QUALITY OF CORN EXTRUDATES AND EXTRUDATES FROM SELECTED CORN

PRODUCTS Dragan Živančev, Slavko Filipović, Šandor Kormanjoš, Jelena Filipović, Marijana Sakač

Institute for food technology, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia

ACKNOWLEDGEMENTSThis 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),

ABSTRACTFood 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 technico-technological parameter of the process, physico-chemical composition and microbiological safety of raw materials before and after extrusion.

CONCLUSIONSStable 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.

Table 1. Particle size distribution of whole-milled corn and light buckwheat flour

Sieve mash Ø (mm)

Sieve overtails (%)Whole-milled corn Light buckwheat

flour/

2.00 19.1 -1.25 25.9 -1.00 9.9 -0.63 13.6 0.20.25 19.9 8.5

0.125 11.5 32.60.63 0.1 46.8

Bottom - 11.9

Table 2. Chemical composition of extruded products and raw materials

Quality characteristic

Whole-milled

corn (%)

Light buckwheat flour (%)

Mixture (90% whole-milled

corn: 10% light buckwheat flour)

Extruded mixture at

115 °C

Extruded mixture at

150 °C

Moisture 17.32 11.70 16.76 13.30 9.63Crude proteins 7.44 11.38 7.83 8.44 8.50

Crude fat 3.44 2.71 3.37 3.40 2.92Starch 62.12 69.16 62.82 65.87 66.90Total sugars

1.44 1.48 1.44 2.16 3.60

Reducing sugars 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 characteristics

Whole-milled

corn (%)

Light buckwheat flour (%)

Mixture (90% whole-milled corn: 10%

light buckwheat

flour)

Extruded mixture at

115 °C

Extruded mixture at

150 °C

Crude proteins 9.00a 12.89c 9.41ab 9.73b 9.41ab

Crude fat 4.16a 3.07b 4.04a 3.92ac 3.23bc

Starch 75.13a 78.32d 75.47ab 75.97b 74.03c

Total sugars 1.74a 1.68a 1.73a 2.49b 3.98c

Reducing sugars 1.16a 0.67bc 1.11a 0.99ac 0.53b

Table 4. Particle size distribution of milled corn

Sieve opening (Ø, mm)

Sieve overtails(%)

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 -

Tabela 5. Chemical composition of milled corn and extruded corn at 90 and 95 °Cin dry matter 22

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 8. Particle size distribution of enriched corn meal and extruded enriched corn meal

Sieve opening(Ø, mm)

Sieve overtails (%)

Corn mealExtruded corn

meal4.00 0.00 0.302.00 0.50 3.001.25 5.00 9.001.00 11.85 7.850.63 23.85 34.300.25 25.75 36.45

0.125 27.55 8.200.63 5.00 0.90

Bottom 0.50 0.00

Table 7. Physical and chemical characteristics of enriched corn meal and extruded enriched corn meal (T = 95 ° C)

Quality characteristicsCorn meal Extruded corn meal at

95 ° C

Water content (%) 14.5 8.50Crude protein content (%) 11 11.0Celullose content (%) 3.5 3.50Starch content (%) 55 50.68Ash content (%) 4.0 2.50Fat content (%) 7.5 7.50Phosphorous (%) 0.50 0.50Calcium (%) 0.20 0.20β-carotene content (mg/kg) 1.10 1.11Test weight (g/l) 526.1 359.0