Skim through

What it does: moisturizer, humectant 

Also called: sorbitolum, glucitol

The science

Sorbitol is naturally found in various fruits and vegetables including apple, plum, cherries, raspberries, peaches, prunes, blackberries and apricots. It helps the skin and hair to hold onto water when used in cosmetic products. It also helps to thicken up products and give them a bit more slip. Sorbitol also acts as a mild surfactant: it is known to bind with dirt and grime in the scalp, making it water-soluble so that it gets washed away easily.

Benefits for your hair

Prevents dryness

It absorbs moisture from the surrounding and helps to retain the moisture in hair strands, thereby keeping the hair it hydrated and nourished.

Cleanses scalp

Sorbitol makes dirt and grime water-soluble so that it gets washed away easily. 

TLDR 

Sorbitol helps to cleanse and moisturize hair, thicken products, and prevent dryness.