I saw an article the other day on someone working on a program to recycle almond waste products from the huge almond industry in Ca. One of his programs involves extracting sugars from the hulls.
The only sugar extraction methods I am aware of involve soaking ground up material in warm or hot water. I would think that it would not be cost effective trying to extract sugars from materials that had low sugar content unless the entire process of sugar extraction and conversion to alcohol could all be done with a minimum of handling and using only solar energy.
Bacteria and other microorganisms can quickly degrade the sugar content in plant material as well so that would have to be guarded against I assume by quick drying or keeping immersed.
I guess my question would be are there currently any industries actively involved in extracting sugars from waste products with low sugar contents generated in food processing and farming industries.
Appreciate this isn’t anything like a complete answer to your general question, but I assume by ‘almond hulls’ the article might have meant the pericarp (the fleshy bit on the outside of the shell) - which is sort of like a very thin, fibrous apricot or peach - so may not actually be all that low in sugar content.
I work with a few companies doing some similar work. Typically they are taking the lignocellulose from waste woody products and treating them with chemical processes, enzymes or microbes to break down the cellulose into the constituent sugars. Sometimes they are looking to convert the waste to other chemicals for use in industry. Again, they can use genetically engineered microbes, enzymes or chemistry to do this.
Its a pretty common theme:
Take waste woody products
treat them to break down into constituents
make new chemicals
magic
profit!
I’ll note that Voltaire is correct…rarely, if ever is the goal actual sugar to be used as sweetener…we already have a lot of that and don’t need anymore.