Food and Nutrition Sciences, 2013, 4, 1247-1254
Published Online December 2013 (
Open Access FNS
Bioavailability of Beta Carotene in Traditional Fermented,
Roasted Granules, Gari from Bio-Fortified Cassava Roots*
Olapeju O. Phorbee#, Ibiyemi O. Olayiwola, Silifat A. Sanni
Department of Nutrition and Dietetics, Federal University of Agriculture, Abeokuta, Nigeria.
Received September 16th, 2013; revised October 16th, 2013; accepted October 23rd, 2013
Copyright © 2013 Olapeju O. Phorbee et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In
accordance of the Creative Commons Attribution License all Copyrights © 2013 are reserved for SCIRP and the owner of the intel-
lectual property Olapeju O. Phorbee et al. All Copyright © 2013 are guarded by law and by SCIRP as a guardian.
Vitamin A Deficiency (VAD) is a major public health issue and of global concern, as it affects millions of preschool
children and pregnant women worldwide. Bio-fortification has emerged as a technology with potential to sustainably
alleviate VAD especially in the sub-Saharan Africa, using staples like cassava. This work studied bioavailability of beta
carotene (BC) in two processed gari samples from bio-fortified cassava varieties: 01/1412 and 01/1371, using 40
weanling albino rats, grouped into four, acclimatized for 1 week and fed experimentally for 4 weeks. Plasma beta caro-
tene (PBC) was determined with HPLC while bioavailable BC calculated using conventional linear dose response plot.
The mean rat weight gain was 5.3 g with significant difference (p < 0.001) among them while mean PBC was 60.5 and
61.2 µg/dL for 01/1412 and 01/1371 respectively. From this study, a large variation of PBC among animals was found
with a weak linear relationship between feed and PBC, showing that BC bioavailability is not limited to intake. The BC
bioavailability of the samples was between 11% and 18% with sample from variety 01/1371 recording higher percent-
age (18%). Gari from bio-fortified cassava roots processed traditionally, had appreciable bioavailable BC, which can
contribute to the fight against VAD and improve nutritional status in developing countries although the magnitude of
the problem requires a combination of strategies, of which bio-fortification is just one. However, further work is neces-
sary on public awareness and adoption of the product.
Keywords: Bioavailability; Bio-Fortification; Beta-Carotene; Cassava; Gari
1. Introduction
Vitamin A deficiency is a major public health issue and
of global concern. According to the World Health Or-
ganization report [1], Africa has the second highest pre-
valence of Vitamin A deficiency after South-East Asia.
Vitamin A deficiency (VAD) affects approximately 127
million preschool children and more than 7.2 million
pregnant women worldwide [2]. It causes impaired vi-
sion in many areas of the developing world and it is the
leading cause of acquired blindness in children [1]. Pub-
lic health interventions to address vitamin A deficiency
include fortification of flour with vitamin A and supple-
mentation (twice yearly vitamin A capsules for preschool
children) as well as dietary diversification [3]. Each of
these approaches has been reported to be beneficial to
vulnerable and at risk groups although with some short-
comings, which limit their impact [4]. Recently, bio-
fortification emerged as a technology with potential to
sustainably alleviate VAD in an efficient manner and
complement the strategies already adopted especially in
the developing sub-Saharan Africa where people live on
staples. However, to make appreciable impact, it is nec-
essary to consider the concentration of provitamin A in
bio-fortified food, the factors of bioavailability and bio-
conversion of nutrients, beyond the effects of used proc-
essing. Cassava (Manihot esculanta, Crantz) is one of the
staples targeted for bio-fortification as it is consumed
daily by populations in Sub-Saharan Africa. It has been
estimated that 70 million people in Africa obtain more
than 500 kcal/day from cassava and major source of die-
*Funds for this study was self provided. Cassava samples, processing
facilities and plant analyses were provided by the International Institute
of tropical Agriculture, Nigeria.
#Corresponding author.
Bioavailability of Beta Carotene in Traditional Fermented, Roasted Granules, Gari from Bio-Fortified Cassava Roots
tary energy for low-income consumers in many parts of
tropical Africa, including major urban areas [5].
