Packaging extends shelf life to meet the demands of the global food industry. The challenge of optimising a package to help a food achieve a required shelf life is motivated by the need to use packaging wisely and to ensure that food is safe and meets quality standards throughout its shelf life. Predicting what food package is necessary to reach a desired shelf life is challenging but useful for assessing package options.
Packaging Defines Shelf Life
The endpoint of a food’s shelf life is defined by the end of its quality and/or the onset of a food safety issue. Lipid oxidation, moisture loss or gain, browning (enzymatic and nonenzymatic), and microbial growth are the deteriorative forces that define food shelf life. Changes in flavor and nutrient content also determine the end of shelf life. These deteriorative reactions define requirements for processing and packaging and conditions for distribution, retail use, and consumer use. Packaging can alter product shelf life considerably and is sometimes dictated by food processing.
For example, peas, shrimp, and milk can be packaged using similar or different materials and formats such as cans, trays, bags, cartons, and bottles. Food and storage conditions impact the functionality of a package. Thermally processed canned peas have a “Best If Used By” date of approximately three years; they may lose quality because of changes in texture and color but are safe to eat beyond three years. Foods that are high in sulfur, such as peas, require a specific coating on the inside of a can and a specific coating on the inside of steel-based caps of glass jars. However, cooked peas sealed within foodservice trays are not safe to consume beyond three to five days. Fresh peas packaged in a microperforated pouch such as ULTRAPERF Technologies’ VegeSteam have a shelf life of 10–15 days and can be steamed in the bag using a microwave. An increase in storage temperature induces an increase in the oxygen, carbon dioxide, and water vapor permeability, depending on the structure of plastic sealed trays and pouches.
The shelf life of shrimp is also determined by different packaging. When packaged within a permeable tray, chilled irradiated shrimp has a shelf life of 15–23 days. Louisiana Direct Seafood distributes individually quick-frozen shrimp in low-permeability bags, which extends the shelf life of shrimp to about six months. In all types of packaging for shrimp, the package must maintain permeable and impermeable states at the defined temperature for food safety.
Similarly, ultra-high temperature (UHT) processed milk within sterilized paper-aluminum-polyethylene TetraPak cartons has a shelf life of 90 days at room temperature. The shelf life benefits of UHT processing would not be possible without the high barrier structure of the aseptic cartons. And refrigerated pasteurized milk packaged in high-density polyethylene (HDPE) jugs achieves a shelf life of 10–14 days.
Achieving the Right Shelf Life
Determining the shelf life of a food product and the package required to reach that shelf life is multifaceted. An appropriate shelf life ensures that quality food is available for consumers, fosters a distribution network to grow product sales volume, and enables production efficiencies associated with larger product volumes. To protect food, the right packaging materials are necessary. For example, additional grease-resistant insulating corrugated packaging is needed for take-out pizza; only plates are needed when pizza is consumed in a restaurant. When optimized, packaging for deliveries and takeout can use less materials while extending the shelf life of food. For example, closed-loop foodservice delivery operations for 10-minute fast- food and Hema market deliveries in China employ extensive reusable packaging so that municipal collection and sorting systems do not need to handle additional packaging. Instead, the outer insulating delivery packaging is reused, and the consumer receives minimal packaging. More