Study On The Processing Technology And Functional Components Of Quinoa Tea

Quinoa is a nutrient-rich pseudo-grain.Its protein content is higher than ordinary grains,close to the value of milk protein.It has the amino acid composition and proportion suitable for human use.The oil is rich in polyunsaturated fatty acids such as omega-3 and omega-6,which are essential for the human body.Quinoa also contains a lot of dietary fiber and other beneficial trace elements such as polyphenols,vitamins and minerals.The nutritional value of quinoa is widely recognized,but its product is single,which greatly limits the circulation and consumption of quinoa.In this research,using quinoa as raw material,and quinoa tea is made by vacuum impregnation,drying and three-stage baking.The content of phenolic compounds and fatty acids were determined by high performance liquid chromatography and gas chromatography respectively,and the aroma components of quinoa tea were analyzed by GC-MS.The results provided a theoretical basis for the industrial production of quinoa tea.The main research contents and results are as follows:(1)The processing technology of quinoa tea was optimized by Plackett-Burman design and response surface methodology,and baking processing was optimized by orthogonal test.Results showed that the optimal processing conditions were vacuum dipping temperature45℃,dipping time 90 min,drying temperature 60℃,drying time 30 min,first stage baking temperature 90℃,baking time 20 min;second stage baking temperature 150℃,baking time15 min,third stage baking temperature 200℃,baking time 7 min.(2)The composition of free and bound phenolic compounds of quinoa and quinoa tea was detected by HPLC.The results showed that the phenolic compounds in quinoa were mostly bound phenolic compounds,and the phenolic compounds were mainly phenolic acids.Gallic acid and ferulic acid accounted for 46% of the content of free phenolic compounds in quinoa.Flavonoids mainly include quercetin and kaempferol.The free phenolic compounds and flavonoid compounds in quinoa tea increased by 54% and 16%,respectively.The free total phenolic index and combined total phenolic index were 2.3 times and 1.2 times of quinoa.The antioxidant capacity of quinoa tea has increased significantly.In the free extract,the DPPH free radical scavenging capacity was increased by 1.38 times,the ABTS radical scavenging ability was increased by 4.61 times,and the FRAP iron ion reducing ability was increased by 2.63 times.In the acid hydrolysis combined extract,the antioxidant capacity of quinoa tea increased slightly.In the alkaline hydrolysis combined extract,the antioxidant capacity of quinoa tea decreased significantly.The content of fatty acid in the processing of quinoa tea were detected by GC.The results showed that the content of unsaturated fatty acids in quinoa accounted for 80.79% of total fatty acids,and the content of polyunsaturated fatty acids accounted for 56.17% of total fatty acids.The PUFA/SFA value and omega-6/ω-3 value of quinoa tea decreased,the polyunsaturated fatty acid content decreased by 33.14%,and the retention rates ofα-linolenic acid,γ-linolenic acid and linoleic acid were 85.18%,75.69% and 65.29%,respectively.During the processing of quinoa tea,the content of MUFA increased first and then decreased,and the content of SFA increased by 23.21%.(3)The volatile aroma components in the processing of quinoa tea were detected by GC-MS.The results showed that the volatile aroma species increased during the processing of quinoa tea.Only 26 aroma components were detected in quinoa,while 61 aroma components were detected in quinoa tea,mainly aldehydes,alcohols,esters,ketones,pyrazines and heterocyclics(furans,pyrroles,Phenols,pyridines,oxazole).Aldehydes(6.700 mg/L)and pyrazines(0.716 mg/L)are the main volatile aroma components of quinoa tea,accounting for 85.67% of the total aroma.Alcohols(4.03%)and ketones(3.13%),the ester content(1.21%)was the least.The fusion of tea and baking aroma constitutes the characteristic aroma of quinoa tea.Its aroma skeleton is mainly isovaleraldehyde(29.40%),2-methylbutanal(25.26%),isobutyraldehyde(9.30%),n-hexanal(5.66%),cyclohexane(4.43%),2,5-dimethylpyrazine(2.55%),2-ethyl-5-methylpyrazine(1.34%),dimethyl sulfide(1.72%).