Effect Of Peeling And Baking On Removal Of Quinoa Saponins And Quality Of Quinoa Milk

Quinoa is rich in protein,a comprehensive variety of amino acids and a balanced ratio.In 2013,Quinoa was recommended by the United Nations as the most suitable for human "whole nutrition food" and listed as one of the top ten healthy nutrition food in the world.However,quinoa contains a high content of saponins(0.9-2.1%),and has a grassy and bitter taste,resulting in a bitter taste in the resulting quinoa milk.Based on this,this study adopts the processing method of peeling and baking to reduce the saponin content of quinoa.On the basis of exploring the mechanism of efficient removal of quinoa saponin by peeling and baking,the low bitterness pure quinoa milk is prepared by means of enzymatic hydrolysis and high pressure homogenization,so as to provide scientific basis for improving and developing the edible quality of quinoa milk drink.At the same time,it provides a new idea for the industrialization development of quinoa.Specific research contents are as follows:Firstly,quinoa was peeled by a rice mill using white,red and black quinoa as raw materials,and the effects of different peeling rates on the total saponin content and saponin fraction of quinoa were investigated.The results showed that the saponin content of untreated white,red and black quinoa was 1.97%,2.02% and 1.48%,respectively,and there was no significant correlation between quinoa saponin content and colour;the total saponin content showed a three-stage decrease with increasing peeling rate,with the rate of decrease of white quinoa k1 being 0.11699,k2 being 0.00831 and k3 being 0.0291;the rate of decrease of red quinoa The decreasing rates k1 were 0.07467,k2 were 0.00843 and k3 were0.02545;the decreasing rates k1 were 0.08549,k2 were 0.01192 and k3 were 0.01601 for black quinoa;when the peeling rate reached 20%,the saponin content of white,red and black quinoa decreased by 53.68%,36.12% and 33.60% respectively.The HPLC results also showed no significant correlation between the content of oleanolic acid,the main component of quinoa saponins,and the colour of quinoa,with oleanolic acid content in white,red and black quinoa being 0.94%,0.57% and 0.77%,respectively.Oleanolic acid was found to be mainly distributed in the outermost layer of white and black quinoa after the peeling treatment,while the distribution of oleanolic acid in red quinoa was relatively more uniform.In addition,the peeling process resulted in the loss of nutrient fractions.The protein content of white quinoa,red quinoa and black quinoa was 12.5%,13.2% and 14.4%,respectively,with protein content gradually increasing as the colour deepened.The rate of protein loss was highest at 11.7-14.8% and 16.8-19.6% for white quinoa and red quinoa,respectively,while the rate of protein loss for black quinoa was relatively stable in the range of 0-20% for peeling.The starch content of white,red and black quinoa was 55.31%,47.83% and 43.11%respectively;both red and black quinoa showed a rapid decrease in starch content at 16%peeling rate,while white quinoa showed no significant loss of starch in the range of 0-20%peeling rate.The ash content of white,red and black quinoa was 0.35%,0.46% and 0.36%,respectively.When the peeling rate reached 20%,the ash content of white and red quinoa decreased by 42.86% and 34.78%,respectively,while the ash content of black quinoa decreased by only 22.22%.Then,Chenopodium melanogaster with 11% peeling rate was used as raw material to bake it.By controlling the baking temperature and baking time,the changes of saponin content and flavor in the baking process were investigated to further explore the way of flavor formation.The results showed that under the same time conditions,the content of saponins decreased with the increase of baking temperature,and it dropped the fastest at 180℃to 215℃.At the same temperature,the saponins content decreased with the increase of baking time,and the decreasing rate was more uniform with the increase of baking temperature.Compared with temperature,the effect of time on the content of saponins is stable.The raw quinoa powder mainly has waxy and grassy flavor.After baking,the nutty flavor and sweet flavor gradually increase,and the burnt flavor also gradually increases with the baking process,while the oil flavor increases first and then decreases.The oil flavor reaches the highest value when the baking temperature is 215℃ and the baking time is20 min.When overbaked,the main component of the aroma has become completely burnt.The change of flavor was closely related to the degree of Maillard reaction.During the baking process,a large number of quinoa proteins were depolymerized,the extraction rate of SDS was significantly reduced,and the Maillard reaction products gradually increased.In addition,polyphenols and flavonoids were also involved in the Maillard reaction.With the progress of the Maillard reaction,the contents of polyphenols and flavonoids decreased first and then increased,and the antioxidant capacity of quinoa powder also decreased first and then increased.Finally,the raw materials of untreated quinoa,peeled and roasted quinoa were used as raw materials,and the enzymatic hydrolysis and high pressure homogenized milk process were used to compare the flavor quality of pure quinoa milk under different peeling conditions and peeling and roasted conditions.The results showed that with the peeling rate increasing,the emulsion stability gradually improved,the average particle size gradually decreased,the solid content of reducing sugar and DE value gradually increased,the bitter,bitter and astringent aftertaste gradually decreased,and the sensory score gradually increased.For peeling combined baking,with the increase of baking time,the stability increases first and then decreases;The average particle size was different but not significant,mainly showing a slow decrease trend.The reducing sugar content and DE value increased gradually,while the solid content increased first and then decreased.Bitter aftertaste,bitter aftertaste and astringent aftertaste all decreased first and then increased;Sensory scores were first increased and then decreased.After peeling and baking,the content of saponins in quinoa decreased,and the quality of quinoa dairy was improved.Quinoa milk made of quinoa after the peeling rate of 11% and baking at 180℃ for 20 min was uniform and stable,with both baking fragrance and unique flavor of quinoa,low bitterness and astringency values,and high sensory evaluation scores.