A new study has revealed that corrugated packaging keeps produce fresher than plastic, with corrugated fibres helping to trap and stifle microorganisms.
Keeping fruit and vegetables fresh and appealing can be challenging for retailers and their suppliers. With recent studies showing that corrugated packaging can keep fruit fresh up to three days longer than returnable plastic crates (RPCs), new scientific work has revealed how this is done.
New Research
This new research is the second study by the team from the University of Bologna’s Department of Agricultural Food Sciences, in Cesena, Italy, led by Professor Rosalba Lanciotti.
The team first investigated the exchange of microorganisms between packaging and fruit and found that cross-contamination is more extensive in RPCs than corrugated packaging. It involved packing fruit in both materials and then tracking the cell loads of the target microorganisms in various circumstances.
Building on the results of the previous study, this new study investigated the reasons for the difference in cross-contamination levels between RPCs and corrugated packaging. The team discovered that the higher levels of packed produce cross-contamination in RPCs were due to microorganisms surviving longer on plastic surfaces than corrugated.
Methodology
The researchers introduced both spoilage microorganisms, which affect the shelf life and quality of fruit, and pathogenic microorganisms, which can cause food-borne disease, onto corrugated and plastic surfaces, taking samples at regular intervals.
While the level of microorganisms decreased over time on both packaging materials, the fall was significantly faster on corrugated, compared to the plastic crates.
The study then explored why microorganisms perished more rapidly on corrugated surfaces than on plastic ones. Their work revealed how microorganisms get absorbed and trapped in the corrugated fibres, then die there from lack of nutrients and water.
The RPC samples, however, showed an impenetrable surface, incapable of entrapping microorganisms and reducing the superficial contamination. This allowed microorganisms to remain longer on the surface, increasing their potential to cross-contaminate packed fresh produce.
Following this, the team used an electron microscope to examine the contaminated surfaces. With the corrugated surface, they found that the microorganisms had become trapped inside the corrugated fibres and were unable to reach the surface, severely reducing their ability to cross-contaminate packed fresh produce.
With the plastic, they found that the smooth, continuous surfaces were unable to trap microorganisms. They also found tiny scratches that could easily fill with organic matter, particularly in worn RPCs.
In suitable environmental conditions, this organic matter would allow microorganisms to multiply.
Corrugated: The Better Choice
Clean packaging minimises cross-contamination and, ultimately, slows fresh produce deterioration rates. Since microorganisms survive longer on plastic surfaces than on corrugated ones, superficial contamination (and, therefore, the risk of contamination) is lower for corrugated packaging, making paper-based packaging cleaner and safer than RPCs.
Through this research, Professor Lanciotti and her team (primarily Dr Francesca Patrignani and Dr Lorenzo Siroli) have strengthened the results of the previous study, which concluded that cross-contamination of fresh produce is less likely to occur in corrugated materials than in RPCs.
It confirms that corrugated packaging is the better choice, by revealing exactly how corrugated reduces spoilage bacteria levels, minimising cross-contamination, ensuring that fresh produce keeps its quality, feel and taste, and extending its shelf life up to three days.
For more information, visit www.corrugated-ofcourse.eu
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