Microwave-assisted extraction of antioxidant compounds from sunflower hulls

Abstract

The objective was to determine the adequate conditions for the microwave-assisted extraction of antioxidant compounds from the seed hull of sunflower hybrids. The existence of genetic and environmental variability in the phenolic content obtained under the selected extraction conditions was also analyzed. The extractions were carried out at 70 °C-20 and 90 °C-10 min, using water as solvent and a power of 600 W. The total phenol, flavonoid and antioxidant activity were evaluated. The microwave extraction process at 90 °C-10 min gave significantly higher values of total phenol (407.13 ± 6.11-512.71 ± 23.54 mg gallic acid⋅100 g −1 hull), flavonoids (210.09 ± 6.15-297.64 ± 5.68 mg catechin⋅100 g −1 hull) and antioxidant activity (76.73 ± 4.40-110.80 ± 3.51 μmol TE⋅g −1 hull) than those obtained at 70 °C-20 min. The cultivation environment also significantly affected the antioxidant yield, with total phenol and flavonoid contents being significantly higher for the hybrids grown in Balcarce than for those from Tandil. A significant interaction between hybrids and cultivation environmental was also observed for the antioxidant activity, indicating that the environmental effects were not similar among hybrids. The results of this study provide valuable information related to giving added value to a residue of the oil industry.

Nutritional Characteristics Assessment of Sunflower Seeds, Oil and Cake. Perspective of Using Sunflower Oilcakes as a Functional Ingredient

“…The hulls contain a low percentage of proteins (7.82%), lipids (8.81%) and ash (2.45%) according to Table 1. Similar values were found by other authors [40,46,48], values ranged within 3.48-12.40% for moisture, 2.3-9.45% for oil, 5.36-7.36% for protein and 2.1-4.11% for ash. Different superscripts letters after the values indicated differences statistically significant at p < 0.05%.…”

Extraction and recovery of chlorogenic acid from sunflower disks using a high‐efficiency system composed of deep eutectic solvents and macroporous resins

“…Sunflower belongs to the genus Helianthus of Compositae. It is one of the three primary oil crops on the world behind soybean and rapeseed (Rodríguez et al, 2019). As one of the main by-products of the sunflower industry, sunflower disks are currently used as animal feed or discarded (Dabbour et al, 2019).…”

Valorization of oil industry wastes: Extraction of phenolic compounds from different sunflower hull fractions (Helianthus annuus L.)

“…The phenolic content of foods depends on the characteristics of the raw material related to intrinsic (genus, species, cultivar) and extrinsic factors (agronomic, environmental, handling and storage conditions) (Balasundram et al, 2006). The quality of the polyphenolic extracts, in terms of antioxidant activity, will also depend both on the chemical structure of its phenolic components and on the extraction method (Nkhili et al, 2009;Rodríguez et al, 2019). Therefore, the selection of the appropriate conditions for extraction and the influence of the type of hybrid studied should be analyzed with great interest (Hayat et al, 2009).…”

“…Solid-liquid extraction by solvent is the most commonly used technique to obtain phenolic compounds, using water or solvents such as ethanol, methanol, acetone or ethyl acetate, either concentrated or diluted in aqueous mixtures to reach the polarity of the phenolic compound (Oroian et al, 2015). The structural variety of antioxidant compounds is so wide that there is no single experimental condition that allows to extract all phenolic compounds (Rodríguez et al, 2019). Thus in the literature the extraction procedures vary a lot, and include conditions ranging from room temperature to boiling temperature or reflux, as well as different processing times, various solvents and concentrations, varied sample to solvent rations, pH, particle sizes and number of extraction steps, which directly affect the extraction efficiency (Nkhili et al, 2009;Oroian et al, 2015).…”

“…Zoumpoulakis et al (2017) analyzed the ultrasound-and microwave-assisted extraction, considering as independent variables the nature of the solvent (methanol, aqueous methanol), solvent volume, temperature and operation time. Rodríguez et al (2019) examined the variables time and temperature for the microwave-assisted extraction (600 W) of phenolic compounds from sunflower hulls using water as solvent. None of these studies analyzed the effect of the particle size.…”