November 18, 2013

Keep flies away from your dried mushrooms

Most mushrooms lend themselves wonderfully to dehydration: their savour is thus concentrated without losing their nutritive value.  Away from humidity, they will keep for a long time, even for years.  When the time comes to consume them, after having immerged them for a few minutes in lukewarm water, they lend themselves to the same recipes as freshly picked mushrooms. 

Dried mushrooms also represent a sought after feed for numerous animals and notably insects that we do not wish to find in our plates. Many species find it an ideal environment to lay their eggs. Generally, these insects stop feeding and reproducing at temperatures lower than 18°C. They then enter into dormancy and can remain in that state for more then a year and by doing so mislead us into lowering our guards. 

We have been marketing large quantities of dried mushrooms and over the years, we were faced with a few unwelcomed intruders. 

Our first experience goes back to the beginning of our business. It implied the mediterranean flour moth (Ephestia kuehniella). If this moth develops in your pantry, your home could well become an insectarium. As its name suggests, it is generally attracted by flour and dried cereal but it will also attacks mushrooms. It reaches an average size of 20mm. 

Two years ago, we ordered some dried maïtake (Grifola frondosa / hen of the woods) from a supplier in Oregon. This gastronomic species which is picked on the oaks in our forests, is commercially cultivated everywhere in the world. After a few weeks, some minute beetles showed up in those bags: the red flour beetle (Tribolium castaneum), a 4mm beetle that appreciates the starch of grains and, as we informed our seemingly unaware supplier, does not disdain maïtake. This insect, common in warmer regions, reproduces at temperatures between 22°C and 40°C and can live up to three years. 

Lately, we had another surprise: the warehouse beetle (Trogoderma variabile). This 4mm long beetle can pierce through a thick plastic bag. Omnivorous, it will not live more than 5 weeks following a larval stage of a month. Plastic containers left in a cool place and in which we store our mushrooms in polypropylene sealed bags, are not totally hermetical. Taken up by our moving the boutique, we probably lowered our guards regarding this common nuisance. 

These examples are only a few of the unwanted guests but proliferation can be avoided. One must know that they die rapidly when exposed to very high temperatures. This is why we suggest that you raise the temperature to 60oC for a few minutes after having dried your mushrooms at the moderate temperature of 42oC as usually recommanded. 

These insects will also die if exposed to frost but the duration of the exposure is decisive: the lower the temperature, the faster they die. They will survive up to 12 weeks at -5oC but hardly a week at -20oC. 

Dispose immediately of infested products after having removed all traces with white vinegar. 

To block the reproduction of the flour moth, traps are sold that efficiently retain the males attracted by a simulated odor of sex pheromone. 

 In view of their flavour, of their vitamin content, minerals, amino-acid, dried mushrooms represent an exceptional food: it is worth all the care that we put into preserving their quality. The tricks discussed here can also be helpful to protect your cereals.

 

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