Roasting green coffee beans using spouted bed roaster: changes in physical characteristics

Abstract

Pea-berry grade of green coffee (Coffea arabica) beans were roasted in a laboratory model spouted bed roaster at different temperatures (150-250°C) and times (30-300 s). The roasted samples were analysed for instrumental colour (hue, chroma and brightness) and texture. Brightness of the roasted samples varied between 5.2 and 20.4%, and time of roasting markedly decreased the brightness values. The chroma showed a curvilinear decrease with both time and temperature of roasting; the lowest values were with highest roasting times and temperatures. The hue or dominant wavelength increased from 576 to 603 nm due to roasting. The maximum force offered by the roasted beans decreased with temperature and/or time of roasting. An appropriate condition for spouted bed roasting of green coffee beans was obtained considering colour of samples and desirable low failure/fracture force.

Farm to Consumer: Factors Affecting the Organoleptic Characteristics of Coffee. II: Postharvest Processing Factors

“…So, SBR‐roasted coffee has its own physical characteristics which normally differ from those of FBR‐ and CDR‐roasted coffee. Nagaraju and Bhatacharya () also determined the physical characteristics of SBR‐roasted Arabica beans and noted that the brightness of beans decreases with an increased roasting period, while brightness variations ranges from 5.2% to 20.4% for a designated time (30 to 300 s) and temperature (150 to 250 °C). The lowest chroma values are detected at terminal time and temperature, with a curvilinear decrease with both parameters.…”

“…Coffee aroma is the consequence of a complex balance of these many compounds. Any fluctuations in the roasting conditions can affect the aromatic profile of roast beans by hampering the complex balance of these volatiles and their intermolecular interactions (Charles‐Bernard, Roberts, & Kraehenbuehl, ; Nagaraju & Bhattacharya, ). Roasting is followed by storage and grinding of roasted beans to equilibrate the moisture and aromatics balance and to increase the bean surface area exposed to extraction or brewing, respectively (Akiyama et al., ).…”

Furanic compounds and furfural in different coffee products by headspace liquid-phase micro-extraction followed by gas chromatography–mass spectrometry: survey and effect of brewing procedures

“…Green coffee beans have high concentrations of furan precursors like carbohydrates and amino acids. Furanic compounds are formed during the roasting process (Murkovic & Derler, 2006 A c c e p t e d M a n u s c r i p t 5 and roasting time are the main factors affecting the formation of furanic compounds in coffee (Nagaraju and Bhattacharya 2010), the brewing procedure can also affect the levels of these compounds (Pavesi Arisseto et al 2011). Coffee can be brewed in several different ways.…”

Effect of edible coating on the aromatic attributes of roasted coffee beans

“…There is very good mixing of solids and effective gas-particle contact in SBR which facilitates HTST (High Temperature Short Time) processing and provides clean uniformly roasted products (Nagaraju and Ramalakshmi 2002). The optimized combinations of temperature and time of roasting considered were 237-250°C and 180-240 s respectively, considering the brightness and maximum force of samples (Nagaraju and Bhattacharya 2010). Moreover, fast roasting is reported to result in higher amount of soluble solids, less degradation of chlorogenic acids, lower loss of volatiles, and lesser burnt flavor (Nagaraju et al 1997).…”

“…Roasting green coffee beans in the spouted bed roaster led to marked change in color and texture of products (Nagaraju and Bhattacharya 2010). Excessive roasting produces more bitter coffee that lacks satisfactory aroma, whereas very short roasting time may be considered as insufficient to develop full organoleptic characteristics (Buffo and Cardelli-Freire 2004).…”