Submitted to: Journal of Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2001
Publication Date: N/A
Interpretive Summary: Soybeans are an important source of high nutritional value and quantity protein. The United States is one of the major producers of soybeans. The production and consumption of soybeans for many years had been confined to south Asia, which explains the many traditional soy foods developed in China, Japan, and other south Asian countries. In the past few years, varietal development and production of soybean in the U.S. has increased sharply. Soy oil was considered the first product of interest, but more recently soy proteins have become the most important component of soybeans. Many American companies have started developing protein based soybean products. This work will help soy protein producers to develop better ways to isolate soy protein and thus increase its uses.
Technical Abstract: DSC was used to estimate thermal properties differences between SPI and MDF soy protein. The measurements were determined in the presence of 15, 20, 25, and 30% corn oil and 2, 4, and 6% amylose levels. The SDS-PAGE profile showed that the SPI material contains aggregates as a result of the isolation procedures and processing. Protein isolate showed 7S protein transition peak at 77 deg C and 11S peak at 170 deg C while the MDF sample produced 7S peak at 69 deg C and 11S peak at 177 deg C. The MDF sample showed (triangle up)H values 4 times more than the SPI. These values reflect the effect of isolation process on the protein. In the presence of corn oil, the MDF sample showed three transition peaks while the SPI sample displayed only two peaks. The MDF sample demonstrated more interaction with oil than the SPI sample. The change in the (triangle up)H was reflective of this interaction. The addition of amylose allowed the appearance of the third peak of the SPI sample. The presence of amylose showed a mixed effect on the two proteins, where peaks of the same protein have reacted differently to amylose level. The increase in amylose level had the most influence on the third peak of the MDF sample. Amylose influence on the two proteins was attributed to the reduction of the amount of free oil in the system.