Biorefinery strategies for upgrading Distillers’ Dried Grains with Solubles (DDGS)

Distillers’ Dried Grains with Solubles (DDGS) is the major by-product of bioethanol and distillery plants. Due to its high content of proteins, water-soluble vitamins and minerals, DDGS has been long marketed as animal feed for livestock. EU legislation on liquid biofuels could raise the demand on bioethanol production in Europe, with a resulting increase in DDGS availability. DDGS contains a spectrum of complex organic macromolecules, particularly polysaccharides, in addition to proteins and vitamins, and its use as a starting raw material within a biomass-based biorefining strategy could lead to the development of multi-stream processes for the production of commodities, platform molecules or speciality chemicals, with concomitant economic benefits and waste reduction for bioethanol plants. The present review aims to outline the compositional characteristics of DDGS and evaluate its potential utilisation as a starting material for the production of added-value products. Parameters of influence on the chemical and physical characteristics of DDGS are discussed. Moreover, various pre-treatment strategies are outlined in terms of efficient DDGS fractionation into several added value streams. Additional processing steps for the production of medium and high added value compounds from DDGS are evaluated and their potential applications in the food and chemical industry sector are identified

Casein Films: The Effects of Formulation, Environmental Conditions and the Addition of Citric Pectin on the Structure and Mechanical Properties

Thin casein films for food packaging applications reportedly possess good strength and low oxygen permeability, but low elasticity and high sensitivity to moisture. Modifying the films to target specific behaviors depending on environmental conditions can enable a variety of commercial applications for casein-based films. The mechanical properties of solvent-cast (15% solids) calcium-caseinate/glycerol films (CaCas:Gly ratio of 3:1) were characterized as a function of processing and environmental conditions, including film thickness, solution formulation and ambient humidity (from 22% to 70% relative humidity (RH) at ~20 °C). At constant RH, the elongation at break (EAB) had a strong positive dependence on the film thickness. When RH increased, the tensile strength (TS) and modulus (E) decreased approximately linearly, while EAB increased. From 0.05% to 1% (w/w) of citric pectin (CP) was then incorporated into CaCas/Gly films following seven different formulations (mixing sequences), to alter the protein network and to evaluate the effects of CP on the tensile properties of CaCas/Gly/CP films. At constant film thickness and ~60% RH, the addition of 0.1% or 1.0% CP to the films considerably increased or decreased EAB, TS and E in different directions and to different extents, depending on the formulation, while optical micrographs also showed vastly differing network configurations, suggesting complex formulation- and stoichiometry-dependent casein-pectin interactions within the dried films. Depending on the desired film properties and utilization conditions, pectin may be a useful addition to casein film formulations for food packaging applications

Antimicrobial soy protein isolate-based films: physical characterisation, active agent retention and antifungal properties against Penicillium italicum

Soy protein isolates (SPI) films were evaluated as carriers of citral and limonene, and their physical and antifungal properties were evaluated. The presence of antimicrobials in SPI films resulted in changes on colour without affecting the transparency. Films with citral added were more extensible; however, a reduction in tensile strength and elastic modulus was observed in films with limonene added. Aroma compounds addition in films induced a slight increase in water vapour properties in relation to discontinuity of network proteins evidenced by SEM. Besides, FTIR spectra evidenced a partial alteration of SPI secondary structure. Citral was less retained than limonene. The increase in limonene release with high relative humidity was explained by increase in protein chain mobility. SPI films enriched with limonene exhibited strong antifungal activity against the postharvest decay pathogen Penicillium italicum under storage conditions