Tandem fusion of hepatitis B core antigen allows assembly of virus-like particles in bacteria and plants with enhanced capacity to accommodate foreign proteins

The core protein of the hepatitis B virus, HBcAg, assembles into highly immunogenic viruslike particles (HBc VLPs) when expressed in a variety of heterologous systems. Specifically, the major insertion region (MIR) on the HBcAg protein allows the insertion of foreign sequences, which are then exposed on the tips of surface spike structures on the outside of the assembled particle. Here, we present a novel strategy which aids the display of whole proteins on the surface of HBc particles. This strategy, named tandem core, is based on the production of the HBcAg dimer as a single polypeptide chain by tandem fusion of two HBcAg open reading frames. This allows the insertion of large heterologous sequences in only one of the two MIRs in each spike, without compromising VLP formation. We present the use of tandem core technology in both plant and bacterial expression systems. The results show that tandem core particles can be produced with unmodified MIRs, or with one MIR in each tandem dimer modified to contain the entire sequence of GFP or of a camelid nanobody. Both inserted proteins are correctly folded and the nanobody fused to the surface of the tandem core particle (which we name tandibody) retains the ability to bind to its cognate antigen. This technology paves the way for the display of natively folded proteins on the surface of HBc particles either through direct fusion or through non-covalent attachment via a nanobody

Preparation and characterisation of novelty food preservatives by Maillard reaction between ε-polylysine and reducing sugars

In order to enhance the application scope and usage effect of ε-polylysine, it was modified by Maillard reaction through endowing antioxidant activity. Characterisations of different type of reaction systems were investigated. Results showed that with increased heating treatment time at constant 90 °C and UV-Vis absorbance at 294 and 420 nm, fluorescence intensity of modified products were increased. DPPH radical scavenging activity of modified products from D-glucose (D-Glc), D-fructose (D-Fru) and D-xylose (D-Xyl) was increased to 40.5%, 44.0% and 69.4%, and the reducing power was increased to 0.9, 1.0 and 1.3 respectively (P < 0.05). Moreover, compared with ε-polylysin, three types of modified products have similar antibacterial property. In addition, three types of modified products showed low cytotoxicity against the cultured human HepG2 cells in vitro. Therefore, the modified products derived from ε-polylysine model could be used as potential food preservatives

3D printing: Development of animal products and special foods

Background: The present review examines the printing properties of different animal protein-based food inks/ materials used in the production of 3D printed constructs. The review examines their microstructural, colorimetric, printability, rheological and textural properties and investigates how these properties correlate to or are reflected in the characteristics of the printed constructs. These characteristics include their shape and dimensional stability, textural, nutritional, microstructural and sensorial properties. The review also examines the potential for development of animal protein-based special diets for people with special requirements such as for dysphagia patients and geriatrics. A special focus has been given to the application of transglutaminase for the development of 3D fish-based products and the possibility of developing cultured meat-based products. Scope and approach: The properties of different food inks and 3D printed constructs based on animal proteins such as beef, poultry, fish, egg, seafood, milk, cheese and dairy ingredients were analysed with emphasis on the studies that were published in the last three years. Studies on the development of special animal protein-based diets and the possibility of 3D printed products based on cultured meat were critically reviewed. Key findings and conclusions: 3D food printing offers numerous possibilities for development of tailored animal protein-based structures and products which includes, but is not limited to, extraordinary flexibility in geometries, textures and flavours and customised nutrition. Technology for production of 3D printed meat products necessitates the reduction of particle size of meat and dilution of meaty and savoury flavour and this is generally expected to reduce the value of premium meat products. However, the technology might be a good option for utilization of lower value and tougher cuts and trimmings. Production of 3D printed cultured meat-based products is still at a conceptual stage and a little or no research has been done in this area. Consumer acceptance of 3D printed cultured meat products seems to be less favourable in Western countries like Australia. Technology for the production of several animal protein-based 3D printed products for special dietary requirements such as for dysphagia patients has been optimized and is currently feasible with good success. Fancy shaped 3D printed cheese and egg products may evolve as a new segment of foods with a focus on children, festive occasions and the personal gift market. This review expands our understanding of how the composition of food inks affects the properties of the printed constructs and generates knowledge that will be crucial for optimizing the 3D printed animal products for maximum nutritional and sensory benefits. Extensive research is required to develop unique animal-based products with functional and nutraceutical value to attract consumers. Scientific knowledge is required to decipher the underlying mechanisms of how 3D printing process affects the food microstructure and sensory characteristics and its impact on consumer acceptance that will expand the use of the technology within the food industry

Ultrasonication as an emerging technology for processing of animal derived foods: A focus on in vitro protein digestibility

Background: Animal products are sources of highly bioavailable proteins and make a significant contribution to human nutrition and wellbeing. Ultrasonication can induce favourable non-thermal effects in food matrices and this has led to a recent increase in its use in the food industry and related research. In addition to prospective improved quality and sensory attributes of animal products, ultrasonication offers opportunities to improve the digestibility of these foods. However, this beneficial effect of the technology has not been reviewed. Scope and approach: The present paper reviews the application of ultrasonication in processing of animal derived foods and examines the effect of ultrasonication on the digestibility of different animal derived food matrices. The underlying mechanisms and optimized conditions for improved protein digestibility of different animal derived food matrices have been critically evaluated and discussed in detail. The review focuses on papers published in the last five years to provide the latest concepts and views on the ultrasonication process. Key findings and conclusions: This green and eco-friendly technology has a wide range of applications in the area of animal derived foods. It has been used to accelerate processes such as filtration, extraction, marination, proteolysis, fermentation, decontamination and drying. It can also improve the functional, sensorial and nutritional properties of animal protein-based foods. Ultrasonication can alter the sensorial, especially textural, and other quality attributes of dairy, egg and meat products by affecting the chemical reactions and processes involved in their processing, such as oxidation, Maillard reaction, proteolysis, esterification and production of volatile flavour compounds. It can also modify food structure. There has been recent interest in the application of ultrasonication to improve the digestibility of various animal protein-based foods. Almost all the papers analysed in this review reported a positive impact of ultrasonication on the digestibility of animal proteins. The main mechanisms responsible are related to altered protein structure and changes in the microstructure of food matrices, which improve the digestibility of the animal proteins by making active hydrolytic sites available for digestive enzymes. This technology can be used to develop novel animal protein-based foods with improved digestibility. Future studies should validate this effect in animal models and possibly in human trials