Silver Bionanocomposites as Active Food Packaging: Recent Advances & Future Trends Tackling the Food Waste Crisis

Food waste is a pressing global challenge leading to over $1 trillion lost annually and contributing up to 10% of global greenhouse gas emissions. Extensive study has been directed toward the use of active biodegradable packaging materials to improve food quality, minimize plastic use, and encourage sustainable packaging technology development. However, this has been achieved with limited success, which can mainly be attributed to poor material properties and high production costs. In the recent literature, the integration of silver nanoparticles (AgNPs) has shown to improve the properties of biopolymer, prompting the development of bionanocomposites. Furthermore, the antibacterial properties of AgNPs against foodborne pathogens leads towards food shelf-life improvement and provides a route towards reducing food waste. However, few reviews have analyzed AgNPs holistically throughout a portfolio of biopolymers from an industrial perspective. Hence, this review critically analyses the antibacterial, barrier, mechanical, thermal, and water resistance properties of AgNP-based bionanocomposites. These advanced materials are also discussed in terms of food packaging applications and assessed in terms of their performance in enhancing food shelf-life. Finally, the current barriers towards the commercialization of AgNP bionanocomposites are critically discussed to provide an industrial action plan towards the development of sustainable packaging materials to reduce food waste.

Nanostructured Antimicrobials for Quality and Safety Improvement in Dairy Products

In the food sector, one of the most important economic activities is the dairy industry, which has been facing many challenges in order to meet the increasing demand by consumers for natural and minimally processed products with high quality. In this sense, the application of innovative and emerging technologies can be an interesting alternative, for example, the use of nanotechnology in packaging and as delivery systems. This technology has the potential to improve the quality and safety of dairy products, representing an interesting approach for delivering food preservatives and improving the mechanical, barrier and functional properties of packaging. Several applications and promising results of nanostructures for dairy product preservation can be found throughout this review, including the use of metallic and polymeric nanoparticles, lipid-based nanostructures, nanofibers, nanofilms and nanocoatings. In addition, some relevant examples of the direct application of nanostructured natural antimicrobials in milk and cheese are presented and discussed, as well as the use of milk agar as a model for a preliminary test. Despite their high cost and the difficulties for scale-up, interesting results of these technologies in dairy foods and packaging materials have promoted a growing interest of the dairy industry.

Storage Behavior of “Seddik” Mango Fruit Coated with CMC and Guar Gum-Based Silver Nanoparticles

Mango fruit (cv. Seddik) is known as a delicate fruit for storage after harvest. Herein, carboxymethyl cellulose (CMC) and guar gum-based silver nanoparticles (AgNPs) were used as fruit coatings, and their effects on postharvest storage behavior and quality attributes were investigated. AgNPs were synthesized using a chemical reduction approach and then combined with CMC and guar gum as coating bases. Mango fruits were coated with the developed and pre-characterized CMC-AgNPs and guar gum-AgNPs, and then packed and stored at 13 °C for 4 weeks. The results showed an increase in weight loss, respiration rate, total soluble solids (TSS), total sugars, and total carotenoids over the storage period. However, this increase was comparatively less significant in coated fruits compared to uncoated fruits. Firmness and titratable acidity (TA) significantly decreased during storage, but this decrease was less in coated fruits. Silver traces in fruit pulp samples were not detected. These findings showed the efficacy of CMC-AgNP and guar gum-AgNP coatings in delaying mango fruit ripening and maintaining fruit quality during cold storage. Therefore, these coatings could be promising alternative materials for extending the postharvest life and marketing period of mango fruit.

Nanotechnology application in food packaging: A plethora of opportunities versus pending risks assessment and public concerns

Environmental factors, oxidation and microorganisms contamination, are the major causes for food spoilage, which leads to sensory features alteration, loss of quality, production of harmful chemicals and growth of foodborne pathogens capable to cause severe illness. Synthetic preservatives, traditional conserving methods and food packaging (FP), although effective in counteracting food spoilage, do not allow the real-time monitoring of food quality during storage and transportation and assent a relatively short shelf life. In addition, FP may protect food by the spoilage caused by external contaminations, but is ineffective against foodborne microorganisms. FP preservative functionalities could be improved adding edible natural antioxidants and antimicrobials, but such chemicals are easily degradable. Nowadays, thanks to nanotechnology techniques, it is possible to improve the FP performances, formulating and inserting more stable antioxidant/antimicrobial ingredients, improving mechanical properties and introducing intelligent functions. The state-of-the-art in the field of nanomaterial-based improved FP, the advantages that might derive from their extensive introduction on the market and the main concerns associated to the possible migration and toxicity of nanomaterials, frequently neglected in existing reviews, have been herein discussed.

