Molecular characteristics and rheological properties of water-extractable polysaccharides derived from okra (Abelmoschus esculentus L.)

Figures & data

Table 1. Compositions of okra polysaccharides.

Compositions	COPs	ROPs
Ash (%)	10.81 ± 0.21^a	5.75 ± 0.03^b
Nitrogen (%)	1.37 ± 0.01^a	0.49 ± 0.00^b
GalA (%)	48.62 ± 1.82^b	62.47 ± 0.47^a
Xylan (%)	2.69 ± 0.05^a	1.12 ± 0.01^b
Starch (%)	0.92 ± 0.01^a	0.03 ± 0.00^b
Total sugar (%)	16.73 ± 0.13^a	13.47 ± 0.46^b
Rha (%)	1.43 ± 0.01^a	1.34 ± 0.02^b
Ara (%)	2.15 ± 0.06^a	1.07 ± 0.00^b
Xyl (%)	0.48 ± 0.00^a	0.40 ± 0.01^b
Man (%)	0.24 ± 0.01	ND
Gal (%)	10.60 ± 0.02^a	10.66 ± 0.04^a
Glc (%)	1.83 ± 0.03	ND
Rha/GalA	0.03 ± 0.00^a	0.02 ± 0.00^b
(Ara + Gal)/Rha	8.92 ± 0.06^a	8.75 ± 0.06^b

ND: not detected. Total sugars are the sum of rhamnose, arabinose, xylose, mannose, galactose, and glucose. Mean values in the same row with different letters are significantly different (p < 0.05).

Table 2. Molecular weight of okra polysaccharides.

	COPs				ROPs
	Total	I	II	III	Total	I	II
Mp (kDa)	–	3430	793.0	26.9	–	3830	32.2
Mw (kDa)	1319	3777	717.5	52.6	2050	3265	36.9
Distribution (%)	100	31.3	15.3	53.4	100	62.3	37.7

Mp: peak molecular weight; Mw: molecular weight.

Figure 1. FTIR spectra of ROPs (A) and COPs (B).

Table 3. Intrinsic viscosity of okra polysaccharides.

	COPs	ROPs
ηsp (mPa·s)	0.33 ± 0.00^b	0.39 ± 0.01^a
ηr (mPa·s)	1.33 ± 0.00^b	1.39 ± 0.01^a
[η] (mL g^−1)	294.69 ± 0.51^b	332.15 ± 3.02^a

η_sp: specific viscosity; η_r: relative viscosity; [η]: intrinsic viscosity.

Mean values in the same row with different letters are significantly different (p < 0.05).

Figure 2. Steady shear and temperature sweeping of okra polysaccharides.

Figure 3. Steady shear and temperature sweeping of ROPs.

Figure 4. Dependence of zero shear viscosity of ROPs.

Figure 5. Stress and frequency sweeping on G' (filled moduli) and G'' (empty moduli).