This paper presents a novel approach to improve the barrier and mechanical properties of extruded glycerol-plasticized vital wheat gluten sheets. The sheets were extruded with a single screw extruder at alkaline conditions using 3-5 wt % NaOH. Salicylic acid (SA), known to improve the extrudability of wheat gluten, was also added alone or in combination with NaOH. Oxygen transmission rate and volatile mass measurements, tensile tests, protein solubility, glycerol migration, infrared spectroscopy, and electrophoresis were used to assess the properties of the extrudate. Electrophoresis showed that the gluten/glycerol sheet and the sheet with 3 wt % NaOH and 1 wt % SA contained the same building blocks in terms of proteins and protein subunits, although the protein solubility in these samples was different. The oxygen barrier, at dry conditions, was improved significantly with the addition of NaOH. On the other hand, the addition of salicylic acid yielded poorer barrier properties. The extrudate was placed on a blotting paper and its aging properties were investigated during the first 120 days. It was observed that the extrudate with 3 wt % NaOH had the most suitable combination of properties (low oxygen permeability, large strain at break, and relatively small aging-induced changes in mechanical properties); the reason is probably due to low plasticizer migration and an optimal protein aggregation/polymerization.

In this study, we report that the addition of ammonium hydroxide (NH4OH) significantly enhance the properties of extruded WG-based materials. The grainy structure disappeared and the extrudate became more uniform and glossy. The barrier properties improved and the oxygen permeability at dry conditions was as low as that for a number of petroleum-based plastics (poly(ethylene terephthalate and polyamide 66). The protein structure in this material was extensively aggregated, which improved the strength and stiffness; there was a ca 4-fold increase in maximum stress compared to that of the NH4OH-free samples. The protein solubility decreased to almost zero. Even a severe sonication treatment in sodium dodecyl sulphate (SDS) did not increase the solubility. The only type of protein that it was possible to extract was the 'thermo-resistant' ω-gliadins lacking disulfide-bonds. Our result provides new opportunities to develop a WG-based film extrudate for potential use as e.g. a renewable barrier layer in food and non-food laminate packagings.

A full biouse of crops for multiple end-uses would contribute to a more economically attractive and thereby more sustainable use of the crop. The purpose of this paper was to evaluate options to develop materials from residuals of rapeseed, originating from the biodiesel (RME) production. Compression molding of rapeseed flour and rapeseed cake residuals was evaluated together with additions of different amount of plasticizer (glycerol), as well as use of various pressing temperatures and times. The results were promising and led to a compact and hard, although somewhat brittle material. The potential to produce materials from the rapeseed residuals from RME production is thus high. Glycerol content was the most important factor increasing tensile strength in the material followed by pressing time. No clear protein polymerization was detected in the produced materials. Thus, despite the promising results, methods to obtain increased protein polymerization should be searched for. Therefore, binding agents, additives, or pretreatment of the rapeseed residuals are needed, or the proteins have to be purified, in order to generate a better polymerization of the proteins.

The purpose of this study was to determine the feasibility of increasing the consumption of dietary 0J-3 fatty acids by incorporating menhaden oil into a French-type salad dressing. Menhaden/soybean oil blends of 10, 20 and 30% menhaden oil (w/w) were used to prepare an emulsified French salad dressing. The oil blends and salad dressings were stored at 22~ in the dark for 20 wk. The fatty acid profile, peroxide value, and anisidine value were determined. The salad dressings also were evaluated by a sensory panel for flavor, aroma, and aftertaste. The w-3 fatty acids were stable over time under these storage conditions. Peroxide values rose slowly and consistently over time reaching higher values when more menhaden oil was added. Peroxide values were also higher in the oil blends which were stored with air in the headspace and not flushed with argon. Anisidine values also were higher with each addition of menhaden oil but did not change over time except for the 100% menhaden oil which was stored in air. After eight weeks the sensory panel rated the salad dressing which contained menhaden oil as lower than the ones which did not contain menhaden oil. While a significant amount of ~-3 fatty acids may be incorporated into foods by the addition of menhaden oil, the development over time of offflavors must be controlled.