How do baking supply companies blanch their hazelnuts? A friend of ours used to own a chocolate factory, and she would get blanched hazelnuts in big boxes. These were only lightly toasted, if at all, but they were perfectly cleaned - not a single recalcitrant paper skin in the bunch.

I've used both the roast &amp; rub method and the baking-soda method (boil water with a couple tablespoons of baking soda, dump in the nuts and boil for a minute or so, rinse &amp; rub) for blanching hazelnuts. While the latter is vastly preferable, it's hard to get the timing &amp; baking soda quantity exactly right, so either you end up with perfectly clean nuts that are a little cooked (not to mention dyed) looking, or you get nuts that are only mostly clean. So whatever the big suppliers do, it doesn't seem to be either of these methods.

Does anybody have actual experience with blanching hazelnuts on a large scale? What method do they use to get those perfect results?

(Failing that, I'll accept pointers on the baking soda method, i.e. how do I tread that line between dye-bath and ineffective?)
I can't say which things are actually used, but this would seem to confirm my above guess, along with the other one - you can use more chemicals in industry than you would in a home.

Product and process of blanching nuts


  A product and process of removing the skins from nuts involves wetting the nut kernels with an alkaline solution and then with a peroxygen solution. The two substances react underneath the skin to liberate gas between the nut meat and the skin. The gas bubbles blister the skin, causing it to become loosened. Slight mechanical brushing is used to dislodge the blistered skins from the nut meats.


Method and apparatus for blanching nuts


  Two counter rotating rollers are provided having elastomeric exterior coatings into which ribs and grooves are formed for intermeshing to blanch nuts at a pinch point therebetween. Grooves in the lower roller hold nuts as ribs on the upper roller pass across the nuts to break skins on the nuts. The elastomeric exterior coatings have surface hardness values which measure around 30 durometer. The squeeze at the pinch point between the two rollers can be repeatably adjusted for running different sizes of nuts.


Not really helpful for doing it at home. Hard to say which ones are commonly used in industry, of course. You can find a lot more patents along these lines.