ENHANCEMENT OF ETHYLENETHIOUREA RECOVERIES IN FOOD ANALYSES BY ADDITION OF CYSTEINE HYDROCHLORIDE

The effectiveness of cysteine hydrochloride (Cys-HCl) as a preservativ e of ethylenethiourea (ETU) in product matrixes and during analysis wa s studied, ETU recoveries were adversely affected by certain product m atrixes when fortified directly into the product, Recoveries in 8 sele cted food items were 0-92% when analyzed 30 min after fortification an d 0-51% when analyzed after 24 h, When Cys-HCl was added to product pr ior to fortification, recoveries increased to 71-95% even after frozen storage for 2-4 weeks, Cys-HCl was added during analysis of 53 untrea ted items, Recoveries improved an average of 15% with Cys-HCl, Without Cys-HCl, recoveries were erratic (20-98%), but with Cys-HCl, recoveri es were 68-113%, Other antioxidants (sodium sulfite, butylated hydroxy anisole, butylated hydroxytoluene, and vitamins A and C) also were eva luated as ETU preservatives, When lettuce was treated first with sodiu m sulfite and then fortified with ETU, recoveries averaged 86%; withou t sodium sulfite, they averaged 1%. The ether antioxidants were less e ffective for preserving ETU in lettuce, giving only 8-46% recoveries, The effect of oxidizers (potassium bromate, sodium hypochlorite, and h ydrogen peroxide) on ETU recovery was also determined, Recovery of ETU from a baby food product (pears and pineapple) was 82%; with oxidizer s, recoveries were 0-8%.