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Tree tomato freeze-drying using induced vacuum surface freezing process was carried out at UNal-Manizales.

The pilot program was carried out at the Biotechnology and Agribusiness Institute.

They improved the color of tree tomatoes.

Professor Carlos Eduardo Orrego, IBA Director.

They also produced fruit pieces using different processes.

The IBA is located at the UNal-Manizales La Nubia Campus.

The procedure was performed by doctoral Chemical Engineering candidate Catalina Álvarez Campuzano and member of the UNal-Manizales Fruit Tree Food Research Group. 

Álvarez showcased her project during and event entitled, “Lessons learned on the characterization, water management, biological control and value adding to Andean fruit trees” carried out at UNal. 

Freeze-drying usually is used in the pharmaceutical industry although it is also used in the food industry, for instance for producing instant coffee. Furthermore cereal companies have been increasing use of this technique, for instance for the pieces of fruit they add to the cereal. 

The purpose of the project was to improve or maintain the quality features of freeze-dried products using less time and consequently less energy. 

“This was carried out with the intention of lowering costs which ultimately is what businesses are more interested in, because freeze-drying is expensive. Álvarez handled and controlled crystallization which is the first stage of freeze-drying using different freezing speeds to discover an optimal freezing speed without impacting the structure of the product,” said Professor Carlos Eduardo Orrego, Director of the Biotechnology and Agribusiness Institute (IBA, for its Spanish acronym). 

Álvarez explained that this technique consists of applying a vacuum during freezing using pressures between 250 and 350 militors for 1 or 2 minutes and then relieving the pressure as fast as possible. 

Furthermore she said this was performed with the purpose of obtaining more organized crystals and producing more nuclei at higher speeds, in other words providing more form and organization to the products. 

Although it was not possible to significantly reduce processing times, the quality features were very superior; hence the color is more like the original fruit instead of pale and white toned product from conventional freeze-drying. 

Tree tomato pieces are then more visually attractive; aromas and antioxidants are preserved compared to other drying methods where it is necessary to increase the temperature to higher levels. 

According to Professor Orrego this was a pilot test using tree tomatoes and UNal technology. Both in Colombia as in other countries and especially in Argentina they are interested in becoming cognizant of this technological progress. 

Orrego also said that when they worked with fruit pulp at the IBA they achieved important time reductions in the process by changing crystallization techniques enabling obtaining porous or pulverized fruit materials.