Cascade extraction of proteins and feruloylated arabinoxylans from wheat bran

Recent advances of wheat bran arabinoxylan exploitation as the functional dough additive

Wheat bran is a significant byproduct of wheat flour milling and is enriched with dietary fiber. Arabinoxylan (AX), the major constituent of dietary fiber, plays a crucial role in the nutrition and processing of cereal food. This review comprehensively focuses on AX as a functional additive, specifically addressing its fractionation methods, structural characteristics, techno-functionality, and interactions with dough components. Structural features such as molecular weight (Mw), branching degree, and ferulic acid (FA) content significantly influence the functionality of AX, affecting gluten protein and starch characteristics during cereal food processing. Specifically, studies have shown that AX with optimum Mw and FA levels improved dough rheology and gas retention during bread-making. Furthermore, the solubility of AX varies across wheat bran fractions, with soluble AX fractions demonstrating notable dough-improving properties. By integrating structural complexity with functional properties, this review highlights the promising applications of wheat bran AX as a sustainable, functional dough additive.

Recent advances in pressurized hot water extraction/modification of polysaccharides: Structure, physicochemical properties, bioactivities, and applications

Pressurized hot water, as a green and efficient physical treatment technology, has been widely utilized for the extraction and modification of polysaccharides, with the objective of enhancing the physicochemical properties and biological activities of polysaccharides applied in food systems. This article reviews the recent advances regarding the effects of pressurized hot water treatment (extraction and modification) on polysaccharide extraction rates, structure, physicochemical properties, and bioactivities. The potential modes and mechanisms of polysaccharides subjected to pressurized hot water treatment and the relevant applications of these treated polysaccharides are also thoroughly discussed. Finally, the challenges that it may encounter in commercial applications are analyzed, and the future trends in this field are envisioned. This article will be of great value for the scientific elucidation of polysaccharides treated with pressurized hot water and their potential food applications.

Aqueous phase extractable protein of wheat bran and germ for the production of liquid and semi-solid foods

To achieve a more sustainable global food production, a shift from animal to plant protein based food is necessary. At the same time, these plant proteins are preferentially derived from side-streams of industrial processes. Wheat bran and germ represent two major side-streams of the wheat milling industry, and contain aqueous-phase soluble proteins with a well-balanced amino acid composition. To successfully use wheat bran and germ proteins in novel plant-based liquid and semi-solid foods, they need to (i) be rendered extractable and (ii) contribute functionally to stabilizing the food system. Prior heat treatment and the occurrence of intact cell walls are important barriers in this regard. Several strategies have been applied to overcome these issues, including physical processing and (bio)chemical modification. We here present a comprehensive, critical overview of the aqueous-phase extraction of protein from (modified) wheat bran and germ. Moreover, we discuss the functionality of the extracted protein, specifically in the context of liquid (foam- and emulsion-type) and semi-solid (gel-type) food applications. In each section, we identify important knowledge gaps and highlight several future prospects that could further increase the application potential of wheat bran and germ proteins in the food industry.

Wheat bran arabinoxylans: Chemical structure, extraction, properties, health benefits, and uses in foods

Wheat bran (WB) is a well-known and valuable source of dietary fiber. Arabinoxylan (AX) is the primary hemicellulose in WB and can be isolated and used as a functional component in various food products. Typically, AX is extracted from the whole WB using different processes after mechanical treatments. However, WB is composed of different layers, namely, the aleurone layer, pericarp, testa, and hyaline layer. The distribution, structure, and extractability of AX vary within these layers. Modern fractionation technologies, such as debranning and electrostatic separation, can separate the different layers of WB, making it possible to extract AX from each layer separately. Therefore, AX in WB shows potential for broader applications if it can be extracted from the different layers separately. In this review, the distribution and chemical structures of AX in WB layers are first discussed followed by extraction, physicochemical properties, and health benefits of isolated AX from WB. Additionally, the utilization of AX isolated from WB in foods, including cereal foods, packaging film, and the delivery of food ingredients, is reviewed. Future perspectives on challenges and opportunities in the research field of AX isolated from WB are highlighted.

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.

Enzymatic upgrading of heteroxylans for added-value chemicals and polymers

Xylan is one of the most abundant, natural polysaccharides, and much recent interest focuses on upgrading heteroxylan to make use of its unique structures and chemistries. Significant progress has been made in the discovery and application of novel enzymes for debranching and modifying heteroxylans. Debranching enzymes include acetylxylan esterases, α-l-arabinofuranosidases and α-dglucuronidases that release side groups from the xylan backbone to recover both biochemicals and less substituted xylans for polymer applications in food packaging or drug delivery systems. Besides esterases and hydrolases, many oxidoreductases including carbohydrate oxidases, lytic polysaccharide monooxygenases, laccases and peroxidases have been also applied to alter different types of xylans for improved physical and chemical properties. This review will highlight the recent discovery and application of enzymes for upgrading xylans for use as added-value chemicals and in functional polymers.

Subcritical Water Extraction of Natural Products

Subcritical water refers to high-temperature and high-pressure water. A unique and useful characteristic of subcritical water is that its polarity can be dramatically decreased with increasing temperature. Therefore, subcritical water can behave similar to methanol or ethanol. This makes subcritical water a green extraction fluid used for a variety of organic species. This review focuses on the subcritical water extraction (SBWE) of natural products. The extracted materials include medicinal and seasoning herbs, vegetables, fruits, food by-products, algae, shrubs, tea leaves, grains, and seeds. A wide range of natural products such as alkaloids, carbohydrates, essential oil, flavonoids, glycosides, lignans, organic acids, polyphenolics, quinones, steroids, and terpenes have been extracted using subcritical water. Various SBWE systems and their advantages and drawbacks have also been discussed in this review. In addition, we have reviewed co-solvents including ethanol, methanol, salts, and ionic liquids used to assist SBWE. Other extraction techniques such as microwave and sonication combined with SBWE are also covered in this review. It is very clear that temperature has the most significant effect on SBWE efficiency, and thus, it can be optimized. The optimal temperature ranges from 130 to 240 °C for extracting the natural products mentioned above. This review can help readers learn more about the SBWE technology, especially for readers with an interest in the field of green extraction of natural products. The major advantage of SBWE of natural products is that water is nontoxic, and therefore, it is more suitable for the extraction of herbs, vegetables, and fruits. Another advantage is that no liquid waste disposal is required after SBWE. Compared with organic solvents, subcritical water not only has advantages in ecology, economy, and safety, but also its density, ion product, and dielectric constant can be adjusted by temperature. These tunable properties allow subcritical water to carry out class selective extractions such as extracting polar compounds at lower temperatures and less polar ingredients at higher temperatures. SBWE can mimic the traditional herbal decoction for preparing herbal medication and with higher extraction efficiency. Since SBWE employs high-temperature and high-pressure, great caution is needed for safe operation. Another challenge for application of SBWE is potential organic degradation under high temperature conditions. We highly recommend conducting analyte stability checks when carrying out SBWE. For analytes with poor SBWE efficiency, a small number of organic modifiers such as ethanol, surfactants, or ionic liquids may be added.