Novel hydrophobic colorimetric films based on ethylcellulose/castor oil/anthocyanins for pork freshness monitoring

 LWT, 164, 2022, 113631

A novel hydrophobic colorimetric film was developed using ethyl cellulose (EC), castor oil (CO) and purple potato anthocyanin (AN) for pork freshness monitoring. The films with CO concentrations of 0% (control), 0.25%, 0.5%, 1% and 2% were developed and expressed as F0, F0.25, F0.5, F1 and F2. Scanning electron microscopy (SEM) images showed that the five films had dense surface and porous internal structures. The F0.5 film exhibited the highest tensile strength (TS) value, optimal color stability, ability to prevent the leaching of AN. The limit of detection (LOD) value of the F0.5 film to ammonia gas was 1.04 μM. The color of F0.5 film turned from red to green along with the spoilage of pork. As a result, the film was expected to be a good colorimetric indicator of pork freshness for intelligent packaging.

A high-stable and sensitive colorimetric nanofiber sensor based on PCL incorporating anthocyanins for shrimp freshness

 Food Chem. 377, 131909 (2022)

A novel bilayer colorimetric film incorporating polycaprolactone (PCL) with clitoria ternatea Linn anthocyanin (CA) via electrospinning was designed. The PCL nanofibers layer acted as a protective layer against harsh environments as the strong hydrophobic with the WCA (water contact angle) values of 101.79°. The PCL-CA layer worked as an indicator for its significant color changes for pH. The sensitivity test verified the ammonia cycler reversibility of the nanofibers is promising for re-use packaging. And the PCL/PCL-CA film was characterized as suitable WVP (water vapour permeability), and the lower velocity of water penetrating. Moreover, higher elongation at break (240.431%), and color stability were achieved. Besides, the film exhibited the color change from pale-blue to yellow-green response as an indication of shrimp spoilage (21 h). These results suggested the potential application of the PCL/PCL-CA film for a reusable freshness sensor tool in food packaging.