Method for producing hydrolysed keratinaceous material

Abstract

The invention relates to a method for producing digestible keratinaceous material comprising the steps of hydrolysing keratinaceous material in the presence of water in a hydrolyser at elevated temperature and at a pressure between about 2 bar and about 15 bar, and drying the resultant hydrolysed keratinaceous material comprising at least partly insoluble material in a dryer at a temperature/time/pressure combination which limits the drop in pepsin and/or ileal digestibility by less than 10%, and/or such that the pepsin and/or ileal digestibility remains higher than 85%, or such that the pepsin and ileal digestibility remains higher than respectively 75% and 85%. Preferably, the drying of the resultant hydrolysed partly soluble keratinaceous material is performed in a dryer at a temperature such that the keratinaceous material remains at a temperature below 90° C., preferably below 80° C.

What is claimed is: 
     
         1 . Method for producing digestible keratinaceous material, preferably from feather, hair, hoof or nails, comprising the steps of hydrolysing keratinaceous material in the presence of water, in a hydrolyser with heat and at a pressure between about 2 bar and about 15 bar, preferably between about 2 bar and about 10 bar, and drying the resultant hydrolysed keratinaceous material comprising at least partly insoluble material in a dryer at a temperature/time/pressure combination which limits the drop in pepsin and/or ileal digestibility by less than 10%, and/or such that the pepsin and/or ileal digestibility remains higher than 85%, or which limits the drop in pepsin and/or ileal digestibility by less than 10%, wherein the pepsin and ileal digestibility remain higher than respectively 75% and 85%. 
     
     
         2 . Method for producing digestible keratinaceous material, preferably from feather, hair, hoof or nails, comprising the steps of hydrolysing keratinaceous material in the presence of water, in a hydrolyser with heat and at a pressure between about 2 bar and about 15 bar, preferably between about 2 bar and about 10 bar, and drying the resultant hydrolysed keratinaceous material comprising at least partly insoluble material in a dryer at a temperature such that the keratinaceous material remains at a temperature below about 90° C., preferably below about 80° C. 
     
     
         3 . The method according to any one of  claims 1 - 2 , wherein the hydrolysis is performed in a continuous hydrolyser. 
     
     
         4 . The method according to any one of the preceding claims, wherein the keratinaceous material is supplied to the hydrolyser with a moisture content of about 30 to about 80 wt % (relative to the weight of moisture plus keratinaceous material). 
     
     
         5 . The method according to any one of the preceding claims, wherein the dryer is a disc dryer processing at reduced pressure, preferably at a pressure between about 10 and about 500 mbar (abs), preferably between about 100 and about 400 mbar. 
     
     
         6 . The method according to any one of  claims 1 - 4 , wherein the drying is performed in a flow of hot air such as in a fluidized bed dryer, ring-type dryer, rotating flash dryers and the like. 
     
     
         7 . The method according to any one of the preceding claims, wherein the dried digestible keratinaceous material has a moisture content of below about 12 wt %, preferably between about 4 and about 8 wt %. 
     
     
         8 . The method according to any one of  claims 2 - 7  wherein the drying step is performed at a temperature/time/pressure combination which limits the drop in pepsin and/or ileal digestibility by less than about 10%, and/or such that the pepsin and/or ileal digestibility remains higher than about 85%, or which limits the drop in pepsin and/or ileal digestibility by less than 10%, wherein the pepsin and ileal digestibility remain higher than respectively about 75% and about 85%. 
     
     
         9 . The method according to any one of the preceding claims, wherein an amount of more than about 2 tons of keratinaceous material is processed per hour and the drying method is not a non-stirred/non-moving drying method. 
     
     
         10 . The method according to any one of the preceding claims, wherein the drying step is performed at a temperature/time/pressure combination which limits the drop in pepsin and/or ileal digestibility by less than about 7%, preferably less than about 5%, and/or such that the pepsin and/ileal digestibility remains higher than about respectively 80% and 90%, more preferably higher than about respectively 82% and 92%. 
     
     
         11 . Hydrolysed, partly insoluble keratinaceous material, obtainable with the method of any one of  claims 1 - 10 , wherein the material has a moisture content of less than about 12 wt % and an ileal and pepsin digestibility of about respectively 75% and 85% or higher, preferably about respectively 80% and 90% or higher or an in vivo digestibility on cecectomized roosters of about 80% or higher, preferably about 82% or higher. 
     
     
         12 . Hydrolysed, at least partly insoluble, keratinaceous material according to  claim 11 , wherein the material has an amount of lanthionine of about 2.0 wt % or less, preferably about 1.5 wt % or less. 
     
     
         13 . Hydrolysed, partly insoluble keratinaceous material according to any one of  claims 11 - 12 , wherein the soluble part of the hydrolysed keratinacious material comprises polypeptides in an amount of more than about 70 wt % having a molecular weight of lower than about 5000 dalton, and more than 30 wt % smaller than about 1000 dalton. 
     
     
         14 . Use of the hydrolysed, partly insoluble keratinaceous material according to any one of  claims 11 - 13  as feed and/or feed additive, like in petfood or for aquaculture, or in cosmetics. 
     
     
         15 . Process for preparing highly digestible keratinaceous material in a dry form, by hydrolyzing keratinaceous material in the presence of water, in a hydrolyser with heat and at a pressure between about 2 bar and about 15 bar, preferably between about 2 bar and about 10 bar, separating a liquid phase containing solubilized proteins from solid keratinaceous material in a press, and drying separately the liquid phase to obtain a product in powder form, having an ileal and/or pepsin digestibility of more than about 95%. 
     
     
         16 . Process for preparing highly digestible keratinaceous material in a dry form with a reduced fat content, by hydrolyzing keratinaceous material in the presence of water, in a hydrolyser with heat and at a pressure between about 2 bar and about 15 bar, preferably between about 2 bar and about 10 bar, separating a liquid phase from solid keratinaceous material in a press, centrifuging the liquid phase to separate an aqueous phase containing solubilized proteins, a fat phase and residuals solids, reincorporating the defatted aqueous phase and the residuals solids into the keratinaceous material and further drying the material to produce a low fat highly digestible feather meal.