Transcript Title: Nutritional evaluation of Cassava (Manihot esculanta

Title: Nutritional evaluation of Cassava (Manihot esculanta) Fractions (Flesh, Peels and
Leaf) from select cultivars
S. K.
1,2,4
Mutayoba ,
C.M.
3
Fauquet ,
and E S.
4
Dierenfeld
1Sokoine
University, Morogoro, TANZANIA; AWARD, Nairobi, KENYA;3Danforth Plant Science Center, St. Louis, MO USA;
4Novus International, Inc. St. Charles, MO USA
Abstract
Dried and ground fractions of peels, leaves and flesh samples of the
improved (p746, p768 and p770) and unimproved (WT) cassava cultivars
were assessed for their proximate composition, carotenoids, minerals,
amino acids and HCN,
Crude protein on DM basis averaged 5.3, 9.6 and 28.5 % for the flesh,
peels and leaves, respectively. Generally the genetically improved
cassava cultivars contained higher levels of protein (2.4% (WT) and 8.1%
(p746) for the flesh), TAA, and other macronutrients compared to
unimproved variety. HCN varied in the flesh among varieties and was 96
in WT and 141 mg/kg in p746.
Fiber fractions (NDF, ADF and lignin) were highest in leaves and lowest in
flesh. Both total amino acid and individual amino acids concentrations
were 2 to 10 times higher in peels fractions compared to flesh of the
same variety. Total carotenoid concentration in the flesh was 0.04 mg/kg
in WT and 1.01 mg/kg in p746. ß-carotene was the primary carotenoid
pigment in the flesh and peels, 75-93% whereas in cassava leaves lutein
was 54-64%. Mineral levels were highest in leaves, followed by peels,
and lowest in the flesh.
This study revealed nutritional differences between cassava cultivars and
plant parts. Furthermore, cassava peels, normally thrown away
contained higher nutrients and therefore could be a good source of
nutrients in livestock diets
RESULTS
Fig 1(b): SP- Flesh
Fig1(a): CP - Flesh
9
8
7
6
5
4
3
2
1
0
% Soluble protein
% Crude Protein
Nutrient Composition
The chemical composition, and nutritive values, for various plant
parts in the cassava cultivars are presented.
Crude protein (CP) content in the various parts averaged 4.98,
8.85 and 26.67% for the flesh, peels and leaves, respectively, with
widest variation observed in CP for the flesh (2.4% (WT) to 8.1%
(p746)). CP concentration was lowest in the unimproved (WT)
cultivar parts when compared to other cultivars. Soluble protein
(SP) and NFC values were highest in the flesh, and lowest in
leaves, whereas fiber fractions (NDF, ADF, and lignin) were
highest in leaves and lowest in the flesh. With the exception for
SP in leaves (only) and NFC (all parts), nutritive constituents were
lowest in the WT variety.
Series1
100
90
80
70
60
50
40
30
20
10
0
•The mineral concentration of the different parts of cassava
showed higher levels in leaves followed by peels and lastly
flesh.
WT P770 p768 p746
WT
P770
p768
Cassava varieties
p746
Cassava variety
Fig 1 (d): SP- Peels
Fig 1©: CP- Peels
% Crude Protein
The cassava plant originated in South America and has spread globally as
an important food crop for 500-800 million people in Africa, Asia and Latin
America. It can be grown under harsh conditions such as low rainfall and
poor soils. The major limitations to utilization are mainly due to sub
optimal nutritional value including low protein content (average ~ 2-4%
protein in cassava, although levels <1% have been reported; Nasser and
Souza, 2007), low vitamin A value, and the presence of cyanogenic
(hydrogen cyanide, HCN) and/or phenolic compounds (Montagnac et al,
2009). Additionally, cassava shows a strong tendency for post-harvest
physiological deterioration (PPD). Recently targeted genetic studies to
enhance the nutritional properties of specific cassava cultivars such as
lowering cyanogens (Jorgensen et al., 2005), increasing ß-carotene
(Akinwale et al., 2010), and/or increasing protein content (Stupak et al,
2006; Abhary et al., 2011) have been carried out. However the resulting
nutritional value for the different cassava parts which can be useful to
animals have not been investigated in detail.
Thus main objective of this preliminary study was to evaluate the nutritive
value of root (flesh), peel, and leaf fractions of the four select cultivars of
cassava (1) unimproved, 2) high-protein, 3) high-ß-carotene, 4) both high
protein and high ß-carotene) as potential byproduct feed for livestock
production.
16
14
12
10
8
6
4
2
0
% Crude protein
INTRODUCTION
100
90
80
70
60
50
40
30
20
10
0
WT
WT
p770
p768
p770
p768
p746
Cassava variety
p746
Cassava variety
Amino Acids
• The mean values for amino acid (AA) composition in the flesh and
peel samples from 4 cassava cultivars are presented in Fig. 2.
•Variation in the distribution of AA, both among varieties and
between plant parts, was noted; variation was higher between peel
compared to flesh fractions.
•Both total amino acid (TAA) and individual AA concentrations were 2
to >10X higher in peel fractions compared to flesh of the same
cassava varieties, depending on the individual AA. Differences in AA
distribution between plant fractions, however, did not appear to be
directly correlated.
•The total concentrations of most AAs were consistently lower in the
WT variety for both plant parts.
•The essential amino acid levels relative to nutrient requirements of
livestock (Ideal Protein (AA) Ratios), both flesh and peels of cassava
were below Ideal AA ratios in all AA except ARG, HIS and TRP for
poultry. In both plant parts, MET, CYS, TYR and TRP were relatively
low while ASP, GLU and ARG were high.