Studies have been reported on bio-fortification of cas-
sava and cassava products ranging from product devel-
opment to carotenoid retention in processing, storage and
consumer acceptability [6-8]. However, bioavailability of
nutrient in cassava and cassava products from the bio-
fortified varieties becomes important in view of diverse
nature of the Nigerian consumers home and abroad al-
though Falia and Chitchumroonchokchai [9] reported a
study on bioavailability of boiled roots. Detailed knowl-
edge of bioavailability in consumption of cassava prod-
ucts from bio-fortified cassava roots is pre requisite of
predicting the efficacy of bio-fortification in combating
vitamin A deficiency. This study therefore looked into
the bioavailability of beta carotene in ga ri, traditional
fermented roasted granules processed under optimal con-
ditions of carotenoid retention.
2. Objective
The main objective of the study was to assess the
bioavailability of beta carotenoid in Gari from bio forti-
fied yellow fleshed cassava roots
3. Materials and Methods
3.1. Materials
Source of Raw Material
Two samples of gari from two bio-fortified cassava va-
rieties processed at varied conditions for optimal carote-
noid retention and consumer acceptability, studied earlier
were used for the study. The samples were from bio-
fortified varieties 01/1412 and 01/1371, both fermented
for 1 day and roasted at 80˚C and 120˚C respectively.
3.2. Methodology
3.2.1. Gari Production
The Gari samples used were produced, using the typical
traditional processing methods although controlled for
carotenoid retention. The grated cassava mash from the 2
varieties; 01/1412 and 01/1371 was fermented for 1 day
each roasted at 80˚ and 120˚ Celsius respectively. The
standardized procedure involved peeling freshly har-
vested bio-fortified cassava roots with stainless steel
knife, washed thoroughly with potable water to remove
all dirt and adhering sand particles. The peeled, washed
cassava roots were grated into mash using a petrol engine
driven stainless grater, packed into Hessian sacks and left
for 1 day, in fermentation trough to ferment after which
the fermented mash was pressed using a hydraulic press
to remove moisture until cake formed (about 40% - 50%
moisture). The fermented cakes were sieved manually
with stainless steel sieve to pulverize the cake and sepa-
rate fibrous materials. The pulverized cake was then
roasted in a large, shallow stainless steel pan at the se-
lected temperatures, with constant stirring until cream,
free-flowing granules were obtained. The final Gari was
spread on a stainless steel tray to cool and then sieved to
obtain granules of uniform particle size before been
packaged into polyethylene bags and stored at 80˚ Cel-
sius prior to laboratory analysis and further studies.
3.2.2. Carotenoid Profile of the Gari Samples from
Bio-Fortified Cassava Varieties (BFCV)
The two gari samples were analyzed for Carotenoid pro-
file using High Performance Liquid Chromatography,
(HPLC) method of Harvestplus [10].
1) Carotenoid Extraction
Total Carotenoid contents (TCC) of the samples were
determined using visible absorption spectrophotometry.
Five grams of samples was weighed into a mortar, cellite
powder and 15 ml ethanol added for extraction, using
grinding. Each sample was extracted three times to as-
certain complete removal of carotenoid from the sample
while vacuum pump was used to filter the extract. The
combined extracts were rinsed with ethanol two times
and acetone once. The extract was filtered using anhy-
drous substance and absorbance read at 450 nm in spec-
trophotometer and absorption coefficient (2592) of
carotene in petroleum ether.
2) Carotenoid Quantification
For the HPLC determinations the organic phase used
for spectrophotometric quantification of TCC, aliquots
(15 mL) were transferred to a glass tube, and dried by
nitrogen evaporator (N-Evap 112, Organomation Associ-
ates, Berlin, MA, USA). Immediately before injection, in
the same tube, the dry extract was totally dissolved in 2.0
mL of (1:1) methanol and methyl tert-butyl ether MeOH:
MTBE HPLC-grade after sonication (10 s) and agitation
in a VWR multi-tube vortexer (2400 rpm; 60 s), and fil-
tered through a 0.22 µm polytetrafluorothylene (PTFE)
filter. Separation and quantification of carotenoids were
achieved using an YMC Carotenoid S-5 C30 reversed-
phase column (4.6 mm × 150 mm: particle size, 5 μm),
with a YMC Carotenoid S-5 guard column (4.0 × 23 mm)
in a HPLC system (Agilent Technologies 1200 series,
Waldbronn, Germany), using DAD detector with three
wavelengths set at 286 nm (for phytoene), 348 nm (for
phytofluene) and 450 nm (for colored carotenoids).
