A comparison between whole grain and pearled oats: acute postprandial glycaemic responses and in vitro carbohydrate digestion in healthy subjects

• Published in: European journal of nutrition Vol. 59; no. 6; pp. 2345 - 2355
• Main Authors: Zhu, Ruixin, Fan, Zhihong, Li, Guojing, Wu, Yixue, Zhao, Wenqi, Ye, Ting, Wang, Linlin
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2020; Springer Nature B.V
• Subjects: Chemistry; Chemistry and Materials Science; Cooking; Glucose; Grain; Meals; Nutrition; Oats; Original Contribution; Pressure; Rice; Glycaemic responses; Oats; Starch fraction; Oat-rice mixed meals; Pearled oats
• ISSN: 1436-6207; 1436-6215
• DOI: 10.1007/s00394-019-02083-5

Purpose To compare the glycaemic response of whole grain oat kernels and pearled oats cooked under normal pressure or higher pressure and examine whether replacing half of the rice in a given meal with either of the two oat grains could make a difference in acute glycaemic responses. Methods In a randomised crossover trial, ten healthy subjects consumed two groups of test meals: (1) oat grain-only, including whole grain oats cooked under normal pressure (WONP) and higher pressure (WOHP) as well as their pearled oat counterparts, PONP and POHP; and (2) mixed meals of aforementioned oat grains and cooked rice (OG + R), including WONP + R, WOHP + R, PONP + R and POHP + R. A postprandial blood glucose test, texture profile analysis and in vitro carbohydrate digestion assay were carried out for each test meal. Results Compared with the rice reference, oat grain-only meals induced lower glucose levels at all time points, lower peak values and smaller glucose excursions at 120 min ( P  < 0.05), but OG + Rs did not have the abovementioned effects. The oat grain-only meals had glycaemic indexes (GIs) ranging from 51 to 58, while those of OG + Rs ranged from 59 to 70. WONP + R had a 21% lower iAUC 0–60 and a 40% lower iAUC 60–120 value than those of rice ( P  < 0.05). Oat-rice mixed meals had lower iAUC 0–60 values compared with that of the rice control ( P  < 0.05), except for POHP + R. Excellent consistency between the hydrolysis index and the GI was observed ( r  = 0.969, P  < 0.001) in oat grain-only meals. Conclusions All oat grain-only meals could be included in the glycaemic management diet, regardless of the oat grain type or cooking treatment. In oat-rice mixed meals, whole grain oats and normal pressure cooking ensured a favourable glycaemic effect.