Centrifugation, Storage, and Filtration of Olive Oil in an Oil Mill: Effect on the Quality and Content of Minority Compounds

Table 3

Individual content of phenolic compounds before and after vertical centrifugation, storage, and filtration, expressed in mg/kg

	Decanter exit	Centrifuge exit/beginning of storage	Unfiltered/end of storage	Filtered
Phenolic alcohols
Hydroxytyrosol	6.24 ± 0.10^a	6.15 ± 0.10^a	–	–
Tyrosol	3.87 ± 0.07^a	2.34 ± 0.15^c	2.85 ± 0.02^b	2.88 ± 0.03^b
Phenolic acids
p-coumaric acid	3.04 ± 0.15^a	1.69 ± 0.09^c	2.74 ± 0.01^b	1.42 ± 0.05^d
Ferulic acid	7.36 ± 0.16^a	5.32 ± 0.13^b	0.77 ± 0.03^c	0.87 ± 0.01^c
Cinnamic acid	1.70 ± 0.08^a	1.64 ± 0.05^a	1.04 ± 0.04^b	0.88 ± 0.29^b
Secoiridoids
3,4-DHPEA-EDA (oleacein)	141.57 ± 3.68^a	94.63 ± 0.32^b	28.93 ± 0.37^c	29.95 ± 0.92^c
3,4-DHPEA-EA	108.14 ± 2.11^a	85.27 ± 2.18^b	27.99 ± 0.29^c	28.98 ± 0.56^c
p-HPEA-EDA (oleocanthal)	75.18 ± 2.98^a	62.30 ± 2.90^b	32.72 ± 0.32^c	32.74 ± 0.24^c
p-HPEA-EA	21.98 ± 2.38^a	17.80 ± 1.49^b	18.45 ± 0.17^b	18.61 ± 0.37^b
Lignans
Pinoresinol + acetoxypinoresinol	14.56 ± 1.37^a	14.05 ± 1.65^a	11.60 ± 0.84^b	11.45 ± 0.46^b
Flavones
Luteolin	7.67 ± 0.29^b	7.50 ± 0.48^b,c	9.75 ± 0.56^a	6.76 ± 0.50^c
Apigenin	5.24 ± 0.48^b	4.49 ± 0.31^c	7.37 ± 0.13^a	6.99 ± 0.23^a
Others
Vainillin	1.85 ± 0.03^a	1.67 ± 0.07^b	1.52 ± 0.04^c	1.56 ± 0.09^c

Values are expressed as mean ± SD; (a, b, c, d) indicate the Fisher’s least significant differences (LSD), with statistically significant differences at 95% confidence level.