Thermal Transitions of Pomegranate Extracts Using Modulated Differential Scanning Calorimeter (MDSC)

Figures & data

Table 1 Glass transition (T _g ) and melting point (T _f ) temperatures of various pomegranate extracts at different water activities

Extract (°Brix)	T g (°C)	T f (°C)	Water activity (a w )
20	−43.3	−2.6	0.99
30	−43.6	−5.6	0.97
40	−44.7	−9.4	0.95
53	−49.3	−16.9	0.89

Figure 1. MDSC thermograms of different pomegranate extracts.

Table 2 Glass transition temperatures () and the onset temperatures of ice melting () in the maximally freeze-concentrated state of different pomegranate extracts, and latent heat of fusion (H _L )

Extract (°Brix)	(°C)	(°C)	H L (kJ/kg)
20	−44.9	−39.6	204.7
30	−46.1	−41.3	136.8
40	−47.4	−42.3	99.51
53	−52.0	−45.3	61.61

Figure 2. MDSC plot for the 20°Brix pomegranate extract.

Figure 3. MDSC plot for the 30°Brix pomegranate extract.

Figure 4. MDSC plot for the 40°Brix pomegranate extract.

Figure 5. MDSC plot for the 53°Brix pomegranate extract.

Table 3 Linear regression correlation coefficients of specific heat values vs. temperature below freezing of different pomegranate extracts

Extract (°Brix)	a	b	R ^2
20	0.0458	4.172	0.96
30	0.0498	4.338	0.91
40	0.0572	4.800	0.99
53	0.0725	5.739	0.96

Figure 6. MDSC specific heat curves for various pomegranate extracts as a function of temperature.

Table 4 Specific heat values (C _p ) above freezing of pomegranate extracts and their corresponding standard deviations (%)

Extract (°Brix)	C p (kJ/kg°C)	SD (%)	Water activity (a w )
20	4.1	7.3	0.99
30	3.6	6.9	0.97
40	2.9	4.5	0.95
53	2.7	11.2	0.89

Figure 7. Specific heat (C _p ) of pomegranate extracts as a function of water activity (a _w ).