(642e) Thermal and Rheological Characterization of Sugar Cane Honeys for the Modeling of Evaporation Systems

Angela L. Alarcón R.¹, Paulo C. Narváez¹, Alvaro Orjuela¹, Edgar Camilo Camacho Poveda²

¹ Chemical and Environmental Engineering Department. Engineering Faculty. Universidad Nacional de Colombia, Bogotá (Colombia) alalarconr@unal.edu.co

² Electric and electronics Engineering Department. Engineering Faculty. Universidad Nacional de Colombia, Bogota (Colombia)

Panela (in South America), or jaggery (in India) is the product obtained by the open evaporation of sugar cane juices. It is also known as non-centrifuged sugar or raw-sugar, and it is mainly composed of sucrose, glucose, fructose, vitamins, minerals and proteins. This product is directly consumed as a sweetener and food, or use for bakery and pastry products in several countries. Panela production starts with the extraction of sugar cane juices (Saccharum Officinarum) with initial concentration of 18 – 20 °Brix, using a mill. Then, the juices are treated with a natural surfactant to remove natural mucilage and other impurities, followed by pH adjustment to avoid sucrose hydrolysis during processing. Subsequently, juices are concentrated by evaporation to achieve 93 – 96 °Brix, and finally, the mix is cool down in molds to obtain square or round blocks for the market.

As blocks are not convenient for consumers, granulation and powdering processes have been carried out using manual procedures (Grinding and sieving) in order to obtain products of rapid dissolution. These have an increasing market as alternative sweeteners for refine sugar. As technification is required, spray drying might be a useful processing technology to obtain powdered jaggery. However, few reports have studied the thermal and rheological properties of sugar cane juices, which are required for process modeling and up-scaling of the spray drying systems.

Taking into account the above, thermal and rheological properties of sugar cane juices such as thermal conductivity, thermal diffusivity, specific heat capacity, density and viscosity were evaluated. The dependence of such properties with water content and temperature were evaluated and regressed with suitable models. A specific experimental device was constructed for evaluation of thermal conductivity.

Sugar cane juices (CSCJ) were collected in Jaggery production facilities that operated with steam or combustion gases as heating source. Collected samples had a concentration of 30.97, 48.81 and 70.81°Brix, and they were characterized by HPLC to evaluate the sugar distribution. Results indicate that jaggery is mainly composed of sucrose (28.76 - 57.59 %), glucose (1.36 - 2.63 %) and fructose (1.11 – 2.09%). On the other hand, evaluated thermal properties between 30 - 75°C corresponded to thermal conductivity (0.47 – 0.27 W m^-1 K^-1), thermal diffusivity (1.13 x10^-7 – 7.19 x10^-8 m² s^-1), specific heat capacity (3.71 – 2.73 J g^-1 K^-1), and density between 20 – 35°C (1.1356 – 1.3512 g ml^-1). Viscosity (3.36 – 36.95 mPas) was evaluated between 35 - 75°C. Finally, mathematical models for thermal and rheological properties were obtained as a function of temperature and concentration.

 

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