Transcript nutrition software

Optimization of the nutritional quality
characteristics of cowpea-fortified nixtamalized
maize using computer-generated response surface
models
Afoakwa E. O., Sefa-Dedeh, S., Cornelius B.
& Sakyi-Dawson E.
Department of Nutrition and Food Science
University of Ghana, Legon, Ghana
INTRODUCTION

Nixtamalization
- Defined
- Nutritional significance

Cowpea fortification

Combined effects of nixtamalization, cowpea
fortification and fermentation

Response surface methodology, an IT
software program.
NIXTAMALIZATION
This refers to the alkaline cooking of corn (Zea mays).
The process involves the cooking and steeping of corn
in excess water containing calcium hydroxide (lime)
solution.
The process can be used to obtain products such as:
 Tortillas
 Tacos
 Tortillas chips
 Corn chips
 Other related products
NUTRITIONAL SIGNIFICANCE:
 Decrease in tannin levels in high tannin grains
 Increase in free calcium levels
 Increase in bioavailability of iron and other
related minerals
 Faster release of amino acids
 Increase in free nicotinic acid
 Increase in availability of niacin
(Hulse et al., 1980; Bharati and Vaidehi, 1989;
Sefa-Dedeh et al., 2002)
COWPEA FORTIFICATION
As a means of resolving the problem of low
energy density of cereal-based foods caused
by high starch content of cereals, cowpea
fortification has led to improvements of the
protein quality and quantity of cereal-based foods
(Afoakwa, 1996; Sefa-Dedeh et al., 2000; SefaDedeh et al., 2001).
COMBINED EFFECTS ...
The combination of nixtamalization, cowpea
fortification and fermentation may prove a means of
improving product functionality, protein nutrition
and micro-nutrient availability in African traditional
foods.
These processes will help introduce variety to the
traditional food base and as well improve food
and nutrition security of Africans.
Response surface methodology
This is a statistical-mathematical method which
uses quantitative data in an experimental design to
determine and simultaneously solve multivariate
equations, to optimize processes or products.
Main objective:
The study aimed at investigating the quality
characteristics of cowpea-fortified nixtamalized
maize using response surface models generated
from STATGRAPHICS an IT software program.
MATERIALS AND METHODS:
 Corn (Zea mays) – Accra market
 Cowpea (Vigna unguiculata) – Crop
Research Institute in Ghana
 Lime (Calcium hydroxide) food grade –
BDH Chemicals Ltd., Poole, England.
Experimental design
A central composite rotatable design (CCRD) for K=3 was
used with variables, Lime concentration (X1), Moisture
content (X2) and Cowpea level (X3) ;
Process variables in CCRD for K=3
.
Variables
Lime concentration (%)
Cowpea level (%)
Moisture content (%)
Variable levels
-1.682
-1
0
0
0.2
0.5
0
6.09
15.02
55
57.03
60
.
1
0.8
23.95
62.97
1.682 .
1
30
65 .
Flow diagram for the preparation of
nixtamalized maize meal
Whole grain
Cook in lime(30 min)
Steep in cooking liquor (18 hours)
Cooked maize (Nixtamal)
Wash
Washed Nixtamal
Mill
Fresh Nixtamalized maize meal
ANALYTICAL METHODS:
 Moisture and protein analyses – AOAC (1990)




pH and Titratable acidity – (Sefa-Dedeh et al, 2000)
Water absorption capacity (Yasumatsu et al., 1972)
Brabender cooked paste viscosity – AACC (1983)
Texture analysis – TA.XT2 Texture Analyzer
RESULTS
pH: The model equation used for the plot is:
Y = -5.3913 + 1.5875X1 + 0.3239X2 – 0.8801X12 – 0.0028X22
Titratable acidity
The model equation : Y = 0.3515 + 0.0055X3 - 0.0017X1X2
Protein content
Y = 15.1290 –0.5079X3 - 0.0017X22 – 0.0013X32 + 0.0103X2X3
Water absorption capacity
Y = 267.1099 + 95.9725X12 - 0.1623X32 – 4.6429X1X2
+0.0524X2X3
Cooked paste viscosity
Y = 109.06 + 316.45X1 – 6.011X3 – 378.44X12 – 0.1747X32
CONCLUSIONS

Lime and cowpea concentration
significantly influence the titratable
acidity, water absorption, protein content
and cooked paste viscosity of fermented
cowpea-fortified nixtamalized maize.

Cowpea fortification in combination with
fermentation can be employed to further
improve the functionality, protein quality
and quantity of energy dense nixtamalized
maize.
CONCLUSIONS (Contd.)

Alkaline cooking improves the protein content
of nixtamalized maize products, which even
become higher when fortified with cowpea.

Nixtamalization, cowpea fortification and
fermentation can be employed in the
improvement of the nutritional quality of
traditional foods made from maize.

IT software programs can be used to optimize
the nutritional quality of processed foods.
Acknowledgement
This study was funded through the
Bean-Cowpea (CRSP) Project by
the USAID Grant No.
DAN-1310-G-SS-6088-00
THANK YOU FOR YOUR
ATTENTION.