Sous vide - under vaccum meals
i´m searching information about safety of sous vide products (meaning cooked "ready to eat" meals), what i found up to now doesn´t make me happy at all, high risk of Cl. botulinum and L. monocytogenes... is there anybody with experience in this technology?
thanks!
The term “sous vide” means “under vacuum” and describes a processing technique whereby freshly prepared foods are vacuum sealed in individual packages and then pasteurized at time-temperature combinations sufficient to destroy vegetative pathogens but mild enough to maximize the sensory characteristics of the product (39, 40). After cooking, the products are chilled, stored refrigerated, and reheated before consumption. Sous vide foods are mainly used in mass catering and restaurants (30). Compared with traditional cooking methods, sous vide has many advantages (40, 42). Economic benefits include better use of labor and equipment through centralized production and extended shelf life due to vacuum packaging, which by excluding oxygen inhibits oxidative processes and growth of spoilage organisms. The shelf life of a sous vide product can be as long as 42 days (42). In addition, the reduced need for preservatives and flavor enhancers, better preservation of vitamins, and retention of most of the original food juices all contribute to higher quality of sous vide foods over conventional meals.
Concerns associated with sous vide processing involve the microbiological safety of the products (40). The psychrotrophic food-borne pathogens and particularly nonproteolytic group II Clostridium botulinum bacteria are of concern due to the methods of preparing, distributing, and storing these products. Mild heat treatments in combination with vacuum packaging may actually select for C. botulinum and increase the potential for botulism. Sous vide products are generally formulated with little or no preservatives and frequently do not possess any intrinsic inhibitory barriers (pH, aw, or NaCl) that either alone or in combination would inhibit growth. Therefore, strict adherence to refrigerated storage below 3.3°C must be maintained to ensure the safety of sous vide products with respect to nonproteolytic C. botulinum (1). However, the temperature control in chill chains is often inadequate, and temperature abuse is common throughout distribution and retail markets and by consumers (8, 16, 27).
The fuller article is here -
http://www.pubmedcen...cgi?artid=91810
maybe things have changed in last 8 years
added - only a brief mention of L.mono in above ref. maybe they considered the selection of C.bot. was a tougher option than L.mono. regarding heating requirements. can't remember which way round it goes (will depend on matrix also), prob. C.bot. is more difficult ? HACCP planners for sous-vide products should know.
Rgds / Charles.C
Please see the link below for more information.
http://www.hi-tm.com/Documents2007/therms-feed-thru-FT100-flyer.pdf
No experiences in sous vide products personally, though I can offer you some help. Mostly the meat used for Sous vide are having the cooking time of 8 hours or longer at a low temperature such as 55oC to 60oC, maybe even 50oC for quality, which is more than enough for safety. The vacuum is used to pull the plastic tight against the food in order to get good heat transfer.
The process time /temperature conditions as per validated studies would take care of the growth of Cl.perfringes and Cl. botulinum. A thorough cleaning of the product processing rooms and packaging rooms can take care of Listeria. To reduce the risk for botulism food items should be cooked adequately; all food contact surfaces and hand contact surfaces have to clean and disinfected thoroughly and adequate refrigeration at below 3o C is advisable.
http://www.fsai.ie/p..._notes/gn15.pdf
and
http://www.fsai.ie/p..._notes/gn20.pdf
Unfortunately, I don't have any practical experience myself. Hope these documents help.
Matt