Chain length distribution of inulin from dahlia tubers as influenced by the extraction method

Figures & data

Figure 1. Purification methods of fructans from dahlia tubers.

Table 1. HPAEC-PAD chromatography conditions.

Method	Analytical column	Flow rate mL/min	Time intervals (min)	Gradient of NaOAc in 0.1 M NaOH
sep 1	CarboPac PA-100 (4х250 mm) injection volume: 50 μL sample+ 100 μL milli Q water	0.5	2ʹ→40ʹ 40ʹ→45ʹ 45ʹ→55ʹ 55ʹ→60ʹ 60ʹ→70’	0 M→ 0.25 M 0.25 M→ 0.6 M 0.6 M isocratic 0.6 M→ 0 M 0 M isocratic
sep 2		1.5
sep 3			0ʹ→15ʹ 15ʹ→55ʹ 55ʹ→65ʹ 65ʹ→70’	0.2 M isocratic 0.2 M→ 0.5 M 0.5 M→ 0.2 M 0.2 M isocratic
sep 4	CarboPac PA-1 (9 х 250 mm) injection volume: 60 μL sample + 100 μL milli Q water		2.5ʹ→55ʹ 55ʹ→65ʹ 65ʹ→70’	0 M→ 0.5 M 0.5 M→ 0 M 0 M isocratic

Figure 2. HPAEC-PAD analysis of dahlia inulins, obtained by purification method pur 3; three elution methods were used as indicated: A – sep1; B – sep2; C – sep3 (for details see Table 1).

Figure 3. HPAEC-PAD analysis of the standard dahlia inulin (Alfa Aesar): A – sep 3 method.

Figure 4. HPAEC-PAD chromatograms of dahlia fructans; A. native inulin; B. fructans obtained using sep 1; C. fructans obtained using sep 2 method; and D. fructans obtained using the sep 3 method.

Table 2. Percentage of monosaccharides, short-, medium-, and long-chain inulin in native fructan and in purified inulin fractions. Results are the mean of three repetitions ± standard deviation.

		Method of fructan purification
Fraction	Native inulin	pur1	pur2	pur 3
Monosaccharides	20.68 ± 0.03	13.57 ± 0.02	16.88 ± 0.02	7.28 ± 0.02
Short-chain inulin	23.31 ± 0.66	30.60 ± 0.75	24.67 ± 0.39	39.36 ± 0.76
Medium-chain inulin	19.12 ± 0.87	47.31 ± 1.04	31.94 ± 1.00	35.88 ± 0.94
Long-chain inulin	9.34 ± 0.33	7.07 ± 0.32	11.85 ± 0.45	13.00 ± 0.36
Total carbohydrates	72.45 ± 1.89	98.54 ± 2.13	85.34 ± 1.86	95.52 ± 2.08