The Mutual Correlation of Glucose, Starch, and Beta-Glucan Release During Microwave Heating and Antioxidant Activity of Oat Water Extracts

Joanna Harasym,Remigiusz Olędzki

doi:10.1007/s11947-018-2065-x

Joanna Harasym, Remigiusz Olędzki

Open Access

https://doi.org/10.1007/s11947-018-2065-x

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Abstract

Starch and beta-glucan are most abundant carbohydrate polymers available in oat products; however, their simultaneous release during extraction depends on morphological and processing conditions of raw material. The study analyzes the mutual correlation between the sample (oat flakes and bran) and treatment types (microwave heating (MW)—1–5 min; conventional heating (CH)—7 min) on water extract properties focusing on beta-glucan, starch, and glucose content as well as the antioxidant activity of water extracts. The strong negative partial coefficient correlation was found between solids-starch (− 0.65) and starch-glucose (− 0.89) content as well as DPPH (− 0.66) antioxidant activity in oat flakes revealing the high release of glucose to the water phase and its prooxidant activity. For the oat bran, positive and very high partial coefficient was found for both glucose (0.98) and beta-glucan (0.98) content in solids while the mutual interaction between them was highly negative (− 0.97), meaning the more beta-glucan, the less glucose in the water phase.

Highlights

The undisputable bioactivity of oats had already met the wide scientific interest leading to EFSA (European Food Safety Authority, European Union) and FDA (Food and Drug Administration, USA) health claim issue which confirmed the oat beta-glucan impact on lipid and glucose metabolism, and appreciated the beneficial effects of the whole oat fiber for gut health (EFSA Panel on Dietetic Products 2011; European Food Safety Authority (EFSA) 2010, 2011)
The nutritional facts delivered by manufactures mainly focused on carbohydrate difference (Fig. 1) while nutritional component characteristic (Table 1) revealed that oat bran surpasses the oat flakes of 20% in protein, total dietary fiber, and ash content
The same was for oat flakes where protein and fat values were similar while carbohydrate content was much higher

Summary

Introduction

The undisputable bioactivity of oats had already met the wide scientific interest leading to EFSA (European Food Safety Authority, European Union) and FDA (Food and Drug Administration, USA) health claim issue which confirmed the oat beta-glucan impact on lipid and glucose metabolism, and appreciated the beneficial effects of the whole oat fiber for gut health (EFSA Panel on Dietetic Products 2011; European Food Safety Authority (EFSA) 2010, 2011). The in situ heat generation alleviates the convectional transfer limitation and creates superheated microsites facilitating the release of active components. Such environment was found as highly efficient in various food industry processes (Guo et al 2017) and as medium supporting extraction (Ekezie et al 2017). In cereals, processing the microwave treatment was used for inactivation of undesired enzymatic activity like betaglucanolytic (Pérez-Quirce et al 2016) or lipolytic (Qian et al 2009), to change the breadmaking properties of gluten-free flours (Pérez-Quirce et al 2017), to assess the structural characteristic of beta-glucan (Ahmad et al 2016), or to measure of antioxidant activity of cereal fraction (Dar and Sharma 2011; Stevenson et al 2008)

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