Effects of the Chemical Composition on the Antioxidant and Sensory Characteristics and Oxidative Stability of Cold-Pressed Black Cumin Oils

Abstract

The antioxidant capacity (AC); amounts of tocopherols, sterols, and polycyclic aromatic hydrocarbons; oxidative parameters; fatty acid composition (FAC); and sensory quality of cold-pressed black cumin oils (CPBCOs) available on the Polish market were analyzed and compared. The AC levels of the CPBCO samples were determined using four assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH = 226.8–790.1 μmol TE/100 g), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS = 385.9–1465.0 μmol TE/100 g), cupric-reducing antioxidant capacity (CUPRAC = 975.3–19,823.3 μmol TE/100 g), and Folin–Ciocalteu assays (FC = 168.1–643.7 μmol TE/100 g). The FAC scores were typical for black cumin oil, except for the sample CPBCO4, which had a higher content of α-linolenic acid (C18:3 = 23.33%), pointing to possible oil adulteration. Additionally, the concentrations of total sterols (TSC = 372 mg/100 g) and tocopherols (TTC = 42.3 mg/100 g) in this sample were higher than those for other investigated oils (TSC = 159–222 mg/100 g, TTC = 1.9–10.4 mg/100 g respectively). The oxidative stability levels (IP = 8.21–37.34 h), peroxide values (PV = 21.36–123.77 meq O2/kg), acid values (AV = 6.40–22.02 mg KOH/kg), and the sums of four specific polycyclic aromatic hydrocarbons (∑4PAHs = 4.48–46.68 μg/kg) in the studied samples differed significantly (p < 0.05). A sensory lexicon including 12 attributes was developed and applied for the sensory evaluation of oils using a quantitative descriptive analysis (QDA).

Variation in the Composition and Quality of Nigella sativa L. Seed Oils—The Underestimated Impact on Possible Health-Promoting Properties

“…The presented shares of fatty acid are close to the results obtained by other scientists [ 1 , 19 , 27 , 28 ]. This indicates that the fatty acid composition of N. sativa L. seeds, independent of cultivation area, is relatively constant.…”

“…23% α-linolenic acid, total polyunsaturated fatty acids approx. 15%, or ca 13% of trans -9-elaidic acid) are exceptional cases [ 2 , 19 , 29 ] and probably misleading samples.…”

“…100% in seeds cultivated in Syria [ 14 ]. Similarly, also variable are fatty acids and unsaponifiable lipid components [ 18 , 19 ], as well as oil quality indices: peroxide value, induction time, acid value, etc. [ 6 , 18 , 19 ].…”

“…Similarly, also variable are fatty acids and unsaponifiable lipid components [ 18 , 19 ], as well as oil quality indices: peroxide value, induction time, acid value, etc. [ 6 , 18 , 19 ]. For example, the peroxide values of black cumin oils can be very low (ca.…”

“…0.2 meq O 2 /kg—Mazaheri et al [ 18 ]) or extremely high (ca. 124 meq O 2 /kg—Szydłowska-Czerniak et al [ 19 ]).…”