Composition and crystallization behavior of solvent-fractionated palm stearin

Figures & data

Table 1. Fatty acid composition of palm stearin (PS) and its fractions.

Key fatty acids in bold (n = 3). Different letters in the same column are significantly different (p < 0.05; n = 3).

Table 2. Triacylglycerol composition of palm stearin and its fractions.

Key TAGs in bold (n = 3). Abbreviations: P (Palmitic), S (Stearic), O (Oleic), and L (Linoleic). Different letters for the same column are statistically different (p < 0.05).

Table 3. Iodine value (IV) and slip melting point (SMP) of PS and its fractions.

PS fractions	IV (g I2/100 g)	SMP (°C)
PS	36.9 ± 1.3^d	50.9 ± 0.1^b
LF30	50.1 ± 0.2^a	32.3 ± 0.2^e
LF35	47.1 ± 0.8^b	37.9 ± 0.1^d
LF40	42.4 ± 1.1^c	44.4 ± 0.1^c
SF30	24.2 ± 0.3^e	55.5 ± 0.0^a
SF35	24.3 ± 0.6^e	55.7 ± 0.4^a
SF40	25.0 ± 0.1^e	55.7 ± 0.1^a

Different letters in the same column are significantly different (p < 0.05; n = 3).

Figure 1. Solid fat content vs. temperature profile of palm stearin (PS) and all fractions following fractionation at 30°C, 35°C, or 40°C (n = 3).

Table 4. Kinetic parameters associated with the isothermal crystallization of PS and all fractions using the Gompertz equation.

	Temperature (°C)	λ (min)	A (%)	μ (%/min)
PS	24	–	40.6 ± 0.3^a	–
LF30		52.6 ± 2.3^a	8.2 ± 0.2^d	0.06 ± 0.00^b
LF35		2.7 ± 0.8^b	18.5 ± 0.0^c	0.37 ± 0.01^a
LF40		–	29.6 ± 0.1^b	–
PS	29	–	36.2 ± 0.2^a	–
LF30		139.7 ± 4.4^a	4.2 ± 0.1^d	0.02 ± 0.00^c
LF35		53.4 ± 2.7^b	13.3 ± 0.4^c	0.06 ± 0.01^b
LF40		5.5 ± 0.7^c	24.5 ± 0.1^b	1.12 ± 0.02^a
PS	40	123.4 ± 3.2^a	20.6 ± 0.2^d	1.73 ± 0.06^b
SF30		15.6 ± 0.8^b	46.6 ± 0.1^a	1.45 ± 0.14^c
SF35		13.8 ± 0.2^bc	45.6 ± 0.4^b	1.22 ± 0.08^c
SF40		12.1 ± 0.9^c	43.6 ± 0.4^c	2.18 ± 0.04^a

Abbreviations: λ: induction time of nucleation; A: maximum fraction of solid fat; μ: crystallization rate; PS: palm stearin; LF: liquid fraction; SF: solid fraction. All R² values > 0.98. Different letters in the same column (for each crystallization temperature) indicate statistically significant differences (p < 0.05).

Figure 2. Putative crystallization curves for PS and all fractions during isothermal crystallization at (a) 24°C, (b) 29°C, and (c) at 40°C.

Figure 3. Crystal morphology of PS and all fractions (LF: liquid fraction; SF: solid fraction) obtained after quiescent crystallization at 24°C (top row) and 29°C (middle row) for 20 h or at 40°C (bottom row) for 4 h. PS: (a), (e), (i); LF30: (b), (f); LF35: (c), (g); LF40: (d), (h); SF30 (j); SF35 (k), and SF40 (l).

Table 5. Crystallization and melting transition temperatures and enthalpies for PS and all fractions.

	Crystallization				Melting
	TC1 (°C)	$\mathrm{\Delta }{H}_1$ (J/g)	TC2 (°C)	$\mathrm{\Delta }{H}_2$ (J/g)	TM1 (°C)	TM2 (°C)
PS	28.4 ± 0.1^b	34.7 ± 1.1^b	4.1 ± 0.1^b	30.4 ± 0.5^d	1.9 ± 0.0^d	51.4 ± 0.0^c
LF30	17.0 ± 0.1^e	9.0 ± 0.4^e	4.2 ± 0.5^ab	41.5 ± 1.2^a	4.0 ± 0.9^b	23.1 ± 0.5^f
LF35	20.8 ± 0.4^d	16.3 ± 0.0^d	4.6 ± 0.0^a	39.9 ± 0.8^b	3.4 ± 0.1^bc	24.4 ± 0.2^e
LF40	24.5 ± 1.5^c	26.4 ± 0.3^c	4.3 ± 0.0^ab	34.0 ± 0.7^c	2.8 ± 1.1^cd	42.3 ± 0.0^d
SF30	34.7 ± 0.4^a	75.4 ± 1.0^a	–	–	8.4 ± 0.0^a	57.4 ± 0.1^b
SF35	34.4 ± 0.1^a	75.3 ± 0.3^a	–	–	8.1 ± 0.2^a	57.7 ± 0.0^ab
SF40	34.3 ± 0.0^a	74.0 ± 0.0^a	–	–	8.3 ± 0.1^a	57.8 ± 0.1^a

Abbreviations: PS: palm stearin; LF: liquid fraction; SF: solid fraction. Different letters in the same column are significantly different (p < 0.05).

Figure 4. Differential scanning calorimetry thermograms for the (a) crystallization and (b) melting of PS and all fractions.

Figure 5. Time-dependent small- (top row) and wide-angle (bottom row) X-ray diffraction patterns of PS (a & d), LF (b & e), and SF (c & f) of PS (obtained from fractionation temperature of 35°C) when cooled from 60°C to 10°C followed by isothermal crystallization at 10°C for 1 h.