Determination of Fructans in Plants: Current Analytical Means for Extraction, Detection, and Quantification

Abstract

Fructans are one of the most significant groups of sucrose‐derived water‐soluble carbohydrates in higher plants and microbes. They are largely differentiated by the linkage type between the terminal sucrose and the adjacent fructosyl units as well as by the degree of polymerisation ranging from oligomers (DP 3–9) to polymers (DP ≥10 up to a few hundred) and whether they are linear or highly branched structures (Section 2). The rapidly increasing scientific evidence for fructans functioning as reserve and structural carbohydrates as well as having antioxidant and immunomodulatory/signalling potential has motivated a recent boost in both fundamental research and in potential applications for food and nutrition. In contrast, analytical methods for fructan determination and discrimination have developed slowly. In this article, we summarise the current knowledge concerning methodologies for fructan analysis. We focus on fructan extraction and isolation (Section 3), quantification (Section 4), separation and detection (Section 5), structural characterisation (Section 6) as well as approaches for tissue‐specific and spatially resolved analysis (Section 7), and nondestructive detection of fructans (Section 8) in various plant materials. Finally, we discuss future perspectives for fructan analysis in plant tissues, also in the context of investigating structure–function relationships (Section 9).

Determination of carbohydrates and fructans content in Cyperus esculentus L.

“…Fructans are generally regarded as dietary fiber, that counter digestion by peopled enzymes since the majority passes through the stomach and small intestine primarily untouched. Fructans are straight immunomodulatory, antioxidant, indirect prebiotic compounds, and used as a remedy for dysbacteriosis, diabetes, cardiovascular disease (Roberfroid 2005;Matros et al 2019). The inulin-type compounds decrease the risk of colon carcinogenesis (Roberfroid 2005).…”

Fructans Are Differentially Distributed in Root Tissues of Asparagus

“…By MALDI-MSI technology, such structural particularities cannot be distinguished. In this regard, separation by high pH anion exchange chromatography (HPAEC) coupled to the high sensitivity of pulsed amperometric detection (PAD) is considered the best technique for the analysis of fructans with a DP of up to 80 [ 5 ]. Thus, to further investigate the variations in fructan profiles, we have manually isolated three different root tissues, namely outer (O), middle (M) and inner (I) tissues ( Supplementary Figure S1 ).…”

“…Therefore, we could assign the observed increased proportion of fructopolysaccharides, relative to small FOS, following a gradient from the outer to the inner root tissues, mainly to inulin neoseries-type fructans ( Figure 3 ). This highlights the demand of combining various analytical measures to elucidate specific abundance patterns of different fructan types [ 5 ].…”

“…Fructans consist of repeating fructose residues linked to a sucrose unit. They are classified according to the position of the sucrose moiety (internal glucose residue, neoseries-type), the kind of linkage between the fructose residues [β (2,1), inulin; β (2,6), levan or containing both β (2,1) and β (2,6)-d-fructosyl units, graminan-type] and the chain lengths [ 5 ]. Fructans can form polymers [with a degree of polymerization (DP) ≥ 10] or oligomers with DP3-9, also referred to as fructooligosaccharides (FOS).…”

Quantification of Fructans in Bioethanol Stillage Based On a Simplified Analytical Method

“…As a result, there are lots of modifications described in literature with the aim of being simpler. These modifications all differ with regard to sample preparation, hydrolysis procedure and subsequent carbohydrate analytics, each with different assets and drawbacks [4,20].…”