Chemical composition and thermal properties of Tilapia oil extracted by different methods

Figures & data

Table 1. Nutrient composition of freeze-dried tilapia (dry weight bases).

Moisture (%)	Fat (%)	Protein (%)	Ash (%)
1.21 ± 0.17	36.69 ± 0.04	49.95 ± 0.35	12.04 ± 0.32

Table 2. Chemical composition of tilapia fish oil.

	Diluted alkaline hydrolysis	Enzymatic hydrolysis	Microwave-assisted method
AV (mg KOH/g oil)	0.77 ± 0.13^c	1.12 ± 0.08^b	1.41 ± 0.10^a
POV (mmol/kg oil)	3.76 ± 0.32^a	4.46 ± 0.33^b	4.67 ± 0.17^c
Moisture and Volatile matter (%)	0.27 ± 0.01^c	0.13 ± 0.10^b	0.05 ± 0.00^a
Impurity (%)	0.02 ± 0.00	0.03 ± 0.01	—
Odor	Fishy smell; No rancid flavor	More fishy smell No rancid flavor	Fishy smell No rancid flavor
Color and Luster (Lovibond, 10 mm)	Y38.9, R2.0 (Buff) No turbidity, no stratification	Y20.0, R10.0 (Orange red) No turbidity, no stratification	Y79.9, R2.9 (Bright yellow) No turbidity, no stratification

Values in the same row with different letters for each species show significant differences (p < 0.05). —, not detected.

Table 3. Content of FAs in tilapia fish oil extracted by three extraction methods (total FAs %).

