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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Plant Polymer Research » Research » Publications at this Location » Publication #142212
Title: INFLUENCE OF ASPEN FIBER ON THE MECHANICAL PROPERTIES OF BAKED CORNSTARCH FOAMS

Author
item Lawton Jr, John
item Shogren, Randal
item TIEFENBACHER, K. - FRANZ HAAS MACHINERY, RIC

Submitted to: Industrial Crops and Products International Conference Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2003
Publication Date: 1/5/2004
Citation: LAWTON JR, J.W., SHOGREN, R.L., TIEFENBACHER, K.F. INFLUENCE OF ASPEN FIBER ON THE MECHANICAL PROPERTIES OF BAKED CORNSTARCH FOAMS. INDUSTRIAL CROPS AND PRODUCTS INTERNATIONAL JOURNAL. 19. 2004. P.41-48.

Interpretive Summary: Foamed articles, such as disposable plates and meat packaging trays, can be prepared from starch by a baking procedure. Starch foams are formed by heating a starch batter inside a closed mold. Previous data shows that baked starch foam trays prepared from a 33% solids cornstarch batter produce brittle weak trays. Brittle weak foams are unacceptable for uses such as disposable plates and trays. This study investigated the effect that aspen fiber (2.5 to 45%) had on the physical properties of the starch-based foams. Batters containing more than 15% fiber needed to be added in higher amounts in the mold to make a complete tray. Baking time of the trays increased with increasing amounts of fiber. Strength of the foam trays increased as fiber content increased, until fiber content reached 15%. Starch-based trays containing 15 to 30% fiber showed no difference in tray strength. Trays containing more than 30% fiber had lower tray strength. Relative humidity also affected the tray strength. Tray strength always decreased when the trays were stored at humidities higher and lower than 50%. Increased fiber content of the trays help lessen some of this decrease in strength. Trays containing between 15 to 30% fiber still lost strength at humidities other than 50%, but the severity of the loss was lessened by the addition of fiber. A cross section of the foam showed that fiber was in the cell walls and on the surface of the foam. Based on tray strength and the fact that added fiber increased both baking time and batter voluem, the optimum fiber content of the trays is thought to be about 15%. This research shows that adding reinforcing fibers to starch-based foam trays increases the utility of the trays in real world applications. Increasing the utility of the trays will increase the likelihood of these trays being used in commerce, and thereby benefit the farmers by increase cornstarch use.

Technical Abstract: Foamed articles, such as disposable plates and meat packaging trays, can be prepared from starch by a baking procedure. Starch foams are formed by heating a starch batter inside a closed mold. Previous data shows that baked starch foam trays prepared from a 33% solids cornstarch batter produce brittle weak trays. Brittle weak foams are unacceptable for uses such as disposable plates and trays. This study investigated the effect that aspen fiber (2.5 to 45%) had on the physical properties of the starch-based foams. Batters containing more than 15% fiber needed to be added in higher amounts in the mold to make a complete tray. Baking time of the trays increased with increasing amounts of fiber. Strength of the foam trays increased as fiber content increased, until fiber content reached 15%. Starch-based trays containing 15 to 30% fiber showed no difference in tray strength. Trays containing more than 30% fiber had lower tray strength. Relative humidity also affected the tray strength. Tray strength always decreased when the trays were stored at humidities higher and lower than 50%. Increased fiber content of the trays help lessen some of this decrease in strength. Trays containing between 15 to 30% fiber still lost strength at humidities other than 50%, but the severity of the loss was lessened by the addition of fiber. A cross section of the foam showed that fiber was in the cell walls and on the surface of the foam. Based on tray strength and the fact that added fiber increased both baking time and batter volume, the optimum fiber content of the trays is thought to be about 15%.