Effect of Ferulic Acid and Its Derivatives on Cold-Pressed Flaxseed Oil Oxidative Stability and Bioactive Compounds Retention during Oxidation.

Ferulic acid (FA) is a naturally occurring phenolic antioxidant that is widely used in the food, pharmaceutical, and cosmetic industries due to its low toxicity. Its derivatives also find numerous industrial applications and may have even higher biological activity than ferulic acid. In this study, the effect of the addition of FA and its derivatives-including vanillic acid (VA), dihydroferulic acid (DHFA), and 4-vinylguaiacol (4-VG)-on the oxidative stability of cold-pressed flaxseed oil and the degradation of bioactive compounds during oxidation was investigated. The results showed that FA and its derivatives affected the oxidative stability of flaxseed oil, but their antioxidant activity depended on the concentration (25-200 mg/100 g oil) and temperature of treatment (60-110 °C). Based on Rancimat test results, flaxseed oil oxidative stability predicted at 20 °C increased linearly with ferulic acid concentration, while its derivatives effectively prolonged the induction time at lower concentrations (50-100 mg/100 g oil). The addition of phenolic antioxidants (80 mg/100 g) generally showed a protective effect against polyunsaturated fatty acids (DHFA and 4-VG), sterols (4-VG), tocols (DHFA), squalene, and carotenoids (FA). The exception was VA, which increased the degradation of most bioactive compounds. It is believed that adding properly composed mixtures of FA and its derivatives (DHFA and 4-VG) can extend the shelf life of flaxseed oil and provide nutritional benefits.

Yellow-coated quinoa (Chenopodium quinoa Willd) - physicochemical, nutritional, and antioxidant properties.

BACKGROUND: Quinoa seeds are an excellent source of nutrients and phytochemical compounds with well documented activity; however, different cultivars are usually characterized by different physical properties and chemical composition. This study presented the physical properties, nutrient content, and antioxidant capacities of 25 cultivars of yellow-coated quinoa. RESULTS: The results demonstrated that quinoa seeds may be an excellent source of dietary fiber (up to 198 g kg-1 d.m. - Baer cultivar), with a 1:2 ratio of the soluble to insoluble fraction. Digestible carbohydrates were present at the highest level in the Puno cultivar (640 g kg-1 ). The highest content of proteins was determined in the Colorado 407D and Faro cultivars (c.a. 16%). The average content of albumin and globulins in the seeds was 29.2 and 65.6 g kg-1 , respectively. The quinoa seeds were characterized by low activity of protease inhibitors. The lowest inhibition of trypsin was determined for the UDEC-3, Faro Orange, and Titicaca cultivars, and the highest value was exhibited by the Titicaca White and UDEC-5 cultivars. Phenolics in the tested cultivars ranged from 7.1 g kg-1 (UDEC-3) to 10.6 g kg-1 (Temuko). The best antiradical properties were determined for Temuco and Rainbow (2.05 g TE kg-1 and 1.85 g TE kg-1 , respectively), while the Baer and Temuco cultivars were characterized by the highest reducing power (2.28 g TE kg-1 and 2.17 g TE kg-1 , respectively). CONCLUSION: This study has shown that quinoa cultivated in European countries is a good source of nutrients, dietary fiber, and antioxidants; however, its composition varies significantly. © 2019 Society of Chemical Industry.

Effect of saponins from quinoa on a skin-mimetic lipid monolayer containing cholesterol.

The study discusses the effect of a quinoa seed coat extract on a cholesterol-based Langmuir monolayer mimicking the intercellular lipid mixture in the skin's outermost layer - stratum corneum. Besides cholesterol (CHOL), the monolayer contains also stearic acid (SA) and ceramide VI (CER), in a molar ratio of 10:14:14. Three quinoa extracts were tested for their surface activity: a) from the whole seed, b) from the dehulled seed, and c) from the seed coat. The latter shows significantly higher ability to reduce surface tension (increase surface pressure) than the others. Its adsorbed layers display also reasonable surface dilational elasticity (storage) modulus, E'. These observations are in line with the literature reports on the high concentrations of triterpenoid glycosidic biosurfactants - saponins, in quinoa seed, especially in its coat. The saponin-rich extract of quinoa seed coat was thus introduced underneath the pre-formed lipid monolayer compressed to surface pressure, Π = 30 mN/m in a Langmuir trough, in order to register the surface pressure response. The increase of both the surface pressure and surface dilational elasticity modulus suggests that saponins, and possibly other surface-active components of the extract, incorporate into the model lipid monolayer, without solubilizing it. This opens new perspectives for the saponin-rich quinoa seed extract as skin penetration-enhancing active components for cosmetics or pharmaceutical purposes.