Applications of nanotechnology in food microbiology

Biopolymers as green-based food packaging materials: A focus on modified and unmodified starch-based films

The ideal food packaging materials are recyclable, biodegradable, and compostable. Starch from plant sources, such as tubers, legumes, cereals, and agro-industrial plant residues, is considered one of the most suitable biopolymers for producing biodegradable films due to its natural abundance and low cost. The chemical modification of starch makes it possible to produce films with better technological properties by changing the functional groups into starch. Using biopolymers extracted from agro-industrial waste can add value to a raw material that would otherwise be discarded. The recent COVID-19 pandemic has driven a rise in demand for single-use plastics, intensifying pressure on this already out-of-control issue. This review provides an overview of biopolymers, with a particular focus on starch, to develop sustainable materials for food packaging. This study summarizes the methods and provides a potential approach to starch modification for improving the mechanical and barrier properties of starch-based films. This review also updates some trends pointed out by the food packaging sector in the last years, considering the impacts of the COVID-19 pandemic. Perspectives to achieve more sustainable food packaging toward a more circular economy are drawn.

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag₂O, Cu, Cu₂O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues.

Insight of nanotechnological processing for nano-fortified functional foods and nutraceutical-opportunities, challenges, and future scope in food for better health

In the twenty-first century food sector, nanotechnological processing is a new frontier that has vibrant impact on enhancing the food quality, nutritional value, food safety, and nano-fortified functional foods aspects. In addition, the added-value of various robust nano-scale materials facilitates the targeted delivery of nutraceutical ingredients and treatment of obesity and comorbidities. The recent advancement in nanomaterial-assisted palatability enhancement of healthy foods opened up a whole new area of research and development in food nanoscience. However, there is no comprehensive review available on promises of nanotechnology in the food industry in the existing literature. Thus, herein, an effort has been made to cover this leftover literature gap by spotlighting the new nanotechnological frontier and their future scope in food engineering for better health. Following a brief introduction, promises of nanotechnology have revolutionized the twenty-first century food sector of the modern world. Next, recent and relevant examples discuss the exploitation and deployment of nanomaterials in food to attain certain health benefits. A detailed insight is also given by discussing the role of nano-processing in nutraceutical delivery to treat obesity and comorbidities. The latter half of the work focuses on improving healthy foods' palatability and food safety aspects to meet the growing consumer demands. Furthermore, marketed products and public acceptance of nanotechnologically designed food items as well as future prospects are also covered herein.

Silver Nanoparticles Biosynthesis, Characterization, Antimicrobial Activities, Applications, Cytotoxicity and Safety Issues: An Updated Review

Rapid advances in nanotechnology have led to its emergence as a tool for the development of green synthesized noble metal nanoparticles, especially silver nanoparticles (AgNPs), for applications in diverse fields such as human health, the environment and industry. The importance of AgNPs is because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including the pharmaceutical industry. Countries with high biodiversity require the collection and transformation of information about biological assets into processes, associations, methods and tools that must be combined with the sustainable utilization of biological diversity. Therefore, this review paper discusses the applicable studies of the biosynthesis of AgNPs and their antimicrobial activities towards microorganisms in different areas viz. medicine and agriculture. The confirmed antiviral properties of AgNPs promote their applicability for SARS-CoV-2 treatment, based on assimilating the virus’ activities with those of similar viruses via in vivo studies. In this review, an insight into the cytotoxicity and safety issues of AgNPs, along with their future prospects, is also provided.

Fabrication and characterization of biodegradable PHBV/SiO2 nanocomposite for thermo-mechanical and antibacterial applications in food packaging

In the present study, biogenic silica nanoparticles (bSNPs) were synthesized from groundnut shells, and thoroughly characterized to understand its phase, and microstructure properties. The biopolymer was synthesized from yeast Wickerhamomyces anomalus and identified as Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by GC-MS and NMR analysis. The bSNPs were reinforced to fabricate PHBV/SiO₂ nanocomposites via solution casting technique. The fabricated PHBV/SiO₂ nanocomposites revealed intercalated hybrid interaction between the bSNPs and PHBV matrix through XRD analysis. PHBV/SiO₂ nanocomposites showed significant improvement in physical, chemical, thermo-mechanical and biodegradation properties as compared to the bare PHBV. The cell viability study revealed excellent biocompatibility against L929 mouse fibroblast cells. The antibacterial activity of PHBV/SiO₂ nanocomposites was found to be progressively improved upon increasing bSNPs concentration against E. coli and S. aureus.

Biosynthesis, characterization, bactericidal and sporicidal activity of silver nanoparticles using the leaves extract of Litchi chinensis

Biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a promising alternative to the conventional chemical synthesis approach. In this study, cost-effective synthesis of AgNPs was attempted using leaves extract of Litchi chinensis. Bio-reduction reaction for the synthesis of NPs was checked by confirming the presence of AgNPs in solution by UV-vis spectrophotometry and with further characterization by fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Surface plasmon resonance (SPR) band showed absorption peak at 422 nm indicating the formation of AgNPs, and FTIR spectra confirmed the presence of biological molecules involved in AgNPs synthesis. TEM analysis revealed the spherical shape of AgNPs with particle size distribution in a range of 5-15 nm. Further, the biosynthesized AgNPs showed significant bactericidal and sporicidal activity against model spore former Bacillus subtilis. AgNPs at concentrations ranging from 25 to 100 µg/mL showed bactericidal activity with inhibition zone ranging from 4-19 mm and sporicidal activity at 100-200 µg/mL in a range of 4.46-61.6% with an exposure time of 2-8 h. These findings exhibit distinctive potential of biogenic AgNPs for their efficient use in developing novel bactericidal and sporicidal agent against spore forming bacilli.