It is well known that food deterioration stems from multiple causes, the primary ones being atmospheric conditions and temperature. A less frequently discussed but harmful factor is ultraviolet (UV) radiation from the sun, which affects the preservation of exposed food. UV radiation is broadly divided into three wavelength ranges: UV-A (315–400 nanometers), UV-B (280–315 nanometers), and UV-C (100–280 nanometers). As the wavelength decreases, the energy and potential danger of the rays increase; consequently, UV-C rays are the most harmful, though fortunately, they do not reach the Earth’s surface because they are completely absorbed by the ozone layer. However, attention should be paid to UV-B rays, which are high-energy and penetrating, triggering a series of reactions in food that compromise its quality. Common effects of UV-B radiation on food include a reduction in nutritional value and a deterioration of organoleptic properties; furthermore, toxic compounds may form, potentially leading to inflammatory processes and chronic diseases in consumers.
The food components most susceptible to degradation by UV-B rays are as follows:
- photodegradable pigments. For instance, chlorophyll—found in leafy vegetables such as spinach, chicory, broccoli, arugula, turnip greens, and kale—degrades upon exposure to UV-B rays, resulting in color loss. Similarly, carotenoids—responsible for the red hues in tomatoes (lycopene) and the yellow-orange tones in carrots and pumpkins (beta-carotene)—deteriorate, causing color changes that are often unacceptable to consumers;
- vitamins, particularly vitamin C (ascorbic acid), which acts as an antioxidant. Its degradation reduces the antioxidant properties of foods containing it, such as citrus fruits. Likewise, riboflavin (vitamin B2) content drops significantly upon exposure to UV-B rays, further diminishing the nutritional profile of foods that contain it (spinach, chard, broccoli, legumes, etc.);
- lipids — specifically the fats abundant in oils, nuts, meat, and dairy products — undergo oxidation caused by UV-B radiation; this leads to the formation of free radicals and the development of unpleasant flavors and odors, often associated with rancidity;
- proteins are rapidly denatured and oxidized by UV-B rays, resulting in changes to texture and flavor that compromise food quality.
Synthetic additives and petroleum-derived packaging materials offer limited protection against UV-B radiation. A more promising solution lies in biomaterials incorporated with anthocyanins — a family of over 600 natural pigments sharing a common basic chemical structure, yet featuring various attached chemical groups that yield a wide range of colors.
A recent review by V. K. Pandey et al. (2025) highlights the properties and potential applications of anthocyanins in bio-based and biodegradable packaging materials, underscoring their role in enhancing food quality and promoting environmental sustainability. In nature, anthocyanins are abundant in certain fruits (blueberries, blackberries, raspberries, grapes, etc.), vegetables (red cabbage, eggplant, purple carrots, etc.), and flowers (roses, pansies, violets, etc.). When present, anthocyanins exert their full range of beneficial properties. For instance, in berries, anthocyanins reduce oxidative stress, thereby extending shelf life.
The concentration and types of anthocyanins vary by source, resulting in a spectrum of colors ranging from red to blue-green. Specifically:
- anthocyanins in grape skins give wine its red color;
- red tropical fruits — such as pomegranates, cherries, and blood oranges — contain red anthocyanins;
- red cabbage primarily contains cyanidin, the color of which shifts between blue and red depending on the pH level. This property is particularly interesting because the pH-induced color change can be utilized in smart packaging to provide a visual indication of product freshness.
Anthocyanins not only absorb and block UV-B rays but also possess strong antioxidant capacity (reducing free radicals) and antimicrobial properties, which extend the shelf life of food. The review outlines the use of anthocyanin-based packaging to protect various types of food from UV-B-induced degradation. For example:
- Chicken or beef — which are prone to lipid oxidation, increased rancidity, loss of omega-3 fatty acids, surface discoloration, and textural changes—benefit from an extended shelf life when films containing anthocyanins are used, primarily due to a 50% reduction in the growth of Salmonella and Escherichia coli;
- for sliced apples, browning is delayed and shelf life is extended by 20% through the use of anthocyanin-based coatings;
- in fruit juices, shelf life is extended by 40% when materials containing anthocyanins are used;
- anthocyanins slow down oil oxidation, reducing rancidity by 70%.
Furthermore, materials incorporating anthocyanins can be used to create active, transparent packaging capable of extending the shelf life of dairy products, fish, and ready-to-eat foods such as salads. Finally, innovative solutions are being explored — such as encapsulating anthocyanins in biopolymers like chitosan, polylactic acid (PLA), and starch — to produce biodegradable, fully recyclable materials with excellent oxygen and moisture barrier properties. For instance, the use of chitosan films containing anthocyanins extends the shelf life of vegetables by up to 30% and reduces weight loss by 25%. However, anthocyanins are thermally and chemically unstable; consequently, current efforts focus on enhancing their stability to enable large-scale production. Additionally, while the cost of anthocyanins is currently high, it is expected to decrease as the technology advances.
In conclusion, anthocyanins hold great potential for the production of innovative, eco-friendly materials capable of protecting food from UV-B radiation while offering antioxidant and antimicrobial properties. Because they change color in response to pH levels, they enable real-time monitoring of food freshness, making them suitable for active packaging applications. Future efforts must, however, aim to scale up their production.
References: V. K. Pandey et al., Journal of Food Process Engineering, 2025 – https://doi.org/10.1111/jfpe.70196