Nanomaterials application in greenhouse structures, crop processing machinery, packaging materials and agro-biomass conversion

The discovery of nanomaterials has flagged off crucial research and innovations in science and engineering. Its unique properties and diverse applications present it as the material for the future. The aim of this study is to presents the relative applications of nanomaterial in some aspects of agriculture production. The study discussed nanotechnology applicability in climate control and photosynthesis in the greenhouse farming, hydroponic systems, solar drying, fabrication of crop processing machine components, oxygen scavengers in crop packaging, and micro-organism stimulant in anaerobic digestion for agro biomass conversion. Some highlights from the review revealed that Nanotechnology can be applied to increase water surface area to volume ratio and heat transfer in the air moving into a greenhouse farming. Water cluster can be changed when treated with nanoparticles through ultraviolet absorption spectrum and nuclear magnetic resonance (NMR) spectroscopy resulting in lower micelles to manipulate water delivery in green house farming. Nano-fluids or Nano-composites can be used to recombine the reactive parts of thermal storage materials after broken at elevated temperature to recover the stored heat for drying purpose during the off-sunshine periods in solar drying of crops. Nanomaterials can be a source of electroluminescence light in hydroponic system and act as coatings and surface hardener in crop processing machinery for post-harvest machines. The reviewed work showed that nanotechnologies has good prospect in adding value in agricultural production in the aspects discussed.

Biopolymers-Based Materials Containing Silver Nanoparticles as Active Packaging for Food Applications-A Review

Packaging is an integral part of food products, allowing the preservation of their quality. It plays an important role, protecting the packed product from external conditions, maintaining food quality, and improving properties of the packaged food during storage. Nevertheless, commonly used packaging based on synthetic non-biodegradable polymers causes serious environmental pollution. Consequently, numerous recent studies have focused on the development of biodegradable packaging materials based on biopolymers. In addition, biopolymers may be classified as active packaging materials, since they have the ability to carry different active substances. This review presents the latest updates on the use of silver nanoparticles in packaging materials based on biopolymers. Silver nanoparticles have become an interesting component of biodegradable biopolymers, mainly due to their antimicrobial properties that allow the development of active food packaging materials to prolong the shelf life of food products. Furthermore, incorporation of silver nanoparticles into biopolymers may lead to the development of materials with improved physical-mechanical properties.

Prospects and application of nanobiotechnology in food preservation: molecular perspectives

Applications of biotechnological tools in food preservation have shown promising results in minimizing food spoilage. Design and development of highly efficient food preservatives are one of the key success factors in this application field. However, due to the inherent shortcomings of the bulk forms of such preservatives, research was in progress to find suitable alternatives to replace conventional modalities. The intervention of nanotechnology has made this approach feasible in almost every aspect of food preservation. This interface domain of nanobiotechnology has been very well explored in the last few decades and vast literature has been reported. Researchers have developed efficient nanopreservatives (NPRs) for diverse applications. However, the literature available on nano-based food preservation is not inclusive of molecular perspectives involved in food preservation. There is a large knowledge gap in the interface domain concerning the physics of intermolecular and interfacial forces and nanotechnology which play decisive roles in designing edible coatings (ECs). There is an urgent need for identifying the nano and molecular level contributing factors for developing efficient NPRs. Moreover, it is imperative to understand the possible health impact of NPRs in public interest and concern. This review revisits the fundamental aspects of food preservation and navigates through the applicability, safety, molecular aspects and future direction of NPRs.

High intensity light pulses to reduce microbial load in fresh cheese

The present study focused on the utilisation of High Intensity Light Pulses (HILP) treatment to preserve mozzarella cheese. First, the susceptibility of Pseudomonas fluorescens and Enterobacteriaceae to HILP (fluences from 0·39 to 28·0 J/cm2) in a transparent liquid was evaluated (in-vitro tests). Afterwards, the effects on inoculated mozzarella cheese were also assessed. Then untreated (Control) and HILP treated samples were packaged and stored at 10 °C for 2 weeks. Enterobacteriaceae, Pseudomonas spp. and pH were monitored during storage. In a transparent liquid (in-vitro tests) there was a significant microbial inactivation just with 2 s of treatment. On the inoculated cheese a relevant microbial reduction of about 1 log cycle was observed, according to the exposure to the treatments. For Pseudomonas spp. in particular, in the treated samples, the microbiological acceptability limit (106 cfu/g) was never reached after 2 weeks of refrigerated storage. To sum up, the efficacy of this treatment is very interesting because a microbial reduction was observed in treated samples. HILP treatment is able to control the microbial growth and may be considered a promising way to decontaminate the surface of mozzarella cheese.

Nanotechnology: An Untapped Resource for Food Packaging

Food commodities are packaged and hygienically transported to protect and preserve them from any un-acceptable alteration in quality, before reaching the end-consumer. Food packaging continues to evolve along-with the innovations in material science and technology, as well as in light of consumer's demand. Presently, the modern consumers of competitive economies demands for food with natural quality, assured safety, minimal processing, extended shelf-life and ready-to-eat concept. Innovative packaging systems, not only ascertains transit preservation and effective distribution, but also facilitates communication at the consumer levels. The technological advances in the domain of food packaging in twenty-first century are mainly chaired by nanotechnology, the science of nano-materials. Nanotechnology manipulates and creates nanometer scale materials, of commercial and scientific relevance. Introduction of nanotechnology in food packaging sector has significantly addressed the food quality, safety and stability concerns. Besides, nanotechnology based packaging intimate's consumers about the real time quality of food product. Additionally, nanotechnology has been explored for controlled release of preservatives/antimicrobials, extending the product shelf life within the package. The promising reports for nanotechnology interventions in food packaging have established this as an independent priority research area. Nanoparticles based food packages offer improved barrier and mechanical properties, along with food preservation and have gained welcoming response from market and end users. In contrary, recent advances and up-liftment in this area have raised various ethical, environmental and safety concerns. Policies and regulation regarding nanoparticles incorporation in food packaging are being reviewed. This review presents the existing knowledge, recent advances, concerns and future applications of nanotechnology in food packaging sector.

