Physicochemical And Processing Properties Of Quinoa Flour

Quinoa is a kind of cereal with comprehensive nutritional value,it is rich in starch,high quality protein,dietary fiber,minerals,vitamins and various active substances.It is known as“whole nutritious food”.Quinoa has health functions such as promoting intestinal health,preventing diabetes,anti-inflammatory and antibacterial,and has become a popular health food in Europe and the United States.At present,enterprises of quinoa processing are also increasing in China,and quinoa products are mainly bread and noodles.However,there are fewer deep processing of quinoa flour in different enterprises,and there are differences in processing standards.In order to analyze the difference between different varieties and the whole flour and pearled flour of quinoa.In this study,the whole flour and pearled flour of three kinds of quinoa of Haili,Geermu,Gannan had been selected as the specimens to analyze the physicochemical and functional properties,antioxidant activities and processing characteristics of quinoa flour.The main conclusions are as follows:（1）The starch and protein content of the pearled flour of the in three cultivars were higher than that of the whole flour.The ash content of the whole flour was higher than that of the pearled flour.There were no significant differences in fat and crude fiber content between the whole flour and the pearled flour.The total contents of 17 kinds of amino acids in the three varieties of quinoa flour was 79.28%～86.07%,and the higher amino acids were glutamic acid（Glu）,proline（Pro）,aspartic acid（Asp）,the first limiting amino acid was methionine+cysteine,which basically meets the ideal amino acid model of FAO/WHO.The SRC of the whole flour of Haili and whole flour of Geermu were higher,the amino acid model was more balanced,and the protein nutritional value was higher.The three highest mineral elements of quinoa flour were potassium,magnesium and calcium.The mineral elements in the whole flour were generally higher than the pearled flour.（2）There were significant differences in the color values of the three cultivars qunioa flour.After pearling,the brightness of the quinoa flour was improved,the color became lighter,and the bulk density became larger.The water-soluble index of quinoa flour decreased first and then increased with the increase of temperature,and the degree of expansion increases with the increase of temperature.There were significant differences in foaming,foam stability,emulsifying properties and emulsion stability.There were no general regular pattern for the functional properties between the whole flour and the pearled flour.The RDS and SDS of the three cultivars of whole flour were lower than that of pearled flour,and RS was higher than the pearled flour.（3）There were significant differences in the gelatinization properties between different quinoa flour.The peak viscosity,breakdown and final viscosity of pearled flour were higher than that of the whole flour in Haili and Geermu;the setback of the whole flour was higher than that of pearled flour in three cultivars.In general,after pearling,the peak viscosity,breakdown and pasting temperature of the quinoa flour increased,and the setback decreased.（4）The total phenolic,flavonoid and saponin contents of whole flour were significantly higher than those of the corresponding pearled flour,and the contents in whole flour of Geermu were the highest,and the the contents in pearled flour of Haili were the lowest.There were significant differences of antioxidant capacities in different cultivars of quinoa flour extracts.The total antioxidant capacity,DPPH·scavenging capacity,·OH scavenging ability,ABTS⁺·scavenging capacity,and O₂^-·scavenging capacity in whole flour were all higher than the pearled flour.There were significant differences of phenolic contents in different varieties of quinoa flour.The highest phenolic were Glycitein, p-Coumaric acid,Quercitrin,The phenolic contents in whole flour were generally higher than the pearled flour.In the simulated gastric digestion and intestinal digestion stage,the total phenolic and flavonoids contents increased;During the gastric digestion,the DPPH·scavenging capacity of quinoa flour increased,and the ABTS⁺·scavenging capacity showed a steady or decreasing trend in intestinal digestion.During the intestinal digestion,the DPPH·scavenging capacity decreased and the ABTS⁺·scavenging capacity increased.（5）With the increase of the amount of quinoa flour,the water absorption rate,formation time and stability time of the mixed dough increased first and then decreased,The breakdown decreased first and then increased,the setback decreased.The breakdown increased significantly from 20%to 30%of quinoa flour proportion.In general,when the amount of quinoa flour was 10%to 20%,the thermomechanical properties of the mixed dough were better.The gelatinization characteristics of quinoa-wheat mixed flour showed that with the increase of the amount of quinoa flour,the peak viscosity and breakdown of the mixed flour showed a downward trend,the trough viscosity and final viscosity first increased and then decreased,and the setback value increased,the mixed flour was difficult to gelatinize.According to the tensile properties,the resistance to extension and extensibility of the mixed dough showed a tendency to decrease.（6）The microstructure of the mixed dough showed that when the proportion of quinoa flour was increased,the continuity of the gluten network structure in the mixed dough was destroyed,and the wheat starch granules will fall off.The dynamic rheological properties and creep-recovery characteristics of the mixed dough showed that the storage modulus G’and the loss modulus G’increased as the proportion of quinoa flour increased.During the creep and recovery stages,the strain of the dough showed a decreasing trend with the increase of the proportion of quinoa flour.