Quality of hot air dried and freeze-dried of garlic (Allium sativum L.)

摘要

The kinetics of drying garlic using hot air at 50, 60 and 70 A degrees C, with and without prior steam blanching at 100 A degrees C for 4 min, was studied, as also the colour changes, inulin, glucose and fructose contents, particle size and glass transition temperatures of garlic powders obtained by air drying and by freeze-drying. The kinetics of forced air-drying indicated an increase in the drying constant with increase in temperature and with the use of blanching. For the freeze-dried garlic powder the parameter L* was greater and the parameters a* and b* smaller than for the forced air dried garlic powder, closer to the colour of in natura garlic. A decrease in the inulin content and increase in the glucose and fructose contents was observed in the dehydrated samples as compared to the in natura sample. The glass transition temperature of the powdered garlic samples increased with decrease in water activity.