Effect of extrusion processing parameters on structure, texture and dietary fibre composition of directly expanded wholegrain oat-based matrices

Oat flour mixed with 30 g/100 g rice flour was extruded with a twin-screw extruder using a central composite orthogonal design. Temperatures (120 °C,140 °C, 160 °C) and moisture (14.5 g/100 g, 17.7 g/100 g, 20.6 g/100 g) were adjusted during extrusion, while screw speed was kept constant (400 rpm). Extrudates were analysed for structure (expansion, density, microstructure), texture (hardness), β-glucan (molecular weight and extractability), as well as fibre content. Expansion varied between 250 and 329%, density between 165 and 457 kg/m3 and hardness between 27 and 64 N. The response surface model showed that more expanded, less dense and less hard extrudates were achieved at low moisture, while high temperature resulted in lower density and hardness. Significant differences in β-glucan extractability were observed depending on extrusion conditions, with values ranging between 0.64 and 1.31 g/100 g. β-glucan extractability correlated with positively with porosity, and negatively with moisture content during extrusion, cell wall thickness and density. The results indicate that conditions that produce a more porous, crispier structure, also increases β-glucan extractability.ISSN:0460-1173ISSN:0023-6438ISSN:1096-112

Synergistic use of fermentation and extrusion processing to design plant protein-based sausages

The synergistic effect of lactic acid fermentation and high-moisture extrusion processing of pea protein on the microbiological and sensory properties of plant-based sausages was investigated. Plant-based sausages were formed by combining fermented pea protein concentrate (PPC) biomass with high-moisture extruded pea protein isolate (PPI). Pea protein concentrate (PPC) was fermented with Lactococcus lactis subsp. lactis and Lactiplantibacillus plantarum to improve the perceived structure, texture, and flavour (specifically via expression of glutamic acid which is connected to umami flavour) of plant-based sausages.The sausages were prepared by stuffing the mixture of extruded PPI and fermented PPC (addition level 70:30) inside vegetarian casings followed by steam cooking. After preparation and cooking of the sausages, a trained sensory panel evaluated the intensities of ten selected attributes defining the flavour, odour, colour, and texture. In addition, dry matter content, acidification, microbial quality, and glutamate contents were analysed.The results demonstrated that fermentation decreased the pea-like odour and improved the texture of the sausages. In addition, yeast-like odour and umami taste were observed. The study was able to demonstrate novel clean-label processing approaches by combined fermentation and extrusion to generate in-situ meat-like flavour and texture based on plant protein ingredients

Effect of Bioprocessing on Techno-Functional Properties of Climate-Resilient African Crops, Sorghum and Cowpea

Sorghum and cowpea are very compatible for intercropping in hot and dry environments, and they also have complementary nutritional compositions. Thus, the crops have the potential to improve food security in regions threatened by climate change. The aim of this study was to investigate different enzymes (carbohydrate-degrading, proteases and phytases) and lactic acid bacteria (LAB) fermentation to improve the techno-functional properties of sorghum and cowpea flours. Results show that sorghum carbohydrates were very resistant to hydrolysis induced by bioprocessing treatments. Most of the protease treatments resulted in low or moderate protein solubilization (from ca. 6.5% to 10%) in sorghum, while the pH adjustment to 8 followed by alkaline protease increased solubility to 40%. With cowpea, protease treatment combined with carbohydrate-degrading enzymes increased the solubility of proteins from 37% up to 61%. With regard to the techno-functional properties, LAB and amylase treatment decreased the sorghum peak paste viscosities (from 504 to 370 and 325 cPa, respectively), while LAB and chemical acidification increased cowpea viscosity (from 282 to 366 and 468 cPa, respectively). When the bioprocessed sorghum and cowpea were tested in breadmaking, only moderate effects were observed, suggesting that the modifications by enzymes and fermentation were not strong enough to improve breadmaking