Abstract:
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In this article we will examine the process for concentration of apple and pear juices as well as concentration
of sugar solutions modelling pear juice (simulation fluid) using a descending film multi-plate freeze
concentrator. It has been determined in advance the freezing point of those fluids in the working
concentration and temperature intervals. In addition, different parameters were studied to allow tracking of
the process of freeze concentration, such as ice accumulation, variation of the content of soluble solids in the
solution and in the ice removed, ice production and energy consumption. The apple and pear juices tested
showed similar behaviour, while the mixture of sugars used for simulation showed better behaviour, due
perhaps to the absence of foam in the process and to the quicker formation of ice. It has been obtained
concentrations of 30.2 and 30.8 °Bx with the apple and pear juices, respectively, and up to 32.7 °Bx with the
simulation fluid.
Industrial relevance: The clarified juices usually are concentrated on an evaporation stage. In this stage the juice is
subjected to high temperatures that cause undesirable reactions, such as non enzymatic browning and
destruction of nutritive compounds. The freeze concentration is a technology that allows eliminatingwater from
the juices at temperatures below the water’s freezing point, what allows obtaining products of better quality. In
this work has been applied this technology to concentrate apple and pear juices, obtaining promissory results. |