Abstract:
Chocolate coating is usually applied using a chocolate enrobing machine. This is a
machine in which the products to be coated pass through a continuous curtain of chocolate. Due
to immense demand of cocoa value added products, several Self Help Groups (SHGs)/ home made
units have started several enterprises in cocoa processing. However, a small capacity enrobing
machines suitable for small and medium scale entrepreneurs are not available. Hence, an attempt
has been made to develop economically feasible chocolate enrobing machine for cookies that will
be suitable for small and medium scale entrepreneurs and beneficial to SHGs. Physico-chemical
and engineering properties of cookies and compound milk chocolate were determined prior to the
development of machine. The machine was designed and fabricated by considering critical
parameters related to both cookies and chocolate. The developed chocolate enrobing machine
consists of chocolate tank with agitator, water tank with heater, conveyor belt, chocolate flow pan,
air flow duct connected with ring blower, vibrator, collecting tank and control panel. To optimize
the process parameters for the enrobing process, Box-Behnken design was selected for the
experimental design with 3 levels of independent variables viz. flow rate of chocolate (3, 4.5 and
6 kg/min), belt speed (2.1, 2.3 and 2.5 m/min) and flow rate of hot air (3.3, 3.6 and 3.9 L/s). The
optimization of process parameters was done based on the responses viz. capacity, enrobing
efficiency, energy requirement and coating thickness. The optimal conditions for the chocolate
enrobing process were chocolate flow rate of 4.5 kg/min, belt speed of 2.5 m/min and hot air flow
rate of 3.3 L/s. Performance evaluation of machine was done under optimized condition in terms
of capacity, enrobing efficiency and energy consumption. The machine achieved a capacity of 190
cookies/hour, enrobing efficiency of 94.74%, energy consumption of 5.48 kWh and coating
thickness of 2.79 mm. The quality attributes of optimized chocolate enrobed cookies were
evaluated in terms of thickness, diameter, water activity and proximate analysis. The energy value
of chocolate enrobed cookies was higher than that of base cookies. Sensory evaluation revealed
that the optimized enrobed cookies was superior in terms of colour, appearance and overall
acceptability among the other samples. The benefit-cost ratio and payback period were calculated
as 1.05:1 and 3.15 years, respectively. It is concluded that the developed chocolate enrobing
machine marks a significant step towards supporting small and marginal cocoa growers and
entrepreneurs. It not only boosts the economic potential of cocoa growers, but also encourages
new entrepreneurial ventures in rural as well as semi urban areas.
