Effect of extracts of oak (Quercus petraea) bark, oak leaves, aloe vera (Curacao aloe), coconut shell and wine on the colloidal stability of milk and concentrated milk

Addition of aloe vera extract, non-dialyzable red wine residue or aqueous methanol extracts of oak bark, oak leaves or coconut shell increased the heat stability of skim milk (at 140°C) and concentrated milk (at 120°C) and retarded rennet coagulation, but had no effect on the alcohol stability of milk. The calcium ion concentration in milk was reduced by the addition of these extracts but calcium chelation does not appear to be the exclusive mechanism responsible for promoting micellar stability. The extracts contained a high concentration of polyphenols, which are highly reactive and may be the active agents in the extracts, responsible for the enhanced stability of casein micelles.