There is great interest in developing biodegradable biopolymer-based packaging materials whose functional performance is enhanced by incorporating active compounds into them, such as light blockers, plasticizers, crosslinkers, diffusion blockers, antimicrobials, antioxidants, and sensors. However, many of these compounds are volatile, chemically unstable, water-insoluble, matrix incompatible, or have adverse effects on film properties, which makes them difficult to directly incorporate into the packaging materials. These challenges can often be overcome by encapsulating the active compounds within food-grade nanoparticles, which are then introduced into the packaging materials. The presence of these nanoencapsulated active compounds in biopolymer-based coatings or films can greatly improve their functional performance. For example, anthocyanins can be used as light-blockers to retard oxidation reactions, or they can be used as pH/gas/temperature sensors to produce smart indicators to monitor the freshness of packaged foods. Encapsulated botanical extracts (like essential oils) can be used to increase the shelf life of foods due to their antimicrobial and antioxidant activities. The resistance of packaging materials to external factors can be improved by incorporating plasticizers (glycerol, sorbitol), crosslinkers (glutaraldehyde, tannic acid), and fillers (nanoparticles or nanofibers). Nanoenabled delivery systems can also be designed to control the release of active ingredients (such as antimicrobials or antioxidants) into the packaged food over time, which may extend their efficacy. This article reviews the different kinds of nanocarriers available for loading active compounds into these types of packaging materials and then discusses their impact on the optical, mechanical, thermal, barrier, antioxidant, and antimicrobial properties of the packaging materials. Furthermore, it highlights the different kinds of bioactive compounds that can be incorporated into biopolymer-based packaging.

Tert-butyl hydroquinone (TBHQ) is a food additive commonly used as a more effective protectant in the food, cosmetic and pharmaceutical industries. However, the long-term exposure to TBHQ at higher doses (0.7 mg/kg) results in substantial danger to public health and brings a series of side effects, including cytotoxic, genotoxic, carcinogenic, and mutagenic effects. As a result, the global burden of chronic diseases has fascinated consumers and governments regarding the safety assessment of food additives. Regarding contradictory reports of various research about the application of food additives, the accurate monitoring of food additives is urgent. Notwithstanding, there are reports of the therapeutic effects of TBHQ under pathologic conditions through activation of nuclear factor erythroid 2-related factor 2. Thus, further investigations are required to investigate the impact of TBHQ on public health and evaluate its mechanism of action on various organs and cells. Therefore, this review aimed to investigate TBHQ safety through an overview of its impacts on different tissues, cells, and biological macromolecules as well as its therapeutic effects under pathologic conditions.

An on-package colorimetric label was fabricated using Hibiscus sabdariffa L. anthocyanin as a freshness indicator because its color depends on pH. The anthocyanins were embedded within a chitosan matrix. The colorimetric labels were applied to estimate the spoilage of fish food during storage at 25 °C for 3 days. According to scanning electron microscopy results, the inclusion of the anthocyanins in chitosan matrix resulted in formation dense and uniform film. The chitosan colorimetric labels had acceptable thicknesses (78–85 µm), moisture contents (14–16%), swelling indices (84–102%), water vapor permeabilities (3.0–3.2 × 10⁻¹¹ g m/m² s Pa), tensile strengths (11.3–12.3 MPa), and elongation at breaks (14–39%). It is noteworthy that the label can distinguish fish spoilage by color turn from light brown (fresh) to grayish (spoiled) by the naked-eye, due to alterations in the pH content and formation of volatile basic nitrogen during storage. Our results indicate that all-natural color labels can be an effective method to monitor the fish spoilage during storage, which may improve food quality and sustainability.

Nanocomposite biopolymer materials containing colorimetric pH-responsive indicators were prepared from gelatin and chitosan nanofibers. Plant-based extracts from barberry and saffron, which both contained anthocyanins, were used as pH indicators. Incorporation of the anthocyanins into the biopolymer films increased their mechanical, water-barrier, and light-screening properties. Infrared spectroscopy and scanning electron microscopy analysis indicated that a uniform biopolymer matrix was formed, with the anthocyanins distributed evenly throughout them. The anthocyanins in the composite films changed color in response to alterations in pH or ammonia gas levels, which was used to monitor changes in the freshness of packaged fish during storage. The anthocyanins also exhibited antioxidant and antimicrobial activity, which meant that they could also be used to slow down the degradation of the fish. Thus, natural anthocyanins could be used as both freshness indicators and preservatives in biopolymer-based nanocomposite packaging materials. These novel materials may therefore be useful alternatives to synthetic plastics for some food packaging applications, thereby improving the environmental friendliness and sustainability of the food supply.

Today, smart indicators especially based on pigments and natural biopolymers have developed significantly in laboratory and industrial scale. In addition to tracking the freshness and spoilage of the product, these intelligent systems inform the consumer about the quality of the packaged product without opening the package. On the other hand, they reduce food waste and minimize food poisoning. In this study, two halochromic smart indicators were constructed by encapsulating saffron petal and barberry anthocyanins in gelatin/chitin nanofiber films for indication of the freshness/spoilage of fish fillets. Insights into the molecular, structural, and optical properties of these indicators were obtained using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy, and colorimetry analyses. The results showed that the indicators had smooth surfaces and that the pigments were evenly distributed throughout the biopolymer network. The barberry and saffron anthocyanin solutions underwent color changes from reddish to yellow for barberry and reddish to pink to violet to greenish and yellow for saffron anthocyanin after being exposed to different pH values (1–14). The change in appearance of halochromic indicators was quantified by measuring their color coordinates (L*, a*, b*). When applied for estimating fish spoilage, the color of the G/ChNF/BA and G/ChNF/SPA indicators turned from pink to yellow and from violet to green, respectively. After 3 days of storage, the pH and total volatile basic nitrogen of fish fillets reached 8.0 and 49.06 mg N/100 g, respectively. Therefore, a direct relationship between the increase in pH values, the increase in volatile nitrogen bases content, and the changes in the color of the smart indicator applied to monitor the fish was observed. The simulation tests showed that pH-responsive smart indicators can reveal visually fish fillets freshness in real time prior to the point of consumption.