Study On Nutritional Components,Color And Edible Quality Of Quinoa

To study the influence of nutritional components and grain color of quinoa(Chenopodium quinoa Willd.)on eating quality,experimental materials were obtained from Xishungou Quinoa Test Base in Zhangbei County,Zhangjiakou,Hebei Province.The effects of quinoa nutrient content,protein disulfide bonds,moisture status and microstructure on eating quality such as pasting,texture and sensory evaluation were investigated,and the volatile components of quinoa of different colors before and after cooking were analyzed.The research results have theoretical or practical significance for the effective utilization of quinoa,food processing and the breeding of high-quality edible varieties.The pasting properties of quinoa flour and texture properties of cooked quinoa were determined by rapid viscosity analyzer and texture analyzer,and the correlations between nutrient content and the pasting properties of quinoa flour,texture properties and sensory quality of cooked quinoa were analyzed.The results showed that there were negative correlations between starch content and hardness,gumminess,chewiness,resilience and cohesiveness of cooked quinoa.Amylose content was positively correlated with hardness,gumminess,chewiness,resilience and cohesiveness.but negatively correlated with sensory evaluation.Protein content showed a significant negative correlation with peak viscosity and trough viscosity,and albumin content showed a significant negative correlation with peak viscosity.Protein content was significantly correlated with hardness,gumminess,chewiness and cohesiveness of cooked quinoa,globulin content was significantly correlated with springiness,and gluten content was significantly correlated with gumminess,springiness and cohesiveness.Protein content was negatively correlated with sensory evaluation of cooked quinoa.A negative relation was found between fat content and resilience.It can be inferred that starch is an important component affecting the pasting properties of quinoa flour,protein is an important component affecting the texture properties and sensory quality of cooked quinoa.Starch and protein content are important indicators for the selection of new varieties of quinoa for food processing and edible quality.The effects of dithiothreitol(DTT)treatment on swelling power,solubility,amylose leaching,pasting and texture properties and microscopic morphology were determined using 8 quinoa as experimental materials.The results showed that after DTT treatment reducing protein disulfide bonds,the swelling power and solubility of quinoa flour were significantly increased,but amylose leaching was reduced.The peak viscosity,trough viscosity,breakdown and final viscosity of treated quinoa flour were significantly decreased,while the setback was significantly increased.The DTT treatment led to an increasing trend in the springiness,chewiness and adhesiveness of cooked quinoa,while the hardness,resilience and cohesiveness were decreased.In addition,the surface of treated quinoa flour was smooth and flat,without intact starch granules.The pores on the surface of cooked quinoa became larger and thinner,and the protein network structure was obviously changed.It can be inferred that the protein network structure connected by disulfide bonds plays an important role in edible quality of quinoa food such as swelling,pasting and texture properties during the production process.The low-field nuclear magnetic resonance,x-ray diffractometer,scanning electron microscope and laser confocal microscope were used to analyze the moisture status,crystalline structure,microscopic morphology and distribution of starch and protein of8 quinoa germplasm after cooking.The results showed that the transverse relaxation time was significantly different but there was no significant difference in the water distribution state among different quinoa after cooking.The gelatinized starch in cooked quinoa interacted with lipids to form a stable V-shaped crystalline structure,which affected the texture properties.There was a gap between the starch granules of cooked quinoa,which was filled with steamed and exuded substances and fully gelatinized starch.The endosperm cell wall of cooked quinoa was in a "honeycomb" shape.Starch and protein are aggregated and combined,and the distribution of starch and protein combination in cooked grains differs from quinoa germplasm.The volatile components of 11 quinoa with different colors were characterized by headspace-gas chromatography-ion mobility spectrometry(HS-GC-IMS).The result showed that a total of 120 peaks were detected,with 61 compounds identified.White quinoa liberated a high concentration of volatiles with grass(n-hexanol)aromas before and after cooking.Flaxen samples uniquely exhibited several sweet and caramel volatiles(decanal,5-methyl-furfural,and 2-furfural)after cooking.Cooked black quinoa exerted more fruity substances(methyl hexanoate and phenylacetaldehyde).HS-GC-IMS combined with orthogonal partial least square discriminant analysis clearly distinguished the volatile compounds of quinoa before and after cooking and differentiated the seeds into different colors.