ABSTRACT
Processing operations affect
starch hydrolysis, digestibility, absorption and glycaemic index (GI) of food.
Although some studies have reported on the effect of boiling, frying, roasting
and baking on glycaemic index of traditional staples. There is limited
information on the contribution of drying, fermentation, boiling and steaming
on starch bioavailability and glycaemic index. This research work aimed at
determining the effect of fermentation, steaming, boiling and drying on starch
bioavailability and predicted GI of some cassava-based traditional foods
consumed in Ghana. The total starch, amylose, amylopectin, dietary fibre and
predicted glycaemic index of the intermediate and finished products were
determined according to standard protocols. This research has revealed the
predicted GI of cassava (47.75%), ampesi (77.30%), akyeke
(79.05%), cooked kokonte with sun dried flour (40.20%) and cooked kokonte
with solar dried flour (61.11%). The dietary fibre content of Capevars
bankye flour was found to be 1.631% and 1.214% for sun and solar drying processes
respectively. The analysis established that steaming and boiling increase GI of
foods, fermentation has no significant influence on predicted GI of fermented
steamed products, and drying has no substantial effect on predicted GI of
cassava flour. However, staples or products prepared from solar dried cassava
flour would have higher predicted GIs than those of sun dried cassava flour.
This work has also provided evidence in support of the fact that starch,
amylose, amylopectin and dietary fibre content of a food affect the glycaemic
index of the food.
CHAPTER ONE
INTRODUCTION
1.1 Background
Cassava utilization and
cassava-based traditional foods consumption in Ghana is on the increase.
However, there are growing concerns about its effect on the health of consumers
and diabetic patients due to the high carbohydrate content (Oppong-Apane,
2013). This has necessitated research into processing methods and glycaemic
index of cassava-based traditional staples.
Most traditional foods are
processed in one form or the other prior to consumption or storage and
cassava-based traditional staples are not an exception. This processing
activity enhances the eating characteristics, sensory and organoleptic
properties, toxic removal, preservation, marketing and distribution of the
food. It also increases food consistency, diversity, shelf-life and value
addition (FAO, 2011). Processing of cassava involves methods such as cleaning,
size reduction, drying, fermentation, cooking methods, heat treatment
(pasteurization and sterilization) and many others (FAO, 2011; Granfeldt et al.,
2000) which improves its palatability, and reduces cyanogen concentration and
its toxicity (FAO and IFAD, 2005).
Studies have shown that these
processing methods play a significant role in starch digestibility, nutrient
metabolism and absorption, as well as the glycaemic index of the food. Further
research has revealed that, there is greater variation in digestion, metabolism
and absorption of food (carbohydrate) which emanates from the source of the
carbohydrate, its composition and the processing methods, the foods go through
during preparation or formulation (Granfeldt et al., 2000; Omoregie and Osagie,
2008). The glycaemic index (GI) of foods is the measure of the rate of
absorption of carbohydrate into the blood after consumption of a meal and is
significantly affected by the processing operations (Omoregie and Osagie,
2008). This is because these operations are suggested to cause cell wall disruption, depolymerization,
retrogradation, gelatinization and hydrolysis of the carbohydrate to facilitate
enzymatic reaction or digestion, for the release of glucose into the blood
after consumption or eating (Bahado-Singh et al., 2011; Chung et al., 2008).
A study conducted by Granfeldt et
al. (2000) on oat and barley flakes revealed that minimal processing operation
like size reduction (product thickness) had no significant influence on GI. A
research by Bahado-singh et al. (2011) on sweet potato cultivars, established a
substantial impact of roasting, baking, frying and boiling on the GI of these cultivars.
A cohort study carried-out on the glycaemic indices of fufuo, kenkey, banku and
tuo-zaafi also indicated that the differences in GIs of the foods may be due to
different processing methods that were used in their preparations (Eli-Cophie et
al., 2017) but did not account for the extent of the impact of the individual
unit operations resulting in the overall GI of the foods. Therefore, the effects
of individual unit operations need to be evaluated separately to actually ascertain
the contribution of each operation towards GI reduction or increment.
1.2 Research problem
Many processed and traditional
foods go through succession of processing operations which may affect their
digestibility and glycaemic index. A lot of works have looked at the effect of
some of these operations on starch digestibility and GI. However, very limited
information is reported on the contribution of drying, fermentation, boiling
and steaming on GI of cassava-based traditional foods.
1.3 Justification
This work would establish and
document the effect of fermentation, steaming, boiling and drying on the GI of
some cassava-based traditional foods, which will contribute to scientific
knowledge and effectively enable the use of glycemic index in conjunction with
other dietary recommendations for proper treatment, management and prevention
of diseases. Moreover, the GI data of local foods such as akyeke,
ampesi and kokonte considered under this research would assist consumers in
making informed food choices.
1.4 Main objective
The principal objective of this
research is to determine the influence of processing methods on the glycaemic
index of cassava-based traditional foods in Ghana.
1.4.1 Specific objectives
To determine total starch, amylose,
amylopectin and dietary fiber content of fresh cassava, ampesi, akyeke and kokonte
samples
To determine predicted glycaemic
index of fresh cassava, ampesi, akyeke and kokonte samples using in-vitro assay
To determine the effects of
fermentation, boiling, steaming and drying on the glycaemic index of
intermediate and final products
For more Food Science & Technology Projects Click here
===================================================================Item Type: Ghanaian Topic | Size: 64 pages | Chapters: 1-5
Format: MS Word | Delivery: Within 30Mins.
===================================================================
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.