CANNING FOOD IN SEMI-RIGID POLYMERIC AND COMPOSITE CONTAINERS

For thermal preservation of food, various types of retail polymeric packaging can be used: rigid, semi-rigid, flexible, and other kinds of containers. To make polymeric (plastic) containers usable for thermal sterilisation, and to ensure long storage of food, they should have a barrier layer that will make them heat-resistant, prevent oxygen ingress, and preserve the product’s quality and nutritive value. Every polymer material has its individual heat resistance characteristics. This paper considers such retail containers for food packaging as a composite can made of metal with a plastic lid and a semi-rigid heat-resistant polymer container with a foil cover. When using different container types for heat sterilisation and prevention of physical defects in cans, the following technological characteristics of cans should be taken into account: closure strength, depressurisation pressure, method of closure, diameter of a container’s opening, absence or presence of a stiffness relief on the cover, temperature of packaging, and other factors. The research includes analysis of existing types of retail composite and polymeric containers for canning food using different heat sterilisation methods. The theoretical and experimental research conducted has resulted in obtaining the values of the closure strength of the containers, an important parameter without which proper heat sterilisation of a product would be impossible. Developing scientifically proved parameters and modes of high-temperature sterilisation of meat and fish products in semi-rigid heat-resistant composite metal-plastic containers will allow enterprises to manufacture high-quality and safe canned food with high nutritive value.

Thermoplastic Fusion Bonding of Polymer-Based Micro Devices Using a Pressure Cooker

A novel method of thermoplastic fusion bonding (TPFB), or thermal bonding, for polymer fluidic devices was demonstrated. A pressure cooker was used in a simple sealing and packaging process with precise control of the critical parameters. Polymer devices were enclosed in a vacuum-sealed polymer container. This produced an even pressure distribution and a precise temperature boundary condition over the whole surface of the device. Deformation indicators were integrated on the devices to provide a rapid means of checking deformation and pressure distribution with the naked eye. Temperature, pressure, and time are the fundamental parameters of TPFB. The temperature and pressure are dominated by the material and contact area of the device. The temperature and pressure can be manipulated by controlling the water vapor pressure. The boiling solution guarantees an accurate, constant temperature boundary condition. Time can be eliminated as a variable by choosing a sufficient time to achieve good bonding, since there was no apparent damage to the microstructures after one hour. This new method of TPFB was demonstrated for sealing and packaging a PMMA (polymethylmethacrylate) microfluidic device. Good results were obtained using the vacuum sealed polymer container in the pressure cooker. This method is also suitable for scaling up for mass production.