(191n) Study of the Drying Kinetics of Sugar Cane Molasses Via Single Droplet Drying Technique

Study
of the drying kinetics of sugar cane molasses via single droplet drying
technique

Valeria
Benalcazar¹, Paulo C. Narvaez¹, Alvaro Orjuela¹

¹Department
of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogotá,
Colombia.

Keywords:
Sugar cane honeys, Drying, Droplet, Drying kinetics, Jaggery

Corresponding
author: aorjuelal@unal.edu.co

Abstract

Panela, also known as Jaggery, brown
sugar or more technically, non-centrifugal cane sugar, is an important
traditional sweetener and food in several countries. It is produced by open
evaporation of the sugarcane juices, obtaining the so called “sugarcane honeys”
or molasses with up to 94 ºBrix (% soluble matter content). These are finally
put into molds were they solidify by cooling with the surroundings, obtaining
the commercial panela blocks. During the evaporation process, the sugarcane honeys
concentrate the carbohydrates, organic salts, vitamins, proteins, and
antioxidants extracted from the sugar cane. In addition to the high energy
content (~ 98% sucrose, glucose, and fructose) and the sweetening potential,
the high content of nutraceutical components make Panela a beneficial product
for human health.

Currently, Colombia is the second world largest
panela producer after India, and the largest per capita consumer (18-22
kg/person/year). The product is mainly commercialized as solid blocks of
different sizes and shapes. Despite panela can have a great potential in the
natural sweeteners market, the current commercial products lack of the rapid
dissolution that is a desired characteristic in most natural sweeteners (e. g.
stevia powder, maple syrup, honey, agave syrup, molasses, etc.). A rapid
dissolution is required when the sweetener is used in the preparation of instant
hot and cold drinks.

Taking into account the above, production
of dry panela powder from sugarcane molasses is a promising method to achieve
easier feedstock handling for industrial applications, and also for a
convenient consumer use. Many attempts have been made by local producers to
obtain powdered panela, mostly using comminuting processes. However, these
processes are mainly artisanal, costly, and with low productivity, generating poor
quality products. Alternatively, a spray drying process can be applied for the
powdering of sugarcane molasses, helping to improve the product stability,
homogeneity, and appearance. However, the design of such spray drying systems
is a complex task. It requires the use of suitable models to predict the
physicochemical behavior of the molasses during processing, along with the
drying kinetics of the material under variable operating conditions.

In this direction, the aim of this work
was to obtain a kinetic model for the drying of sugarcane molasses, as a tool
for the design of a spray drying system. Using a single droplet drying
technique, the kinetics of the process was explored under different operating
conditions. The experimental set up was composed of an insulated air duct where
a suspended filament, connected to a high precision balance, was located. Then
a droplet of sugarcane molasses was hung from the filament and it was put in
contact with an air stream, at different velocities and temperatures. The
drying process was tracked by following the droplet weight and size with time under
different operating conditions (i.e. molasses concentration, initial droplet
size, and air velocity, temperature and humidity). Based upon the experimental
data, a characteristic drying curve for the material was obtained, and a drying
kinetic model was regressed using the reaction engineering approach (REA). The
obtained model fits reasonably well with the experimental observations, and it
can be used for the further design of a spray drying powdering system for
sugarcane molasses.    

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