The relative porosity was calculated from determined bulk and true density data. Bulk density was mea- sured by weighing a container of known volume filled with the sample immersed in packed sand in a vibratory plate for 5 min vibration and knowingthe weight ofthis containerfilled with sand, the displaced volume of sand was obtained, calcu- lating the volume of the snack sample previously dried and weighed. True density was measured with a gas pycnometer (AccuPyc II 1340 Micromeritics Instrument Corp., Norcross, GA) that measures the helium displaces volume by samples previously dried and weighted. Calculation was carried out with the following formula:
Relative Porosity ¼ 1 − bulk density=true density