Studies On Manuracturing Process And Suspensible Stability Of Pumpkin Juice Blend

In this dissertation, Effect of thermostatic treatment on the pectin extraction frompumpkin and suspensible stability of pumpkin juice was investigated, and processparameters of amylase treatment to starch in lotus roots was optimized. The formulaoptimization to the mixed juice made of pumpkin juice, lotus roots juice, apple juice andpineapple juice in different proposition was carried out. The suspensible stability of thepumpkin juice blend was investigated. The research results and corresponding findingswere summarized as follows:Effect of thermostatic treatment on pectin yield from pumpkin and suspensiblestability of the juice was investigated. The results showed that the rate of pectin extractionfrom pumpkin increased at the beginning and reduced at final stage with prolonging of timeand elevation of temperature, and its juice suspensible stability had the similar trend.Significant interaction effect (p＜0.05) of time and pH on pumpkin juice suspensiblestability was observed using Response Surface Methodology analysis. The optimumprocess parameters for pumpkin juice suspensible stability were temperature 43.8℃, pH6.44 and time 70.9 min.The effect of temperature, time and amylase dose on the rate of juice extraction fromlotus roots pulp, and the change of reducing sugar in lotus root juice were observed. Theoptimum process parameters were determined employing a second-order central compositerotatable design in combination with response surface methodology. The results showedthat the reducing sugars in lotus roots pulp increased with time, and two hours later, thechange of reducing sugars content was not significant. The reducing sugars increased at thebeginning and reduced at final stage with elevation of temperature. The reducing sugars inlotus roots pulp increased with increase of amylase dose. But the change was not significantwhen amylase concentration was more than 0.15%. The optimum combination was to keeptemperature at 66.7℃for 116.4 min when amylase dose was 0.15%. In this condition, amaximum hydrolytic degree of 76.9% of the starch was obtained.The preparation process of the mixed juice of pumpkin juice blended with lotus rootsjuice, apple juice and pineapple juice was studied. The Mixture-D-optimal design was usedwith sensory evaluation value as a response value. Statistical analysis showed that the optimum combination was 40% pumpkin juice, 30% lotus roots juice, 17% apple juice, 13% pinneapple juice. Addition of 0.02% xuanthan gum and 0.06% pectin in the pumpkinjuice blend, and then homogenizing twice under 20 MPa at 40℃, the pumpkin juice blendsuspensible stability was well, and no separation and sediment was observed within30-day storage.