Development of hot and cold beverages from coffee (coffea arabica l.) Husk

Abstract

Coffee husk is the most abundantly available agricultural waste in many coffee-producing areas of the tropics including Ethiopia. To date, it does not have much commercial or industrial value other than, becoming the major polluting agent of rivers and lakes. It contains caffeine and other chemicals which could be extracted and incorporated in to beverages in the process of brewing. This potential of the coffee husk to be utilized as a raw material for making a beverage could be among the solutions for the problem of it being a waste coming out of coffee bean processing operations. Thus, this study was conducted to investigate the possibilities of developing hot and cold beverages of acceptable sensory quality from the dry coffee husk. The study, comprised of three roasting temperatures, roasting times and different levels of dose, laid out in 3x3x3 factorial arrangement for the sensory evaluation and 3x3 factorial arrangement for proximate analysis in CRD. Data were collected on physicochemical characteristics and sensorial response variables and analyzed using SAS version 9.2 Software. The results of the study revealed that almost all of the response variables were significantly affected by the interaction of roasting temperature, roasting time and dose. As a result, the caffeine content of roasted coffee husk was higher in samples subjected to 1400C for 3, minute than in the rest of the samples compared. Carbohydrate content is higher in row coffee husk than in the roasted ones and lowest in samples roasted at 1600C for 5 minutes. Coffee husk hot beverage produced from 1600C roasting temperature, 3 minute roasting time with 24g/l dose was more accepted by consumers for all sensory attributes except color, which was favored for the same dose of coffee husk roasted at 1400C for 5 minutes. More than 50% of the treatment combinations resulted in overall acceptability score of 4 and above showing various degrees of liking of the hot beverage. Cold beverage produced from 24g of coffee husk roasted at 1400C for 3 minutes and brewed in a liter of water was more accepted by the consumers for most of the attributes investigated than the others cold beverage produced by different combination of the treatments. It is possible to produce cold beverages of acceptable sensory quality with a number of treatment combinations of 140 and 1500C roasting temperatures and 3 and 5 minutes of roasting time at doses of 20 and 24 g/l. Correlation analysis among the response variables indicated that moisture content was negatively and very highly significantly (P<0.01) correlated with fiber, ash and protein contents of the roasted husk. However, it had no significant (P<0.05) correlation with caffeine. Fiber content showed very highly significant (P<0.01) and negative association with carbohydrate. Caffeine had significant correlation with protein. The relationship between sensory quality attributes of both hot and cold beverages of the coffee husk is very highly significant (P<0.01) and positive with each other. It can be concluded that the chemical composition of coffee husk and consumer likings of the beverage are significantly affected by roasting temperatures, roasting times and doses. The findings from this study could promote the consumption of coffee husk in the form of hot and cold beverages which, with no doubt, can be considered as one of mitigation strategy against environmental pollution which otherwise would be debilitating to our coffee industry. However, additional studies need to be done using more number of varieties to come up with a comprehensive recommendation.