Materials and Methods:
Cassava materials
Samples of dried and ground fractions (tuber flesh, peels, and leaves)
of 4 cassava cultivars (WT (unimproved), p746 (high protein), p768
(high ß-carotene) and p770 (both high protein & ß-carotene) from
ITLAB Danforth Center, St Louis, USA were analyzed to determine
proximate composition and amino acid profiles (tuber fractions only),
cyanide,, carotenoid pigments, and mineral content using standard
laboratory methods.
0.45
Amino acids conc. peels and flesh
0.4
0.35
0.3
% Amino acid
Laboratory analysis
Dried, ground fractions (flesh, peel, leaf) were subjected to laboratory
analyses to determine proximate composition (crude and soluble protein,
crude fat, non-fiber carbohydrates (NFC), ash), fiber fractions (neutral
detergent fiber, NDF; acid detergent fiber (ADF), and lignin), and macroand trace mineral concentrations, as well as calculated energy content
using standard (AOAC, 1990) methods.
Amino acids were characterized using AOAC Official Methods of Analysis
(2006) method 982.30 E (a,b,c).
Anti-nutritional properties (cyanic acid and HCN were characterized using
picrate paper kits for determination of total cyanogens in cassava roots
and all tuber products described by Bradley et al (1999) total
polyphenols were measured as catechins using a Folin-Ciocalteu UV
methodology (Singleton et al, (1999) and the carotenoids profile was
determined using spectrophotometer.
0.25
Flesh
Peels
0.2
0.15
0.1
0.05
0
ASP
THR
SER
PRO
GLY
HCN and Carotenoids
Differences among varieties were noted for HCN in the flesh,
ranging from (96 to 141 mg/kg) in varieties WT and p746,
respectively.
Total carotenoid content differed both among cassava cultivars
and plant parts. Total carotenoid concentration was negligible
in the WT flesh cultivar(0.04 mg/kg), and highest in p746 (1.01
mg/kg).
ß-carotene was the primary carotenoid pigment
detected in flesh and peels, comprising 75-93% of total
carotenoids measured. In contrast, cassava leaves contained
more of lutein, contributing 54-64% of total carotenoids
measured. α-crypotxanthin and lycopene were not detected
in all but zeaxanthin was less than 10% of total carotenoids in
the plant fractions
Energy and Minerals
•The energy content was flesh>leaf>peel fraction, although in
Cultivar p746, peels contained higher calculated energy
compared to leaves.
ALA
CYS
VAL
MET
ILE
LEU
TYR
PHE
LYS
HIS
TRP
Macro- and trace minerals concentrations in cassava (Manihot esculanta) cultivars/parts.
(air-dry basis)
Cultivar/
WT p770 p768 p 746 WT p770 p768 p746 WT p770
Part
Tuber Tuber Tube Tube Peel Peel Peel Peel Leaf Leaf
r
r
Ash, %
2.26 1.94 3.76 6.15 4.14 6.23 5.91 5.45 5.81 5.54
Macrominerals,
%
Calcium
0.06 0.06 0.14 0.19 0.69 1.15 1.25 0.85 0.99 0.76
Phosphorus
0.13 0.13 0.18 0.19 0.11 0.15 0.14 0.12 0.33 0.36
Magnesium
0.07 0.07 0.15 0.15 0.08 0.20 0.17 0.14 0.32 0.27
Potassium
1.13 0.87 1.73 3.04 1.25 1.52 1.30 1.46 1.34 1.70
Sodium
0.02 0.04 0.06 0.07 0.01 0.03 0.02 0.02 0.02 0.02
Sulfur
0.02 0.04 0.03 0.03 0.09 0.33 0.29 0.18 0.42 0.36
Trace Minerals,
mg/kg
Copper
Iron
Manganese
Molybdenum
Zinc
3.00
14.00
3.00 4.00 5.00 <1.0 6.00 3.00 2.00 7.00 7.00
9.00 10.00 12.00 52.00 66.00 66.0 44.00 86.00 73.00
0
12.00 10.00 23.00 25.00 12.00 97.00 63.0 43.00 217.0 133.0
0
0
0
<0.1 0.10 0.30 0.30 0.80 <0.1 0.50 1.10 1.00 1.00
6.00 6.00 8.00 10.00 20.00 40.00 35.0 40.00 57.00 51.00
0
Discussion:
Crude protein content of 2.4% for WT was within the range of
unimproved varieties (1.2-4.72%) reported in the literature.
Higher CP noted in the other cultivars did conform to findings
reported by Abhary et al., 2011. A change in the distribution of
nutrients was also noted. Differences in CP content between
cassava varieties are normally observed and in most cases the
bitter varieties have slightly higher protein content. The higher
CP content in the peels observed in the present study was
similar to findings reported by Okigbo 1980) and was slightly
higher for the sweet variety.
Conclusion
This study showed nutritional differences between cassava
cultivars and plant parts. The transgenic varieties contained high
protein compared to normal cassava cultivars. Additionally
cassava peels, normally thrown away contained higher nutrients
compared to the flesh and therefore could be a good source of
nutrients in livestock diets. Further studies to determine nutrient
utilization are recommended.
Acknowledgments
The authors would like to thank ITLAB Danforth Center, USA for
providing the research materials, NOVUS International, Inc, USA
for laboratory analyses and AWARD program, for granting
research fellowship to S.K.Mutayoba.