In the recent article published in the journal Sensors, researchers developed a colorimetric indicator using electrospun nanofibers impregnated with anthocyanins for detecting beef spoilage in smart packaging. The indicator aims to provide a visual cue to consumers regarding the freshness of meat products, addressing food safety concerns and reducing food waste.
Study: Nanofiber Indicators for Meat Spoilage Detection. Image Credit: Creativa Images/Shutterstock.com
Background
The study utilized the unique properties of anthocyanins, which are especially responsive to changes in pH, to detect spoilage effectively. By embedding these dyes into polylactic acid (PLA) nanofibers through electrospinning, the researchers developed a sensitive and cost-effective tool for real-time freshness assessment in meat packaging. This approach not only promises to improve consumer awareness of product safety but also contributes to efforts to reduce food waste by indicating spoilage in a clear and timely manner.
The Current Study
In the present study, the researchers developed a technique to create a colorimetric indicator for detecting meat spoilage using electrospun nanofibers loaded with anthocyanins. The preparation of the polylactic acid (PLA) solution involved dissolving PLA pellets in a 15 % (w/v) solution of 2,2,2-trifluoroethanol (TFE) and ethanol (EtOH), stirred until homogeneous. A custom electrospinning setup featuring a syringe pump and high-voltage power supply facilitated the spinning process. The PLA solution, loaded into a syringe with a metallic needle, was extruded at a constant flow rate to ensure even deposition of the fibers.
Morphological analysis of the nanofibers was conducted using a scanning electron microscope (SEM) at 10–15 kV to investigate their structure and arrangement pre- and post-dip-coating. Fiber diameter was quantified using image analysis software, while the weight and thickness of the nanofiber mats were measured with a balance and micrometer, respectively.
The porosity of the nanofibrous mats was determined via two methods: the apparent density method, which calculates density from the mass and volume of a punched-out circular area of the mat, and the liquid intrusion method, where ethanol infiltration into the mat's structure helped calculate porosity percentages.
Anthocyanin dyes extracted from red cabbage were immobilized onto the PLA mats using a dip-coating method. Mats were submerged in varying concentrations of dye solution and agitated on a shaker for 24 hours to achieve a uniform coating. This physical adsorption process allowed the anthocyanins to adhere effectively to the nanoporous PLA.
To test the indicators for meat spoilage detection, the researchers established specific scanning times for the indicators on meat samples. These samples were treated with phosphate buffer saline (PBS), homogenized, serially diluted, and spread on agar plates for total viable count (TVC) analysis. Following incubation, the growth of bacterial colonies indicated spoilage levels, allowing for an effective assessment of meat freshness. This innovative approach offers a promising solution to enhance food safety and reduce waste by providing a clear, visual indication of meat quality directly through the packaging.
Results and Discussion
SEM images of the electrospun PLA nanofibers, both before and after the introduction of dye, exhibited a uniform and random distribution of nanofibers. The average diameter of the nanofibers in pristine mats was maintained at 0.9 μm post-dip-coating, demonstrating the structural stability of the nanofibers even after the anthocyanin dye was immobilized. This consistent morphology is essential for preserving the integrity and effectiveness of the colorimetric indicator.
The porosity of the nanofiber mats was evaluated using both apparent density measurements and liquid intrusion methods, revealing only a slight reduction in porosity in the dye-coated samples compared to the pristine mats. This minor decrease is likely due to the additional mass from the dye coating.
Despite these changes, comparative analyses confirmed that the dip-coating process had minimal impact on the key properties of the nanofiber mats. The study underscored the effectiveness of the dip-coating method in creating a uniform, nanoporous layer infused with anthocyanin, suitable for the intended application.
Bacterial growth was assessed using Total Viable Count (TVC) analysis, which involved serial dilution of meat samples prepared with phosphate buffer saline (PBS) and subsequent incubation on agar plates. This allowed for the quantification and growth assessment of bacterial colonies, providing valuable insights into meat spoilage. The indicator's response time during scanning was crucial for evaluating its efficacy in detecting spoilage in meat products.
Conclusion
The anthocyanin-impregnated PLA nanofiber-based colorimetric indicator demonstrates significant potential for detecting spoilage in beef within smart packaging solutions. Its ability to change color in response to pH variations, combined with its cost-effectiveness and straightforward fabrication process, positions it as a viable tool for enhancing food safety and minimizing waste in the meat industry. Ongoing research and further optimization could improve its practical application in real-world settings.
Journal Reference
Karimi Alavijeh, D., Heli, B., et al. (2024). Development of a Sensitive Colorimetric Indicator for Detecting Beef Spoilage in Smart Packaging. Sensors, 24, 3939. https://doi.org/10.3390/s24123939, https://www.mdpi.com/1424-8220/24/12/3939