STATE OF THE ART

MARTIN A. MASUELLI & MARISA ZANON

Biopackaging

CRC Press

Lugar: Miami; Año: 2017; p. 9 - 14

The current market approach to flexible packaging is technically structured, highly visual, easy to handle, functional, suitable for automatic machinery and creative forms. The current requirements of food producers are higher than some years ago, so it is a priority to compete with containers that successfully perform at least the following functions: Containment: must provide mechanical strength and elongation, these properties often determine the amount of plastic material needed to form the wall of a container. They must be resistant to perforations and tearing, since many products have irregular geometries such as sharp edges or sharp tips so the material must be resistant to mechanical damage that could produce these forms, yielding elastically without breaking or deforming. Protection: aspects such as seal tightness and barrier functions are included. All flexible containers must be closed, the vast majority of them being heat sealed. The integrity of the heat sealing is achieved by knowing the packaging material and the sealing conditions such as temperature, pressure, residence time of the material between the jaws, film tension and film thicknesses. When there is control over these parameters, drawbacks such as capillary leakage, seal unevenness, delaminations, burned material residues, adhesion degradation and low seal strength will be avoided. In terms of barrier functions, the industry provides packaging with low permeabilities to both gases and vapours as well as light and aroma. Gases such as nitrogen and carbon dioxide are used in technologies for packaging in modified atmosphere and controlled atmosphere. The ideal mixture of these gases will depend on the type of product to be packaged, the effect sought and the properties of each gas. Processing capacity: It is important to consider several aspects, such as those described below. ? Thermal properties of the package, ie if it is able to withstand the direct application of heat during baking, sterilization or some other method of heat preservation. Resistance to low temperatures is also considered as some foods are kept refrigerated or frozen; ? Hot tack resistance; ? Mechanical properties of the package, which can be used in automatic forming- packaging machines, for which good elongation capacity and dimensional stability are required for adequate thermoforming; ? Coefficient of friction for its optimum slip and working speed in the forming-packaging machine.