The Merit variety of soybean (Glycine max L.) harvested in 1971 was germinated in the dark at 21∼25℃ for 10 days. The soybean sprout were divided into cotyledons and seedling axis and subjected to the determination of lipoxygenase activity and fatty acid composition of triglycerides, free fatty acids, phosholipids and crude fat fractions at two-day intervals during the germination periods.
The results are summarized as follows :
1) The lipoxygenase activity in cotyledons declined sharply after second day, but the activity in seedling axis inclined slightly after second day. However, the decrease of lipoxygenase activity in cotyledons coincided with decrease of linoleic and linolenic acids in cotyledons and increase of lipoxygenase activity in seedling axis coincided with increase of those acids in seedling axis.
2) The iodine value of neutral fat in cotyleons decreased continuously, but the iodine value of the neutral fat in seedling axis remained almost constant. Iodine valve in cotyeldons was greater than in seedling axis.
3) In the fatty acid composition of triglycerides in cotyledons, palmitic acid did not changes significantly, stearic acid increased continuously, oleic acid changed irregularly, linoleic and linolenic acids continuously decreased significantly.
But in the fatty acid composition of triglycerides in seedling axis, palmitic acid remained unchanged, linoleic and linolenic acids slightly increased continuously, stearic and oleic acids changed irregularly.
4) Composition of free fatty acids in cotyledons and seedling axis changed irregularly, suggesting that all fatty acids produced by hydrolysis of triglycerides by lipase are used for either biosynthetic purpose or energy production at random.
5) Fatty acids with odd-numbered carbon chain were not detected in the triglycerides and free fatty acid fractions during the germination periods, suggesting that all fatty acids are utilized as C₂-unit in degradation and biosynthesis.
6) The changes of fatty acids composition of phospholipid in cotyledons and seedling axis during the germination were similar to those of triglyceride fraction.
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