Processors will find the guidelines valuable when developing processes and procedures designed improve manufacturing efficiency and hygiene standards.

The guidelines recommend implementing control measures, which include heat treating and acidification to a pH below 4.6.

The Food and Drug Adminstration (FDA), which issued the guidelines this month, advises processors to ensure all food contact surfaces and equipment are cleaned and sanitized to prevent the post-processing contamination of their juice products.

Ensuring packaging closures perform to effectively seal the juice and minimize the risk of contamination is also recommended.

The FDA said it issued the guidelines in response to a growing number of contamination incidents involving carrot juice.

Botulism in carrot juice was responsible for six cases of food poisoning in the US and Canada in autumn 2006.

All of the cases were linked to processed carrot juice produced at a single farm. The products had been pasteurized but had not been heated to a temperature that would kill c. botulinum, the most resistant form of the pathogen that causes botulism in humans.

This pathogen only develops under extreme temperature changes, and the FDA believes the juice that caused the illnesses must have been left unrefridgerated for an extended period, either during distribution or storage.

Although not common, with about 110 cases reported in the US each year, botulism can cause serious paralytic illness and even death.