Abstract
The effects of grinding (medium-coarse) and extraction time (14–22 h) on the physicochemical and sensorial properties of cold brew coffee produced using two types of Colombian specialty coffees (Huila and Nariño) were evaluated. Cold coffee brewed under coarse grinding and 22 h of extraction exhibited the highest values of total dissolved solids, extraction yield, pH, titratable acidity (TA), and total phenolic content. The type of coffee used mainly affected the TA and pH. All cold brew coffee samples had lower TA values than their hot counterparts. Nariño cold brew samples had higher TA values than those of Huila in all treatments evaluated. Higher scores were reported in the sensorial evaluation of cold brew coffee when prepared using the shortest time (14 h) and coarse grinding for both coffee types. These coffees were characterized by strong sweetness, fruity and floral flavours, medium bitterness and acidity, and a creamy body. Furans, pyrazines, ketones, aldehydes, pyrroles, esters, lactones, furanones, and phenols were detected as odour-active compounds. The findings of this study demonstrate that the particle size, contact time, and coffee type affect the physicochemical and sensorial characteristics of cold brew coffee, leading to cold brew coffees with different flavour profiles.
Highlights
IntroductionApproximately 2.25 billion cups of coffee are consumed globally[1]. The popularity of coffee arises from the stimulating effects of caffeine and from its pleasant aroma and flavour and, more recently, from its health benefits[2,3,4]
Every day, approximately 2.25 billion cups of coffee are consumed globally[1]
Publications regarding cold brew coffee and their phenolic content are scarce. Chlorogenic acids and their related molecules have been associated primarily with the functional properties of coffee, recent studies in cold brewing using different origins of coffee have reported low total caffeoylquinic acid (CQA) concentrations and total antioxidant activities compared with their hot brew counterparts[27]
Summary
Approximately 2.25 billion cups of coffee are consumed globally[1]. The popularity of coffee arises from the stimulating effects of caffeine and from its pleasant aroma and flavour and, more recently, from its health benefits[2,3,4]. Since the 1990s, coffee quality has been related to the term “specialty coffee” or “café gourmet”, which refer to the highest quality of green coffee beans, with an excellent and unique flavor[6]. Volatile and non-volatile flavour compounds are extracted from the ground coffee and are dispersed in the final coffee beverage[12] In this process, the size reduction of the roasted beans by grinding is a prerequisite for the controlled extraction and dispersion of the chemical compounds in the coffee brew. Studies have been carried to evaluate the influence of the product formulation (e.g., bean botanical type, post-harvest processes, roasting degree) and brewing process variables (extraction time, flow rate, temperature, particle size distribution, and water pressure) on the physicochemical attributes and sensory profiles[5,8,9,14,15,16]. Cold brew coffee can be made by dripping, direct or indirect immersion or by the French press method[10]
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