Optimization Of Extraction Technology And Quality Of Pumpkin Seeds By Microwave Oven Baking And Heating

The optimal process conditions of the new aqueous method for recovering oil and de-oiled meal from Pumpkin seed kernels were: baking the kernels at 110 °C for 1 min,grinding them to pass through a sieve with 150 ?m pore size,adding 1.60 ml brine to 10 g ground kernels,stirring for 30 min at 30 °C,centrifuging at 4000 r/min for 30 min and cold-pressing the residue from centrifugation.This method recovered > 94% oils.Its oil recovery rate was comparable to that of solvent extraction and higher than that of enzyme-assisted aqueous method or hot pressing.It recovered edible oil with higher quality and level of coenzyme Q10,tocopherols,carotenoids,total phytosterols and squalene as compared with solvent extraction or hot pressing and requirements of China national standard.It is superior to enzyme-assisted aqueous method or hot pressing for recovering de-oiled meal suitable for making texturized protein.New aqueous method is a green technology which has been developed recently and have application prospect.Experimental results indicated that in order to obtain high oil recovery(90.54% without heating treatment)and higher product quality,heating treatment process was needed when the new aqueous method was applied.In terms of oil recovery(94.13%)and product quality,oven treatment has practical application value.Compared with baking treatment in oven,microwave treatment can obtain slightly higher oil recovery(95.55%),better product quality(including lower peroxide value of oil,higher flavone content,higher polyphenol content,higher DPPH clearance rate and equivalent acid value);the solubility of protein in de-oiled powder is higher,the power consumption is only 6.4%,and the treatment time is only 10%.Pumpkin seed meal protein was extracted from pumpkin seed meal under the optimum conditions of microwave improved new Aqueous method.At the same time,proteins of Solvent pumpkin seed meal and cold pressed pumpkin seed meal were prepared.The functional characteristics of the three kinds of meal protein were determined and compared.The isoelectric point of the new water agent method pumpkin seed meal protein was p H = 4.5,and that of the other two kinds of pumpkin seed meal protein was p H = 5.5.When p H = 5 near the isoelectric point,the functional properties of the new Aqueous protein are the lowest.When p H = 5,the solubility of the new water agent was 24.07%,which was higher than 8.41% and 17.12% of the extraction and cold pressed meal protein;the water holding capacity was 0.9g/g,which was lower than 0.97g/g and 1.14g/g of the extraction and cold pressed meal protein;the emulsifying capacity was 63.73%,which was higher than 41.46% and 38.96% of the extraction and cold pressed meal protein;the emulsifying stability was 75.8%,which was lower than 87.03% of the extraction and cold pressed meal protein 56.37%,foaming capacity was 8.57%,lower than that of extraction and cold pressing protein 9.9% and 12.47%;foam stability was 41.47%,lower than that of extracted protein,54.17%,higher than that of cold pressed meal protein;at room temperature,oil holding capacity was 2.44g/g,lower than that of extraction and cold pressing protein 2.51g/g and 2.46g/g.The solubility,emulsification,emulsifying stability and foam stability of the new aqueous meal protein are generally better than those of the other two methods at p H=5.