Phenolic acids, avenanthramides, and antioxidant activity of oats defatted with hexane or supercritical fluid

Deep Eutectic Solvent-Based Aqueous Two-Phase Systems and Their Application in Partitioning of Phenol Compounds

This work studies the partition of phenolic compounds, namely caffeic acid, syringic acid, vanillic acid, ferulic acid, and vanillin, in aqueous two-phase systems (ATPSs) formed by acetonitrile and deep eutectic solvents (DESs) based on choline chloride ([Ch]Cl) and carbohydrates (sucrose, d-glucose, d-mannose, arabinose, and d-xylose). The binodal curves built at 25 °C and 0.1 MPa using DES were compared with ATPS composed of [Ch]Cl and the same carbohydrates. The ability to form ATPS depends on the number and kind of hydroxyl groups in DES's hydrogen-bond donor compound (carbohydrates). ATPS based on DES showed biphasic regions larger than the systems based on [Ch]Cl and carbohydrates alone due to the larger hydrophilicity of DES. The ATPS were used to study the partition of the phenolic compounds. For all the systems, the biomolecules preferentially partitioned to the acetonitrile-rich phase (K > 1), and the best recovery in the top phase ranged between 53.36% (caffeic acid) and 90.09% (vanillin). According to the remarkable results, DES-based ATPS can selectively separate ferulic acid and vanillin for the top phase and syringic, caffeic, and vanillic acids for the bottom phase, achieving a selectivity higher than two.

Avenanthramides, Distinctive Hydroxycinnamoyl Conjugates of Oat, Avena sativa L.: An Update on the Biosynthesis, Chemistry, and Bioactivities

Avenanthramides are a group of N-cinnamoylanthranilic acids (phenolic alkaloid compounds) that are produced in oat plants as phytoalexins, in response to pathogen attack and elicitation. The enzyme catalysing the cinnamamide-generating reaction is hydroxycinnamoyl-CoA: hydroxyanthranilate N-hydroxycinnamoyltransferase (HHT, a member of the super family of BAHD acyltransferases). HHT from oat appears to have a narrow range of substrate usage, with preferred use of 5-hydroxyanthranilic acid (and to a lesser extent, other hydroxylated and methoxylated derivatives) as acceptor molecules, but is able to use both substituted cinnamoyl-CoA and avenalumoyl-CoA thioesters as donor molecules. Avenanthramides thus combine carbon skeletons from both the stress-inducible shikimic acid and phenylpropanoid pathways. These features contribute to the chemical characteristics of avenanthramides as multifunctional plant defence compounds, as antimicrobial agents and anti-oxidants. Although avenanthramides are naturally and uniquely synthesised in oat plants, these molecules also exhibit medicinal and pharmaceutical uses important for human health, prompting research into utilisation of biotechnology to enhance agriculture and value-added production.

Cereal Waste Valorization through Conventional and Current Extraction Techniques-An Up-to-Date Overview

Nowadays, in the European Union more than 100 million tons of food are wasted, meanwhile, millions of people are starving. Food waste represents a serious and ever-growing issue which has gained researchers’ attention due to its economic, environmental, social, and ethical implications. The Sustainable Development Goal has as its main objective the reduction of food waste through several approaches such as the re-use of agro-industrial by-products and their exploitation through complete valorization of their bioactive compounds. The extraction of the bioactive compounds through conventional methods has been used for a long time, whilst the increasing demand and evolution for using more sustainable extraction techniques has led to the development of new, ecologically friendly, and high-efficiency technologies. Enzymatic and ultrasound-assisted extractions, microwave-assisted extraction, membrane fractionation, and pressure-based extraction techniques (supercritical fluid extraction, subcritical water extraction, and steam explosion) are the main debated green technologies in the present paper. This review aims to provide a critical and comprehensive overview of the well-known conventional extraction methods and the advanced novel treatments and extraction techniques applied to release the bioactive compounds from cereal waste and by-products.

Characterization and antioxidant activity of avenanthramides from selected oat lines developed by mutagenesis technique

From a mutagenized oat population, produced by ethyl methanesulfonate mutagenesis, hulled grains from 17 lines with elevated avenanthramide (AVN) content were selected and their AVN structures, concentrations and antioxidant potentials were determined by HPLC-MS² and HPLC equipped with an on-line ABTS⁺ antioxidant detection system. The data obtained showed qualitative and quantitative differences in the synthesis of AVNs in the different lines, with a total AVN concentration up to 227.5 µg/g oat seed flour in the highest line, compared with 78.2 µg/g seed in the commercial line, SW Belinda. In total, 25 different AVNs were identified with avenanthramide B structures being among the most abundant, and AVN C structures having the highest antioxidant activity. The findings indicate the potential of oat mutagenesis in combination with a high precision biochemical selection method for the generation of stable mutagenized lines with a high concentration of total and/or individual AVNs in the oat seed grain.

Current Knowledge of Content and Composition of Oat Oil—Future Perspectives of Oat as Oil Source

The oat oil composition is unique among cereals; however, the industrial exploitation of oat oil still needs more attention. The health claims authorized by the FDA and the EFSA have led to a significant increase in the industry’s interest in oats as an industrial crop. The current focus is put on the extraction of fibre/beta-glucan or oat proteins. In contrast, the fat present in oats and especially its functional components do not attract sufficient industrial attention. The paper presents a concise analysis of the current state of knowledge about the content and composition of oat oil (perceived as oil as product, not fat content) regarding oil extraction methods and analysis. The profound study suggests that oil separation should be obviously taken into account during oat fractionation for industrial products. Such an approach will be in agreement with sustainable management of natural resources and should be taken into account when planning full utilization of each plant crop.