Cold Brew Coffee-Pilot Studies on Definition, Extraction, Consumer Preference, Chemical Characterization and Microbiological Hazards.

Linda Claassen,Steffen Schwarz,Gertrud Winkler,Maximilian Rinderknecht,Theresa Porth,Andreas Scharinger,Dirk W Lachenmeier,Daniela Noack,Julia Röhnisch,Hatice Yasemin Seren,Vera Gottstein

doi:10.3390/foods10040865

Abstract

Cold brew coffee is a new trend in the coffee industry. This paper presents pilot studies on several aspects of this beverage. Using an online survey, the current practices of cold brew coffee preparation were investigated, identifying a rather large variability with a preference for extraction of medium roasted Arabica coffee using 50–100 g/L at 8 °C for about 1 day. Sensory testing using ranking and triangle tests showed that cold brew may be preferred over iced coffee (cooled down hot extracted coffee). Extraction experiments under different conditions combined with nuclear magnetic resonance (NMR) analysis showed that the usual extraction time may be longer than necessary as most compounds are extracted within only a few hours, while increasing turbulence (e.g., using ultrasonication) and temperature may additionally increase the speed of extraction. NMR analysis also revealed a possible chemical differentiation between cold brew and hot brew using multivariate data analysis. Decreased extraction time and reduced storage times could be beneficial for cold brew product quality as microbiological analysis of commercial samples detected samples with spoilage organisms and contamination with Bacillus cereus.

Highlights

There are numerous ways to prepare a coffee beverage
Extraction experiments under different conditions combined with nuclear magnetic resonance (NMR) analysis showed that the usual extraction time may be longer than necessary as most compounds are extracted within only a few hours, while increasing turbulence and temperature may increase the speed of extraction
There is a complete lack of definition of cold brew, not even what is meant by “cold”. It might be self-evident that cold brew coffee is extracted with cold water, it is not yet specified how cold the water should be

Summary

Introduction

There are numerous ways to prepare a coffee beverage. Different extraction methods are used depending on personal preferences as well as the geographic, cultural and social context [1]. The extraction method influences the composition of the beverage [2]. Most common is the consumption of hot brewed coffee [3]. The brewing process significantly influences the aroma of the coffee [3]. Cold brew as a new extraction method has established itself on the market, and showed a 580% increase in sales in the US from 2011 to 2016 [4]. The new trend is replacing iced coffee more and more [5]. Iced coffee is hot brewed coffee which is cooled [2]

Objectives

Methods

Results

Discussion

Conclusion