| Yunnan is one of the earliest provinces to grow coffee.Due to its unique geographical environment and climatic conditions,Yunnan coffee has formed a unique flavor of strong but not bitter,fragrant but not strong,with a little fruity taste.Coffee is rich in protein,fat,sucrose,starch,caffeine and other substances.After being made into a beverage,it has rich aroma,delicious taste and rich nutrition.However,Yunnan’s deep processing is not perfect,and it is difficult to make use of its resource advantages to build its own brand internationally,so Yunnan’s small coffee is mainly exported.In addition,the current research on coffee mainly focuses on the baking technology of hot-extracted coffee,while the research on cold-extracted coffee is scattered.According to the above reasons,this paper mainly focuses on cold-extracted coffee,taking Yunnan small coffee beans with different processing methods and grades as the experimental objects,and studies the hot air baking process,and obtains the best hot air baking process parameters for preparing cold-extracted coffee;Secondly,the content of the main flavor components of the cold-extracted coffee prepared under the optimal roasting process parameters is analyzed,which provides a theoretical basis for the optimal hot-air roasting process parameters.The main research contents and conclusions are as follows:(1)Taking different grades of Arabica coffee beans from Pu ’er,Yunnan Province as the research object,three main factors affecting coffee quality,namely baking air temperature,baking time and feeding amount,were selected for single factor test,and the extraction rate and sensory score were taken as the research objects,and the data were analyzed by comprehensive score,and the optimal three-level factor values of hot air baking for sun-dried beans and washed beans were obtained,that is,the optimal three-level values of baking air temperature for sun-dried beans were 230℃ and 235℃.At 240℃,the best three-level values of baking time are 15 min,16min and 17 min,and the best three-level values of feeding amount are 110 g,120g and 130 g;The best three-level values of baking air temperature of washed beans are 230℃,235℃ and 240℃,the best three-level values of baking time are 16 min,17min and 18 min,and the best three-level values of feed rate are 120 g,130g and 140 g.(2)On the basis of single factor experiment,the orthogonal experiment of three factors,namely baking air temperature,baking time and feed rate,was carried out,and the comprehensive score of extraction rate and sensory score was taken as the inspection index of the experiment.The optimal hot air baking process parameters of sun-dried beans and washed beans for preparing cold-extracted coffee were obtained,that is,baking air temperature of 230℃,baking time of 16 min and feed rate of 120 g g.The optimum hot air baking process parameters of washed beans are: baking air temperature 230℃,baking time16 min,and feed rate 140 g g.The variance analysis of the orthogonal test results shows that the significant factors affecting the test results are baking temperature and baking time.Finally,the optimal process was verified by experiments.Under this process,the extraction rate of cold-extracted coffee prepared from sun-dried beans was 13.30%,the sensory score was 66.3,and the comprehensive score was 0.9845.The extraction rate of cold-extracted coffee prepared by washing beans was 12.67%,the sensory score was 61.7,and the comprehensive score was 0.9827.(3)The main taste components of the cold-extracted coffee made from sun-dried beans and washed beans were determined,and the contents of caffeine,chlorogenic acid and trigonelline were determined by HPLC.The results showed that the contents of caffeine,chlorogenic acid and trigonelline in the cold-extracted coffee made from sun-dried beans were 1.431g/kg,0.733g/kg and 5.406g/kg.The contents of caffeine,chlorogenic acid and trigonelline in the cold-extracted coffee prepared by washing beans were 0.43g/kg,0.733g/kg and 1.186g/kg,By comparison,it was concluded that washing beans in sun-dried silly boy was more suitable for preparing cold-extracted coffee. |
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