Dissertation
EXPLORING THE PHYSICOCHEMICAL INTERACTIONS BETWEEN INGREDIENTS TO ENABLE INCORPORATION OF INSOLUBLE FIBERS INTO DIRECT EXPANDED STARCH EXTRUDATES
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004387
Handle:
https://hdl.handle.net/2376/118837
Abstract
Starch-rich direct-expanded extruded products are processed using extrusion to form light and crispy textures. The demand for fiber inclusion in direct-expanded products is increasing due to the growing health awareness among consumers. Usually, high-fiber inclusion results in products with dense and hard textures, thus unappealing to the consumers. Several studies have focused on resolving the issue of reduced extrudate expansion with high-fiber inclusion. There is still a critical need to understand the fundamental mechanism dictating the expansion with high-fiber inclusion. Therefore, this research focused on a) identifying reasons for low expansion on high-fiber inclusion and b) exploring strategies to improve expansion with high-fiber incorporation. Extrudate expansion reduces with high inclusion of larger particle-sized fiber because they fail to uniformly distribute in the starch matrix and break the starch melt continuity formed during extrusion. Apple pomace (AP) was modified using a mild-acid treatment, and their incorporation during extrusion did not impact the expansion compared to the unmodified AP. Learnings from this study were then extended to investigate the effect of modified fiber, cellulose nanocrystals (CNC), and microcrystalline cellulose (MCC). Due to its lower particle size and crystallinity, CNC inclusion at ≤10% w/w supported a high extrudate expansion relative to MCC inclusion.
Low expansion occurs at fiber inclusion (>10% w/w) due to the incompatibility between starch and fiber, leading to fiber aggregation. Thus, sugar was used as a co-solvent to reduce the phase separation between starch and fiber during extrusion. Sugar inclusion at a low concentration, 2% w/w in starch-fiber, did not impact the expansion compared to the control. But at higher sugar inclusion, 10% w/w, the expansion of starch-fiber extrudates reduced. The plausible reason for this is the phase separation between starch, fiber, and sugar and the aggregation of fiber particles in the extrudate.
Further investigations are recommended on firstly reducing the phase separations between starch-fiber during extrusion by solubilizing fiber using chemical, mechanical, or enzymatic treatments. Secondly, studying the effect of added fiber on sensory attributes of extruded products such as appearance, texture, aroma, and flavor. These recommendations would be helpful for food manufacturers to produce high-fiber extruded snacks.
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Details
- Title
- EXPLORING THE PHYSICOCHEMICAL INTERACTIONS BETWEEN INGREDIENTS TO ENABLE INCORPORATION OF INSOLUBLE FIBERS INTO DIRECT EXPANDED STARCH EXTRUDATES
- Creators
- Debomitra Dey
- Contributors
- Girish M Ganjyal (Advisor)Helen S Joyner (Committee Member)Steven R Saunders (Committee Member)Carolyn F Ross (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Food Science
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 271
- Identifiers
- 99900883136101842
- Language
- English
- Resource Type
- Dissertation