Vegetables – How Long to Blanch Baby Peas for Perfect Texture

To prevent the vegetable from going 'off' in the freezer.

From answers.com:

Blanching is the scalding of vegetables in boiling water or steam. Blanching slows or stops the action of enzymes. Up until harvest time, enzymes cause vegetables to grow and mature. If vegetables are not blanched, or blanching is not long enough, the enzymes continue to be active during frozen storage causing off-colours, off-flavours and toughening. Blanching time is crucial and varies with the vegetable and size of the pieces to be frozen. Under-blanching speeds up the activity of enzymes and is worse than no blanching. Over-blanching causes loss of flavour, colour, vitamins and minerals.

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.