Molecular characteristics of oxidized and cross-linked lotus (Nelumbo nucifera) rhizome starch

Figures & data

Table 1. Carbonyl and carboxyl contents and degree of cross-linking of native and modified lotus rhizome starches*.

Samples	Carbonyl content (%)	Carboxyl content (%)	Degree of cross-linking (%)
NLS	ND	ND	ND
OLS 1	0.03 ± 0.00^f	0.07 ± 0.00^f	ND
OLS 2	0.04 ± 0.00^e	0.10 ± 0.01^e	ND
OLS 3	0.04 ± 0.00^d	0.13 ± 0.00^c	ND
CLS 1	ND	ND	4.31 ± 0.56^f
CLS 2	ND	ND	11.8 ± 1.34^e
CLS 3	ND	ND	18.9 ± 1.86^d
COLS 1	0.07 ± 0.00^a	0.15 ± 0.01^a	47.34 ± 2.67^c
COLS 2	0.07 ± 0.00^b	0.14 ± 0.01^b	53.52 ± 1.53^b
COLS 3	0.06 ± 0.01^c	0.10 ± 0.00^d	58.28 ± 2.22^a

*n = 3; Results are expressed as mean values ±SD. ND = Not determined. Means in a column with the same superscripts are not significantly different (p < 0.05).

1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3).

Table 2. Physicochemical properties of native (NLS) and modified lotus rhizome starches*.

					Paste clarity (%)
Samples	Amylose	WBC (g/g)	L*	Degree of crystallinity (%)	Day 0	Day 1	Day 2	Day 3	Day 4
NLS	20.6 ± 0.4^a	1.8 ± 0.0^h	91.8 ± 0.1^h	28.1 ± 0.4^j	25.6 ± 0.2^h	20.2 ± 0.5^h	10.7 ± 0.3^gh	7.5 ± 0.2^g	5.6 ± 0.2^g
OLS 1	17.4 ± 0.0^f	1.8 ± 0.0^bd	92.7 ± 0.1d^e	31.9 ± 0.0^f	36.8 ± 0.3^f	26.9 ± 0.2^f	18.9 ± 0.2^f	14.3 ± 0.2^f	13.8 ± 0.2^f
OLS 2	15.7 ± 0.1^h	1.9 ± 0.0^bc	94.19 ± 0.0^c	34.1 ± 0.0^b	77.1 ± 0.0^b	76.6 ± 0.3^b	76.4 ± 0.2^b	75.5 ± 0.4^b	74.6 ± 0.3^b
OLS 3	13.6 ± 0.3^i	1.9 ± 0.0^a	96.0 ± 0.4^a	36.3 ± 0.1^a	95.8 ± 0.3^a	94.8 ± 0.6^a	94.1 ± 0.7^a	93.8 ± 0.3^a	92.7 ± 0.5^a
CLS 1	19.5 ± 0.0^b	1.8 ± 0.0^dg	91.9 ± 0.1^g	29.5 ± 0.0^i	28.6 ± 0.1^g	21.7 ± 0.1^g	10.5 ± 0.3^h	5.3 ± 0.2^i	5.0 ± 0.2^h
CLS 2	18.4 ± 0.1^d	1.8 ± 0.0^g	92.0 ± 0.1^fg	31.2 ± 0.1^g	25.4 ± 0.3^h	20.2 ± 0.4^h	11.2 ± 0.3^g	6.3 ± 0.2^h	4.4 ± 0.3^i
CLS 3	17.2 ± 0.0^f	1.8 ± 0.0^cde	93.0 ± 0.1^d	33.5 ± 0.1^d	24.3 ± 0.3^i	19.5 ± 0.2^i	8.4 ± 0.2^i	6.3 ± 0.2^h	4.9 ± 0.2^h
COLS 1	18.7 ± 0.1^c	1.9 ± 0.0^b	92.3 ± 0.0^ef	29.7 ± 0.0^h	63.8 ± 0.0^c	52.6 ± 0.1^c	49.1 ± 0.1^c	42.8 ± 0.0^c	41.2 ± 0.2^c
COLS 2	17.7 ± 0.1^e	1.8 ± 0.0^df	93.8 ± 0.0^c	32.1 ± 0.0^e	58.9 ± 0.1^d	48.8 ± 0.0^d	44.2 ± 0.0^d	40.6 ± 0.0^d	38.9 ± 0.0^d
COLS 3	16.1 ± 0.1^g	1.8 ± 0.0^efg	94.9 ± 0.0^b	33.7 ± 0.0^c	52.1 ± 0.1^e	44.1 ± 0.1^e	38.4 ± 0.1^e	32.5 ± 0.0^e	34.7 ± 0.0^e

*n = 3; Results are expressed as mean values ±SD. Means in a column with the same superscripts are not significantly different (p < 0.05).

L* = lightness/whiteness; WBC = water-binding capacity (g/g); ND = not determined.

1. Native lotus rhizome starch (NLS):;2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3).

Figure 1. Swelling power of native (NLS) and modified lotus rhizome starches at different temperatures.

Swelling power: 1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3): at different temperatures.

