Preparation of KDP isolate
HEAT
Double-scoured wool (Wool Services International, Christchurch, New Zealand) was solubilized and degraded for nutritional application using a novel process in which a reaction mixture was formed containing food grade citric acid (90 mM) and ascorbic acid (6 mM) at pH 2.3. Ascorbic acid acts as a stabilizing and reducing agent preventing repolymerization of keratin protein through reformation of keratin disulphide bonds. The reaction mixture was processed by microwave radiation, heat and pressure, using a temperature-controlled 20 kW, 2450 MHz magnetron microwave into a reaction mix with a pH of 4.1. The reaction mix was centrifuged to generate three separate fractions: a liquid fraction (supernatant), emulsified fraction (precipitate), and solid fraction (plug). The supernatant, containing high concentrations of soluble components: citric acid, ascorbate and free amino acids, were discarded. The high molecular-weight precipitate and plug were freeze dried, ground to a fine powder, combined (50:50 ratio), and vacuum packed for storage prior to use. The full KDP production process is described in Ref. [