Exploring the formation of molecular bonds between starch and fiber during production of cereal-based puffed snacks using infrared spectroscopy

Primary author: Debomitra Dey
Co-author: Bon-Jae Gu
Faculty sponsor: Dr. Girish Ganjyal

Primary college/unit: Agricultural, Human and Natural Resource Sciences
Campus: Pullman


Puffed snacks are manufactured using “Extrusion processing” which is a high-temperature-high-shear-short-time processing system. Most puffed snacks are rich in starch. There is an increase in the demand for high-fiber snacks. However, most high-fiber snacks currently available have poor taste and texture. Fiber is known to be inert in the expanded starch matrix during extrusion. However, our preliminary studies indicated, addition of small amounts of fiber can improve the texture of puffed products. Thus, it is critical to understand the starch-fiber interactions to develop products with high fiber without compromising the texture and taste.

We hypothesize, that the application of FT-IR (Fourier Transform-Infrared) spectroscopy can be employed for identification intermolecular changes between starch-fiber during extrusion. The mixture of starch and insoluble fiber were preconditioned water and extruded. The extrudates were characterized using FTIR and the expansion ratio (ER) were measured.

The ER was highest for low fiber extrudates. The FTIR spectra showed significant changes in the regions of 1045-950 cm-1 and 3500-3000 cm-1 providing an estimate of the degree of starch gelatinization and O-H bond formation during extrusion processing. The increase in insoluble fiber led to a decrease in the degree of starch cooking, which can be the result of the competition from fiber for absorption of water. This study presents the application of FTIR for qualitatively identifying the bonds formed between starch and fiber. We believe the information on molecular bond formation can be a valuable tool for the industry to develop direct-expanded products with high-fiber content.