• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.995-1000
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• 1996

The present study was attempted to preprare calcium-fortified soymilk using proteases to improve calcium intolerance of soymilk protein and to evaluate its nutritional properties. The protease from Bacillus polymyxa was chosen as an enzyme source because it produced the least bitter taste and calcium-aggregation of soymilk among various enzymes. The optimum treatment time was 10 minutes at $50^{\circ}C$ for the best result. In vitro protein digestibility of calcium-fortified soymilks was comparable with that of control soymilk. Calcium in the digested soymilks was mostly in the ionic form and the amount of ionic calcium increased in accordance with the amount of fortified calcium in soymilk. This suggests that fortified calcium in the soymilk is bioavailable.

• The Korean Journal of Food And Nutrition
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• v.15 no.4
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• pp.331-336
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• 2002

Conformation of soymilk protein was examined to obtain basic information for improved calcium intolerence of soymilk protein partially hydrolyzed with protease. Surface hydrophobicities of three proteins showed the order of SMP(soymilk protein) < SPI(soy protein isolate) < PT-SMP(protease treated soymilk protein). Total thiol group contents of SMP and PT-SMP were similar but larger than that of SPI. Reducing rate of disulfide bond in PT-SMP after 2-mercaptoethanol treatment was laster than that in SMP. And so, this result indicates that PT-SMP may be less compacting due to protease treatement. From circular dichroism result, PT-SMP showed different pattern from SMP and SPI suggesting change of secondary structure by hydrolysis. And analysis of heat denaturating property by DSC showed that denaturation enthalpy of three proteins were all small. Especially enthalpy of PT-SMP was least, and this result suggested that PT-SMP was denatured easily by heating due to less compacting structure.