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2010 Issue
3
Design, Fabrication and Performance Evaluation of a
Batch-Type Coffee Roaster for
Small-Scale Roasting
Ruel M. Mojica1, Engelbert K. Peralta2 and Jessie C. Elauria3
ABSTRACT
A batch-type coffee roaster that can be used for small-scale roasting was designed and fabricated at the
College of Engineering and Agro-Industrial Technology, UPLB, College, Laguna. The machine consisted
of the roasting chamber, the outside drum, the hopper, the auger, the heating plate, the burner and an elec-
tric motor. The machine’s performance was evaluated to establish the best combination of the operating
parameters involved namely: auger speed, roasting time and fuel valve opening. Results show that auger
speed ranging from 40-60 rpm did not significantly affect all the dependent variables. However, varying
levels of roasting time (50-70 min) and fuel valve opening (1/2 open to fully-open) have significant effect in
almost all the responses. Based on the results of sensory evaluation, coffee obtained using treatment combi-
nation of 40-rpm auger speed; 60-minute time of roasting; and ¾ open valve gave the highest coffee rating
of 86.1. Cost and return analysis revealed that using the coffee roaster for custom work is a profitable busi-
ness with an annual net income of PhP 63, 451.49.
Keywords: roasting, coffee, batch-type
1 Assistant Professor, Department of Agricultural and Food Engineering, Cavite State University, 4122 Indang, Cavite,
Philippines.
2
Associate Professor,
3
Professor, Agricultural and Bio-Process Division, Institute of Agricultural Engineering, College of
Engineering & Agro-Industrial Technology, University of the Philippines Los Baños, 4031 College, Laguna , Philippines.
Introduction
offee roasting is the process of applying heat
for the purpose of drying off impurities for
oxidizing products. It is similar to many other cook-
ing processes in that the goal is to apply the right
amount of heat, over the right amount of time, in a
uniform manner to achieve the desired flavor.
In the Philippines, the roasting of coffee beans is
dominated by multinational companies with huge
roasting equipment so that an ordinary coffee
grower cannot compete. In like manner, these multi-
national companies have an incentive package that
motivates the farmers to market their produce
directly to them even at a very low price. Often-
times, dried coffee beans are contracted for faster
economic return and minimize farmer’s cost of
production.
Torres (2001) reported that there are only four avail-
able coffee roasters in the whole Southern Tagalog
region. Coffee roasting equipment is seldom seen
due to high investment cost. Coffee farmers are not
keen on the value adding processes of their prod-
ucts. Peren (1996) attempted to develop a 10-kg
capacity coffee roaster utilizing agro-wastes as fuel.
However, there are problems on uneven distribution
C
