Comparative Study and Quality Evaluation of Italian Focaccias Seasoned with Extra Virgin Olive Oil

Figures & data

Table 1 Mean results of the routine analyses for each oil sample examined. ^a

Samples	FFA (%)	PV (meq O2/kg)	K232	K270	ΔK	TOTOX
Extra virgin olive oil	0.60	16.4	2.11	0.14	−0.02	39.02
Oil extracted from:
Onion-topped focaccia	1.40	19.9	3.92	1.08	0.03	46.11
Potato-topped focaccia	1.19	20.8	3.16	0.84	0.02	50.61
Rosemary-topped focaccia	1.12	29.7	4.14	1.02	0.02	63.80
^aMean values of two independent repetitions. FFA: free fatty acids; PV: peroxide value; K232: specific absorption at 232 nm; K270: specific absorption at 270 nm; ΔK = K270 − (K266 + K274)/2; TOTOX = 2PV + p-AV (p-AV, p-anisidine value).

Table 2 Percentage values (w/w) in oil of the main substance classes constituting the polar compounds for each oil sample examined. ^a

Samples	TGP	ox-TG	DG	2TGP + ox-TG
Extra virgin olive oil	0.08 ± 0.01a	0.75 ± 0.04a	1.63 ± 0.16a	0.91
Oil extracted from:
Onion-topped focaccia	0.15 ± 0.01b	1.16 ± 0.08b	1.81 ± 0.11a	1.46
potato-topped focaccia	0.14 ± 0.00b	1.00 ± 0.01c	1.74 ± 0.02a	1.28
rosemary-topped focaccia	0.14 ± 0.00b	1.33 ± 0.01d	1.76 ± 0.01a	1.61
^aResults of statistical analysis at p < 0.05. Mean values of three independent repetitions ± SD; one common letter following an entry indicates no significance. TGP: triglyceride polymers; ox-TG: oxidized triglyderides; DG: diglycerides.

Figure 1 HPSEC chromatogram of the polar compounds of the oil extracted after baking from the potato-topped focaccia. TGP: triglyceride oligopolymers; ox-TG: oxidized triglycerides; DG: diglycerides; ST: free sterols and triterpene diols; FFA: free fatty acids.

Table 3 Percentage values (w/w) in oil of the trans-isomers of fatty acids for each oil sample examined. ^a

Samples	C18:1t	C18:2t+C18:3t	Total trans-isomers
Extra virgin olive oil	0.022 ± 0.002a	tr.a	0.022 ± 0.002a
Oil extracted from:
Onion-topped focaccia	0.061 ± 0.008b	0.008 ± 0.001a	0.069 ± 0.009b
Potato-topped focaccia	0.054 ± 0.007b	0.024 ± 0.013a	0.079 ± 0.019b
Rosemary-topped focaccia	0.074 ± 0.003b	0.008 ± 0.011a	0.082 ± 0.013b
^aResults of statistical analysis at p < 0.05. Mean values of three independent repetitions ± SD; one common letter following an entry indicates no significance. tr., traces (not integrated).

Table 4 Results of two-way ANOVA, with interactions, performed on the data. ^a

	Topping			Technology
	Onion	Potato	Rosemary	Artisan	Industrial	Topping × technology
TGP	A	C	B	a	b	p < 0.0001
ox-TG	B	C	A	a	b	p < 0.0001
DG	A	B	A	a	a	p = 0.001
^aA common letter indicates no significant difference (p < 0.05). A > B > C, a > b.

Figure 2 Biplot of PCA, principal component analysis. EVO: extra virgin olive oil; O: onion-topped focaccia; P: potato-topped focaccia; R: rosemary-topped focaccia; A: artisan focaccia; I: industrial focaccia.