# Hybrid Heat Products: Incorporation of White Bean Flour in Lean Pork Burgers
## 3 Results and Discussion
### Thermal Properties  
To evaluate the effect of composition on the thermal properties of BF-burgers, thermodynamics corresponding to formulations in extreme BF or W/BF levels (1, 3, 4, and 6) were analyzed. All formulations exhibited five endothermic transitions without significant differences among their peak temperatures (Tp): 54.56 \(\pm\) 0.08 \({}^{\circ}\)C; 67.3 \(\pm\) 0.2 \({}^{\circ}\)C; 73.7 \(\pm\) 0.1 \({}^{\circ}\)C; 80.6 \(\pm\) 0.2 \({}^{\circ}\)C; and 96.4 \(\pm\) 0.2 \({}^{\circ}\)C. As an example, Figure 3 shows one of the thermograms. To assign thermal transitions with the different components in the burger, differential scanning calorimetry was also performed on pork meat/salts mix and bean flour (Figure 3). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Response Variable**} & \multirow{2}{*}{**Optimization Criteria**} & \multirow{2}{*}{**Predicted Values**} & \multicolumn{2}{c}{**Experimental**} \\ \cline{3-4}  & & & & **Confidence Interval (\(\alpha\) = 0.05)** \\ \hline BF & Maximum & 15 & – & – \\ Process yield (\%) & Maximum & 90.29 & 90.40 (0.5) & 88.40–92.17 \\ Hardness (N) & 12 & 15.23 & 12.5 (0.8) & 10.49–19.97 \\ Cohesiveness & 0.545 & 0.536 & 0.513 (0.004) & 0.51–0.55 \\ Springiness & 0.81 & 0.832 & 0.76 (0.01) & 0.78–0.89 \\ b* & 13 & 12.60 & 12.8 (0.1) & 11.30–13.89 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Optimization criteria and predicted and experimental values of process yield, hardness, cohesiveness, springiness, and yellowness (b*) obtained for the optimized BF-burger. The three first transitions (A, B, and C in Figure 3) were also observed in the pork meat/salts mix thermogram at similar Tp (\(p\) > 0.05) and could be associated with the denaturation of different pork meat protein fractions in presence of salt [38], corresponding as follows: A to myosin (Tp = 54.14 \({}^{\circ}\)C), B to sarcoplasmic proteins and collagen (Tp = 66.34 \({}^{\circ}\)C), and C to actin (Tp = 73.42 \({}^{\circ}\)C). To analyze the effect of bean flour in the enthalpies associated with these thermal transitions, after peak integration, \(\Delta\)H were corrected to express all per gram of pork meat. Results showed that the addition of bean flour produced a significant increase (\(p\) < 0.05) in the energy required to make myosin denaturation, which was increased when comparing the BF-burgers formulations with lower (1 and 3) and higher (4 and 6) flour levels. Enthalpies were 0.52, 0.64, and 0.95 W/g pork meat for 0, 8, and 15 g BF/100 g, respectively. The second transition enthalpy did not show significant differences and for the third peak enthalpy was difficult to measure due to a noticeable overlapping with the fourth transition. The fourth and fifth transitions in BF-B (D and E in Figure 3) were associated with bean flour components as they were similar to those in the bean flour thermogram (located at 77.5 \(\pm\) 0.2 \({}^{\circ}\)C and 90.1 \(\pm\) 0.3 \({}^{\circ}\)C). The fourth transition (D) was attributed to starch gelatinization and the latter (E) related to protein denaturation [39; 40]. The shift of these peak temperatures would be attributed to the disruption of starch crystallites that may form complexes with other molecules in the meat system [41] or to the presence of salt and the influence of a protein network system [42]. Thermal transitions in the cooked BF-B were also analyzed, both in the center and on the surface. No peaks were observed in the thermograms of the surface of the cooked BF-B (figure not shown). Conversely, thermograms of the center of cooked BF-burgers showed one transition at 85 \({}^{\circ}\)C (Figure 3). As the burger center reached 71 \({}^{\circ}\)C during the cooking process, meat proteins were almost denaturized, but the bean starch would not gelatinize and persist natively in the cooked product. Probably, as a consequence of the lower water availability or/and stronger interactions with the system, the starch gelatinization temperature was observed at higher values.