Effects of Compostable Packaging and Perforation Rates on Cucumber Quality during Extended Shelf Life and Simulated Farm-to-Fork Supply-Chain Conditions

Development of chitin nanofiber coatings for prolonging shelf life and inhibiting bacterial growth on fresh cucumbers

The widespread usage of petroleum-based polymers as single-use packaging has had harmful effects on the environment. Herein, we developed sustainable chitin nanofiber (ChNF) coatings that prolong the shelf life of fresh cucumbers and delay the growth of pathogenic bacteria on their surfaces. ChNFs with varying degrees of acetylation were successfully prepared via deacetylation using NaOH with treatment times of 0-480 min and defibrillated using mechanical blending. With longer deacetylation reaction times, more acetamido groups (-NHCOCH3) in chitin molecules were converted to amino groups (-NH2), which imparted antibacterial properties to the ChNFs. The ChNF morphologies were affected by deacetylation reaction time. ChNFs deacetylated for 240 min had an average width of 9.0 nm and lengths of up to several μm, whereas rod-like structured ChNFs with a mean width of 7.3 nm and an average length of 222.3 nm were obtained with the reaction time of 480 min. Furthermore, we demonstrated a standalone ChNF coating to extend the shelf life of cucumbers. In comparison to the rod-like structured ChNFs, the 120 and 240-min deacetylated ChNFs exhibited a fibril-like structure, which considerably retarded the moisture loss of cucumbers and the growth rate of bacteria on their outer surfaces during storage. Cucumbers coated with these 120 and 240-min deacetylated ChNFs demonstrated a lower weight loss rate of ⁓ 3.9% day-1 compared to the uncoated cucumbers, which exhibited a weight loss rate of 4.6% day-1. This protective effect provided by these renewable ChNFs holds promising potential to reduce food waste and the use of petroleum-based packaging materials.

To Wrap Or to Not Wrap Cucumbers?

In light of increasing public pressure, retailers strive to remove plastic packaging as much as possible from fresh fruits and vegetables to reduce the environmental impacts along their supply chains. Plastic packaging, however, also has an important protective function, similar to the fruit's peel. For cucumbers transported from Spain and sold in Switzerland, our investigations in the form of a life cycle assessment study showed that the plastic wrapping has a rather low environmental impact (only about 1%) in comparison to the total environmental impacts of the fruit from grower to grocer. Hence, each cucumber that has to be thrown away has the equivalent environmental impact of 93 plastic cucumber wraps. We found that plastic wrapping protects the environment more by saving more cucumbers from spoilage than it harms the environment by the additional use of plastic. If, by using the plastic wrap, we reduce cucumber losses at retail only by 1.1%, its use already has a net environmental benefit. Currently, in the cucumber import supply chain from Spain to Switzerland, the use of plastic wrapping lowers the cucumber losses at retail by an estimated 4.8%; therefore, it makes sense to use it from an environmental perspective. The environmental benefit of food waste reduction due to plastic wrapping the cucumbers was found to be 4.9 times higher than the negative environmental impact due to the packaging itself. Alternative strategies to preserve fresh cucumbers without using plastic wrapping will have to compete with this challenging limit.

Microperforated Compostable Packaging Extends Shelf Life of Ethylene-Treated Banana Fruit

Plastic packaging preserves the quality of ethylene-treated bananas by generating a beneficial modified atmosphere (MA). However, petroleum-based plastics cause environmental pollution, due to their slow decomposition. Biodegradable packaging may help resolve this controversy, provided it shows adequate preservation efficacy. In this study, we tested the compostable biodegradable polyester packaging of ethylene-treated bananas in comparison with commercially available petroleum-based plastic alternatives. When compostable packaging was used in a non-perforated form, it caused hypoxic fermentation, manifested as impaired ripening, off-flavor, and excessive softening. Micro-perforation prevented fermentation and allowed MA buildup. Furthermore, no water condensation was observed in the biodegradable packages, due to their somewhat higher water vapor permeability compared to conventional plastics. The fruit weight loss in biodegradable packaging was higher than in polypropylene, but 3–4-fold lower than in open containers. The control of senescence spotting was the major advantage of microperforated biodegradable packaging, combined with the preservation of acceptable fruit firmness and flavor, and low crown rot incidence. Optimal biodegradable packages extended the shelf life of bananas by four days compared with open containers, and by two days compared with the best commercial plastic package tested. Microperforated biodegradable packages combined the advantage of improved sustainability with superior fruit preservation.

Retaining red bell pepper quality by perforated compostable packaging

Retail packages are widely used to preserve pepper fruit quality. However, due to the negative impact of conventional plastics on the environment there is an urgent need to replace these packaging materials with recyclable or compostable alternatives. Hereby, we evaluated the effects of compostable modified atmosphere packages with different perforation rates on keeping the quality of red bell pepper fruit during extended shelf life and simulated supply chain conditions. The results indicated that micro-perforated (µP) compostable packages creating an atmosphere of 15%-18% O2 and 2%-5% CO2, as well as macro-perforated (MP) compostable packages creating an atmosphere of 20%-21% O2 and 0.1%-0.5% CO2, effectively retained red bell pepper quality by reducing fruit weight loss, shriveling and softening, and by retaining flavor acceptance and visual appearance. On the other hand, nonperforated compostable packages resulted in the creation of anaerobic conditions (O2 < 1% and CO2 > 9%), and harmed produce quality as manifested by enhanced softening, decay, peel damage, and off-flavors. Overall, µP and MP compostable packages extended pepper fruit shelf life from 1 week to 3 weeks under continuous shelf life conditions, and from 2 weeks to 4 weeks under simulated supply chain and refrigerated storage conditions.