Development of shrimp freshness indicating films by immobilizing red pitaya betacyanins and titanium dioxide nanoparticles in polysaccharide-based double-layer matrix

A comparative study on the structure, physical property and halochromic ability of shrimp freshness indicators produced from nine varieties of steamed purple sweet potato

Nine varieties of purple sweet potato were steamed and used for the production of shrimp freshness indicators. The impact of purple sweet potato's variety on the structure, physical property and halochromic ability of indicators was determined. Results showed different varieties of purple sweet potato had different starch, crude fiber, pectin, protein, fat and total anthocyanin contents. The microstructure, crystallinity, moisture content, water vapor permeability, tensile strength and elongation at break of indicators were affected by crude fiber content in purple sweet potato. The color, transmission and halochromic ability of indicators was associated with the total anthocyanin content in purple sweet potato. Freshness indicators produced from Fuzi No. 1, Ganzi No. 6, Ningzi No. 2, Ningzi No. 4, Qining No. 2 and Qining No. 18 of purple sweet potato were suitable to indicate shrimp freshness. This study provides useful information on screening suitable varieties of purple sweet potato for intelligent packaging.

Plant betalains-mixed active/intelligent films for meat freshness monitoring: A review of the fabrication parameters

The plant pigments called betalains are nutritionally safe polar compounds. They are subdivided into betaxanthins (having orange to yellow hues) and betacyanins (purple to red violet hues). Betacyanins change color with a change in pH, particularly in the range 6-8 and 9-11. Perishable foods like fish, chicken, beef, pork, and others tend to release total volatile base-nitrogen (TVB-N) during storage or deterioration, which leads to a change in the pH of pH-sensitive materials in the vicinity. pH-sensitive pigment-incorporated polymeric films with inherent active properties (or active/intelligent films) are increasingly being studied as an alternative to synthetic pH indicators to detect the accumulation of TVB-N by changing its color to indicate the stage of perishable food spoilage. There are many methods of developing such films under different conditions using different bio-based biodegradable polymer(s) and biocompatible plasticizer combinations. Among the reported methods, solution casting method has been the preferred one in most studies covered in this review. This method can be carried out under mild conditions. As such, betacyanins-incorporated polymeric films essentially require mild processing conditions because of their heat sensitivity, which will invariably affect the performance in food freshness monitoring. In this review, film fabrication parameters like temperature and duration of dissolution of polymers, plasticizer concentration, pH of the film-forming solution, film drying, and conditioning/aging, have been critically appraised based on the available literature. The lack of studies on the safety of active/intelligent films has been systematically highlighted in this review to focus future studies on this area.

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Irreversible colorimetric bio-based curcumin bilayer membranes for smart food packaging temperature control applications

Research into innovative food safety technologies has led to the development of smart packaging with embedded chemical sensors that can monitor food quality throughout the supply chain. Thermochromic materials (TM), which are able to dynamically change colour in response to temperature fluctuations, have proven to be reliable indicators of food quality in certain environments. Natural colourants such as curcumin are becoming increasingly popular for smart packaging due to their low toxicity, environmental friendliness and ability to change colour. The innovation in this research lies in the production of a bio-based bilayer membrane specifically designed for irreversible temperature monitoring. Membrane A was prepared by dissolving cellulose acetate and curcumin in acetone at room temperature, with glycerol serving as a plasticiser. At the same time, membrane B was carefully formulated by dissolving cellulose acetate and triethanolamine in acetone, with sorbitol as plasticiser. The preparation of these different membranes revealed a remarkable event: a gradual and irreversible colour transition from an initial yellow to a brick-red hue after 24 hours of storage at 25 °C. The chemical structure and morphological analyses of the membranes were performed using several techniques, including FTIR, DSC and SEM. The membrane labels were adhered to aluminium cans and their colorimetric response was observed over a period of 10 days. Minimal colour variations were observed, confirming the reproducibility and stability of the curcumin-based membranes as temperature sensors.

Preparation, Characterization, and Application of pH-Response Color-Changeable Films Based on Pullulan, Cooked Amaranth (Amaranthus tricolor L.) Juice, and Bergamot Essential Oil

Pullulan-based smart packaging films were prepared by mixing cooked amaranth juice and bergamot essential oil. The impact of cooked amaranth juice and bergamot essential oil on the color-changeability, structural characterization, and barrier, antioxidant, mechanical and thermal properties of pullulan-based films was determined. Results showed the cooked amaranth juice contained pH-response color-changing betacyanins. The pullulan films containing cooked amaranth juice were color-changeable in pH 9-12 buffers and in ammonia vapor. The color-changeable property of betacyanins in cooked amaranth juice was unaffected by bergamot essential oils. The inner structure of pullulan films was greatly affected by cooked amaranth juice, forming big and ordered humps in film cross-sections. The crystallinity of pullulan films was improved by the combined addition of cooked amaranth juice and bergamot essential oil. Among the films, the pullulan film containing cooked amaranth juice and 6% bergamot essential oil showed the highest UV-vis light barrier property, antioxidant activity, and tensile strength; while the pullulan film containing cooked amaranth juice and 4% bergamot essential oil showed the highest oxygen barrier property and thermal stability. Moreover, the pullulan films containing cooked amaranth juice were able to monitor the freshness of shrimp by presenting color changes from reddish purple to dark red.

Betalains as promising natural colorants in smart/active food packaging

Betalains are water-soluble nitrogen pigments with beneficial effects, including antioxidant, antimicrobial, and pH-indicator properties. The development of packaging films incorporated with betalains has received increasing attention because of pH-responsive color-changing properties in the colorimetric indicators and smart packaging films. As such, intelligent and active packaging systems based on biodegradable polymers containing betalains have been recently developed as eco-friendly packaging to enhance the quality and safety of food products. Betalains could generally improve the functional properties of packaging films, such as higher water resistance, tensile strength, elongation at break, and antioxidant and antimicrobial activities. These effects are dependent on betalain composition (about its source and extraction), content, and the kind of biopolymer, film preparation method, food samples, and storage time. This review focused on betalains-rich films as pH- and ammonia-sensitive indicators and their applications as smart packaging to monitor the freshness of protein-rich foods such as shrimp, fish, chicken, and milk.

Locust Bean Gum, a Vegetable Hydrocolloid with Industrial and Biopharmaceutical Applications

Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.). In addition, this hydrocolloid is easily modified by derivatization or crosslinking. These LBG-related products, besides their applications in the food industry, can be used as encapsulation and drug delivery devices, packaging materials, batteries, and catalyst supports, among other biopharmaceutical and industrial uses. As the new derivatized or crosslinked polymers based on LBG are mainly biodegradable and non-toxic, the use of this polysaccharide (by itself or combined with other biopolymers) will contribute to generating greener products, considering the origin of raw materials used, the modification procedures selected and the final destination of the products.