Carbohydrate composition and amylase activity of sweet potato (ipomoea batatas) root
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Date
2016-08
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KNUST
Abstract
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
Description
A thesis submitted to the department of food science and technology, college of science in partial fulfillment of the requirements for the degree of Doctor of Philosophy