The Comprehensive Utilization Of Protein And Diatery Fiber In Walnut Dregs

Walnut dregs are the by-product of walnut oil production and are favorable raw materials for food processing because of abundant nutrient compounds such as protein and dietary fiber. It causes resource waste to use walnut cake as animal feed or even discard. In order to comprehensive use and improve the added value of the walnut dregs, this study developed nutritional walnut paste breakfast with optimum composition, walnut protein extraction with alkali-solution and acid-isolation method, protein fractional hydrolysis with two enzyme, walnut peptide production. The products described above all used walnut dregs as raw materials and the residuums were made into walnut dietary fiber biscuit. The detail of the study was elaborated as follows:1.The optimum formula of nutritional walnut paste breakfast: Walnut dregs11.9g, skim milk powder 8.4g, extruded rice powder 4.6g, granulated sugar 4.0, peanut powder 2.0g. Fuzzy sensory evaluation score of the paste breakfast under this formula reached 96.93.2. Using the extraction rate as index and through the single factor experiment and response surface experiments, the optimal walnut protein extraction conditions w e r e u l t r a s o n i c t i m e 1 h, 5 5 ° C, p H 8. 5, a n d t h e r a t i o o f s o l i d t o l i q u i d w a s 1:19. The dissolution rate of protein can be up to 65.58%. The optimal pH value was 4.5 and the yeild of protein could reach 80%.3.With the hydrolysis degree and nitrogen yield as index, through the single factor test and response surface experiment, the condition of fractional hydrolysis with trypsin and neutral protease was studied and determined as follows: First, hydrolysis for 4h at 55°C, pH8.0 by 2000 u/g Pr trypsin; Second, hydrolysis for 2.7h at 50°C, pH7 by3100 u/g Pr neutral protease.Then the hydrolysis rate could reach 36.35%. The recovery ratioe of nitrogen could reach 92.53%. Compared with single enzyme hydrolysis by trypsin or neutral protease, the hydrolysis rate increased by 17.79% or 20.11%. The nitrogen yield increased by 27.29% or 29.20%.4.The optimum formula of walnut dietary fiber biscuit: The walnut slag particle size was 80 mesh; Porous agent(the ratio of sodium bicarbonate and ammonium hydrogen carbonate) was 1:0.2; Walnut slag addition was 15%, bulking agent addition was 1%, xylitol was 15% and oil content was 10%. The actual sensory quality score was 89.23.