Optical Analysis of the Oils Obtained from Acrocomia aculeata (Jacq.) Lodd: Mapping Absorption-Emission Profiles in an Induced Oxidation Process

Abstract

Acrocomia aculeata is a palm tree typical of the Brazilian savanna. Oils extracted from the pulp and kernel of Acrocomia aculeata fruits have gained considerable attention mainly due to their nutritional and medicinal features. Despite their potential applications, a detailed analysis of their oxidative stability is still needed. The present study shows a close analysis of the oxidative stability of the oils obtained from the kernel and pulp of Acrocomia aculeata fruits, evaluating the influence of the intrinsic antioxidants and the fatty acid composition on the oil's thermal stability. A complete characterization of the physical-chemical and optical properties of the oils was performed. The results showed that 66% of the fatty acids present in the pulp oil are unsaturated, while 75% are saturated in the kernel oil. A higher content of intrinsic antioxidants was obtained in the pulp oil, and an induction period (at 110 • C) of 65 and 43 h was determined for the pulp and kernel oil, respectively. Additionally, oil absorption increases due to the formation of degradation products, and a new fluorescent compound was formed during the oil oxidation process at 110 • C. Even though the pulp presented a high content of unsaturated fatty acids, the pulp oil was more stable than the kernel oil due to its higher content of intrinsic antioxidant, especially carotenoids. The results also demonstrated that oil oxidation can be optically determined by analyzing the absorption at 232 and 270 nm, as well as the emission at 424 nm.

Extraction of macauba kernel oil using supercritical carbon dioxide and compressed propane

“…Macauba kernel oil contains high concentrations of saturated fatty acids, predominantly lauric acid (40.97–67.8 %), as seen in Figure a. Other studies have reported levels of 31.6–50 % of this fatty acid in macauba kernel oil . The oils also showed high levels of oleic, myristic, and caprylic acids.…”

“…The amount of oil available in macauba fruit is highest in the kernel, i.e., 46.6–52.9 %. The oil is transparent in appearance, with the predominance of lauric and oleic acids . It also contains active compounds such as tocopherols and phytosterols, which confer greater oxidative stability when compared to pulp oil …”

“…In order to obtain the oil from Acrocomia aculeata kernels, previous reports have used solvent extraction in a Soxhlet apparatus, pressing, and the Bligh and Dyer method . However, a promising method that has not yet been explored for obtaining this oil is extraction using pressurized fluids at sub‐ or supercritical conditions.…”

Characterization and oxidative stability of oils and bioactive compounds of the fruits of Byrsonima cydoniifolia A. Juss. at different ripening stages

“…It is well known that chlorophylls present two absorption bands, in the violet‐blue (350–450 nm) and red (650–700 nm) regions, while carotenoids absorb in the blue‐green (400–500 nm) range . Additionally, it is also well established that carotenoids and chlorophylls are responsible for emission in the 400–550 nm range and 650–750 nm range, respectively . Furthermore, it is worth pointing out that both UV‐visible absorption and fluorescence results revealed that the chlorophyll content decreased during the course of ripening, almost reduced to zero in the ripe oil.…”

“…35,36 Additionally, it is also well established that carotenoids and chlorophylls are responsible for emission in the 400-550 nm range and 650-750 nm range, respectively. 36,37 Furthermore, it is worth pointing out that both UV-visible absorption and fluorescence results revealed that the chlorophyll content decreased during the course of ripening, almost reduced to zero in the ripe oil. Differently, carotenoid content was detected at similar concentrations for the unripe and intermediate oils (in fact, in a slightly lower concentration in the intermediate when compared with the unripe) and an increased content for the ripe oil.…”