Designing Fortified Rice-Based Analogues for the Elderly Population

Population aging is a growing global phenomenon, and Latin America has a habit of consuming rice with beans that present adequate amino acid balance. Vitamin D and magnesium are essential nutrients at this stage of life. However, deficiencies are common due to low intake and limited sun exposure. Food fortification by using rice analogue emerges as an effective solution to resolve these nutritional deficiencies. This study aimed to obtain a rice analogue made from rice and cowpea enriched with vitamin D and magnesium using cooking and cold extrusion. Rice flour (RF), bean flour (BF), extruded rice flour (ERF), and emulsified extruded rice flour (EERF) were obtained by milling and thermoplastic extrusion and used in the pasta-making process. The analogues (T1, T2, T4, T7, T7+, T8, T9, T9+) showed 7.29–7.91 mm length, 2.49–2.76 mm width, and an L/W average ratio in the range of 2.64–3.10, thus classified as long grain. The cooking time was shorter (6–12 min) than that of control rice (14 min), presenting weight increases of 59–152 and 5.08–15.95% soluble solid loss. The TPA texture profile revealed 8.72–46.48 N hardness, 2.50–12.94 of chewiness, and 2.78–26.65 gumminess, comparable to those of polished rice. The color measurements showed a whiteness index (W.I.) of 83.06–90.45, similar to the control (93.19). Regarding pasting properties, analogues showed 477.33–683.66 cP peak viscosity (PV), 47.33–399 cP breakdown viscosity (BDV), and 474–1762 cP setback viscosity (SBV). As expected, all analogues showed a decrease in gelatinization parameters compared to the control (polished rice) since extruded flours were used in the eight formulations. The retrogradation tendency of analogues is an important differentiating advantage, since Brazilian consumers prefer loose rice. In addition, the gelatinization temperature measured by differential calorimetry varied from 78.79 to 86.04 °C, which is similar to that of polished rice (83.01 °C). In terms of proximate composition, the rice analogues with addition of the vitamin–mineral mix showed 7.65% proteins, 0.81% dietary fiber, and 187.14 J/g energy value/50 g portion. Finally, the analogues (T7+, T9+) are classified as “rich in vitamin D and magnesium”, as they provide a final concentration of 4.53 μ/100g of vitamin D, 278 mg/100g of Mg, and for up to 4 months, there was no significant difference in vitamin D loss (p < 0.05). Furthermore, the T9+ formulation is the most similar to the control (polished rice) in terms of hardness (8.72 and 10.26 N), cohesiveness (0.48 and 0.44), and gumminess (4.21 and 4.51), and the technological qualities of the analogues were improved by the addition of EERF.