Dragan Živančev, Slavko Filipović, Šandor Kormanjoš, Jelena Filipović, Marijana Sakač
Institute for food technology, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia
ACKNOWLEDGEMENTS
This work was supported by Ministry of Science and Technological Development, Republic of Serbia, the Project No. 20068
(Foods for Consumers with Special Demands and Needs),
ABSTRACT
Food production worldwide is one of the major challenges of the modern life. Therefore, novel technology processes are applying to
increase the nutritional value of raw materials, food and feed. One sophisticated technological process for improving nutritional value
and quality of raw materials is extrusion.
Heat treating of cereals is used for improving their nutritional, hygiene, physico-chemical and other properties, i.e. it increases the
nutrient value of some nutrients, improve sensory properties (i.e. increasing, "sweetness" of extruded product), provides the
microbiological safety of the products and inactivate possibly present thermo-labile nutrients. This paper presents the technicotechnological parameter of the process, physico-chemical composition and microbiological safety of raw materials before and after
extrusion.
Table 1. Particle size distribution of whole-milled corn and light
buckwheat flour
Sieve mash Ø
(mm)
2.00
1.25
1.00
0.63
0.25
0.125
0.63
Bottom
Sieve overtails (%)
Whole-milled corn Light buckwheat
flour/
19.1
25.9
9.9
13.6
0.2
19.9
8.5
11.5
32.6
0.1
46.8
11.9
2.00
14.9
1.25
15.4
1.00
8.1
0.63
18.5
0.25
34.8
0.125
8.3
0.063
-
Bottom
-
Quality
characteristic
Moisture
Crude
proteins
Crude fat
Starch
Total sugars
Reducing
sugars
17.32
7.44
Light
buckwheat
flour (%)
11.70
11.38
Mixture (90%
Extruded
whole-milled
mixture at
corn: 10% light
115 °C
buckwheat flour)
16.76
7.83
13.30
8.44
Extruded
mixture at
150 °C
9.63
8.50
3.44
62.12
2.71
69.16
3.37
62.82
3.40
65.87
2.92
66.90
1.44
1.48
1.44
2.16
3.60
0.96
0.59
0.92
0.86
0.48
Table 3. Chemical composition of Chemical composition of extruded products
and raw materials in dry matter
Quality
characteristic
s
Crude
proteins
Crude fat
Starch
Total sugars
Reducing
sugars
WholeLight
milled buckwheat
corn (%) flour (%)
Mixture (90%
whole-milled
corn: 10%
light
buckwheat
flour)
Extruded
mixture at
115 °C
Extruded
mixture at
150 °C
Sieve opening
(Ø, mm)
4.00
2.00
1.25
1.00
0.63
0.25
0.125
0.63
Bottom
Quality
characteristic
Corn (%)
Extruded corn at
90 °C
Extruded corn at
95 °C
Crude proteins
9.25c
9.07b
8.97a
Crude ash
1.83b
1.56a
1.58a
Crude fiber
3.45c
2.47a
2.80b
Crude fat
4.80c
2.08a
2.66a
NSI
15.91c
6.66a
6.21a
Starch
70.90c
67.06b
64.98a
Total sugar
1.00a
3.99b
4.12b
Reducing sugar
0.40a
0.42a
0.45a
Table 7. Physical and chemical characteristics of enriched corn meal and extruded
enriched corn meal (T = 95 ° C)
Quality characteristics
9.00a
12.89c
9.41ab
9.73b
9.41ab
4.16a
75.13a
1.74a
3.07b
78.32d
1.68a
4.04a
75.47ab
1.73a
3.92ac
75.97b
2.49b
3.23bc
74.03c
3.98c
1.16a
0.67bc
1.11a
0.99ac
0.53b
Sieve overtails (%)
Extruded corn
Corn meal
meal
0.00
0.30
0.50
3.00
5.00
9.00
11.85
7.85
23.85
34.30
25.75
36.45
27.55
8.20
5.00
0.90
0.50
0.00
Tabela 5. Chemical composition of milled corn and extruded corn at 90 and 95 °C
in dry matter 22
Table 2. Chemical composition of extruded products and raw materials
Wholemilled
corn (%)
Table 8. Particle size distribution of enriched corn
meal and extruded enriched corn meal
Table 4. Particle size distribution of milled corn
Sieve opening
Sieve overtails
(Ø, mm)
(%)
Water content (%)
Crude protein content (%)
Celullose content (%)
Starch content (%)
Ash content (%)
Fat content (%)
Phosphorous (%)
Calcium (%)
β-carotene content (mg/kg)
Test weight (g/l)
Corn meal
14.5
11
3.5
55
4.0
7.5
0.50
0.20
1.10
526.1
Extruded corn meal at
95 ° C
8.50
11.0
3.50
50.68
2.50
7.50
0.50
0.20
1.11
359.0
CONCLUSIONS
Stable products were obtained by extrusion of whole-milled corn and light buckwheat flour mixture (ratio 9:1) at 115 ºC and 150 ºC.
Application of higher extrusion temperature caused greater changes in physico-chemical properties of extrudates. Statistically significant
changes in starch content, total and reducing sugar content, crude fat content and test wieght were detected for extrudate at 150 °C in
comparison with extrudate obtained at lower temperature (115 °C) and with nonterated mixture.
Corn extrusion at 90 and 95 ° C leads to physico-chemical changes in treated material, primarily to changes in the structure of proteins,
which is demonstrated through significantly different levels of NSI, and accompanied by statistically significant differences of crude
protein content. Dry extrusion of corn resulted in statistically significant changes of crude fat content in extruded product in comparison
to untreated corn. The starch content of extruded corn was statistically significantly lower, with the consequent increase in the content of
total sugar and reducing sugar.
Extruded enriched corn meal feed have higher nutritional value in comparison to the meal which is not extrude, also it is microbiological
safe.