Introduction:

The drying of nopal offers an alternative for their preservation, storage, handling and consumption.

Objective:

The effects of microwave drying on the microstructural characteristics of nopal and their thermodynamic properties at the food-water interface were evaluated.

Methodology:

Nopal cladodes were microwave-dried by applying powers of 75 and 158 kW·kg-1. Microstructure of the samples was evaluated by Scanning Electron Microscope. Adsorption isotherms were determined at temperatures of 10, 20, 30 and 40 °C. Net isosteric heat (qst) was calculated using the Clausius-Clapeyron equation and the Peleg model.

Results:

Samples dehydrated at 75 kW·kg-1 showed greater preservation of their internal and external structure. When applying a higher power (158 kW·kg-1), greater damage was observed in the microstructure of the material. Type III adsorption isotherm curves were obtained according to the Brunauer classification. The qst of the dehydrated nopal was 7.51 kJ·mol-1 for a moisture content of 0.05 kgH2O·kg-1.

Limitations of the study:

The results obtained are valid only for microwave drying by applying powers of 75 and 158 kW·kg-1.

Originality:

This work proposes the microwave drying of nopal as an alternative method that reduces drying time and allows the preservation of the material’s structural properties.

Conclusions:

The power applied in the microwave drying of nopal had a direct impact on the microstructure of the samples. The use of a power of 75 kW·kg-1 was the best drying condition to preserve the structures constituting the cladodes.