Effect of Blanching on Properties of Water Yam (<em>Dioscorea alata</em>) Flour

Abstract

Properties of flour from blanched tubers of two water yam (Dioscorea alata) cultivars were compared with those from the non blanched ones. The results showed that the proximate composition of flours from the yellow cultivar was different from that of the purple cultivar. Steam blanching (97±2°C, 7 min) on the purple cultivar resulted in more significant reduction on yield and the Lightness (L) value. However, it had significant effect on some components of the flours such as protein, ash, amylose and fiber. Results of proximate composition showed crude fat yellow and purple water yam ranging from 0.4 to 0.55%, crude protein 5-8%, dietary fiber 16-26% and starch 41-76%. Starch granule size between 20-40 µm. Blanched yellow water yam flour has the highest water and oil absorption which is 2.02 and 1.18 g/g. Dioscorine and water soluble polysaccharides, bioactive components from Dioscorea, of purple water yam flour are larger than the yellow flour. Purple water yam flour is better to be proceed as a functional food because it has a high peak viscosity, more stable to heat and has greater content of bioactive compounds. Steam blanching decrease the yield of dioscorine and water soluble polysaccharide.

Physico-chemical Properties of Starches from Two Varieties of Sweet Potato and Yam Tubers Available in Nigeria

“…Water yam flour can serve as a source of energy and nutrients (carbohydrates, beta-carotene and minerals) and can provide dietary fiber to processed food products. Addition of various proportions of water yam flour to wheat flour can enhance its nutritive values in terms of fiber and bioactive compounds such as resistant starches, dioscorine, diosgenin and a water soluble polysaccharides [8]. Yams (Dioscorea spp.)…”

Impacts of Cooking Times (Steaming and Cooking on Embers) on Some Physico-Functional Parameters of Yam (Dioscorea bulbifera) Flours Cv Dougon-won Consumed in Côte d'Ivoire

“…The OAC for these different oils were higer than those obtained from yam Dioscorea. alata cv yellow (0.96 g/g) flour [20] and lower in potato flour (168± 10.95 %) [21] and Nigerian jackfruit seed flour (300 %) [22]. However, the cooking on embers decreased significantly (P <0.05) the absorption capacity of olive oil, maize oil, red oil, dinor oil and sunflower oil from Dioscorea bulbifera flours cv Dougou-won.…”

Effect of Different Yam Varieties and Addition on Resistant Starch Type III Formation and Physical Properties of Steamed Rice Bowl Cake

“…As the temperature higher than 50°C, there was a progressive increase in swelling power of yam [20]. In this research, the starch granules gelatinization during steaming about 100°C, starch granule hydrate progressively, hydrogen bonds are ruptured resulting in crystalline regions being converted into amorphous regions and granules continue to imbibe water and swell [16,20], caused starch granules swelled and collapse [16]. It was observed in Table 5 that Da shan line 2 showed the higher swelling power (11.4, 8.5 and 8.6 g/g) than Tainung 5 (8.3, 7.6 and 6.9 g/g), but similar to the results of Heng chun (9.2, 9.1 and 8.1 g/g).…”

“…Especially, yam has higher amylose content when comparing to potato, rice and cassava [17]. Previours research further reported the yam with 21.69-31.56% amylose content [16], which amylose retrogrades quickly during the first few hours of cooling after gelatinization during steamed rice bowl cake preparation [5].…”

“…Yam (Family Dioscoraeceae) is a high economic value food crop, and an important source of energy [15,16] in people's diets. Starch is the major component of yam and provides large proportion of daily caloric intake.…”