Effects of Drying Air Temperature on the Structural Properties of Garlic Evaluated During Drying

True Density Prediction of Garlic Slices Dehydrated by Convection

“…Nevertheless, in the scientific literature, it has been described that, in the case of foodstuffs, true density depends on composition, the temperature of drying (Boukouvalas and others ), the amorphous or crystalline phase in which the material is found (López‐Ortiz and others ), and the drying method (Krokida and Maroulis ; Boukouvalas and others ). In the convective drying method, the variables that influence the drying kinetics may also affect ρ p , including air velocity ( ν ), relative humidity (RH), and the temperature ( T a ) of the air.…”

“…Recently, it has been demonstrated in garlic that chemical and/or second‐order phase changes have a bearing on the nonlinear tendency of ρ p in terms of moisture content (Rodríguez‐Ramírez and others ; López‐Ortiz and others ). This nonlinearity is represented by an empirical equation (Eq.…”

“…Furthermore, as first and second‐order transition affect ρ w , it is probable that the first‐order (that is, the denaturing of proteins) and second‐order phase transitions (that is, glass transition) that occur during the drying process (Roos 2003) may also affect ρ s . López‐Ortiz and others () stated that: A change in tendency in the concave‐down behavior of true density as a function of moisture content, is associated with a critical point, where T g (glass transition temperature) intersects with T i (inside temperature), indicating a second‐order phase transition. The phase transition, which occurs as a consequence of the drying process, modifies the physical properties of the raw material, and most likely, chemical composition as well. …”

“…This conclusion is valid only for simple molecules and is based on the increase of hydrogen atoms (Franklin ). In foodstuffs (complex materials), variations in ρ p and ρ s may be caused by changes in the structural and/or molecular arrangement, which are dependent on the thermal history ( T a , in drying) and internal temperature ( T i ) of the material (Rodriguez, and others ; López‐Ortiz and others ). Therefore, the variable T i could be introduced into true density models.…”

“…Additionally, the nonlinear comportment of ρ s is evidenced with different materials. The proposed model was analyzed, discussed, and validated using experimental data on sliced garlic, obtained from López‐Ortiz and others .…”