The Role of Plastic Films in Food Preservation

The preservation of food products packaged in plastic films relies heavily on maintaining their original quality by shielding them from external factors that cause deterioration. This protection is primarily achieved through the barrier properties of the packaging material, which control the transfer of gases, vapors, and moisture that could compromise the freshness and safety of the food.

Since the early 1960s, polymer films have become the dominant packaging material in the snack food, bakery, and confectionery industries. Their popularity stems from their versatility, cost-effectiveness, and ability to preserve product quality. Most plastic films are naturally transparent and do not easily take on color through dyeing or pigments. To produce opacity or a matte appearance, manufacturers often “cavitate” the films during production, introducing tiny voids that scatter light and give a white or opaque look.

Plastic films offer several practical advantages. They are heat-sealable, which allows for airtight and tamper-evident packaging, and they possess excellent resistance to grease and oil, protecting the contents from contamination. Depending on the specific product requirements, protection can be provided by a single polymer layer or enhanced through multilayered films that combine different polymers, coatings, and even metal foils. These composite structures are carefully designed to balance strength, flexibility, and barrier performance.

The effectiveness of a film largely depends on its permeability to gases and vapors. For example, exposure to oxygen can lead to oxidation and spoilage, while water vapor loss may cause undesirable drying, negatively affecting texture and taste. For this reason, materials with superior moisture and oxygen barrier properties are crucial, particularly for products like chips, cookies, and chocolate. Special coatings can further enhance the oxygen barrier, extending shelf life and preserving flavor.

Typically, packaging films are less than 100 micrometers thick. They are used to wrap individual products, overwrap packages, and form sachets, bags, and pouches. In many cases, they are laminated with other materials to improve strength, sealability, or visual appeal. Through continuous innovation, plastic films have become an indispensable tool in modern food preservation, ensuring that products remain fresh, safe, and appealing from factory to consumer.
The Role of Plastic Films in Food Preservation

Advancing Food Preservation: The Role of Controlled Atmosphere Storage

Controlled atmosphere (CA) storage has been a groundbreaking innovation in the fruit and vegetable industry, significantly transforming the storage and distribution of perishable goods since the 20th century. This technology meticulously adjusts the levels of oxygen (O2) and carbon dioxide (CO2) within storage environments, often incorporating additional measures such as ethylene removal and, in some cases, the introduction of carbon monoxide. The continuous monitoring and precise regulation of these gases ensure the storage atmosphere meets optimal conditions for preserving product quality.

The principle behind CA storage lies in its ability to manipulate the metabolic rates of fruits and vegetables. By lowering O2 levels and increasing CO2, the respiration rate is reduced, thereby delaying ripening and senescence. However, incorrect levels can lead to physiological damage, such as tissue browning, off-flavors, or cell death, with the severity and type of damage varying by product and exposure duration.

Apples and pears are the most common beneficiaries of CA storage, with the technology allowing these fruits to maintain their freshness for up to 10 months. This capability has enabled year-round availability, stabilized market prices, and reduced food waste. Advances in mechanized handling, including the use of bulk bins and pallets, have complemented this technology, while innovations in sensors and automated control systems have made it easier to maintain precise conditions of temperature, humidity, and gas composition.

CA storage also plays a critical role in grain preservation. Here, the focus is on lowering moisture content to below 12% before sealing the grain in airtight silos or structures. Aeration fans are used to dry and cool the grain, ensuring that temperature and humidity remain within safe ranges throughout the storage period. This method prevents spoilage from mold, pests, and oxidation, enhancing food security and extending shelf life.

Recent developments in CA storage technology include the use of machine learning algorithms and IoT-enabled sensors for real-time monitoring and predictive adjustments. These advancements have further improved efficiency and reduced operational costs. Additionally, the integration of renewable energy sources for powering storage facilities has made the technology more sustainable.

In conclusion, controlled atmosphere storage remains a cornerstone of modern post-harvest management, ensuring the extended preservation of fresh produce and grains while contributing to global food supply chains and sustainability efforts.
Advancing Food Preservation: The Role of Controlled Atmosphere Storage

Heating in food processing

Heating is one of the most essential methods for food preservation mechanism that applied by the food processor to render food products commercial sterile – that is free from pathogenic and spoilage microorganisms likely to grow during the normal distribution and shelf-life of the product.

Conventional heating methods sue external heat sources including hot water and steam. Heat may be transferred by one or more of the three mechanisms of conduction, convection and radiation.

Most industrial heat transfer operations involve a combination of these but it is often the case that one mechanism is dominant.

Heat sterilization of food in containers is an old technology largely attributed to the work of Nicholas’s Appert in the 1800s.

As introduced and developed in the initial stages, the primary focus of canning was safety and shelf stability. The application of heat processes to containers requires not only the ability to heat and cool the container contents efficiently but also the ability to do so while minimizing the stresses imposed upon the container.

Whether electrical or conventional, heating may be broadly classified as unit operations in blanching, cooking, drying, pasteurization, sterilization and thawing and involve raising the product to some final temperature that depends on the particular objective of the process.
Heating in food processing

Bio-preservation of Food

There exist microorganism that are nontoxic and have been found even to be beneficial, directly or indirectly, to human health.

The inhibition of foodborne pathogens by lactic acid bacteria is one form of natural food preservation.

Nowadays, this tendency for natural preservation of foods has provided the basis for the development of new methods of preservation, such as bio-preservation or biological preservation of foods.

Use of natural antimicrobial systems is studied because consumers and governments move away from extensive use of artificial preservatives.

Bio-preservation aims for the reduction of health risks without changing the organoleptic properties of the products.

It is biological preservation of foods referred to as extension of shelf life and the improvement of safety of products by mean of the endogenous microflora or using cultures as starters for protective, and/ or their metabolites.

It also referred to a combination of fermentation and preservation processes and entails the extension of shelf life and improving the safety of food.

The main goal of bio-preservation is the enhancement of safety using bacteria with antimicrobial capabilities or their substances.

The preserving action of this bacteria is not necessarily associated with their ability to ferment the food of interest.

Bacteria used in bio-preservation should be harmless to humans, complete well with spoilage and pathogenic microorganisms for nutrients of food if conditions are conducive to microbial growth, and produces acids and other antimicrobial agents, particularly bacteriocins.

Bacteriocins can be defined as protein containing macromolecules with a capacity to exert bactericidal action on susceptible bacteria.

E. coli produce colicins and lactococci produce nisin and diplococcion. The bacteriocins inhibit some gram-positive bacteria, spore forming bacteria and food borne pathogens, including Listeria monocytogenes.
Bio-preservation of Food