Peaks were identified by comparing retention time and
spectral characteristics against a pure standard from Ca-
roteNature GmbH, Lupsingen, Switzerland: β-Cryp-
toxanthin-N˚0055 HPLC 97%; β-Carotene-N˚0003 HPLC
96%. 9-cis and 13-cis isomers of β-carotene were identi-
fied according to the following combined information:
elution order, UV-visible spectrum (λmax, spectral fine
structure, peak cis intensity). Their calibration was made
Open Access FNS
Bioavailability of Beta Carotene in Traditional Fermented, Roasted Granules, Gari from Bio-Fortified Cassava Roots
Open Access FNS
using the/all-trans β-carotene curve. Quantity of each
carotenoid was determined by integration of peak area
against respective standard curves.
3.2.3. Determination of Bioavailability of Carotenoids
in Gari from Bio-Fortified Cassava Varieties
1) Rats and Procedures
For this study, bioavailability of carotenoid in the two
Gari samples were determined using rats according to
the methods of Howe and Tanumihardjo [11] and Chan-
drika et al., [12] with few modifications intended to bet-
ter determine the BC bioavailability in the rats. All pro-
tocols regarding the rat study was approved by the De-
partment of Animal Science, University of Ibadan, Nige-
ria. Forty healthy male albino weanling rats of Wister
strain and weight between 52 ± 20 gram were obtained
from the Department of Animal Sciences of the Univer-
sity of Ibadan, Nigeria and acclimatized for one week.
Rats were individually housed in stainless steel metabolic
cages and fed ad lithium. After the acclimatization phase,
all the rats were sorted into weight matched treatment
groups of four in a (4 × 10) complete randomized block
design (control, basal and two experimental feeding
groups). The control group feed comprised of white Gari
(from carotenoid-free cassava roots) as the principal en-
ergy source, casein as protein source, non-vitamin A for-
tified vegetable oil, wheat bran for dietary fiber, bone
meal for minerals, pre-mix and dried carrot for carote-
noid source. The basal diet has similar composition to
that of control but without carrot. The experimental
groups 3 and 4 consisted of Gari from white flesh cas-
sava (no carotenoid) and each of the experimental sam-
ples of Gari from yellow fleshed cassava roots at ratio
1:1. The carrots used was also calculated and mixed to
achieve an equalized BC concentration with the yellow
fleshed Gari samples. Each group of rats was subjected
to the feeding for four weeks while feed intake of each
rat was taken daily by weighing fresh and remnant feed.
Weights of rats were taken weekly while blood sampling
was done fortnightly after one week acclimatization. A
total of three sets of blood samples were collected in the
study; at the beginning of the feeding after acclimatiza-
tion, mid-way into the feeding and after the study. At the
end of the study, all the rats were killed and liver taken
for vitamin A analysis (bioconversion).
2) Serum Isolation and Liver Sample Processing
Blood samples were centrifuged 2200 part per million
for 15 minutes in BD Vacutainer Gel and Clot Activator
tubes for serum isolation. Livers of the rats were excised
and stored at 80˚ Celsius prior to analysis. All animal
handling procedures were approved by the University of
Ibadan-Departments of Animal Science and Physiology.
The plasma samples were analyzed for beta-carotene
and vitamin A respectively using HPLC at the University
College Hospital Laboratory, University of Ibadan, Ni-
3.2.4. Rat Feed Composition for Bioavailability Study
of BC in GBFCV
The composition of feed for the different four groups of
the rat is as shown in the Table 1.
Determination of Plasma Beta Carotene (PBC) of the
Studied Rats.
The method described by Shi et al. [13] was used in
determining the PBC content of the rats fed with yellow
fleshed Gari diets. 0.2 ml serum sample was pipetted into
a set of sterile graduated beakers. 10 ml of extraction
solvent was added and mixed properly. Extraction sol-
vent is a mixture of 0.1% of quinol plus acetone and light
petroleum. The supernatant was transferred to a separating
Table 1. Feed composition of the four groups of rats used in the study .
