Potential of Inulin-Fructooligosaccharides Extract Produced from Red Onion (Allium cepa var. viviparum (Metz) Mansf.) as an Alternative Prebiotic Product.

Jakkrit Aisara,Chutamas Maneewong,Somkid Deejing,Apinun Kanpiengjai,Chartchai Khanongnuch,Paul Kosma,Kridsada Unban,Markus Blaukopf,Pairote Wongputtisin

doi:10.3390/plants10112401

Abstract

Red onion is a popular ingredient in many Thai dishes and has recently been promoted for commercial cultivation. In this study, inulin-fructooligosaccharides (inulin-FOSs) were extracted from red onions in a simplified extraction method. The extract contained 24.00 ± 0.38 g/L free glucose, fructose and sucrose, while the level of FOSs was recorded at 74.0 ± 2.80 g/L with a degree of polymerization of 4.1. The extract was resistant to simulated gastrointestinal conditions, while selectively promoting probiotic lactobacilli. These outcomes resulted in inhibitory effects against various pathogenic bacteria. The in vitro batch culture fermentation of the extract by natural mixed culture indicated that an unknown sugar identified as neokestose was more rapidly fermented than 1-kestose and other longer-chain inulin-FOSs. Notably, neokestose selectively encouraged a bifidogenic effect, specifically in terms of the growth of Bifidobacteirum breve, which is an infant-type probiotic bacterium. This is the first report to state that neokestose could selectively enhance the bifidogenic effect. In summary, inulin-FOSs extract should be recognized as a multifunctional ingredient that can offer benefits in food and pharmaceutical applications.

Highlights

80% of the dry matter of onion bulbs (Allium cepa L.) is composed of nonstructural carbohydrates that basically consist of glucose, fructose, sucrose and fructooligosaccharides (FOSs) [1]
Inulin-FOSs were extracted from red onions using a simplified method
The resulting extract was considered inulin-FOSs syrup consisting of 98.00 ± 0.28 g/L total carbohydrates and included 6.95 ± 0.29 g/L glucose, 3.23 ± 0.24 g/L fructose and 13.76 ± 0.24 g/L sucrose, resulting in approximately 74.00 ± 2.8 g/L of inulin-FOSs with an average degree of polymerization (DP) of 4.1

Summary

Introduction

80% of the dry matter of onion bulbs (Allium cepa L.) is composed of nonstructural carbohydrates that basically consist of glucose, fructose, sucrose and fructooligosaccharides (FOSs) [1]. As far as this report is concerned, FOSs are one of the most acceptable prebiotic substances of oligosaccharide prebiotics; i.e., galactooligosacharides (GOSs) and lactulose [4]. Based on their color, onion bulbs are classified as yellow, red and white. Onion bulbs are classified as yellow, red and white They are classified according to their sweetness as being either sweet or non-sweet [5]. White onion has a sweet taste, and neither the fresh nor cooked form is preferably consumed among

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