Nutritional and textural properties of amaranthus-enriched rice-based pasta

A broad variety of gluten-free (GF) cereal-based products are available for celiac people. Unfortunately, most of them are of very poor quality, particularly when compared with goods from wheat, suggesting that more attention should be paid to the nutritional and sensory quality of GF products. In this context, the addition of amaranthus (25%) to heat-treated rice flour offers good opportunities for GF pasta production. Amaranthus flour not only is free of any toxic prolamin, but also it has interesting nutritional features, such as a high content in minerals (in mg/kg: Fe, 69; Ca, 271; Zn, 28), and fiber (4.9% db). The addition of amaranthus flour decreases the pasting temperature of rice starch from 80 to 70°C and improves the starch swelling capacity, increasing the hot viscosity from 120 to 190 BU in the MVAG test. Starting from a mixture of heat-treated rice flour and amarathus flour (75:25), a pasta sample (Pasta 1) was prepared in a pilot-scale conventional plant, as done for a reference pasta (Pasta 2) made from 100% rice flour. The dough was shaped into macaroni and dried using a low-temperature drying cycle (50°C for 14 hours). As expected, the pasta enriched with amaranthus showed an higher mineral content (in mg/kg: Fe, 98; Ca, 346; Zn, 32) than Pasta 2 (in mg/kg: Fe, 16; Ca, 37; Zn, 7) and, despite its higher fiber content (4.5 vs. 3.2% db), the presence of amaranthus flour did not increase leaching into cooking water at optimal cooking time but assured a higher water absorption during cooking than Pasta 2. This trend could assess the lower firmness of Pasta 1, as shown by sensory analysis. Evidence for a role of amaranth proteins in formation of mixed polymers with rice proteins will be discussed. Support by CONACyT-Mexico to Francisco Cabrera-Chavez is gratefully acknowledged.