Evaluation of some phytochemicals in raw and cooked Ipomea batatas (Lam), (Sweet potato), Solanum tuberosum (Irish potato) and Dioscorea cayenensis (Yellow yam)

Cooking induces numerous phytochemical changes in food. This study is aimed at determining the amount of phytochemicals present in raw and cooked sweet potato, Irish potato and yellow yam. The amount of tannin, alkaloids, saponin, flavonoids and phenol were determined in raw and cooked samples of each food crop. The result showed that tannin, alkaloids, saponin, flavonoids, phenol contents was high in Irish potato and sweet potato but was far much present in Irish potato, while it was seen in minute quantity in yellow yam. The values obtained for each phytochemicals in each food sample raw and cooked respectively, in mg/100g were; Yellow yam: Tannins (0.10 and Nil), Alkaloids (2.00 and 0.51), Flavonoids (1.18 and 0.87), Saponins (2.00 and 1.02) and Phenols (0.72 and 0.10). Sweet potato: Tannins (0.32 and 0.28), Alkaloids (2.17 and 0.62), Saponins (2.10 and1.58), Flavonoids (1.28 and 0.97) and Phenols (1.42 and 0.72). Irish potato: Tannins (0.55 and 0.49), Alkaloids (2.17 and 0.81), Saponins (4.00 and 2.13), Flavonoids (5.00 and 2.91) and Phenols (2.00 and 0.91). The % loss of phytochemicals after cooking were; Yellow yam: Tannins (Nil), Alkaloids (74.5), Saponins (49.0), Flavonoids (26.3) and Phenols (86.1). Sweet potato: Tannins (12.5), Alkaloids (71.4), Saponins (24.8), Flavonoids (24.2) and Phenols (49.3). Irish potato: Tannins (10.0), Alkaloids (62.7), Saponins (46.8), Flavonoids (41.8) and Phenols (54.5). These results indicate that boiling of the samples seems to reduce their phytochemical contents as the raw samples showed higher amounts of the phytochemicals. The results also revealed that Tannins are more stable to heat across the 3 food samples, followed by Flavonoids, Saponins, Phenols and Alkaloids. The loss in some of the phytochemicals after cooking did not significantly affect the nutritional quality of the food samples.

A study of Aerodynamic properties of Yam flour

The aerodynamic properties of five varieties of Yam namely: white yam, purple yam, three leaves yam, water yam and yellow yam were investigated under oven drying methods at 33oC. The dried yams were milled to flour and were taken to laboratory to determine their aerodynamic properties with respect to pneumatic conveying of the yam flours. The yam flour varieties recorded terminal velocity range of 1.38 to 1.60 m/s. Drag coefficient of 0.47 and Reynolds number varying from 0.63 to 0.97x10-5 kgm-2 /s. The analysis of variance conducted on the effect of yam varieties on the aerodynamic properties of yam flour did not show significant difference at both 5% and 1% level of probability. The study will guide engineers in design of yam flour pneumatic conveying equipment.

Comparative Studies on the Susceptibility of Three Tubers of Dioscorea Species to Dry Rot in Anyigba, Kogi State

Various yam species are cultivated but white yam (Dioscorea rotundata Poir.), water yam (Dioscorea alata L.) and yellow yam (Dioscorea cayenensis Lam.) are among the most cultivated in Nigeria. The Susceptibility of three tubers of Dioscorea species (D. rotundata, D. alata and D. cayenensis) to dry rot pathogens was investigated. Isolation was made from rotted tuber tissues, followed by pathogenicity test and identification of isolates; two fungal species Aspergillus niger and Rhizopus stolonifer were isolated and identified as the major fungi causing yam tuber dry rot in the study area. There was significant difference (P<0.05) in the susceptibility of the various Dioscorea tuber species studied to rot caused by Aspergillus niger [D. rotundata (20mm), D. alata (11mm) and D. cayenensis (3.5mm)] and Rhizopus stolonifer [ D. rotundata (17.5mm), D. alata (10mm) and D. cayenensis (2mm)]. The phytochemical contents of the three tubers of Dioscorea species examined also varied significantly, with the bioactive substances of D. cayenensis and D. alata relatively higher when compared to D. rotundata. Therefore, this research reveals that three metabolites; Saponin, Flavonoid and Tanin constitute the major trait for resistant ability of D. cayanesis and D. alata to dry rot causing pathogen. Therefore, it is necessary that the differences in susceptibility be considered when developing yam barns. Also, researchers should work on genetically improving the susceptible white yam (D. rotundata) which is commonly eaten by millions of Nigerians with a possibility of increasing the quantities of the deficient phytochemicals.

PENGARUH PERBANDINGAN TEPUNG UBI UNGU (Ipomea batatas L.) DENGAN PATI UBI KUNING (Ipomea batatas L.) SERTA TEPUNG KEDELAI (Glycine max) TERHADAP MI ORGANIK KERING MIX (GLUTEN FREE)

The purpose of this research is to know the effect of composition ratio of purple yam flour and yellow yam starch and addition of soybean flour to the characteristics of dry organic noodles. In addition, to improve the healthy lifestyle of the community by eating organic foods and inform the public about alternative materials made from organic yam and organic soybean as a local commodity. This study used Randomized Block Design (RAK) with 2 factors and 3 repetitions. This research consisted of two factors: composition ratio of purple yam flour with yellow yam starch (K) consisting of: k1 = (90%: 10%), k2 = (70%: 30%), k3 = (50%: 50 %) and addition of soy flour (T) consisting of: t1 = (8%), t2 = (10%), t3 = (12%). Response used in this research consist of: water content, protein content, carbohydrate content, swelling index, cooking loss also organoleptic response that is color response, aroma, taste and texture. Selected samples were tested for antioxidant activity. The addition of organic soy flour affects the response of aroma, taste, texture, moisture content, carbohydrate content, protein content, swelling index, and cooking loss but no effect on color response. The selected treatment is k1t3 formulation which is 90% purple yam flour ratio and 10% yellow yam starch. Based on organoleptic, chemical, and physical response with water content 9,59%, protein content 8,53, and carbohydrate content 62,60%.