Nutrients Sources % Group 1: Control (kg)Group 2: Basal (kg)Group 3: *EGS 1 (kg) Group 4: *EGS 2 (kg)
Energy White Gari 72 3.6 3.6 1.8 1.8
Protein Casein 10 0.5 0.5 0.5 0.5
Fat Vegetable oil 8 0.4 0.4 0.4 0.4
Dietary fiber Wheat Bran 5 0.25 0.25 0.25 0.25
Minerals Bone meal 4 0.20 0.20 0.20 0.20
Vitamins Pre-mix 1 0.05 0.05 0.05 0.05
Beta carotene Carrot 0.03 - - -
EGS 1 - - 1.8 -
EGS 2 1.8
Total 100 5.0 5.0 5.0 5.0
*Experimental Gari samples.
Bioavailability of Beta Carotene in Traditional Fermented, Roasted Granules, Gari from Bio-Fortified Cassava Roots
funnel containing 5 ml ultra-pure water after shaking for
10 min. Another 10 ml of ultra pure water was added and
shaken to dilute acetone in the supernatant solution light
petroleum solution from which the acetone had been re-
moved was then transferred to the top of the column
while gentle suction was applied to assist the passage of
the liquid through the column. The beta carotene passed
straight through the column, leaving all other fractions
absorbed on top of the column. Light petroleum was then
used to rinse the column to ensure complete removal of
the BC. (Colorlessness of the eluate was an indicator of
complete elution.) The sample solution was made up to
25 ml column while it was stored for use for BC analysis
using HPLC.
All samples were analyzed under gold fluorescent light
to prevent photo-oxidation and isomerization.
3.2.5. Calculat i on of B ioavailable Beta C arotene (BC)
The bio availability was calculated using a conventional
linear dose response plot. Concentration of BC in diet
was on x axis while the y axis has the concentration of
plasma BC. The slope was then calculated in percentage.
3.2.6. Determinati on of Vitamin A (Retinol) in the
Liver of Rats Fed with Bio-Fortified Gari Diets
Sample Extraction for Vitamin A (Retinol) Determination
0.5 gram of the liver samples were ground, homoge-
nized with 1.15% potassium chloride and then mixed
with 9 ml hexane-2 propanol (2:3). 0.125 µL of the liver
sample was measured into a set of clean test tubes and
made to 500 µL volume with ultra pure water. 1.0 g/L of
ascorbic acid was added as an antioxidant and shaken for
5 min followed by another 5 min sonication. To the mix-
ture, 0.5 g/L of Triton (a detergent) and 400 µL acetoni-
trile was added and thoroughly mixed. This acted as the
internal standard. Also, 400 µL n-hexane was measured
and added. (This contained 5 g/L BHT). The mixture was
vigorously shaken for 4 min and centrifuged for 2 min at
8000 rpm. The supernatant was collected for Vitamin A
(Retinol determination in HPLC).
Sample extracts were injected into the HPLC. The
separation was carried out, using BDS Hypersil CN 150
mm, 5 µm columns in combination with a javeln NH2
guard column. The isocratic mobile phase consisted of
hexane isopropanol (98.5:1.5). The flow was fixed at a
rate of 1.5 mL/min while the wavelength was set at 325
nm. Diode array detector was used to check the purity of
the peaks.
3.2.7. Calcul a t i on of Hepati c Re ti nol C on v ersi on
The HRC was calculated in percentage of the slope of
graph of liver retinol versus BC in feed. Concentration of
BC in diet was on x axis while the y axis has the concen-
tration of retinol in the liver of the rats.
3.2.8. Statistical Analysi s
Values are means ± SD. Data was analyzed using statis-
tical Analysis Software (SAS version 9.5). Outcome of
interests were rat weight gain, rat feed intake, plasma
beta carotene, and liver vitamin A. Beta carotene con-
centrations were evaluated using 1-way ANOVA. Dif-
ferences between treatment groups were determined us-
ing least significant differences, LSD at α < 0.05. A cor-
relation between rat plasma and feed BC was also deter-
mined with Pearson correlation analysis.
4. Results
4.1. Carotenoid Concentration of Gari Samples and
Carrots Used for Bioavailability Study
No beta carotene was detected in the white Gari used for
the study and the basal diet. The carotenoid profile in the
two Gari samples used for the bioavailability study is as
shown in the Table 2. The two samples were not signifi-
cantly different from each other in terms of carotenoid
profile. The 13-cis isomers for sample from 01/1412 and
01/1371 were 0.88 µg/g and 0.85 µg/g respectively. Also,
15-cis isomers were 0.28 µg/g and 0.26 µg/g respectively.
