Animal Science and Food Technology

Improving the quality of soybeans by alkaline microwave treatment

Alla Мakarynska, Olena Kananykhina, Tetiana Turpurova, Ilya Bozhko
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Abstract

The article aimed to investigate the effect of combined microwave and alkaline treatment on the nutritional value of soybeans and the degree of inactivation of trypsin inhibitors. Experimental studies were conducted on soybeans of Ukrainian origin with an initial moisture content of 9%. The buffer capacity of soybeans was determined and it was found that to achieve pH 8, it is necessary to add 1% baking soda by weight of the raw material. Three soybean fractions were studied: whole beans, coarse grinding (2-3 mm) and fine grinding (0.5 mm). It was found that the coarsely ground fraction demonstrated the optimal ratio between moisture retention capacity and alkaline solution permeability. Microwave treatment was carried out at a power of 600 W for 30-150 seconds with a step of 30 seconds. To assess the qualitative parameters, an infrared spectrometer was used to determine the activity of trypsin inhibitors and protein solubility in potassium hydroxide. The results showed that the combined microwave-alkali treatment provided more effective inactivation of trypsin inhibitors compared to pure microwave treatment. At a treatment time of 150 seconds, the activity of trypsin inhibitors decreased from 29.8 mg/g in the control sample to 7.1 mg/g in the microwave treatment and to 4.7 mg/g in the combined microwave-alkaline treatment, which is a decrease of 76.2% and 84.2%, respectively. At the same time, the protein solubility remained at a high level – 87.4% for microwave and 88.2% for microwave-alkaline treatment. It has been established that a preliminary increase in pH to 8 contributes to the partial destruction of the buffer properties of protein components and increases the efficiency of subsequent heat treatment. The optimal processing parameters were determined as raw material moistening up to 15%, use of coarsely ground fraction, preliminary alkaline treatment to pH 8, and microwave heating for 120-150 seconds at a power of 600 W. The proposed method allows to significantly increase the nutritional value of soy raw materials while maintaining high protein solubility, which makes it promising for implementation in the food industry and feed production

Keywords

trypsin inhibitors; antinutritional factors; protein denaturation and solubility; alkaline and heat treatment

Suggested citation
Мakarynska, A., Kananykhina, O., Turpurova, T., & Bozhko, I. (2025). Improving the quality of soybeans by alkaline microwave treatment. Animal Science and Food Technology, 16(4), 89-104. https://doi.org/10.31548/animal.4.2025.89
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