State Diagram of Freeze-dried Garlic Powder by Differential Scanning Calorimetry and Cooling Curve Methods

Abstract

: The state diagram of freeze‐dried garlic powder was developed using freezing curve, glass transition line, and maximal‐freeze‐concentration condition. Freezing points of garlic powder were measured by differential scanning calorimetry (DSC) and the cooling curve method, whereas glass transitions were measured by DSC. The freezing curve and glass transition line were modeled using the Clausius‐Clapeyron equation, adjusted with unfreezable water, and the Gordon‐Taylor model, respectively. Maximal‐freeze‐concentrated condition was found as X′s (characteristic water content) = 0.82 [X′g (characteristic solids content) = 0.18] with the characteristic temperature of glass formation being T′m (characteristic glass transition) =−38.6°C and T′m (characteristic end point of freezing) =−26.0°C. Other characteristic glass transitions T″g and T‴g equal to −29.3°C and −48.6°C, respectively.

A Review of Methods, Data and Applications of State Diagrams of Food Systems

“…The T m 0 obtained with the cooling curve method is comparable to that determined with DSC [148]. However, the cooling curve method for determination of T m 0 is less sensitive than DSC for concentrated foods [144].…”

“…Characterizing Melting/Freezing Temperature A differential scanning calorimetry method is used extensively to characterize the onset of ice melting (T m 0 ) and the decrease in melting temperature ice crystals, due to increasing solids content in foods [144,148]. Thermograms provide melting endotherms and glass transition temperatures of maximum-freeze-concentrated solutions for foods containing freezable water (Fig.…”

“…At the initial freezing temperature, the slowest cooling rate is observed. The cooling curve method was used to obtain the freezing curve of dates [96], garlic [144], abalone [177] and tuna flesh [146]. This method can be used for solids, liquids and viscoelastic materials.…”

Detection of butter adulteration with water using differential scanning calorimetry

“…Samples were obtained by mixing with a homogenizer of different amounts of water (5,10,15,20,25, and 30%) with anhydrous butter fat (w/w).…”

“…The concept of bound water was discussed as controversial by Wolfe et al [11], who posed a question ''what is unfreezable water, how unfreezable is it and how much is there?''. Unfreezable water content was estimated also by comparing DSC endotherms of samples having freezable water from the plot of melting enthalpy as a function of water content in strawberries [12], dates [13], cabbage [14], and garlic [15]. If ice formation, i.e., the transition into the crystalline state, does not occur in subzero temperatures, then water is found in the so-called vitreous, i.e., amorphous state.…”