The same trend was found in other carotenoid.
The carotenoid profile of the carrot was relatively
higher than those of bio-fortified cassava roots. The B-
cryptoxanthin was 1.2 µg/g while the 13-cis and 15-cis
BC were 104.4 µg/g and 3.34 µg/g respectively. For the
trans isomer, it was 167.3 µg/g and that of 9-cis was 5.95
µg/g. The total BC in the carrot used (on fresh weight
basis) was 84.23 µg/g.
Table 2. Mean beta carotenoid profile of carrot and the gari samples used for bioavailability study.
S/N B-cryptoxanthin 13-cis β carotene 15-cisTrans 9-cis Total BC
Conc (µg/g)
01/1412 fermented for 1 day & roasted at 80˚C 0.89 0.88 0.28 2.01 1.59 4.76
01/1371 fermented for 1 day & roasted at 120˚C 0.93 0.85 0.26 1.97 1.56 4.64
Carrots 1.20 104.40 3.34 167.3 5.95 84.23
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4.2. Results of the Bioavailability Study
4.2.1. Mean Weekly Rat Weight Gain and Feed
All the animals in their various groups gained weight all
through the study irrespective of feed composition of
each group. The mean rat weight gain across the group
was 5.3 g and ranged from 4 to 7 g with significant dif-
ference (p < 0.001) in their weight gain.
Across the group and over the study period, the feed
mean weekly intake was 55 g and ranged from 47 to 67
gram. Statistically, there was a difference (p < 0.001) in
intake among the rats. Rat weight gain was correspon-
dent to feed intake across the groups; the more the intake,
the more the rat weight gain and vice versa. Table 3
shows the summary of the mean weight gain and food
intake across the groups.
4.2.2. Mean Feed and Plasma BC Concentration
The mean feed BC was 114 µg/g, 112 µg/g and 113 µg/g
for acclimatization, first and second 2 weeks respectively
with significant difference across the groups of the ani-
mals. After the acclimatization week, the mean plasma
beta carotene (PBC) was 64 µg/dL with a range of 61.4
to 68.5 µg/dL and the concentrations did not differ statis-
tically across the groups as shown in Table 4. For the
Table 3. Mean of rats weight gain and feed intake across the groups during the e xperimental feeding.
Group W1 (g)W2 (g) W3 (g) W4 (g)Mean (g) Fd1 (g)Fd2 (g)Fd3 (g) Fd4 (g) Mean (g)
Control 4.1 7.6 7.6 8.6 7.0 44.2 51.9 53.2 54.4 49.4
Basal 3.3 5.2 6.3 7.3 5.5 63.5 69.3 64.7 65.6 66.7
Experimental 1 1.8 3.9 4.2 6.1 4.0 51.3 58.5 53.9 53.6 55.5
Experimental 2 2.4 3.0 6.0 7.8 4.8 48.3 56.6 48.2 55.4 51.6
Means 2.9 4.9 6.0 7.5 5.3 51.82 59.1 55.0 57.3 55.8
Min 1.8 3.0 4.2 6.1 4.0 44.2 51.9 48.2 53.6 48.2
Max 4.1 7.6 7.6 8.6 7.0 63.5 69.3 64.7 65.6 66.7
CV (%) 10.5 15.9 16.5 19.6 16.4 19.8 22.4 20.0
LSD (0.05) 5.6 9.4 10.4 13.2 8.0 10.9 11.6 10.7
Pr. > F ** ** ** ** ** ** ** ns
**p = 0.001, ns = not significant. W1, W2, W3 and W4 are the weight of rats in the first, second, third and fourth week of feeding respectively. Fd1, Fd2, Fd3
and Fd4 are the weekly food intake of rats in the first, second, third and fourth week.
Table 4. Mean of Beta Carotene (BC) in feed and plasma during the experimental feeding.
