Effective moisture diffusivity of garlic cloves undergoing microwave-convective drying

• Published in: Journal of food engineering 2004-12, Vol.65 (4), p.609-617
• Main Authors: Sharma, G.P, Prasad, Suresh
• Format: Article
• Language: English
• Subjects: activation energy; air flow; air temperature; Allium sativum; Aroma and flavouring agent industries; Biological and medical sciences; diffusion; diffusivity; drying; drying quality; equations; Food engineering; Food industries; Fundamental and applied biological sciences. Psychology; garlic; General aspects; heat transfer; heat transfer coefficient; mass flow; mass transfer; mathematical models; microwave power; microwave radiation; microwave treatment; process control; velocity; water activity; water content
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2004.02.027

Drying of garlic cloves was done using microwave-convective technique, using microwave power of 10–40 W, air temperature of 40–70 °C and at air velocity of 1–2 m/s. The effective moisture diffusivity varied from 1.29 to 31.68 × 10 −10 m 2/s. A third order polynomial relationship was found to correlate the effective moisture diffusivity ( D eff) with moisture content. The D eff increased for the same values of drying air temperatures and velocities as the applied microwave power was increased. However, D eff decreased at all temperatures and applied microwave power with increase in air velocity. The activation energy in the microwave-convective drying ranged between 4.08 and 10.50 kJ/mol, which was much lower than the convectionally heating activation energy values for moisture diffusivities for most vegetables.