Changes in the structure and the composition of proteins and oils in soya bean grain affected by infrared and microwave radiation
2007
Žilić, S., Maize Research Institute Zemun Polje, Belgrade - Zemun (Serbia) | Šobajić, S., Faculty of Pharmacy, Belgrade (Serbia). Institute of Bromatology | Božović, I., Maize Research Institute Zemun Polje, Belgrade - Zemun (Serbia) | Kovčin, S., Faculty of Agriculture, Novi Sad (Serbia)
The grain of the soya bean cultivar ZPS 015 was exposed to the microwave treatment during 1, 2, 3, 4, and 5 minutes and to infrared rays at the temperatures of 100 deg C, 125 deg C, 140 deg C and 150 deg C. Depending on a thermal treatment, temperature and duration of grain exposure to the increased temperature, the content of total proteins varied in soya bean products. The temperature increase in both applied treatments caused the reduction of proteins soluble in water and salt solutions, available lysine, trypsin inhibitor, as well as the reduction in the activity of urease and lipoxyhenase 1. The temperature developed in the microwave treatment did not result in significant change in the oil content, while this content was statistically significantly higher in soya bean flakes than in raw grains. Palmitic acid showed thermostability. The reduction in the content of polyunsaturated fatty acids that was not compensated by the increase in the content of unsaturated fatty acids with a lower number of double bonds in the molecule, resulted in the increase in the stearic acid content mainly in micronised soya bean products. Noticable thermal degradation of linolenic acid was observed already at the initial temperatures. However, a further temperature increase did not have a greater effect on the linolenic acid content in soya bean products. Micronisation process had greater impact on the polyunsaturated fatty acid content in comparison with the microwave treatment.
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