Food is an ideal medium for the growth of microorganisms. Therefore, by inhibiting the development of these, we can increase the shelf life of food.
There are many causes that negatively influence the quality of food, either by intrinsic factors of the food, such as its nutrient content, water availability, pH, etc., or by extrinsic factors such as temperature of storage, relative humidity, exposure to sunlight and air, handling and processing of raw materials, etc.
The main objective of food preservation is to maintain a product in perfect hygienic conditions and to protect its rheological and organoleptic qualities (Casp and Abril, 2003).
The processes of food preservation allow us to obtain safe products of high quality at a reasonable price. The permanent increase in the demands of consumers in terms of quality and prolongation of the useful life of the food, causes continuous changes in the way in which the food is produced, distributed, stored and sold. The food industry is constantly searching for new methods that are less aggressive with food, with lower energy consumption, and more effective against pathogenic microorganisms.
Among the different procedures that guarantee these expectations, we can highlight its relevance to packaging.
Packaging is a conservation method that protects food from light, moisture and other environmental contaminants. For a correct packaging process, the following factors must be taken into account:
- Storage: capacity to be stacked and transported, control of quantity produced, conservation of small products,
- Protection: against deterioration, leakage, breakage, dehydration, contamination, theft and alteration. Physical protection against shock, vibration, compression, temperature, etc. Barrier protection against oxygen, water vapor, dust, bacteria, etc.
- Information: identification of the product, description of use or preparation, warning about risks derived from improper use, list of ingredients, nutritional data and price, etc.
- Promotion: marketing tool to differentiate the product from similar ones and attract attention in shops and supermarkets using, for example, brands, colors, illustrations and forms.
- Transport: greater ease and safety to move products from the manufacturer to the warehouse and the vendors (tertiary containers) and even the consumer (primary packaging).
Currently we can find a variety of materials for the manufacture of containers, with different gas permeabilities, with variable resistances and permissiveness to light (transparent, translucent, opaque), but also, there are elements that allow us to know if temperature has been constant during storage or if there have been breakages of the cold chain, as well as the concentration and composition of the gas inside (Rodríguez, 2004).
Due to its versatility in shape and size, being light and hygienic, the most used materials are synthetic plastics. However, because they are products that do not decompose, they are a cause of environmental pollution. Therefore, in recent years new types of less polluting or easy to recycle materials have been developed, which are called biodegradable packaging.
The biodegradable containers come from renewable sources and many of them are characterized as being edible. They are applied as a barrier for microorganisms and to improve sensory properties such as appearance, color, brightness and transparency.
Currently the container, in addition to fulfilling its basic functions of containment, protection and information, is becoming a medium that performs sophisticated interactions with its content and in a registry of important information for both the consumer and the intermediaries of the chain of value, thus creating the concept of active packaging.
It is considered to be an active element when there is another function other than providing an inert barrier against external conditions. They belong to this group of products when food components or some material are used as an indicator of the history and quality of the product. There are two mechanisms of action to create this type of packaging: introduce the active element inside the container together with the food or that it is part of the food itself.
A way to achieve active packaging by incorporating natural antioxidants such as tocopherols, which allows to increase the shelf life of foods by inhibiting or delaying the oxidation of lipids or other compounds (Quezada-Gallo, 2009).
Among the active packaging, the concept of intelligent packaging stands out. It is a packaging system capable of collecting and processing information from the environment in order to transmit it to the consumer (Aguirre, et al, S / F) Its objective is to ensure the quality of the product by monitoring the processes that alter the food
Another method of food preservation that has stood out in recent years, is packaging in modified atmosphere. It consists of the alteration of the environmental gases to reduce the microbial growth and the speed of the internal chemical reactions.
In commercial practice, oxygen reduction and increase of carbon dioxide and / or nitrogen are usually used. Carbon dioxide acts as a destructive agent of bacteria and fungi and reduces the multiplication of pathogenic microorganisms.
In the process of packaging in modified atmospheres it is not necessary, in general, to maintain the composition of the gas throughout the storage, so it is more practical and economical.
When calculating the amount of modified gases, it must be kept in mind that the effect is not the same for all products and working conditions. It varies according to the composition, characteristics and sanitary status of the food to be conserved, the composition of the atmosphere and the storage temperature, as well as the packaging materials and packaging technology. (R. Catalá and R. Gavara, 2001)
Nowadays, packaging is vital in the marketing of food, since in addition to providing better conservation, longer life of the food and information for the consumer, they must produce a visual impact that makes them differentiate themselves from similar products to be chosen by the final consumer (Cruz, 2006).
A suitable container should avoid contamination of the food by preventing the passage of outside substances. In some cases, the packaging can cause alterations to the taste, smell or texture of food and be harmful to health, so it is necessary to control the materials with which it has been manufactured
The main advantages that good packaging brings to the quality and conservation of food are:
- To preserve the organoleptic properties of the food and, therefore, its quality.
- Lengthen the shelf life of the product.
- Slow down enzymatic and microbial reactions.
- Decrease weight loss due to evaporation.
- Enable a more hygienic transport and storage.
- Eliminate dripping and unpleasant odors.
- Improve the final product presentation