Abstract
The effectiveness of cysteine hydrochloride (Cys–HCI) as a preservative of ethylenethiourea (ETU) in product matrixes and during analysis was studied. ETU recoveries were adversely affected by certain product matrixes when fortified directly into the product. Recoveries in 8 selected food items were 0–92% when analyzed 30 min after fortification and 0–51% when analyzed after 24 h. When Cys–HCI was added to product prior to fortification, recoveries increased to 71–95% even after frozen storage for 2–4 weeks. Cys–HCI was added during analysis of 53 untreated items. Recoveries improved an average of 15% with Cys–HCI. Without Cys–HCI, recoveries were erratic (20–98%), but with Cys–HCI, recoveries were 68–113%. Other antioxidants (sodium sulfite, butylated hydroxyanisole, butylated hydroxytoluene, and vitamins A and C) also were evaluated as ETU preservatives. When lettuce was treated first with sodium sulfite and then fortified with ETU, recoveries averaged 86%; without sodium sulfite, they averaged 1%. The other antioxidants were less effective for preserving ETU in lettuce, giving only 8–46% recoveries. The effect of oxidizers (potassium bromate, sodium hypochlorite, and hydrogen peroxide) on ETU recovery was also determined. Recovery of ETU from a baby food product (pears and pineapple) was 82%; with oxidizers, recoveries were 0–8%.