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Structures and physicochemical properties of starch from immature seeds of soybean varieties (Glycine max (L.) Merr.) exhibiting normal, low-linolenic or low-saturated fatty acid oil profiles at maturity
- Stevenson, D.G., Jane, J.I., Inglett, G.E.
- Carbohydrate polymers 2007 v.70 no.2 pp. 149
- soybeans, starch, seeds, Glycine max, varieties, fatty acid composition, crystal structure, amylose, starch granules, amylopectin, molecular weight, thermal properties, pasting properties, gelatinization, viscosity, lipids, food analysis
- Soybean varieties bred for normal (NM), low-linolenic (LL) or low-saturate (LS) fatty acid composition were collected 20 d prior to harvest. Seed starch structure and functional properties were studied. Soybean starch had small granules (0.5-4.5 μm diameter), and C(B)-type crystallinity. LL and LS soybean starch had significantly lower absolute amylose than NM soybean. Weight-average amylopectin molecular weight, measured by HPSEC, ranged from 5.91 x 10⁸ g/mol for LL to 8.92 x 10⁸ g/mol for NM. Soybean amylopectin had short average branch chain-length (DP 19.9-21.9) and LS amylopectin had significantly larger percentage of DP 6-12 than LL and NM soybeans. No significant differences among soybean varieties were observed for starch thermal and pasting properties, with onset gelatinization temperature (51.0-51.8 °C) and peak viscosity (79-100 RVU, 8% starch suspension). Further research is needed to understand if amylose content or amylopectin fine structure in developing soybean seeds relates to fatty acid composition of soybean oil at maturity.