the number of Gram-negative bacteria (SD, 0.18 log(plate count u nits)), and the repeatability (CV, 6-10%) was high. The assay may be u seful for screening raw materials for UHT milk production, as the endo toxin content of the raw material is related to the rest proteinase ac tivity in the UHT milk.