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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #85755
Title: PARTIAL CHARACTERIZATION OF BUCKWHEAT (FAGOPYRUM ESCULENTUM MOENCH) STARCH.

Author
item QIAN, JUNE - CER SCI, NDSU, FARGO, ND
item RAYAS-DUARTE, PATRICIA - CER SCI, NDSU, FARGO, ND
item Grant, Linda

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Buckwheat starch that had been isolated in the laboratory was compared to commercially produced corn and wheat starches that are used industrially in the U.S. and Europe. It was found that buckwheat didn't dissolve in water as readily as corn and wheat starches at specific temperatures, and that it took longer for it to gelatinize. However once dissolved, buckwheat starch could hold greater amounts of water and became a thicker gel than corn and wheat starches. As a result of this characteristic, buckwheat starch could be gelled and stored in the refrigerator from 3-10 days without the gel weeping when warmed up and could also be frozen and thawed several times without the gel weeping excessively or becoming runny. This study showed that buckwheat starch could be used successfully as a thickening agent in products that would undergo inadvertent temperature changes during processing, transit and\or use.

Technical Abstract: Laboratory isolated buckwheat starch was compared to commercial corn and wheat starches. Buckwheat starch had higher amylose content, water-binding capacity, and peak viscosity and lower intrinsic viscosity than corn and wheat starches. Buckwheat starch showed restricted swelling power at 85-95 deg C, lower solubility in water at temperature ranges of 55-95 deg C and was more susceptible to acid and enzymatic attack compared to the corn and wheat starches. Gelatinization temperature determined by differential scanning calorimetry (DSC) ranged from 61.1 to 80.1 deg C for buckwheat starch compared to 64.7 to 79.2 deg C and 57.1 to 73.5 deg C for corn and wheat starches, respectively. A second endothermic transition was observed at 84.5 deg C due to an amylose-lipid complex attributed to the internal lipids in buckwheat starch as evidenced by selective extraction. The retrogradation of buckwheat, corn and wheat starch gels was examined after storage at 25, 4, and -12 deg C for 1-15 days. In general, buckwheat starch retrogradation was slower than corn and wheat starches but increased as storage time increased as did the other starch pastes. Buckwheat starch had a lower percentage of water syneresis when stored at 4 deg C for 3-10 days and better stability to syneresis after three freeze-thaw cycles of the samples stored at -12 and 25 deg C compared to commercial corn and wheat starch pastes.