	Diluted alkaline hydrolysis	Enzymatic hydrolysis	Microwave-assisted method
C4:0	0.03 ± 0.00^a	0.22 ± 0.13^b	0.10 ± 0.01^ab
C5:0	—	—	0.01 ± 0.00
C6:0	0.10 ± 0.00^a	0.01 ± 0.00^b	0.02 ± 0.00^c
C7:0	0.12 ± 0.01^a	0.12 ± 0.00^a	0.34 ± 0.04^b
C8:0	0.03 ± 0.00^a	—	0.01 ± 0.00^a
C9:0	0.22 ± 0.09^b	0.06 ± 0.00^a	0.24 ± 0.07^b
C10:0	0.03 ± 0.02^a	0.03 ± 0.02^a	0.04 ± 0.00^a
C11:0	0.29 ± 0.04^a	0.12 ± 0.03^b	0.19 ± 0.04^c
C12:0	0.12 ± 0.01^b	0.12 ± 0.01^b	0.08 ± 0.02^a
C13:0	0.25 ± 0.06^b	0.14 ± 0.04^a	0.07 ± 0.01^a
C14:0	3.12 ± 0.07^b	3.16 ± 0.07^b	2.95 ± 0.04^a
9cC14:1	0.15 ± 0.02^c	0.15 ± 0.00^b	0.13 ± 0.00^a
C15:0	0.32 ± 0.00^c	0.32 ± 0.00^b	0.31 ± 0.00^a
10cC15:1	0.03 ± 0.00^b	0.01 ± 0.00^a	0.04 ± 0.00^b
C16:0 PA	22.78 ± 0.35^a	23.09 ± 0.18^a	23.16 ± 0.28^a
9tC16:1	0.57 ± 0.06^a	0.56 ± 0.08^a	0.61 ± 0.11^a
9cC16:1	5.88 ± 0.01^c	5.79 ± 0.03^b	5.56 ± 0.06^a
C17:0	0.37 ± 0.00^b	0.38 ± 0.00^c	0.35 ± 0.00^a
10cC17:1	5.29 ± 0.00^b	0.22 ± 0.01^a	0.22 ± 0.01^a
C18:0 SA	5.29 ± 0.17^a	5.49 ± 0.03^b	5.62 ± 0.03^c
9tC18:1 n-9	0.80 ± 0.06^a	0.78 ± 0.12^a	0.82 ± 0.08^a
11tC18:1	0.49 ± 0.03^c	0.19 ± 0.02^a	0.36 ± 0.00^b
6cC18:1	—	0.18 ± 0.13	—
9cC18:1 n-9 OA	26.19 ± 0.15^b	25.88 ± 0.06^a	25.73 ± 0.22^a
11cC18:1	4.02 ± 0.02^b	3.93 ± 0.02^a	3.93 ± 0.00^a
C19:0	0.09 ± 0.01^a	0.10 ± 0.01^a	0.10 ± 0.00^b
9t12tC18:2 n-6	0.08 ± 0.00^b	0.05 ± 0.01^a	0.06 ± 0.01^a
9c12cC18:2 n-6 LA	15.98 ± 0.07^c	15.79 ± 0.06^b	15.69 ± 0.03^a
C20:0	0.27 ± 0.00^a	0.29 ± 0.01^b	0.29 ± 0.00^b
C18:3 n-6 GLA	1.18 ± 0.00^c	1.17 ± 0.00^b	1.14 ± 0.01^a
8cC20:1	0.14 ± 0.00^a	0.16 ± 0.00^b	0.24 ± 0.02^c
C18:3 n-3 ALA	1.68 ± 0.15^a	1.57 ± 0.23^a	1.60 ± 0.28^a
11cC20:1 n-9	1.47 ± 0.16^a	1.55 ± 0.23^a	1.49 ± 0.25^a
C20:2 n-6	0.76 ± 0.00^a	0.76 ± 0.02^a	0.78 ± 0.00^b
C22:0	0.20 ± 0.01^a	0.20 ± 0.01^a	0.21 ± 0.00^a
C20:3 n-6	0.80 ± 0.02^a	0.80 ± 0.01^a	0.81 ± 0.03^a
C20:3 n-3	0.37 ± 0.01^a	0.37 ± 0.01^a	0.37 ± 0.02^a
C20:4 n-6 AA	0.94 ± 0.00^a	0.95 ± 0.00^a	1.08 ± 0.05^b
C23:0	0.17 ± 0.00^a	0.32 ± 0.00^b	0.38 ± 0.02^c
C22:2 n-6	0.10 ± 0.01^b	0.10 ± 0.01^b	0.06 ± 0.00^a
C20:5 n-3 EPA	0.41 ± 0.05^b	0.23 ± 0.05^a	0.28 ± 0.02^a
C24:0	0.11 ± 0.01^a	0.11 ± 0.01^a	0.34 ± 0.00^b
C22:3 n-3 + C24:1 n-9	0.06 ± 0.00^a	0.06 ± 0.00^a	0.08 ± 0.05^a
C22:4 n-6	1.31 ± 0.49^a	1.23 ± 0.15^a	1.21 ± 0.29^a
C22:5 n-6	0.91 ± 0.01^b	0.84 ± 0.03^a	0.89 ± 0.01^a
C22:5 n-3 DPA	0.84 ± 0.01^b	0.84 ± 0.01^b	0.81 ± 0.01^a
C22:6 n-3 DHA	1.89 ± 0.06^a	1.89 ± 0.04^a	1.92 ± 0.12^a
∑SFA	32.78 ± 0.34^a	34.32 ± 0.22^b	34.64 ± 0.24^b
∑MUFA	39.10 ± 0.77^b	37.57 ± 0.18^a	37.21 ± 0.77^a
∑TFA	1.29 ± 0.02^a	1.54 ± 0.03^b	1.75 ± 0.02^c
∑ω-3 PUFA	5.28 ± 0.00^c	5.07 ± 0.02^b	5.02 ± 0.01^a
∑ω-6 PUFA	21.92 ± 0.01^c	21.58 ± 0.01^a	21.61 ± 0.00^b

Values in the same row with different letters for each species show significant differences (p < 0.05). —, not detected.

Table 4. Comparison of DSC transition temperatures for melting and crystallization curves of fish oil samples.

Curve	Sample	Transition temperature (°C)
		1	2	3
Melting	Dilute alkali hydrolysis	–37.88	–2.03
	Enzymatic hydrolysis	–39.28	–3.20
	Microwave-assisted method	–4.37
Crystallization	Dilute alkali hydrolysis	–73.41	–34.51	3.26
	Enzymatic hydrolysis	–74.46	–17.98	3.33
	Microwave-assisted method	–74.79	–18.96	2.18

Figure 1. DSC melting curves of tilapia fish oil.

(A: Diluted alkaline hydrolysis; B: Enzymatic hydrolysis; C: Microwave-assisted method)

Figure 2. DSC crystallization curves of tilapia fish oil.

(A: Diluted alkaline hydrolysis; B: Enzymatic hydrolysis; C: Microwave-assisted method)

Figure 3. Infrared spectra of tilapia fish oil samples from three extraction methods.

(A: Diluted alkaline hydrolysis; B: Enzymatic hydrolysis; C: Microwave-assisted method)