Plasticization and Antiplasticization by Small Molecules in Brittle Cellular Food: TMDSC and Mechanical Properties

Figures & data

Table 1 Average composition of commercial bread toast

Component	g/100 g of product
Protein	15
Carbohydrate	76
Fat	3
Fiber	2
Moisture	3.6

Figure 1. Sorption isotherm data fitted by the GAB and BET models.

Table 2 GAB (X _m, C, K) and BET (X _m, C) parameters fitted to the isotherm of moisture sorption of toast

Model	X m	C	K	R ^2	P (%)
BET	0.038	5.326	—	0.998	1.852
GAB	0.054	2.338	0.934	0.996	9.017

Note: R ², Regression coefficient.

Figure 2. (A) Temperature modulated differential scanning calorimetry thermogram showing the glass transition and enthalpic relaxation of bread toast. (B) Lissajous figure obtained during heating of bread toast from 0°C to 20°C at 2.5°C/min with a 40 s period and amplitude of 0.5°C.

Figure 3. Midpoint glass transition temperature of bread toast equilibrated at different water activities.

Figure 4. State diagram from T _g analysis of bread toast as determined by TMDSC at heating rate of 2.5°C/min, 40 s of period and 0.5°C of amplitude.

Table 3 Fitted parameters obtained from the Gordon–Taylor (k) and Kwei (k, q) equations

Model	k	q	R ^2
G-T	6.85	—	0.988
Kwei	8.92	195.3	0.991

Note: R ², Regression coefficient.

Table 4 Strain at fracture (ε _H ) and Young's modulus (E) as a function of water activity (a _w)

a w	E (10^3 kPa)	ε H
0.186	1.10a	0.32a
0.310	1.11a	0.29ab
0.398	1.53b	0.34ac
0.418	1.17a	0.29ab
0.449	1.32ab	0.33ac
0.529	0.91c	0.34ac
0.551	0.82c	0.36c
0.648	0.75c	0.40d
0.720	0.21d	0.36c
0.811	0.08d	0.27b

Note: Measurements with equal letters are not significantly different at p≤0.05.

Figure 5. Stress–strain behavior at different water activities.

Figure 6. Behavior of the mechanical properties as a function of water activity. (A) Young's modulus, (B) stress at fracture.