Yesterday morning, my wife brought home some raspberries from the Glens Falls Farmers market. Given that they were undoubtedly picked the day before and it had been raining all night, it was no surprise to discover mold already encroaching on a number of the berries. It was disappointing though, but then I recalled an article I had recently read in the new York Times.
In this article, Harold McGee describes a way to inhibit mold growth on normally mold friendly berries, a problem that anyone who has picked or purchased fresh berries has no doubt encountered. McGee's technique:
"I bought pints of various berries, divided each batch into two samples,
and heated one by immersing and swishing its plastic basket in a pot of
hot water. I emptied the heated sample onto towels to cool down and
dry. Then I repacked it, and encouraged both baskets to spoil by
wrapping them airtight and letting them sweat on the kitchen counter.
After 24 hours I counted the moldy berries in each basket…I tried the same treatment, 125 degrees for 30 seconds, on raspberries
and blackberries, and got the same good results. There were many fewer
moldy berries in the heated samples."
As the quote above shows, Harold used water heated to a specific temperature, presumably with an immersion circulator. Not having an immersion circulator, I had something else I could try. – a CVap oven! Already set to cook a sirloin roast at 125ºF, I laid the raspberries out on a sheet pan and placed the pan in the oven for 30 seconds. I was skeptical when I removed the pan as I couldn't really discern any temperature change for either the berries or the pan, but I placed the berries in a single layer on a paper towel and covered the container with Press'n'Seal wrap before putting them back in the refrigerator.
I checked the berries this morning and lo and behold, there was not a trace of mold, even though a number of them had mold already present when placed back in the fridge! Unfortunately, I did not take any "before" photos, but here is what they looked like this morning:
This is a technique that I will clearly use in the future, especially for raspberries and blackberries. The CVap ws a perfect tool for this and a great substitute for an immersion circulator, but there is the rub. The technique couldn't be simpler for anyone with either of those tools, but I don't know of too many homes that have either of these. I imagine that with careful attention, one could simply heat water to temperature and quickly add the berries before the temperature rises too much further, but I imagine that approach could have a steep learning curve. Anyone with other approaches to this problem?