Increasing the shelf life of fresh in-hull pistachio using nanocomposite packaging of zinc nanoparticles and pistachio green hull essential oil

 Sci. Hort. 313, 111888, 2023

Fresh in-hull pistachio is one of the highly consumed but perishable forms of pistachio and can still be contaminated by aflatoxin-producing fungi. In this study, the packaging film prepared from an electrospun nanofibers was evaluated in order to increase the shelf life of raw pistachios. For this purpose, PVC and zinc nanoparticles combined with pistachio green hull essential oil (PGHEO) were used as the matrix and reinforcing phase of the composite, respectively. According to the results, monoterpenes such as α-pinene and limonene constitute more than 90% of PGHEO. The minimum inhibitory concentration (MIC) values of the essential oil ranged from 62.5 to 500 μg/mL which were more effective against Aspergillus flavus, a mycotoxigenic fungus affecting pistachio safety and quality, than other studied fungi. According to FE-SEM images, fibers were formed on film surfaces with diameters ranging from 89 nm to 295 nm. EDX spectra revealed some characteristic peaks for zinc indicating the existence of ZnO nanoparticles on the top surface of the composite. The prepared nanocomposite indicated the antifungal activity against Candida albicans, Aspergillus flavus and Aspergillus parasiticus with the growth inhibition percentage approximately 16.20, 9.60 and 2.88%, respectively. Finally, raw pistachios could be stored for 60 days in packaging made of nanocomposite, so that the amounts of aflatoxin B1 and B2 were lower than the allowed maximum level (< 12 ppb). It seems that the packaging used in this study can be a suitable solution to increase the shelf life of raw pistachios and reduce the waste caused by its spoilage.

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.

Development of nanofiber indicator with high sensitivity for pork preservation and freshness monitoring

 Food Chem. 381, 132224 (2022)

A visual Polyvinylidene Fluoride (PVDF) fibrous film incorporated with Roselle anthocyanin (RS) and Cinnamon essential oil (CEO) (PRC film) was designed via electrospinning technology for pork preservation and freshness monitoring. The PRC film presented well structural integrity and stability in buffer solutions without leaking out RS. And PCR film had well hydrophobic and high permeability with water contact angle (WCA) of 109.52° and water vapor permeability (WVP) of 2.63 × 10−7 g m−1h−1Pa−1. Importantly, PRC film exhibited good antibacterial activity with the inhibition diameter at 29.0 mm and 27.1 mm which against Escherichia coli and staphylococcus aureus, respectively. Finally, the PRC film was employed as a colorimetric sensor for monitoring pork freshness. It presented visible color changes from pink to blue and effectively prolonged the pork shelf-life by 2 days at 4 °C. These results indicate a great potential in intelligent and active packaging.