A novel self-powered time-temperature integrator (TTI) using modified biofuel cell for food quality monitoring

Capsule-based colorimetric temperature monitoring system for customizable cold chain management

The COVID-19 pandemic and the resulting supply chain disruption have rekindled crucial needs for safe storage and transportation of essential items. Despite recent advances, existing temperature monitoring technologies for cold chain management fall short in reliability, cost, and flexibility toward customized cold chain management for various products with different required temperature. In this work, we report a novel capsule-based colorimetric temperature monitoring system with precise and readily tunable temperature ranges. Triple emulsion drop-based microfluidic technique enables rapid production of monodisperse microcapsules with an interstitial phase-change oil (PCO) layer with precise control over its dimension and composition. Liquid-solid phase transition of the PCO layer below its freezing point triggers the release of the encapsulated payload yielding drastic change in color, allowing user-friendly visual monitoring in a highly sensitive manner. Simple tuning of the PCO layer's compositions can further broaden the temperature range in a precisely controlled manner. The proposed simple scheme can readily be formulated to detect both temperature rise in the frozen environment and freeze detection as well as multiple temperature monitoring. Combined, these results support a significant step forward for the development of customizable colorimetric monitoring of a broad range of temperatures with precision.

Nanomaterials in Smart Packaging Applications: A Review

Food wastage is a critical and world-wide issue resulting from an excess of food supply, poor food storage, poor marketing, and unstable markets. Since food quality depends on consumer standards, it becomes necessary to monitor the quality to ensure it meets those standards. Embedding sensors with active nanomaterials in food packaging enables customers to monitor the quality of their food in real-time. Though there are many different sensors that can monitor food quality and safety, pH sensors and time-temperature indicators (TTIs) are the most critical metrics in indicating quality. This review showcases some of the recent progress, their importance, preconditions, and the various future needs of pH sensors and TTIs in food packaging for smart sensors in food packaging applications. In discussing these topics, this review includes the materials used to make these sensors, which vary from polymers, metals, metal-oxides, carbon-based materials; and their modes of fabrication, ranging from thin or thick film deposition methods, solution-based chemistry, and electrodeposition. By discussing the use of these materials, novel fabrication process, and problems for the two sensors, this review offers solutions to a brighter future for the use of nanomaterials for pH indicator and TTIs in food packaging applications.

Expanding the Applicability of an Innovative Laccase TTI in Intelligent Packaging by Adding an Enzyme Inhibitor to Change Its Coloration Kinetics

Enzymatic time–temperature indicators (TTIs) usually suffer from instability and inefficiency in practical use as food quality indicator during storage. The aim of this study was to address the aforementioned problem by immobilizing laccase on electrospun chitosan fibers to increase the stability and minimize the usage of laccase. The addition of NaN₃, as and enzyme inhibitor, was intended to extend this laccase TTI coloration rate and activation energy (Ea) range, so as to expand the application range of TTIs for evaluating changes in the quality of foods during storage. A two-component time–temperature indicator was prepared by immobilizing laccase on electrospun chitosan fibers as a TTI film, and by using guaiacol solution as a coloration substrate. The color difference of the innovative laccase TTI was discovered to be <3, and visually indistinguishable when OD₅₀₀ reached 3.2; the response reaction time was regarded as the TTI’s coloration endpoint. Enzyme immobilization and the addition of NaN₃ increased coloration Km and reduced coloration Vmax. The coloration Vmax decreased to 64% when 0.1 mM NaN₃ was added to the TTI, which exhibited noncompetitive inhibition and a slower coloration rate. Coloration hysteresis appeared in the TTI with NaN₃, particularly at low temperatures. For TTI coloration, the Ea increased to 29.92–66.39 kJ/mol when 15–25 μg/cm² of laccase was immobilized, and the endpoint increased to 11.0–199.5 h when 0–0.10 mM NaN₃ was added. These modifications expanded the applicability of laccase TTIs in intelligent food packaging.

Informative and corrective responsive packaging: Advances in farm-to-fork monitoring and remediation of food quality and safety

Microbial growth and fluctuations in environmental conditions have been shown to cause microbial contamination and deterioration of food. Thus, it is paramount to develop reliable strategies to effectively prevent the sale and consumption of contaminated or spoiled food. Responsive packaging systems are designed to react to specific stimuli in the food or environment, such as microorganisms or temperature, then implement an informational or corrective response. Informative responsive packaging is aimed at continuously monitoring the changes in food or environmental conditions and conveys this information to the users in real time. Meanwhile, packaging systems with the capacity to control contamination or deterioration are also of great interest. Encouragingly, corrective responsive packaging attempting to mitigate the adverse effects of condition fluctuations on food has been investigated. This packaging exerts its effects through the triggered release of active agents by environmental stimuli. In this review, informative and corrective responsive packaging is conceptualized clearly and concisely. The mechanism and characteristics of each type of packaging are discussed in depth. This review also summarized the latest research progress of responsive packaging and objectively appraised their advantages. Evidently, the mechanism through which packaging systems respond to microbial contamination and associated environmental factors was also highlighted. Moreover, risk concerns, related legislation, and consumer perspective in the application of responsive packaging are discussed as well. Broadly, this comprehensive review covering the latest information on responsive packaging aims to provide a timely reference for scientific research and offer guidance for presenting their applications in food industry.

