Antioxidant Activities, Physical&Chemical Properties And Composition Analysis Of Almond Protein Hydrolysate

As seeds of apricot, the sweet almonds have very high nutritional value. Theapricot is widely planted in Northeast of China, North China and Northwest ofChina. Although the harvest resources of the almond are rich, researching on theprotein of them is still in a primary stage. Study of almond protein will improvetheir availability and provide the basis theory for the development of variousalmond products.This dissertation studied the almond protein by using alkaline protease,neutral protease, papain and trypsin to decompose the protein. The results showedthat alkaline protease was better under the conditions of concentration of2%and10000u/g of E/S and the degree of hydrolysis could reach to19.3%. For trypsin,the most optimized concentration was1%and the optimazed E/S was10000u/g.The experiment proved that under such conditons, the degree of hydrolysis isbetween14%～16%and showed the best antioxidant activity. SDS-PAGE showedthat part of the almond protein was decomposed to shorter peptide whichmolecular weight was less than10KDa.In order to further researching the component of almond protein hydrolysate,the chromatography of Sephadex G-100and Sephadex G-25were adopted toseparate the almond protein hydrolysate which was modifed by alkali protease.Five constituents such as APH-1,APH-2,APH-21,APH-22,APH-23wereobtained.And the method of HPLC was used to analyze almond proteinhydrolysate and related components, which showed that low molecular weightpeptide consisted over90%in the constituents of APH-2.To expand the potential application area of the protein hydrolysate, thephysical property between almond protein hydrolysate and protein isolate wasstudied comparely, which proved that the protein hydrolysate was better than protein isolate in dissolubility, hydroscopicity and oil absorption. In0minutes, theprotein isolate was better than protein hydrolysate in foamability, while was worsethan protein hydrolysate in foam stability. When the concentration of NaClapproached to0.2mol/L, the emulsification ability of protein hydrolysate andprotein isolate were the best that attained to37.04m/g and47.44m/g separately.When the concentration of sugar appoached to0.4g/L, the emulsification ability ofprotein hydrolysate and protein isolate were the best and reached to17.58m/g and18.34m/g. The emulsion stability of protein isolate was better than proteinhydrolysate.In practical production, since spray drying technology had influces on thedrying effect and antioxidant activity of almond protein hydrolysate, a responsesurface experiment was designed to study the information. It concluded that thebest comprehensive effect could be reached when feed speed was270～320mL/h,dehydration ratio was between0.5～0.6and the inlet temperature was about200℃.The study will provide theoretical basis for the practical production of almondprotein hydrolysate.