Background and methodology:
This study investigated the effect of long-term (9-year) storage at room temperature on the chemical composition and histological structure of soybeans that had been cultivated by conventional and organic farming systems. The soybeans had been harvested from fields using conventional practices, and in neighboring fields where organic practices had been used for more than three years.
Just after harvest, the protein, calcium, potassium, and phosphorus content in organic soybeans was higher than in conventional soybeans. However, after long-term storage, organic soybeans had a significantly higher protein content and more minerals (particularly potassium) than conventional soybeans.
The breaking strength and pH of organic soybeans were higher than conventional soybeans. Optical microscopic examination revealed collapsed tissue and gaps in the internal and external parts of conventional soybeans. Transmission electron microscopic photographs of conventional soybeans confirmed the presence of collapsed cell walls and protein bodies.
These results indicate that the type of farming system resulted in different chemical composition and structure after storage. Results also indicated that the high calcium content of organic soybeans strengthened cell wall structure and prevented the loss of contents during storage.
Nakamura, Y. N., Fujita, M., Nakamura Y., & Gotoh, T. (2007). Comparison of nutritional composition and histological changes of the soybean seeds cultivated by conventional and organic farming systems after long-term storage - preliminary study. Journal of the Faculty of Agriculture, Kyushu University 52 (1), 1-10. Available on-line at: https://qir.kyushu-u.ac.jp/dspace/bitstream/2324/9272/1/p001.pdf