A worldwide review of illness outbreaks involving mixed salads/dressings and factors influencing product safety and shelf life

The trends toward healthy living, vegetarianism, and busy schedules have increased salad popularity. Salads are usually consumed raw without any thermal treatment, and therefore, without proper care they can become major vehicles for foodborne illness outbreaks. This review examines the microbial quality of 'dressed' salads which contain two or more vegetables/fruits and salad dressings. The possible sources of ingredient contamination, recorded illnesses/outbreaks, and overall microbial quality observed worldwide, besides the antimicrobial treatments available are discussed in detail. Noroviruses were most frequently implicated in outbreaks. Salad dressings usually play a positive role in influencing microbial quality. However, this depends on several factors like the type of contaminating microorganism, storage temperature, dressing pH and ingredients, plus the type of salad vegetable. Very limited literature exists on antimicrobial treatments that can be used successfully with salad dressings and 'dressed' salads. The challenge with antimicrobial treatments is to find ones sufficiently broad in spectrum, compatible with produce flavour which can be applied at competitive cost. It is evident that renewed emphasis on prevention of produce contamination at the producer, processor, wholesale and retail levels plus enhanced hygiene vigilance at foodservice will have a major impact on reducing the risk of foodborne illnesses from salads.

Automated summary

The popularity of salads has increased due to trends toward healthy living, vegetarianism, and busy schedules. However, it is important to take proper care of salads as they can become major sources of foodborne illness outbreaks if not handled correctly. This review examines the microbial quality of 'dressed' salads and discusses the sources of contamination, recorded illnesses/outbreaks, overall microbial quality, and available antimicrobial treatments. Noroviruses are the most frequently implicated in outbreaks. Prevention of produce contamination and enhanced hygiene vigilance at all levels of the food supply chain will have a major impact on reducing the risk of foodborne illnesses from salads.