I read that 100kg of potato will process 35kg of potato crisp. I have tried it and did not achieve that result. I used 100kg of potato to process only 15kg of potato crisp.Please does blanching have effects on the shrinkage or what should i do to achieve that result? I am new in a small scale manufacturing of potato crisp
35% by weight is extremely optimistic considering that an average potato is 75% water (according to a number of internet sources). If you don't peel the potatoes and they're 100% usable (no bruising, no black spots) really 25% is the best you can hope for in potato weight. Obviously, you want as little of the final weight as possible to be oil, both because oil is more expensive than the potatoes and also for the sake of the quality of the final product.
I don't know how it is done industrially, but homemade crisps (chips) are generally not blanched, just soaked in cold water to remove excess starch, then allowed to dry before frying. You might find this of interest: How to make crispy/dry potato chips/crisps?.