EFFECT OF VARIOUS ALKALINITY-INDUCING AGENTS ON CHEMICAL AND PHYSICAL-PROPERTIES OF PROTEIN PRODUCTS ISOLATED FROM CHROMIUM-CONTAINING LEATHER WASTE

We have demonstrated that gelable and hydrolyzed protein products can be obtained from chromium-containing leather waste. Depending on the c hoice of alkalinity-inducing agent added, products with varying chemic al and physical properties can be isolated. Also, we have shown that t he ash content of these isolated protein products will be dependent no t only on the choice of alkalinity-inducing agent, but also on the che mical make-up of the original substrate. One of the components of the ash is chromium and its content is also influenced by the choice of al kalinity-inducing agent. We found that adding magnesium oxide in combi nation with sodium or potassium hydroxide increases the chromium conte nt in the gelable protein products over that obtained with magnesium o xide alone. Substituting carbonate salts for sodium or potassium hydro xide lowers the chromium content of the gelable protein products. Choi ce of alkalinity-inducing agent has little effect on the chromium cont ent of the hydrolyzed protein products. With respect to Bloom value an d viscosity of the gelable protein products, magnesium oxide alone giv es the superior product, whereas the introduction of carbonates and hy droxides has a detrimental effect. Hydroxide is more detrimental than carbonate. In this study we have shown that a variety of products can be isolated with varying properties and these properties will be depen dent on the desired end use of the protein product.