Differences in Oils from Nuts Extracted by Means of Two Pressure Systems

Figures & data

FIGURE 1 Physicochemical quality parameters of almond, pistachio, and walnut oils extracted by means of hydraulic press and screw press. No significant differences among extraction systems were found for the same nut oil.

TABLE 1 Stability parameters of almond, pistachio, and walnut oils extracted by means of hydraulic press and screw press

	Total polyphenols (mg caffeic acid/kg of oil)	Oxidative stability (h)
Almond-hydraulic	18.8 ± 7. 8^ns	20.5 ± 0.3^ns
Almond-screw	22.8 ± 7. 8^ns	19.7 ± 0.3^ns
Pistachio-hydraulic	23.30 ± 7.07^ns	31 ± 2^a
Pistachio-screw	22 ± 5^ns	37.15 ± 1.06^b
Walnut-hydraulic	17 ± 4^ns	6.35 ± 0.07^ns
Walnut-screw	29 ± 3^ns	6.9 ± 0.4^ns

^a,bDifferent superscripts for the same type of nut oil indicate significant differences among extraction systems.

ns: no significant differences among extraction systems.

TABLE 2 Fatty acid composition of almond, pistachio, and walnut oils extracted by means of hydraulic press and screw press. No significant differences among extraction systems were found for the same nut oil.

	Almond		Pistachio		Walnut
	Hydraulic	Screw	Hydraulic	Screw	Hydraulic	Screw
Miristic C14:0	0.03 ± 0	0.03 ± 0	0.05 ± 0	0.06 ± 0	0.03 ± 0	0.2 ± 0
Palmitic C16:0	6.6 ± 0	6.6 ± 0	10.75 ± 0.07	10.75 ± 0.07	7.35 ± 0.07	8 ± 0
Palmitoleic C16:1	0.7 ± 0	0.6 ± 0	1 ± 0	1.1 ± 0	0.15 ± 0.07	0.2 ± 0
Margaric C17:0	0.05 ± 0	0.04 ± 0	0.06 ± 0	0.06 ± 0	0.05 ± 0	0.05 ± 0
Margaroleic C17:1	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0
Stearic C18:0	2 ± 0	2 ± 0	1.15 ± 0.07	1 ± 0	3 ± 0	3 ± 0
Oleic C18:1	68.8 ± 0.2	68.90 ± 0.14	59.2 ± 0.5	59.0 ± 0.7	17.20 ± 0.35	18 ± 0
Linoleic C18:2	21.6 ± 0.1	21.50 ± 0.14	26.8 ± 0.5	26.8 ± 0.6	60.30 ± 0.35	60 ± 0
Linolenic C18:3	0.1 ± 0	0.1 ± 0	0.4 ± 0	0.5 ± 0	12 ± 0	12 ± 0
Arachidic C20:0	0.04 ± 0	0.04 ± 0	0.05 ± 0	0.04 ± 0	0.04 ± 0	0.04 ± 0
Gadoleic C20:1	0.1 ± 0	0.1 ± 0	0.3 ± 0	0.3 ± 0	0.2 ± 0	0.2 ± 0
Behenic C22:0	0.02 ± 0	0.03 ± 0	0.03 ± 0	0.05 ± 0	0.03 ± 0	0.03 ± 0
Lignoceric C24:0	0.05 ± 0	0.05 ± 0	0.04 ± 0	0.04 ± 0	0.02 ± 0	0.02 ± 0

FIGURE 2 Principal sums of the fatty acids of the almond, pistachio, and walnut oil samples. ^a,bDifferent superscripts indicate significant differences among nut oils; ns: no significant differences.

FIGURE 3 Ratios of the fatty acids of the almond, pistachio, and walnut oil samples.^a,bDifferent superscripts indicate significant differences among nut oils; ns: no significant differences.

TABLE 3 Sterol composition of almond, pistachio, and walnut oils extracted by means of hydraulic press and screw press. No significant differences among extraction systems were found for the same nut oil

	Almond		Pistachio		Walnut
	Hydraulic	Screw	Hydraulic	Screw	Hydraulic	Screw
Colesterol	0.2 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.2 ± 0	0.2 ± 0
Brassicasterol	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0
Campesterol	3 ± 0	3.2 ± 0	4.1 ± 0	4 ± 0	5 ± 0	4.75 ± 0.07
Stigmasterol	1 ± 0	1.30 ± 0.07	0.6 ± 0	0.70 ± 0.07	0.25 ± 0.07	0.25 ± 0.07
Δ7-stigmastenol	0.30 ± 0	0.3 ± 0	0.55 ± 0.07	0.6 ± 0	0.15 ± 0.07	0.15 ± 0.07
Apparent β-sitosterol	95 ± 0	95 ± 0	94 ± 0	93.60 ± 0.14	94.40 ± 0.14	94.30 ± 0.14
Total sterols (mg/kg)	2467 ± 10	2762 ± 25	4221 ± 117	4476 ± 241	1429 ± 51	1448 ± 23
Erytrodiol+ Uvaol	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0	0.1 ± 0