Characteristics and Antioxidant Potential of Cold-Pressed Oils—Possible Strategies to Improve Oil Stability

Abstract

The relations of the antiradical capacity to oxidative stability parameters and the contents of fatty acids, sterols, tocopherols, phenols, flavonoids, chlorophyll, Cu, and Fe were assessed in 33 cold-pressed seed oils: Walnut (7 brands of oils), rosehip (3), camelina (6), milk thistle (5), flax (6), and pumpkin (6). The antiradical capacity of oils depended strongly on tocopherol contents with a synergistic effect with polyphenols. The efficacy of tocopherols in cold-pressed oils was accompanied by a negative correlation of their antioxidant capacity with the peroxide value increase after 3 months of shelf life. This study also showed a positive correlation between the content of phytosterols and the antiradical capacity in the lipophilic fraction of cold-pressed oils rich in n-3 polyunsaturated fatty acids (PUFAs). Multiple regression analysis identified groups of antioxidants naturally occurring in cold-pressed oils in relation to their fatty acid composition, which added to the cold-pressed oils could provide possible strategies to improve their stability. Achieving high stability is primarily a result of high phytosterol content exceeding the molar ratio of 1:100 for total phytosterols to α-linolenic acid. However, the molar ratios of tocopherols to linoleic acid below 1:2000 and polyphenols to linoleic acid below 1:3000 does not prevent oxidation in oils with the predominance of linoleic acid.

Fatty Acid Composition of Cannabis sativa, Linum usitatissimum and Camelina sativa Seeds Harvested in Lithuania for Food Use

“…The PI index of all seeds was higher than that indicated by Kang et al [55] as the most favorable range (80-90) to reduce the risk of CVD. It is well-known that PUFAs and particularly ALA are highly susceptible to oxidation [58], which increases the risk of oil deterioration. Although in the present study, the PI index shows poor oxidative stability of oils, it is known that whole flaxseeds [59] and likely other oil crop seeds are chemically stable.…”

Beneficial Effects of High Intensity Interval Training and/or Linseed Oil Supplementation to Limit Obesity-Induced Oxidative Stress in High Fat Diet-Fed Rats

“…Its antidiabetic, anti-inflammatory, anti-cancer, and cardioprotective actions are mainly attributed to ALA [44][45][46][47]). LO also contains phytosterols [24], antioxidant vitamins (especially γ-tocopherol and β-carotene, at lower concentration), lignans [48], and phenolic compounds [25] that contribute to its antioxidant properties, in addition to ALA [49]. Moreover, we previously showed that compared with sunflower oil, LO contains higher levels of n-3 PUFA and has a better n-6/n-3 PUFA ratio [30].…”

“…A recent systematic review of randomized controlled trials in patients with metabolic syndrome and related disorders demonstrated that LO supplementation significantly reduces malonedialdehyde (MDA), a lipid peroxidation marker, and increases the total antioxidant capacity [21]. Among the different bioactive compounds contained in LO, alpha-linoleic acid (ALA; the most abundant) [22,23], phytosterols [24], antioxidant vitamins (especially γ-tocopherol and β-carotene; present at lower concentration), and phenolic compounds [25] have a strong antioxidant activity. Moreover, to counteract the deleterious effects of the Western diet, dietary oils with modified fatty acid profiles have been manufactured to improve fatty acid intake and limit the risk of chronic diseases [26].…”

The Quality Characteristic and Fatty Acid Profile of Cold-Pressed Hazelnut Oils during Nine Months of Storage

“…Moreover, fresh oils usually have PV below 10 meq/kg, and a rancid taste becomes noticeable above PV of 20 meq O 2 /kg. Other studies have reported an increase in AV and PV after storage of cold pressed oils from nuts and seeds [15,[25][26][27][28]. AnV is an indicator of secondary oxidation products and measures non-volatile aldehydes, the larger the value, the more severe the oxidative deterioration [29].…”

“…Additionally, hazelnut oil can be consumed crude or refined. Virgin hazelnut oil is obtained directly from hazelnuts without any refinement, which is known to provide high nutrition due to its comprehensive monounsaturated fatty acids (MUFA) and rich minor compounds, such as bioactive substances recovered in the pressing [15]. The cold pressing technique involves gentle pressure on the crude material, but due to the low processing, this technique is usually expensive.…”