Extraction of alkylresorcinols from wheat bran with supercritical CO2

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.

Bioactive Compounds of a Wheat Bran Oily Extract Obtained with Supercritical Carbon Dioxide

A wheat bran oily extract obtained with supercritical carbon dioxide at 25.0 ± 0.1 MPa and 40 ± 2 °C has been analyzed in order to determine some valuable bioactive compounds as alkylresorcinols, α-linolenic acid, steryl ferulates, tocopherols and phenolic compounds, which levels were around 47, 37, 18, 7 and 0.025 mg/g oily extract, respectively. To our knowledge, this is the first time that the presence of steryl ferulates has been observed in a supercritical fluid extract of wheat bran and that γ-tocopherol has been described in wheat bran oily extracts. Other common quality parameters, directly correlated with oxidative degradation, were also evaluated. Acidity values around 15% oleic acid were detected, while low levels of hydroperoxides (around 2.4 meq O₂/kg) and very low levels of hexanal (0.21 ppb) were found. Composition of the wheat bran oily extract was stable during 155 days of storage at 21 °C and darkness, and only a slight decrease in alkylresorcinols and tocopherols contents (13% and 20%, respectively) was observed. These results indicated an attractive potential of the obtained oily extract for industrial applications as food ingredients, nutraceuticals, and others.

Targeted Metabolite Profiling-Based Identification of Antifungal 5-n-Alkylresorcinols Occurring in Different Cereals against Fusarium oxysporum

A rapid and convenient biochemometrics-based analysis of several cereal-derived extracts was used to identify n-alkyl(enyl)resorcinols (AR) as antifungals against Fusarium oxysporum. Total AR content and liquid chromatography/mass spectrometry (LC-MS)-based profiles were recorded for each extract, in addition to their antifungal activity, to help integrate these chemical and biological datasets by orthogonal partial least squares regression. In this study, we developed and used a micro-scale amended medium (MSAM) assay to evaluate the in vitro mycelial growth inhibition at low amounts of extracts. Triticale husk-derived extracts had the highest AR content (662.1 µg olivetol equivalent/g dry extract), exhibiting >79% inhibition at the highest doses (10.0–1.0 µg/µL). Correlation of the chemical and antifungal datasets using supervised metabolite profiling revealed that 5-n-nonadecanylresorcinol, 5-n-heneicosylresorcinol, and 5-n-tricosyl-resorcinol were the most active ARs occurring in cereal products from Colombia. Hence, we propose the biochemometrics-based approach as a useful tool for identifying AR-like antifungals against F. oxysporum.

Development of Wheat Bran Oil Concentrates Rich in Bioactives with Antioxidant and Hypolipidemic Properties

Wheat bran, an abundant byproduct of the milling industry, comprises fat-soluble bioactives and fibers. In the present study, two concentrates were prepared from wheat bran oil (WBO) using silicic acid coupled with acetone (WBA) and hexane (WBH). WBA extract had enhanced color and viscosity and was enriched with fat-soluble bioactives (sterols, oryzanol-like compounds, tocopherols, and carotenoids) as evidenced from NMR and other techniques. In in vitro studies, WBA exhibited significant free radical scavenging activity, limited DNA and LDL oxidation, and inhibiting HMG-CoA reductase and lipase activity better than WBH and WBO. Further, an in vivo study with WBA 2 or 3.5% containing high fat diet ameliorated malonaldehyde (MDA) level, lipid profile, and antioxidant enzyme (SOD, catalase, GPx, and GR) activities in liver. A possible reason for this effect is downregulation of HMG-CoA reductase expression with WBA. Thus, WBA has significant potential as an ingredient in health food formulations.