Prediction of fruit quality based on the RGB values of time-temperature indicator

Time-temperature indicators (TTIs) are cost-efficient tools that may be used to predict food quality. In this paper, a diffusion TTI was used to predict fruit quality during storage. Both the color changing characters of TTI and the quality parameters, including weight loss, soluble solids content, vitamin C content, titratable acidity, and antioxidant capacity of three kinds of fruits (kiwifruit, strawberry, and mango), were investigated for storage temperatures (5, 10, 15, and 20 °C). The relationships between the color changing properties and fruit quality parameters have been built based on the activation energy (E_a ). The results showed that the storage temperature and time had significant effects on the color changing of TTI and fruit quality. The RGB value of TTI decreased with time, and the higher the storage temperature, the faster the RGB value reduced. Also, the higher the storage temperature, the faster the fruit quality changed and the poorer they were. Furthermore, all of the differences of E_a between TTI color response and fruit quality change are less than 25 kJ/mol, which indicates that the TTI can be used to predict these fruit quality. Finally, prediction models were built and validated based on the RGB values of TTI. It provides the possibility for low-cost quality monitoring and has more application potential in food quality predicting. PRACTICAL APPLICATION: By monitoring the color change of diffuse time-temperature indicator (TTI) and the quality change of fruit, the feasibility of TTI for fruit quality monitoring was determined and the quality prediction model was established. The diffusion TTI and fruit quality prediction model can realize the monitoring and predicting of fruit quality based on the TTI, which provides a basis for the combination of TTI Quick Response Code and fruit quality monitoring, with a view to achieving fruit quality status by scanning the Quick Response Code of TTI with mobile phones in the future. This method may provide a new solution to monitor the fruit quality during storage and distribution based on visualization technology that can simplify the methods of detecting fruit quality and achieve fast quality detection. It provides the possibility for low-cost quality monitoring and has more application potential in food quality predicting. Further studies on diffusion TTI are needed to develop its application in more field of food and make the diffusion TTI an intelligent mean for food quality monitoring and predicting.

Development of a novel Maillard reaction-based time-temperature indicator for monitoring the fluorescent AGE content in reheated foods

Dietary advanced glycation end products (AGEs) are formed via the Maillard reaction in foods, especially in reheated foods, and can cause chronic diseases. In this study, a series of Maillard reaction-based time-temperature indicators (TTIs: TTI-1, TTI-2, and TTI-3) were developed with lysine and xylose for monitoring the dynamic formation of fluorescent AGEs in reheated foods. The discoloration kinetics of Maillard reaction-based TTIs and the dynamics of fluorescent AGE formation were explored. Formulas were derived to illustrate the relationship of the color change in the TTIs with time and temperature. The activation energies (E a values) for generating the TTIs were 96.17, 87.98, and 83.55 kJ mol-1, respectively. TTI-1 was the optimal indicator for instant soy milk powder because it showed the lowest activation energy difference in this study. The results show that this series of Maillard reaction-based TTIs can be used to monitor the AGE contents in various reheated foods.

Shelf Life of Food Products: From Open Labeling to Real-Time Measurements

The labels currently used on food and beverage products only provide consumers with a rough guide to their expected shelf lives because they assume that a product only experiences a limited range of predefined handling and storage conditions. These static labels do not take into consideration conditions that might shorten a product's shelf life (such as temperature abuse), which can lead to problems associated with food safety and waste. Advances in shelf-life estimation have the potential to improve the safety, reliability, and sustainability of the food supply. Selection of appropriate kinetic models and data-analysis techniques is essential to predict shelf life, to account for variability in environmental conditions, and to allow real-time monitoring. Novel analytical tools to determine safety and quality attributes in situ coupled with modern tracking technologies and appropriate predictive tools have the potential to provide accurate estimations of the remaining shelf life of a food product in real time. This review summarizes the necessary steps to attain a transition from open labeling to real-time shelf-life measurements.

Feasibility of a Gelatin Temperature Sensor Based on Electrical Capacitance

The innovative use of gelatin as a temperature sensor based on capacitance was studied at a temperature range normally used for meat cooking (20–80 °C). Interdigital electrodes coated by gelatin solution and two sensors of different thicknesses (38 and 125 µm) were studied between 300 MHz and 900 MHz. At 38 µm, the capacitance was adequately measured, but for 125 µm the slope capacitance versus temperature curve decreased before 900 MHz due to the electrothermal breakdown between 60 °C and 80 °C. Thus, for 125 µm, the capacitance was studied applying 600 MHz. Sensitivity at 38 µm at 868 MHz (0.045 pF/°C) was lower than 125 µm at 600 MHz (0.14 pF/°C), influencing the results in the simulation (temperature range versus time) of meat cooking; at 125 µm, the sensitivity was greater, mainly during chilling steps. The potential of gelatin as a temperature sensor was demonstrated, and a balance between thickness and frequency should be considered to increase the sensitivity.