Figure 2. Solubility of native and modified lotus rhizome starches at different temperatures.

Solubility: 1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3): at different temperatures.

Figure 3. X-ray diffractograms of native and modified lotus rhizome starches.

X-ray diffraction pattern: 1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3).

Figure 4. Scanning electron micrographs (magnification 1000×) of native and modified lotus rhizome starches.

Scanning electron micrographs (magnification 1000×): 1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3)

Figure 5. FTIR spectra of native and modified lotus rhizome starches.

FTIR spectra: 1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3)

Table 3. Pasting properties of native (NLS) and modified lotus rhizome starches*.

Sample	PV (cP)	TV (cP)	BV (cP)	FV (cP)	SV (cP)	P temp (°C)
NLS	6214 ± 2^a	2091 ± 1^d	4123 ± 1^a	2894 ± 3^d	976 ± 1^b	77.5 ± 0.1^f
OLS 1	4314 ± 39^e	1190 ± 14^h	3122 ± 7^b	1966 ± 11^g	763 ± 28^e	76.9 ± 0.0^g
OLS 2	3102 ± 14^g	592 ± 10^i	2514 ± 30^e	1062.5 ± 34^h	433 ± 11^g	76.1 ± 0.0^h
OLS 3	2817 ± 5^i	225 ± 4^j	2589 ± 3^d	234 ± 3^i	9 ± 2^j	76.0 ± 0.2^i
CLS 1	5952 ± 14^b	2985 ± 6^c	2962 ± 8^c	3995 ± 14^c	102 ± 16^a	78.4 ± 0.0d^e
CLS 2	5492 ± 9^c	3337 ± 6^b	2163 ± 10^f	4126 ± 11^b	794 ± 9^d	78.6 ± 0.0^c
CLS 3	5094 ± 4^d	4105 ± 7^a	1999 ± 6^g	4383 ± 6^a	288 ± 2^h	79.3 ± 0.1^a
COLS 1	3287 ± 14^f	2040 ± 8^e	1231 ± 9^h	2851 ± 8^e	825 ± 13^c	78.3 ± 0.0^e
COLS 2	2886 ± 11^h	1747 ± 11^f	1149 ± 4^i	2344 ± 7^f	624 ± 19^f	78.8 ± 0.1^cd
COLS 3	2590 ± 4^j	1686 ± 7^g	912 ± 7^j	1950 ± 8^g	250 ± 6^i	78.7 ± 0.0^b

*n = 3; Results are expressed as mean values ±SD. Means in a column with the same small letters superscripts are not significantly different (p ≤ 0.05).

PV = peak viscosity (cP); TV = trough viscosity (cP); BV = breakdown value (cP); FV = final viscosity (cP); SV = setback value (cP); Ptemp = peak temperature (°C).

1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3).

Table 4. Thermal properties of native (NLS) and modified lotus rhizome starches*.

Samples	To (°C)	Tp (°C)	Tc (°C)	ΔHgel (Jg^−1)
NLS	68.3 ± 0.5^d	72.0 ± 0.3^e	76.8 ± 0.4^i	13.7 ± 0.2^a
OLS 1	72.5 ± 0.5^b	75.9 ± 0.2^c	83.6 ± 0.1^f	13.0 ± 0.0^f
OLS 2	71.0 ± 0.1^c	75.5 ± 0.1^c	82.9 ± 0.1^g	13.0 ± 0.1^g
OLS 3	70.5 ± 0.1^c	75.4 ± 0.1^c	82.4 ± 0.1^h	12.4 ± 0.0^h
CLS 1	70.9 ± 0.0^c	72.7 ± 0.1^d	86.2 ± 0.1^c	13.2 ± 0.1^e
CLS 2	70.8 ± 0.0^c	73.0 ± 0.1^d	86.5 ± 0.0^b	13.4 ± 0.1^c
CLS 3	70.7 ± 0.1^c	73.1 ± 0.1^d	86.8 ± 0.0^a	13.6 ± 0.1^b
COLS 1	72.9 ± 0.0^ab	77.7 ± 0.1^b	83.8 ± 0.1^f	13.1 ± 0.0^e
COLS 2	73.4 ± 0.1^a	77.8 ± 0.1^ab	85.0 ± 0.1^e	13.3 ± 0.1^d
COLS 3	73.7 ± 0.1^a	78.4 ± 0.1^a	85.6 ± 0.1^d	13.4 ± 0.1^c

*n = 3; Results are expressed as mean values ±SD. Means in a column with the same superscripts are not significantly different (p < 0.05).

To = onset temperature (°C); Tp = peak temperature (°C); Tc = conclusion temperature (°C); ΔHgel = enthalpy of gelatinization (Jg⁻¹).

1. Native lotus rhizome starch (NLS); 2. Oxidation level-1 (OLS1); 3. Oxidation level-2 (OLS2); 4. Oxidation level-3 (OLS3); 5. Cross-linking level-1 (CLS1); 6. Cross-linking level-2 (CLS2); 7. Cross-linking level-3 (CLS3); 8. Dual modification-1 (COLS1); 9. Dual modification-2 (COLS2); 10. Dual modification-3 (COLS3).