Storage Stability of Kinnow Fruit (Citrus reticulata) as Affected by CMC and Guar Gum-Based Silver Nanoparticle Coatings

The influence of carboxy methyl cellulose (CMC) and guargum-based coatings containing silver nanoparticles was studied on the postharvest storage stability of the kinnow mandarin (Citrus reticulata cv. Blanco) for a period of 120 days (85%-90% relative humidity) at 4 °C and 10 °C. Physicochemical and microbiological qualities were monitored after every 15 days of storage. Overall results revealed an increase in total soluble solid (TSS), total sugars, reducing sugars and weight loss but this increase was comparatively less significant in coated fruits stored at 4 °C. Ascorbic acid, total phenolics, and antioxidant activity was significantly enhanced in coated fruits stored at 4 °C. Titratable acidity significantly decreased during storage except for coated kinnow stored at 4 °C. In control samples stored at 10 °C, high intensity of fruit rotting and no chilling injury was observed. Total aerobic psychrotrophic bacteria and yeast and molds were noticed in all treatments during storage but the growth was not significant in coated fruits at 4 °C. Kinnow fruit can be kept in good quality after coating for four months at 4 °C and for 2 months at 10 °C.

Packaging optimisation to prolong the shelf life of fiordilatte cheese

In this work, an active coating and modified atmosphere packaging (MAP) were investigated to prolong the shelf life of Fiordilatte packaged in traditional brine. First, the screening of MAP was performed in order to select the best gas composition. Then, the combined effect of MAP and coating was investigated. Finally, the coating was loaded with potassium sorbate and its effects under MAP conditions were also assessed. Results highlighted that MAP was able to control growth of the main spoilage microbial group (Pseudomonas spp.); however, the solubilisation of carbon dioxide into the brine compromised Fiordilatte texture. Therefore, the presence of the active coating avoided the damage of gas solubilisation and promoted a shelf life prolongation by about 157%.

Pepsin-digested bovine lactoferrin prevents Mozzarella cheese blue discoloration caused by Pseudomonas fluorescens

The aim of this work was to check the efficacy of bovine lactoferrin hydrolyzed by pepsin (LFH) to prevent blue discoloration of Mozzarella cheese delaying the growth of the related spoilage bacteria. Among 64 Pseudomonas fluorescens strains, isolated from 105 Mozzarella samples, only ten developed blue discoloration in cold-stored Mozzarella cheese slices. When Mozzarella cheese samples from dairy were treated with LFH and inoculated with a selected P. fluorescens strain, no pigmentation and changes in casein profiles were found up to 14 days of cold storage. In addition, starting from day 5, the count of P. fluorescens spoiling strain was steadily ca. one log cycle lower than that of LFH-free samples. ESI-Orbitrap-based mass spectrometry analyses allowed to reveal the pigment leucoindigoidine only in the blue LFH-free cheese samples indicating that this compound could be considered a chemical marker of this alteration. For the first time, an innovative mild approach, based on the antimicrobial activity of milk protein hydrolysates, for counteracting blue Mozzarella event and controlling psychrotrophic pigmenting pseudomonads, is here reported.

Evaluation of silver-infused polylactide films for inactivation of Salmonella and feline calicivirus in vitro and on fresh-cut vegetables

There is a growing trend to develop packaging materials with an active role in guarantying that the quality and safety characteristics of packaged products will remain or improve from preparation throughout shelf-life. In the present study, 0.001-1.0 wt.% silver ions were satisfactorily incorporated into polylactide (PLA) films by a solvent casting technique. Silver migration from the films was measured by voltamperometry and then correlated with its antimicrobial efficacy against Salmonella enterica and feline calicivirus (FCV), a human norovirus surrogate, by using the Japanese industrial standard (JIS Z 2801). The PLA-silver films showed strong antibacterial and antiviral activity in vitro, with increasing effects at higher silver concentrations. Moreover, results show that FCV was less susceptible to silver than Salmonella. When films were applied on food samples, antibacterial and antiviral activity was reduced as compared to in vitro. Antimicrobial activity was very much dependent on the food type and temperature. In lettuce samples incubated at 4 °C during 6 days, 4 log CFU of Salmonella was inactivated for films with 1.0 wt.% and no infectious FCV was reported under the same conditions. On paprika samples, no antiviral effect was seen on FCV infectivity whereas films showed less antibacterial activity on Salmonella.