Analysis Of Factors Affecting The Quality Of Cold Brew Coffee And Preliminary Study On Its Release Kinetics

Coffee has become one of the three major beverages in the world with its unique flavor.Cold brew coffee is a new hot spot for coffee beverages and has become one of the new products in the rapidly growing market.At present,coffee research is more focused on the factors affecting the preparation process of hot brew coffee and the efficacy of coffee.There are few reports on cold brew coffee.The factors affecting the quality of cold brew coffee and the release rules of its main components are still not completely clear.Therefore,this study explored the effects of different factors on the quality(physical and chemical indicators,antioxidant activity,sensory quality)of hot and cold brewed coffee through correlation analysis;and analyzed the main difference volatile components in cold and hot brewed coffee through GC-MS;Using kinetic equation fitting to predict the release law of the main components in hot and cold brewed coffee,and provide a scientific basis for the development and quality control of high-quality cold brew coffee.Research indicates:1)The effect of water quality on the quality of cold brewed coffee is significantly stronger than that of hot brewed coffee,and the effect of extraction time on the quality is also relatively stronger than that of hot brewed coffee.The ratio of powder to water,temperature,and grind(particle size)affect the quality of hot brewed coffee.The effect is stronger.The content of soluble solids,conductivity,p H,metasilicic acid,Mg²⁺,Ca²⁺,Na⁺in water quality are the main factors that affect the physical and chemical,functional indicators and sensory quality of coffee.The influence of these factors on cold brew coffee TDS,extraction rate,and total phenol index showed a significant positive correlation(p<0.01),while the influence of these factors on titratable acid,total sugar,ABTS clearance rate,and color index showed a significant negative correlation(p<0.01);In addition,K⁺cannot significantly affect coffee quality.2)The PCA cluster analysis of the quality indicators of hot and cold brew coffee found that the roasting degree of coffee beans has a stronger effect on the quality of hot and cold brew coffee than the processing method and variety(origin)of the coffee beans,and the roasting degree has a stronger effect on the quality of cold brew coffee.The effect is stronger than hot brew coffee.Through GC-MS determination,35 main volatile components were identified in hot brewed coffee,43 main volatile components were identified in cold brewed coffee,and the content of 2,4-di-tert-butylphenol and indole in cold brewed coffee It is significantly lower than hot brewed coffee,and the content of linalool and?-terpineol is significantly higher.The extraction method of coffee has a significant impact on the types and content of volatile components.Further analysis of aroma components by PLS can better distinguish between hot and cold brewed coffee,and cold brewed coffee also contains isovaleraldehyde,2-heptanol,n-hexyl formate,2-propionyl furan,isoamyl carboxyl furfur,There are 8 characteristic components of nerol,furfural acetone and 3,4-dimethoxystyrene.The flavors of these components are mainly fruit and floral.The aroma components of cold brew coffee tend to be floral and fruit aroma components,while the aroma components of hot brew coffee Prefers baking aroma.3)The main components in the coffee liquor were quantitatively determined by HPLC,and four models were selected for fitting.Except for the oxalic acid,fumaric acid,and chlorogenic acid of cold brewed coffee,they all conform to the Logistic model,and the fit is R2 Both are greater than 0.85.The logistic prediction of the caffeine and trigonelline models shows that the saturated content of caffeine and trigonelline in cold brewed coffee is lower than that of hot brewed coffee;while the predictions of 9 organic acid models show that the total organic acid saturation of cold brewed coffee The content is higher than hot brew coffee.In summary,water quality is an important factor affecting the quality of cold brew coffee.Among them,the content of soluble solids,electrical conductivity,pH,metasilicic acid,Mg²⁺,Ca²⁺and Na⁺have a significant impact(p<0.05)on the quality of cold brew coffee;it is present in cold brew coffee 8 kinds of characteristic ingredients,8 kinds of ingredients generally have a floral and fruit aroma,which may be the main reason why the flavor of cold brew coffee is biased towards flowers and fruits;the release of organic acids in cold brew coffee is higher than that of hot brew coffee,while caffeine and fenugreek The release of alkali is lower than that of hot brew coffee,which may also be the reason why cold brew coffee has stronger acidity(fruit sourness)and weaker bitterness.