Study On Technology And Quality Analysis Of Golden Matcha From Western Hunan

Golden tea is a kind of ancient,unique and rare local tea species resources in western Hunan,has the characteristics of early germination,high yield,strong resistance to adversity and excellent quality.Amino acid content can be as high as7.47%,which is more than twice that of green tea at the same time,tea polyphenols content can be as high as 18.80%,water extract content is more than 40%.The high quality characteristics of high water extract and low phenol-ammonia ratio make it suitable to be used as raw material for matcha production.In this paper,according to the advantages of golden tea,taking taste and color as indicators,the key technology process optimization of golden matcha research and development will be carried out to provide theoretical basis and technical support for the production of high-quality golden matcha.1.Shading treatment is carried out during the growth of golden tea,the results showed that the water content of fresh leaves,the hundred-weight of buds and the density of buds increased correspondentially after shading.With the growth of golden tea,the contents of water extract,chlorophyll,tea polyphenols,free amino acids and phenol-ammonia ratio showed an increasing trend,Compared with the control group,80%shading rate and 40%shading rate can promote the growth of golden tea to high quality direction,and 80%shading rate has more significant effect.The quality of golden tea can be improved by covering it immediately after pruning.In this study,D₁treatment was the best for reducing the bitter taste of golden tea,improving the freshness and freshness,and the color is more emerald.Under these conditions,the contents of chlorophyll and free amino acids increased by 5.84%and 3.05%,respectively,while the contents of water extract,leaf tea polyphenols and phenol-ammonia ratio decreased by 4.60%,10.52%and 13.57%,respectively,during the one-bud and three-leaf stage.2.Through comparative analysis,it was found that the chlorophyll content of golden matcha could be significantly increased by the process of alkali immersion steam degreening.Through Plackett-Burman test,three significant influencing factors were obtained:lye concentration,soaking time of lye and steaming time.On this basis,through steepest climbing test and Box-Behnken test,the optimal technological conditions were obtained as follows:lye concentration 0.15%,soaking time 20 min,steaming time 92 s,solid-liquid ratio 1:20 g/m L,steaming layer thickness 1 cm.Under these conditions,the chlorophyll content of golden matcha was 2.26 mg/g.3.The effects of six different drying methods on the quality and antioxidant activity of golden matcha were compared and analyzed.The results show that the water leaching rate of vacu?m freeze drying and combined drying is faster,but the water leaching index is relatively low.Compared with other heat treatments such as blast and vacu?m drying,the two low temperature drying methods,vacu?m freezing and combined drying,retain chlorophyll,tea polyphenols and free amino acids to a great extent.Vacu?m freeze-blast drying had the highest sensory score,which increased by 6.20%compared with vacu?m drying with lower score.Vacu?m freeze drying showed the strongest scavenging ability to ABTS·and DPPH·,followed by combined drying.Vacu?m freeze drying requires too much time and costs too much.Combined drying greatly shortens the time.Moreover,the combination of freezing and heat drying makes the comprehensive sensory quality of golden matcha better.After comprehensive consideration,vacu?m freezing-blast drying is the best drying method for golden matcha4.The difference of physical and chemical properties of gold matcha powder with different particle size was studied,The results showed that the size of tea powder particles decreased significantly after ultrafine grinding.The cell fragmentation rate of25?m ultrafine powder can reach 99.22%.With the decrease of particle size,the bulk density gradually increases and then decreases slightly,the agglomeration of powder becomes more compact,the fluidity becomes worse,and the water solubility,water holding capacity and dilatancy are significantly enhanced.When the particle size decreased and soaking time prolonged,the concentration of soluble sugar,soluble protein,tea polyphenols and free amino acids increased gradually.The relationship between time concentration(t/Ct)and time(t)showed a linear upward trend,and all of them satisfied the second-order kinetic equation.As the particle size decreases,the saturation concentration(C?)increases,which greatly improves the bioutilization of matcha.Moreover,the dispersion in the four colloidal solutions is better,and the system becomes more stable.