Tuesday, March 25, 2008

More On Cleaning Cantaloupe

I'm going to come clean. I use soap. On my melons. I have for years, ever since I learned the rinds harbor nasties. Well, lately I use a commercial Veggie Wash, but still.

I remember working in a hospital kitchen years ago and watching how cantaloupe was prepared for the masses. The particular food service employee whose job it was to present fresh cantaloupe, cubed, had a unique way of handling his melons. He rolled them around whole on his cutting board as he sliced the rind off in pieces. Picture a Samurai. Just about every piece of cantaloupe served to the recumbent folks upstairs came in contact with the rinds of all of those melons.

I'm still wondering why the FDA advises against using anything but water, cool tap water, to clean cantaloupe prior to slicing. (See my post, How To Handle A Melon.) I shared my how-to-clean-cantaloupe question. Here's some feedback.1 Items in italics are mine.
  1. Cutting melons after peeling the rind was found effective in reducing the transfer of Salmonella Poona into the tissue in comparison with cutting of melons and removing the rind later. (My samurai was on the right track.)
  2. Wet the surface using water with a touch of detergent then drop the melon in 200 ppm chlorine. A Tbsp 6% bleach/quart would be 1:256 or a smidgen less than 200 ppm (50,000/256 = 195.3129 ppm for the anal.) (You gotta love analysis.)
  3. Treatment with lactic acid or ozone reduced the levels by 2.5 and 2.3 log10 CFU/cm2 respectively on the surface. (Do they sell those at the Acme?)
  4. When water treatments were used, the presence of Salmonella-positive "next to" and remote sites indicated that bacteria were spread from inoculated site on the rind to uninoculated sites either through the rinse water (40-70 CFU/ml of Salmonella) or scrub brush (400-500 CFU/brush). (Wait a second, so the FDA's advice to "Scrub whole cantaloupes by using a clean produce brush and cool tap water immediately before eating." may in fact spread microorganisms? But ...)
  5. ... This transfer was eliminated when 200 ppm total chlorine was used. When 200 ppm total chlorine was used, Salmonella could not be detected in the water or on the scrub brush. (This jives with the content in item No. 2. But ...)
  6. ... There have been quite a few studies looking at the use of chlorine, peroxide, and other products in washing cantaloupe. The results are mixed. Some studies showed chlorine more effective while others peroxide.
  7. Salmonella can survive for 22 days at 4C (39.2 degrees F) on wounded rind and penetration into tissue was enhanced by co-infection with mould, hence the recommendation to discard the entire melon when only a small area shows visual decay. (A point that contradicts the FDA's "cut-away" advice.)
  8. Some strains of Salmonella are quite virulent. Plus, there are acid-tolerant strains that survive stomach passage well. (I wondered how effective stomach acid was.)
  9. Heat a large pot of water to boiling and submerge the cantaloupe for between 30 seconds and a minute. Heat gives you better penetration than any of the chemical sanitizers into the crevices in the surface of the fruit and it also softens the rind and makes the melon easier to peel. (Large pot.)
  10. From an FDA site: Depending on the strain, "Infective dose - As few as 15-20 cells." (Wow. That's not much.)
  11. When sanitized or hot water treated whole cantaloupes were re-inoculated with Salmonella, higher counts were recovered than from untreated controls. Don't store cleaned cantaloupes.
  12. It would be good if we could apply e-beam irradiation to whole melons. Their round shape would not allow it as of now. We are working on getting around this shape issue. (The shape issue. Thank god for the shape issue.)
  13. Vinegar should work. Have not tested it on produce but have tested it on meats. The only problem would be the smell.
  14. From the research, there is no question that the growing areas are widely contaminated with salmonella. ... We are faced then with the question of how do we wash and sanitize the melon and I suggest only a few people will ever do it. ... They aren't going to wash and sanitize their melon because I don't think they will believe they need to. In addition, you are not going to get the grocers and processors to wash and sanitize the melon well enough to get the salmonella to a non infectious level because that is a mammoth task. Maybe the best is to tell cooks and consumers they have 6 hours at room temperature after they cut the melon to eat it ... in this way limit growth because there will be salmonella and there will be growth and our only solution is to limit the growth. If the melon is at 45F or less, then maybe we can allow a few days after it is cut because that is the practical low growth temp for Salmonella and E coli. ("There will be salmonella and there will be growth." I don't think I'll be ordering cantaloupe in a restaurant anytime soon.)
Some said they thought the problem was best tackled at the source, or further up the distribution line. ("The problem is not to figure out how the consumer can remove virulent pathogens from food products, but how to keep these pathogens out from the beginning.") But what do you do about reinfection further down the line? Also, see Item No. 11 above.

I want to thank the thinkers of these thoughts. I learned a lot!

How do you clean your cantaloupe, if at all?
1 Anonymous, out of context, some from scientific studies ... a real mish-mash.
Thanks again to Bill Marler.
Photo of Japanese samurai in armor, circa 1860, from Wikipedia.

No comments: