Rheological and Functional Characterization of Oat Drink By-Product : Effects of β-Glucan Molecular Weight, Solids Content, and Processing Conditions

Abstract

With a growing global population, the demand for food increases, and the development of more sustainable food production becomes increasingly important. One way to improve sustainability within food production is to repurpose nutritious by-products to new food ingredients. Oat drink by-product (ODBP), generated during the production of oat-based beverages, is one such stream. ODBP contains significant amounts of β-glucan (BG), a type of dietary fiber associated with various health benefits such as preventing diabetes, reducing hypertension, and lowering glycemic index. While BG adds desirable nutritional value to ODBP, its remarkable influence on the rheological properties of food systems, could be a contributing factor to the complicated handling of ODBP, which is essential for its repurpose into new food products. Therefore, this study aims to investigate the rheological and functional properties of ODBP and the contribution of β-glucans to these properties.

Flow behavior and apparent yield stress were characterized across varying temperatures and total solids (TS) content using a rheometer and Rapid Visco Analyzer (RVA). To assess the contribution of BG, enzymatic hydrolysis was applied to generate samples with different BG Mw. The resulting flow curves were fitted to the Herschel-Bulkley and Bingham plastic fluid models, and the resulting parameters were used to evaluate the effects of temperature, TS, and BG Mw on ODBP yield stress and flow behavior.

The results demonstrated that BG Mw, temperature, and TS content all significantly affected the rheology of ODBP. Higher BG Mw increased the resistance to flow and promoted shear thinning behavior at low shear rates. Increasing the temperature significantly lowered the apparent viscosity, though the effect was smaller at higher temperatures. Lower TS content markedly decreased apparent yield stress.

Comparison of analytical methods indicated similar overall rheological trends, although some differences were observed. The rheometer provided greater precision and enabled measurements at lower shear rates, while the RVA was able to cover a broader shear rate range. Absolute values of apparent yield stress varied substantially depending on the measurement method and the suitability of the two rheological models, where shown to be dependent on both the shear rate interval measured as well as the BG Mw.

To assess potential storage effects on fresh and freeze-thawed ODBP, texture analyses were performed. The results indicate no effect on fresh samples over a three-day period, regardless of storage temperature, while there were significant effects in the hardness of freeze-thawed ODBP over the same testing period.

A strong influence of BG Mw and TS on the functional properties of dried ODBP could not be confirmed. Instead, the average particle size of the dried by-product exhibited the greatest impact on the measured properties. Thus, further studies are required to conclusively determine the role of BG in shaping the functional properties of dried ODBP.

Popular Abstract

From Side-Stream to Food: Unlocking the Potential of Oat Drink By-Product

As the world’s population continues to grow, finding sustainable ways to produce food has become increasingly important. One promising approach is to make better use of side-streams from food manufacturing instead of letting them go to waste. This can help reduce both the envi-ronmental impact of food production and reduce food waste.

One such side-stream is oat drink by-product (ODBP), a nutrient-rich residue, created during the production of oat-based beverages. ODBP contains high levels of a type of dietary fiber called, β-glucan (BG) which is linked to various health benefits such as lower risk of cardiovascular disease and high blood pressure. Despite its nutritional value, ODBP is currently underutilized largely because of its thick consistency, which makes it difficult to transport and incorporate into new food products. Part of this thickness is believed to come from these β-glucans.

The key to overcoming this challenge lies in understanding the material’s rheology. Rheology is the science of how materials flow and deform when pressure is applied. By understanding how ODBP behaves under different conditions, it becomes possible to design efficient production processes that can make better use of this valuable resource.

The results from the study show that the flow behavior of ODBP is strongly influenced by the temperature, water content and the size of the β-glucan molecules. β-glucans are actually long chains of sugar molecules, and the length of these chains determines how they interact with each other and other molecules in the ODBP. These interactions play an important role in determining the material’s properties. Longer molecules were shown to make ODBP thicker and more re-sistant to flow, while shorter molecules resulted in less viscous material.

Temperature was also shown to have a significant effect. As ODBP becomes warmer, it flows more easily and requires less force to move through pipes and processing equipment. However, when reaching high enough temperatures, these benefits became smaller. In practice, this insight can be used to design food production processes that apply just the right amount of heat to make the product flow more easily (and keep them safe from harmful microbes) without wasting energy on excessive heating.

Ultimately, these findings bring ODBP one step closer to becoming a practical ingredient in new food products, which could reduce waste, create more sustainable food and unlock the potential of this nutritious material that is currently overlooked.

• author: Eriksson, Maya
• supervisor: Anna Fureby; Stina Burri; Johan Qvist
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLTM06 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Agriculture and Food Sciences; Technology and Engineering; Chemistry
• keywords: Rheology, Beta-glucan, β-glucan, Oat drink by-product, Oat okara, Oat fiber residue, Herschel-Bulkley, Bingham plastic, RVA, Rheometer, Yield Stress, Food engineering nutrition and food chemistry
• language: English
• id: 9250008
• date added to LUP: 2026-09-07 09:16:55
• date last changed: 2026-09-07 09:16:55