The strawberries fared best when I heated them at 125 degrees for 30 seconds. In two samples from different sources, this treatment gave a total of 1 moldy berry out of 30, where the untreated baskets had 14. I also treated some bruised berries, including one with a moldy tip. After 24 hours none were moldy. The tip mold not only hadn’t spread, it had disappeared.
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.For thicker-skinned blueberries, a Canadian study recommended a 140-degree treatment for 30 seconds. I tested it twice, with samples of around 150 berries each time. That heat took the bloom off. It melted the natural wax that gives the berries their whitish cast, and left them midnight blue. It also cut the number of moldy berries from around 20 per sample to 2.
-Harold McGee, New York Times