Browsing by Author "Mensah, Eric Owusu"

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    Carbohydrate composition and amylase activity of sweetpotato (Ipomoea Batatas) root
    (AUGUST, 2016 ) Mensah, Eric Owusu
    Selection of sweetpotato clone(s) for production and utilisation depends on its quality attributes especially sugars, dry matter, starch content and amylase activity. The levels of these attributes are however influenced by factors such as the diversified production environments, cooking treatments, and genotypic compositions. The aim of the study is to determine the range of variation and factors of significant influence on concentrations of these attributes during growth and processing of sweetpotatoes. Development of an efficient and accurate technique for rapid assessment of these quality attributes was also relevant to the study. In order to achieve the overall aim, two main approaches were adopted; varying the levels of identified factors that alter the concentration of the attributes, and using near-infrared reflectance spectroscopy technique to develop a prediction model for their assessment. Sugars (sucrose, glucose, fructose and maltose), starch, dry matter content, amylase activity and sweetness were evaluated at harvest, during heating and after cooking. Adaptive Main Effects and Multiplicative Interaction (AMMI) model was employed to ascertain the magnitude of interactions between the factors tested. It was established that concentrations of the quality attributes were significantly affected by all the factors examined. Genotype contributed the highest variability during the growth stage while cooking treatment produced the highest effect during processing. Effect of interaction was more pronounced on amylase activity compared to sugars, dry matter and starch content. Sucrose was the predominant sugar in the raw form while levels of maltose increased substantially during cooking. High precision calibration was also developed for evaluating sugars and starch content in cooked sweetpotato roots. Sweetpotato varieties in Ghana have a wide range of quality attributes, making it a versatile crop for many food applications. Nonetheless recommendation for specific application should consider choice of production environment and processing conditions, which have significant impact on the final quality of the processed product.
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    The Effect of Steeping Regimes and Gibberellic Acid (GA3) on Enzymatic Activity of Rice Malt for the Production of Glucose Syrup
    (2009-08-25) Mensah, Eric Owusu
    The effect of three malting conditions (steeping period, air-rest, and gibberellic acid-3 application) on malting quality of rice grains for the production of glucose syrup was investigated. The rice grain (Jasmine 85 variety) was soaked for 12 to 72 hours and germinated for 12 days at a temperature of 28 + 1 °C. Air-rest treatment of 2 to 8 hours and GA3 concentrations of 10* to 10 mg/L were applied. Parameters measured included out-of-Steep Moisture Content (SMC), germination energy, malting Joss, diastase and alpha amylase activities, shoot length, protein content, rate of reaction, and total soluble solids (sugars). Results obtained indicated that SMC, malting loss, germination energy, diastatic activity, and shoot length of rice malt increased with increasing steeping period. The effect of air-rest treatment on the rice malt quality was more significant at 6-hour period producing an average diastatic activity of 1001.72 U/g dry malt at out-of-steep and shoot length of 5.24cm. GA3 application at a concentration of lOmg/L resulted in the highest diastatic activity of 1305.27 U/g dry malt, and shoot length of 2.93cm after 60 hours of germination. The maximum diastatic activity of rice malt obtaine4 from the combine (GA3 and air rest) and air-rest treatment alone was found on the 8th day of germination, occurring earlier than that of the control, 10th day. Moreover, the combined treatment produced malt with the highest diastatic activity (1545.94U/g) compared to that of air-rest treatment alone (1528.01U/g) and the control (1456.33U/g), averagely. Cassava starch (Agbelifia) had a higher affinity for the malt prepared under the combined treatment producing more soluble sugars in the final glucose syrup. Therefore to obtain rice malt with the highest diastatic activity, rice grains should be soaked for 48 hours. Moreover, applying air rest-treatment of 6 hours during steeping in lOmg/L of GA3 solution could further enhances the total hydrolytic potential of rice malt.