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

Abstract

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.

Trends and challenges of fruit by-products utilization: insights into safety, sensory, and benefits of the use for the development of innovative healthy food: a review

“…These processes are suitable for getting phenolics out of waste streams from the food industry using different membrane types (Papaioannou et al 2022 ; Tapia-Quirós et al 2022 ). The EAE method uses enzymes commonly lactase, protease/lipase, lipase, phospholipase, pectinases, cellulases, and hemicellulases to release phytochemicals found in cells of aromatic and medicinal plants (Ebrahim 2023 ; Fărcaș et al 2022 ). These enzymes can destroy or disrupt the cell walls and membranes of plants, resulting in a more effective release and extraction of active chemicals.…”

Overview of the Sustainable Valorization of Using Waste and By-Products in Grain Processing

“…The grain processing chain generates significant amounts of waste known as lignocellulosic biomass [14,96]. Grain wastes that include carbohydrate fractions, especially hemicelluloses, are bran, straw, and hulls/husks.…”

“…In rye bran, the most important phenolic compounds (for antioxidant activity) include the group represented by p-hydroxybenzoic acid and its derivatives (especially vanillic and syringic acid) and the group represented by p-coumaric acid and its derivatives (ferulic and caffeic acid) [152]. Phenolic acids, as antioxidant compounds recovered from grain waste and by-products, are used in the food industry as additives to extend the shelf life of food [96]. Vanillin from ferulic acid through biotechnical processes is very often used as a flavoring in the food industry [116].…”

Comparison between Ultrasound- and Microwave-Assisted Extraction Methods to Determine Phenolic Compounds in Barley (Hordeum vulgare L.)

“…Specifically, the level of methanol affects both the solubility of the compounds into the solvent and the transmission of the ultrasounds-i.e., a lower percentage of methanol may facilitate the transmission of the waves but present a lower capacity to solubilize the phenolic compounds [53]. On the other hand, in MAE, since the solvent does not play the same role as in UAE, the composition of the solvent, and therefore its ability to solubilize the compounds to be extracted, becomes the main factor to be considered [54].…”