Fourier-Transform Infrared Spectra Combined with Chemometrics and Fatty Acid Composition for Analysis of Pumpkin Seed Oil Blended Into Olive Oil

Figures & data

FIGURE 1 PCA of EVOO, PSO, and other vegetable oils: (a) score plot and (b) loading plot. GSO: grape seed; CO: corn; SeO: Sesame; SFO: Sunflower; SO: soybean; WO: walnut; RBO: Rice bran; PSO: Pumpkin seed; PO: palm; CaO: canola oil.

FIGURE 2 (a) FTIR normal spectra of extra virgin olive oil and pumpkin seed oil, scanned at mid infrared region (4000–650 cm⁻¹). The first derivative FTIR spectra at frequency region of 3050–2800 (b), and at 1100–900 cm⁻¹ (c).

TABLE 1 The performance of multivariate calibrations for analysis of PSO blended into EVOO

			R^2
Multivariate calibration	Spectra treatment	Factor	Calibration	Prediction	RMSEC (% vol/vol)	RMSEP (% vol/vol)
PLSR	Normal	4	0.999	0.992	0.166	1.32
	1st der	8	0.999	0.998	0.003	1.14
	2nd der	8	0.999	0.147	0.001	3.47
PCR	Normal	10	0.999	0.991	0.316	1.44
	1st der	10	0.999	0.998	0.122	1.14
	2nd der	10	0.996	0.967	0.923	3.08

TABLE 2 The contents of major fatty acids in PSO blended into EVOO, as determined using GC–FID

	Ratio (PSO:EVOO)
FA^†	(0%:100%)	(5%:95%)	(10%:90%)	(15%:85%)	(20%:80%)	(25%:75%)	(30%:70%)	(35%:65%)	(40%:60%)	(100%:0%)
C16:0	10.48 ± 0.12^a	10.65 ± 0.04^ab	10.70 ± 0.04^ab	10.71 ± 0.09^ab	10.83 ± 0.06^b	10.91 ± 0.00^bc	11.15 ± 0.21^cd	11.16 ± 0.18^cd	11.26 ± 0.11^d	11.58 ± 0.00^e
C16:1	0.66 ± 0.01^j	0.63 ± 0.02^i	0.61 ± 0.01^h	0.57 ± 0.01^g	0.55 ± 0.01b^f	0.51 ± 0.00^e	0.46 ± 0.01^d	0.41 ± 0.01^c	0.32 ± 0.00^b	0.10 ± 0.00^a
C18:0	3.20 ± 0.02^a	3.19 ± 0.02^a	3.33 ± 0.02^b	3.53 ± 0.05^c	3.67 ± 0.04^d	4.06 ± 0.00^e	4.27 ± 0.03^f	5.86 ± 0.06^g	6.83 ± 0.08^h	7.47 ± 0.13^i
C18:1	71.50 ± 1.15^i	70.24 ± 0.31^i	67.79 ± 0.31^h	65.57 ± 0.38^g	63.41 ± 0.35^f	60.51 ± 0.00^e	55.96 ± 0.88^d	53.07 ± 0.13^c	45.05 ± 1.13^b	32.51 ± 0.31^a
C18:2	10.65 ± 0.29^a	12.46 ± 0.21^b	14.77 ± 0.86^c	16.59 ± 0.53^d	19.05 ± 0.94^e	21.44 ± 0.00^f	25.48 ± 0.08^g	27.61 ± 0.66^h	32.82 ± 0.27^i	46.26 ± 0.00^j
C18:3	0.65 ± 0.01^j	0.59 ± 0.01^i	0.58 ± 0.01^h	0.55 ± 0.01^g	0.53 ± 0.01^f	0.50 ± 0.00^e	0.46 ± 0.00^d	0.44 ± 0.00^c	0.38 ± 0.00^b	0.23 ± 0.00^a
C22:0	0.30 ± 0.00^g	0.29 ± 0.01^f	0.28 ± 0.01^ef	0.27 ± 0.01^e	0.25 ± 0.00^d	0.24 ± 0.00^d	0.22 ± 0.00^c	0.21 ± 0.00^c	0.18 ± 0.01^b	0.10 ± 0.00^a

^†Each value in the table represents the means of triplicate analysis; SD is given after ±. Means within each row with different letters are significantly different at P < 0.05. FA = fatty acid.

FIGURE 3 The number of factor or latent variables used for modeling PLS calibration.

FIGURE 4 The Coomans plot for the classification of EVOO and that mixed with pumpkin seed oil (PSO). (□) Pure EVOO; (Δ) EVOO blended with PSO.

FIGURE 5 The percentage changes of main FAs during the blending of PSO with certain levels (0, 5, 10, 15, 20, 25, 30, 35, and 40% vol/vol) into EVOO.