FUNCTIONAL, PASTING, AND THERMAL PROPERTIES OF YAM (DIOSCOREA ROTUNDATA) FLOURS FROM HABANERO AND COLOMBIANO CULTIVARS

Yam is an important food in the Puerto Rican diet, serving as a valuable source of carbohydrates. The functional, pasting, and thermal properties of yam flour (Dioscorea rotundata cultivars Habanero and Colombiano) were studied to understand their potential for product development and crop value enhancement. Pasting behavior is a key predictor of flour pastes’ performance during and after cooking. The yams were peeled, sliced, dried at 40 °C for 24 h, milled, sieved through a 60-mesh screen, and packed. Chemical, functional, pasting, and thermal properties were determined using standard analytical methods. Significant differences (P<0.05) were observed in the results. The chemical composition of flour was 6.29 to 6.58% moisture, 4.31 to 4.37% protein, 1.22 to 1.57% fat, 2.14 to 2.24% ash, 1.19 to 1.51% crude fiber, and 84.85 to 83.73% nitrogen-free extract. Mineral content ranged from 106.54 to 115.48 mg/100g phosphorus, 949.80 to 1008.49 mg/100g potassium, 27.64 to 31.28 mg/100g magnesium, and 20.10 to 34.70 mg/100g calcium. The water absorption index (WAI), water solubility index (WSI), and oil absorption capacity (OAC) of the yam flours ranged from 2.28 to 2.36 g/g dry solid, 7.32 to 7.50%, and 1.04 to 1.05 g of oil per g of flour, respectively. No significant differences (P≤0.05) were observed among the cultivars in WAI, WSI, and OAC. Pasting parameters were analyzed with a Rapid Visco Analyzer (RVA), and thermal properties by differential scanning calorimetry (DSC). Both cultivars showed a wide range of peak viscosity (4345.33 to 5651.33 cP), breakdown (1851.33 to 3040.33 cP), and setback (1302.33 to 1392 cP). No significant difference (p<0.05) was found in hot paste viscosity (2494 to 2611 cP), final viscosity (3829.67 to 4003 cP), peak time (4.71 to 4.72 min), and pasting temperature (81.80 - 81.83 °C). Pastes form below the boiling point of water, which benefits commercial applications through energy savings. The peak time for both cultivars was short. Flours with shorter pasting times, like these, may be suitable for producing quick-processing foods. Thermal properties of the yam flours ranged: gelatinization onset (T_o, 72.03 -72.63 °C), gelatinization peak (T_p, 77.10 - 78.02 °C), gelatinization end (T_e, 85.82 - 87.92 °C), gelatinization enthalpy (∆H, 3.31 - 3.61 J/g). No significant differences (P≤0.05) were observed among the cultivars in their thermal properties. In conclusion, flours from Dioscorea rotundata cultivars Habanero and Colombiano show great potential as ingredients in the food industry based on their nutritional value, physicochemical, functional, and pasting properties.