How Guar Gum Affects the Properties and Digestion of Processed Starches

Jim Crocker
17th June, 2024

How Guar Gum Affects the Properties and Digestion of Processed Starches

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Zhejiang University of Technology found that adding guar gum (GG) to starch and using extrusion changes the starch's structure
  • The combination of GG and extrusion makes starch granules more cohesive and irregular, enhancing their gelatinization properties
  • GG addition increases slow-digestible and resistant starch levels, leading to a slower glucose release and lower glycemic index
  • The effects of GG and extrusion vary by starch type, with sweet potato starch showing the most health benefits
The recent study conducted by researchers at Zhejiang University of Technology assessed the impact of guar gum (GG) on the physical and chemical attributes and the in vitro digestibility of maize starch (MS), pea starch (PS), and sweet potato starch (SPS) subjected to extrusion treatment[1]. This research is significant as it explores how the combination of GG and extrusion can alter the properties of different starches, potentially leading to healthier food products with lower glycemic indices. Extrusion is a process that forces material through a shaped opening to produce a specific shape and texture. In this study, starch with 25% moisture content was combined with GG in a 9:1 ratio and subjected to extrusion. The combination of GG and extrusion was found to disrupt the ordered structure of starch and induce the aggregation of starch granules, resulting in a more cohesive structure. Scanning electron microscopy and differential scanning calorimetry confirmed these structural changes. GG addition further evolved this structure into a more intricate and irregular form. Rheological assessments, which measure the flow and deformation of materials, demonstrated a remarkable enhancement in the gelatinization characteristics of starch with GG addition. Gelatinization is the process where starch granules absorb water and swell upon heating, leading to increased viscosity. The study found that GG addition led to elevated flow resistance and increased viscosity, indicating a stronger and more elastic gel formation. The in vitro digestive characteristics of the starches were also evaluated. The addition of GG to starch augmented the levels of slow-digestible starch and resistant starch. Slow-digestible starch is broken down more gradually, leading to a slower release of glucose into the bloodstream. Resistant starch, on the other hand, resists digestion in the small intestine and reaches the colon intact, where it can have various health benefits. Consequently, the addition of GG resulted in diminished digestibility and a lowered glycemic index, which is a measure of how quickly foods cause an increase in blood glucose levels. The effects of extrusion and GG addition varied across different starches. For sweet potato starch (SPS), the combination proved advantageous, enhancing the resistant components and potentially leading to healthier food products. Conversely, extrusion manifested contrasting outcomes for maize starch (MS) and pea starch (PS), indicating that the interaction between GG and starch is complex and dependent on the type of starch. These findings align with earlier studies that have explored the interaction between hydrocolloids (such as GG) and starch. For instance, a study on the effects of guar and xanthan gums on high-amylose corn starches found that the interaction between dispersed amylose and hydrocolloids contributed to an earlier onset of viscosity increase during the pasting process and stronger gel formation[2]. Similarly, another study demonstrated that partially hydrolyzed guar gum (PHGG) influenced the properties of wheat flour dough by increasing water absorption and starch gelatinization[3]. Moreover, the study's findings on the impact of GG on postprandial hyperglycemia are supported by earlier research that showed guar gum's ability to maintain viscosity during digestion and significantly reduce plasma glucose levels[4]. This suggests that the addition of GG to starch not only alters its physical and chemical properties but also has beneficial effects on blood sugar levels. In conclusion, the study by Zhejiang University of Technology provides valuable insights into how the combination of guar gum and extrusion can enhance the properties of different starches, leading to healthier food products with lower glycemic indices. This research builds on previous studies and highlights the potential of using hydrocolloids like guar gum to improve the nutritional quality of starch-based foods.



Main Study

1) Effect of guar gum on the physicochemical properties and in vitro digestive characteristics of extruded starches.

Published 14th June, 2024

Related Studies

2) Impacts of guar and xanthan gums on pasting and gel properties of high-amylose corn starches.

3) Effect of partially hydrolyzed guar gum on pasting, thermo-mechanical and rheological properties of wheat dough.

4) Viscosity of gums in vitro and their ability to reduce postprandial hyperglycemia in normal subjects.

Journal: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas, Issue: Vol 30, Issue 12, Dec 1997

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