Studies On Walnut Oil And Protein From Cold Pressing Walnut

In this study, some advanced technologies were used to systematically research the preparation of walnut oil with cold pressing of walnut, the extraction of walnut oil for aqueous enzymatic extraction appling to deal with cold pressed cake, the preparation and the hydrolysis of walnut protein, and the determination of physicochemical properties and functional properties for walnut polypeptide. The theoretical basis was provided to develop walnut resources synthetically. The results are as follows:1. Technical study on cold pressing of walnut for getting walnut oilIn this study, walnut was used as the material. Virgin walnut oil was obtained by decorticating, peeling, microwave heating , coldpressing. Refine virgin walnut oil can be obtained through secondary filter. Then leaching walnut cake, crude walnut oil was obtained and refined. The conditions of degumming were: with 3%～5%boiling water, and precipitation 3h. The conditions of deacidification were: at the temperature of 40℃,with 10.45% sodium alkali solute, stirring speed 50r/min. Drying and decoloration were: 3%～5% decolorize chalk, the pressure of 10KPa, at the temperature of 100℃and time 30min. Intermittent deodorization was at the temperature of 190℃, pressure of 95.76 KPa, time 3h～5h.2. The study of aqueous enzymatic method from the cold pressed walnut cake for getting walnut oilThe technology of extracting walnut oil by aqueous enzymatic method and centrifugally demulsification was studied. The influences of temperature, time, pH and enzyme dosage on the walnut oil extracting ratio were investigated. Furthermore, the effects of centrifugation speed and time on the extraction ratio were studied. The optimum technology conditions were as follows: enzyme dosage 0.4%, temperature 40℃and pH 7.0. Under these conditions the walnut oil extracting ratio was 56.2% with eentrifugation speed 10000 r/min and time 30 min.3. Study on walnut protein isolateThe technology of extraction and purification of walnut protein was studied, obtaining optimum technology conditions:alkaline extraction pH 9.0, temperature 45℃,flour and water ratio is 1:12 extract 30min, acidic precipitation pH 4.8, temperature 45℃extract 30min. The radio of protein gained is 72.5%, the purity of the walnut protein reached over 91% after purification.4. The preparation of walnut peptide by enzyme hydrolyzing walnut proteinUse degree of hydrolysis as the index to investigate the enzymolysis technology of neutrase to walnut protein. The optimum technological conditions were as follow: enzymatic hydrolysis temperature 47.3℃, enzymatic hydrolysis time 3.8h, hydrolysis temperature pH 7.1, substrate concentration 10% and enzyme dosage 5200(u/g substrate), the hydrolysis rate could reach 12.4%, the hydrolysate tastes a little bitter.5. Study on the physical and chemical properties of walnut proteinWe studied the functional properties of walnut protein and walnut peptide. The result indicated that walnut peptide had higher solubility and is almost free from pH variation. Meanwhile, compared with walnut protein, walnut peptide was much superior in hygroscopicity, oil absorption, emulsification, emulsion stability and foamability. However, foam stability of walnut peptide was lower.