Group F12BC (µg/g) F34BC (µg/g) Mean (µg/g) BC1 (µg/dl) BC2 (µg/dl) Mean (µg/dl)
Control 86.5 96.9 74.1 69.9 51.5 60.9
Basal 0 0 0 60.1 51.3 60
Exptl 1 185.8 181.9 194.6 59.8 58.1 60.5
Exptl 2 177.4 175.4 185.3 63.6 57.5 61.2
Means 112.4 113.5 113.5 63.4 54.6 60.6
SD 87.39 84.98 93.38 4.73 3.73 0.53
SE 43.7 42.5 46.7 2.4 1.9 0.3
Min 0 0 0 59.8 51.3 57.5
Max 185.8 181.9 194.6 69.9 58.1 65.5
CV (%) 21.2461 23.4504 13.3 27.9
LSD (0.05) 22.098 24.603 7.87 14.2
Pr. > F ** ** *
**p = 0.001, *p = 0.01, ns = not significant. F12BC and F34BC are the BC in feed taken during, first 2 wk and last 2 wk respectively. BC1 and BC2 are the BC
the rat plasma after first 2 wk and last 2 wk respectively. in
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Bioavailability of Beta Carotene in Traditional Fermented, Roasted Granules, Gari from Bio-Fortified Cassava Roots
basal group, PBC maintained a consistent drop since the
feed was deficient in BC. However, for the two experi-
mental groups, the mean PBC after the four week feeding
was 60.5 and 61.2 µg/dL for 01/1412 and 01/1371 re-
spectively. No significant difference was found in the
PBC of the two samples. On the association between
feed and plasma BC, a very weak linear relationship was
found (Table 5).
4.3. Bioavailability and Relative Bioavailability
Figures 1-3 show result of the BC bioavailability in form
of linear dose response plots of the BC concentration of
the feed consumed by the rats and that of the plasma for
acclimatization using carrots and the experimental feeds
from samples 01/1412 and 01/1371 respectively.
Table 6 shows the result of Bioavailability of BC in
GFBCR across the two varieties. The mean bioavailabil-
ity was between 8.5% and 17.4%, and a significant dif-
ference (p < 0.05%) was found between the two studied
samples with that of variety 01/1371 was higher (17.4%).
5. Discussion
The carotenoid profile of the two gari samples is note-
worthy for its high trans BC content, biosynthesis of each
Table 5. Pearson correlation coefficients of plasma and feed
BC0 0.17625 0.16817 0.18441
0.2898 0.3129 0.2677
BC1 0.10557 0.07716 0.05562
0.5282 0.6452 0.7401
BC2 0.19504 0.11509 0.12906
0.2406 0.4914 0.4400
N = 38.
Table 6. Bioavailability and liver yield of BC in the rat
Groups BAV after
1st 2 wk (%)
BAV after
2nd 2 wk
Control 29.30 46.60 37.95 1000.120
Basal 0.00 0.00 0.00 0000.020
diet 1 6.26 10.80 8.53 0.220.026
diet 2 18.45 16.44 17.44 0.460.011
1. 01/1412 fermented for I day & roasted at 80˚C; 2. 01/1371 fermented for I
day & roasted at 120˚C; BAV: Bioavailability.
Figure 1. Graph of plasma BC Vs feed BC of the rats at
Figure 2. Graph of plasma BC Vs feed BC of the rats in diet
from BFCV of Gari sample 1 (01/1412 fermented for 1 day
and roasted at 80˚C).
Figure 3. Graph of plasma BC Vs feed BC of the rats in diet
from BFCV of Gari sample 1 (01/1371 fermented for 1 day
and roasted at 120˚C).
of its 5 major carotenoids is likely to be up regulated in
these varieties since BC is the precursor of beta cryp-
toxanthin and zexanthin [14]. Also, there was an appre-
ciable percent of BC in the total carotenoid, which
agreed with Chavez et al., [15]. This is advantageous in
bio-accessibility of the carotenoid from cassava and a
promising attribute of cassava as a vehicle to fight vita-
min A deficiency challenge in Africa, where cassava is a
staple crop.
