Use of Preservatives to Delay Toxin Formation by Clostridium botulinum (Type B, Strain Okra) in Vacuum-Packed, Cooked Potatoes

Abstract

Storage at temperatures below 4°C prevents growth and toxin production by Clostridium botulinum in vacuum-packed, cooked potatoes. The use of preservatives as an additional, built-in safety factor has been investigated. Dipping potatoes in a solution of ascorbic and citric acid before vacuum-packing and cooking (95°C for 50 min) inhibited growth and toxin production by proteolytic C. botulinum type B at an incubation temperature of 15°C for 70 d and at 20°C for at least 14 d. This preservative treatment also resulted in an organoleptically acceptable product with a prolonged shelf life. Risk analysis showed that the presence of C. botulinum in vacuum-packed, cooked potatoes may be expected, i.e., one spore in each 1585 kg of product. A preservative treatment with a combination of ascorbic and citric acid will limit the public health risk even if the potato product is accidently stored for a short time at a temperature higher than 4°C.