Rodrigo Ortega-Toro

Properties of starch–hydroxypropyl methylcellulose based films obtained by compression molding

Corn starch-glycerol (1:0.3) films, containing or not citric acid (1g/100g starch) and HPMC (10 and 20g/100g starch), are obtained by compression molding. The microstructure of the films, the thermal behavior, the X-ray diffraction spectra and the physical properties (mechanical, barrier and optical) were analyzed after 1 and 5 storage weeks at 25°C and 53% relative humidity. The bonded citric acid and film solubility were also determined. Starch-HPMC blend films showed a dispersed phase of HPMC in a continuous, starch-rich phase with lower glass transition than HPMC-free films. The addition of citric acid also provoked a decrease in glass transition in line with the partial hydrolysis of starch chains. Both components implied a decrease in the water vapour permeability while the oxygen permeability slightly increased. Although citric acid only provoked a small hardening effect in the films, it greatly decreased their extensibility (weak cross-linking effect), which seems to increase during film storage. Starch crystallization during storage was inhibited by both citric acid and HPMC.

Active bilayer films of thermoplastic starch and polycaprolactone obtained by compression molding

Bilayer films consisting of one layer of PCL with either one of thermoplastic starch (S) or one of thermoplastic starch with 5% PCL (S95) were obtained by compression molding. Before compression, aqueous solutions of ascorbic acid or potassium sorbate were sprayed onto the S or S95 layers in order to plasticize them and favor layer adhesion. S95 films formed bilayers with PCL with very good adhesion and good mechanical performance, especially when potassium sorbate was added at the interface. All bilayers enhanced their barrier properties to water vapour (up to 96% compared to net starch films) and oxygen (up to 99% compared to PCL pure). Bilayers consisting of PCL and starch containing 5% PCL, with potassium sorbate at the interface, showed the best mechanical and barrier properties and interfacial adhesion while having active properties, associated with the antimicrobial action of potassium sorbate.

Enhancement of interfacial adhesion between starch and grafted poly(ε-caprolactone)

The use of a modified poly(ε-caprolactone) (gPCL) to enhance polymer miscibility in films based on thermoplastic starch (S) and poly(ε-caprolactone) is reported. PCL was functionalized by grafting with maleic anyhdride (MA) and/or glycidyl methacrylate (GMA) by reactive blending in a batch mixer. gPCL based materials were analysed in terms of their grafting degree, structural and thermal properties. Blends based on starch and PCL (wt. ratio 80:20) with including gPCL (0, 2.5 and 5wt.%), as a compatibilizer, were obtained by extrusion and compression moulding, and their structural, thermal, mechanical and barrier properties were investigated. Blends containing gPCL evidenced better interfacial adhesion between starch and PCL domains, as deduced from both structural (XRD, FTIR, SEM) and bulk properties (DSC, TGA). Moreover, grafted PCL-based compatibilizers greatly improved functional properties of S-PCL blend films, as pointed out from mechanical performance and higher barrier properties, valuable to meet the food packaging requirements.

Future of Starch-Based Materials in Food Packaging

Materials based on starch are considered attractive alternatives mainly due to their eco-friendly character. Moreover, these biopolymers not only partially replace existing plastics in several applications but also provide new materials with specific final properties. Different processing methods and their influence on starch film properties are described as well as different strategies to improve their functional properties such as thermomechanical processing, plasticization, chemical modification, incorporation of fillers, and additives or blending with other polymers and compatibilizers. These properties are compared with those of more frequently used conventional plastic films, by analyzing the advantages and drawbacks of starch based packaging materials. In this chapter technological processing methods, final properties, and future challenges of starch-based materials are discussed in order to wide their applications, bringing potential solutions to insert these products in the commercial market.

Physicochemical and microbiological properties of Macabi (Elops saurus)-based sausages added with fibres

At present, considerable interest has been generated in the development of new products with functional properties. Also, it is increasingly evident the need to use the resources of each region to meet the needs of people in the population. That is why a product rich in bonefish fibre, corn oil and grape fibre from the Colombian Caribbean region is developed. The bromatological and microbiological properties 3722 Karen Paola María Ortiz et al. were measured and the stability during storage time was determined. The results confirm that it is a product with a high content of proteins and low in fat compared to comparable products. It also complies with Colombian regulations for the microbiological control and is stable at 4 °C for 14 days.