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There was a strong linear relationship between feed
intake and animal weight gain; this means that irrespec-
tive of BC content, the more the animal eat the food, the
more their weight gain (the feed composition was ade-
quate to maintain the animal weight gain) although the
hidden hunger of vitamin A deficiency could still be
From the bioavailability study, a large variation of
PBC and hepatic retinol among animals within each
group was found. This suggested a marked variability in
BC utilization and efficiency of conversion of BC and
storage of vitamin A among individual rats, which agreed
with the report of Siqueira et al., [16]. The significant
difference found in the bioavailability result of the two
samples of gari showed the effect of cassava varieties in
the bio-accessibility of pro-VA carotenoids for absorp-
tion. Gari from yellow-fleshed cassava root especially
that from variety 01/1371 had appreciable level of
bioavailable beta carotene, which could have been fa-
vored by the other nutrient components in the feed for-
mulation [17]. Also fermentation of the cassava mash
could have improved BC absorption, although short in
this study. Fermentation provides an optimal pH for en-
zymatic degradation of phytate, which may increase the
amount of soluble calcium, iron and Zinc [18] and then
enhance that of BC. According to Hedren, et al. [19],
when carotenoids are retained after processing, disrup-
tion of the plant matrix markedly enhances their potential
for intestinal absorption (bio-accessibility). Grating and
fermentation in gari processing had disrupted the food
matrix thus easy bounding to protein and lipid molecules
in the feed formulation, hence, improved BC absorption
by rats [16,20]. However, it was observed that intake of
the Gari-based feed could be increased if the feeds are
presented in grits, bigger particle sizes or pellets rather
than smooth and low particle size [17]. This may trans-
late to increased bioavailability although the correlation
between feed intake and plasma BC was found to be very
weak. This shows that there are other factors, apart from
intake that are responsible for nutrient bioavailability.
These include types of carotenoid, molecular linkage,
amount of carotenoids consumed in a meal, matrix in
which the carotenoid is incorporated, effectors of absorp-
tion and bioconversion, nutrient status of the host, ge-
netic factors, host-related factors, and mathematical in-
teractions [17,21]. Also, there is a level that intake of the
nutrient may not result in increased bioavailability. This
is in agreement with the published reports [17,22]. The
efficiency of carotenoid absorption is typically inefficient,
being affected by structure of carotenoid, nature of the
embedding matrix, level of dietary fat, nature and type of
carotenoid, food matrix, style of processing, other dietary
components, and nutritional and physiological status,
presence of antioxidants and fibers. Thus, reliable pre-
diction of carotenoid bioavailability is problematic. How-
ever, from this study, cassava beta-carotene could main-
tain rat growth and avoid vitamin A deficient symptoms.
This also agreed with the report of Siqueira, et al. [16].
6. Conclusion
Gari from some bio-fortified cassava varieties especially
that from 01/1371, processed at low temperature and
short fermentation period had appreciable bioavailable
BC, which can maintain rat growth and prevent vitamin
A deficient symptoms, beside the hepatic retinol recov-
ery. This could be an important step to improve the nutri-
tional quality of the popularly consumed Gari and to
protect the health of the consumers. The relatively good
retention of BC during traditional processing of cassava
provides additional experimental support for the feasibil-
ity of cassava bio-fortification as a means to alleviate
vitamin A deficiency. From the result of the bio-avail-
ability, cassava can be used as a sustainable vehicle to
reduce vitamin A deficiency in the sub Saharan Africa.
Bio-fortification is a promising new approach, which is
technically feasible and the nutritionally enhanced foods
can help to control micronutrient deficiencies. It could be
an important tool for improving nutritional status in de-
veloping countries. Although, the magnitude of the prob-
lem requires a combination of strategies, of which bio-
fortification is just one. However, further work is neces-
sary on public awareness and adoption of the product
while cassava breeders should target higher level of bio-
fortification, taking cognizance of losses during process-
ing and storage.
7. Acknowledgements
We thank the International Institute of Tropical Agricul-
ture, Nigeria for providing the cassava roots and facilities
for gari processing. Also, Dr(s). R. A. Sanusi, O. T. Ade-
poju and Folake Samuel of Department of Human Nutri-
tion, University of Ibadan. Nigeria; the entire staff of the
Department of Animal Sciences, University of Ibadan
especially Mrs. Lawal and Mr. Idris. Finally, Ms. Seri
Agbato amd Mr. Segun Dare for assisting in the rat study,
and Mr. Moshood Bakare for the data analysis.
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BC: Beta Carotene;
PBC: Plasma Beta Carotene;
VAD: vitamin A deficiency;
HPLC: High Performance Liquid Chromatography;
TCC: Total Carotenoid Content
BFCV: Bio-Fortified Cassava Varieties
GBFCV: Gari from Bio-fortified Cassava Varieties
HRC: Hepatic Retinol Conversion
LSD: Least Significant Difference
EGS: Experimental Gari Sample