The Study Of White Tea Quality Control And Production Line Under Multi-wavelength LED Treatment

As one of the classic export tea type of Fujian,white tea contains abundant active ingredient and has many health function including clear heat,decrease internal heat,prompting fashionistas and so on.Besides,the silver appearance,the simple and elegant tea rhyme can make people shed more fidgety,feel the goodness of life.White tea going though long withering time and needed a solar photochemical effect to promote its characteristics quality formation during the withering processes.But the weather in spring usually cold and wet which impacting the quality and hinder its large-scale production.According to the quality control principle during white tea processing including "warm,wet,wind,light" and other factors.This thesis carried out the study of white tea quality control during withering and standing process under the treatment of combination of multi-wavelength LED.Than established multiple wavelength LED withering production line in white tea and its process test research.The main research contents and it's results as follows:1.The study of quality control by four combination LED(1Y1B4W,1Y2B3W,1Y3B2W,1Y4B1W)in white tea showed that light treatments can significantly improve the content of water extract,flavonoids,theanine(69.60-166.00?g/ml),essential amino acids(13.57-33.98?g/ml)and total amino acids(119.59-298.70?g/ml),promate catechins degradation(total catechins decreased by 2.95-24.08mg/g)contrasting with dark treatment.Heat map analysis showed that the Z1(1Y1B4W)treatment is the most beneficial to the catechins composition oxidative decomposition,the amino acid composition of Z2(1Y2B3W)and Z3(1Y3B2W)treatments are more similar than others,especially the Z2 treatment,for it's essential amino acids(187.73?g/ml)and total amino acids(1122.67?g/ml)contents are highest,also can reduce phenol ammonia,which beneficial to the formation of white tea sweet taste and reduce bitterness.2.The study of quality control by four intensity and time combination LED(20?mol·m-2.s-1,24h?40?mol·m-2·s-1,12h?80?mol·m-2·s-1,6h?120?mol·m-2·s-1,4h)in white tea withering process showed that moisture loss rate is the fastest under the same accumulated light(480?mol·h·m-2·s-1)condition,low light intensity and long illuminate time's and it can also promote catechins degradation,but make against with water extract and tea phenol ammonia reduction ratio.In addition,long illumination time will reduce the content of amino acids.Heat map analysis showed that the amino acid composition of Q1(20?mol·m-2·s-1,24h)and dark treatments are more similar than others and high light intensity with short illuminate time can significantly improve the content of theanine and total amino acids but have higher tea phenol ammonia,medium light intensity and medium illuminate time Q2(40?mol·m-2·s-1,12h)treatment promoting sweet amino acids accumulation,its essential amino acids and total amino acids keep higher level,also the quality of primary white tea is best.3.The study of quality control by different wavelength LED(LED combination lights(1Y2B3W,410-730nm),near-infrared(735nm),ultraviolet light(395nm)and sun light in white tea stacking process showed that the order of water loss rate of different wavelength treatments from large to small is sun light>LED combination light>LED ultraviolet light>LED near-infrared>dark.Besides tea polyphenols continue oxidize degradation,amino acids and flavonoids content continue to accumulate after light treatment during stacking process.Among them tea phenol ammonia is lower under LED near-infrared treatment and LED ultraviolet light' tea phenol ammonia ratio,the flavonoids content is higher.The sensory score of primary tea as the following order:LED combination light>sun light>LED near-infrared>LED ultraviolet light>dark.The liquor color,aroma and taste quality of LED combination light treatment are superior to others,LED near-infrared treatment is beneficial to taste quality,sun light treatment is good for liquor color and aroma quality.In addition,the stacking time should keep in 18h to making the best primary tea quality.4.Setting up multi-wavelength LED white tea withering production line equipped with 900 of yellow blue and white LED lights(1Y2B3W),light intensity is 25-40?mol·m-2·s-1,8 can dehumidification machines and 16 sets of large air circulation fan.The total power of these machines is 108KW that can accommodate 1500-2000kg of fresh leaves,the production efficiency is 15-22kg/h.This system can sense the withering environment temperature,wet(20-35?,60-80%),the withering way of"sunlight withering" and "combined withering" by artificial light LED.5.The study of six illumination times(4h?8h?12h?16h?20h?24h)by multi-wavelength LED in white tea withering production line showed that illumination time below 4h or more than 20h are not conducive to the formation of white tea quality.The taste and infused leaf quality of primary tea in illuminate 16-20h are obvious weak in 8-12h.The sensory score of primary tea quality is highest(91.40)after illuminate 12h,for its appear,taste and infused leaf which is good for accumulation of inclusions reducing the bitter,astringent and enhancing mellow,also can improve white tea clean and flowery flavor aroma compounds content such as benzyl alcohol,phenylethyl alcohol,benzaldehyde,benzene acetaldehyde,nerolidol 2,linalool oxide,cedrol,?-ionone.LED light 24h of PPO and POD activity in withering leaf are significantly higher than dark treatment,and its PPO activity nearly 2 times higher than 2h illuminated.POD activity increased 22.98%after 6h illuminated.Illuminating can ahead of peak appears time,improve the level of the peak and promote the transformation of polyphenols during withering process.In the same illuminate time(12h),different illumination period experimental study showed that the intermittent light way is beneficial to moisture loss during withering process and improve water extract content.Continuous illumination can keep withering leaf soluble sugar content.The traditional combined withering method(0h-6h-0h-6h)have highest sensory score(92.20)and benefit for its taste mellow,sweet,and the flowery flavor.