Properties of poly(vinyl alcohol) films as determined by thermal curing and addition of polyfunctional organic acids

The aim of the study was to assess the effect of the addition of citric and malic acid and heat curing on the mechanical, physical and optical properties of poly(vinyl alcohol) (PVOH) films. The addition of the organic acids without successive thermal treatments has a mere plasticising effect, while their application with heat curing has a combined crosslinking and plasticising effect. While conventional plasticizers and crosslinkers improve either extensibility or tensile strength of films, respectively, the addition of citric and malic acid coupled with heat curing determined good tensile strength and extensibility. Hydrophilicity was significantly reduced by thermal curing and even further reduced with the organic acids addition. The high transparency of the PVOH films was not affected either by heat-curing, acid addition and their combination, while the use of high curing temperature coupled with acid addition caused a slight yellowing of the films. The use of citric and malic acid in combination with thermal curing is a viable strategy for tailoring the performances of PVOH films thus broadening their spectrum of application

Assessment of the secondary shelf life of Bolognese sauce based on domestic use simulation

Household food waste contributes significantly to global food waste throughout the food supply chain, resulting in a substantial waste of resources. The inability of consumers to utilize food before it spoils generally leads to its disposal, thus representing one of the causes of food waste. The secondary shelf life (SSL) is the period a product should be consumed within once open, specified in the label, which sometimes is extremely short and may lead to a significant amount of discarded food. This study focuses on evaluating the SSL of Bolognese sauce through domestic use simulation and monitoring its microbiological and sensory quality, to explore the potential extension of the SSL, allowing consumers more time to consume the product. Results show that, even under harsh usage conditions, Bolognese sauce can have a SSL longer than 13 days, 2–3 times longer than the current SSL. The results highlight the influence of consumer behavior in determining the SSL, suggesting that improved food management could further reduce household food wast

Improvement of Paper Resistance against Moisture and Oil by Coatings with Poly(-3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and Polycaprolactone (PCL)

Surface hydrophobicity and grease resistance of paper may be achieved by the application of coatings usually derived from fossil-oil resources. However, poor recyclability and environmental concerns on generated waste has increased interest in the study of alternative paper coatings. This work focuses on the study of the performances offered by two different biopolymers, poly(3hydroxybutyrate-co-3hydroxyvalerate) (PHBV) and polycaprolactone (PCL), also assessing the effect of a plasticizer (PEG) when used as paper coatings. The coated samples were characterized for the structural (by scanning electron microscopy, SEM), diffusive (water vapor and grease barrier properties), and surface properties (affinity for water and oil, by contact angle measurements). Samples of polyethylene-coated and fluorinated paper were used as commercial reference. WVTR of coated samples generally decreased and PHBV and PCL coatings with PEG at 20% showed interesting low wettability, as inferred from the water contact angles. Samples coated with PCL also showed increased grease resistance in comparison with plain paper. This work, within the limits of its lab-scale, offers interesting insights for future research lines toward the development of cellulose-based food contact materials that are fully recyclable and compostable

Microbiota Survey of Sliced Cooked Ham During the Secondary Shelf Life

Sliced cooked ham packaged in a modified atmosphere is a popular ready-to-eat product, subjected to abundant microbial contamination throughout its shelf life that can lead to deterioration of both sensorial properties and safety. In this study, the microbial load and the chemical–physical features of cooked ham of five producers were monitored for a period of 12 days after the opening of the packages (i.e., the secondary shelf life), during which the products were stored in a domestic refrigerator at 5.2 ± 0.6°C. The sensorial properties presented a perceivable decay after 8 days and became unacceptable after 12 days. High-performance liquid chromatography analysis and solid-phase microextraction coupled with gas chromatography profiling of volatile metabolites indicated that lactic acid, ethanol, acetic acid, acetoin, 3-methyl-1-butanol, and 2-3 butanediol were the main metabolites that characterized the evolution of the analyzed cooked ham. The microbiota was monitored by 16S ribosomal RNA gene profiling and culture-dependent techniques. Already at the opening of packages, all the products presented high microbial load, generally dominated by lactic acid bacteria, with evident differences among the products. The increase of lactic acid bacteria somehow protected samples from abundant contamination by other bacteria, concurring with the evolution of more safe products. This role was exerted by numerous Latilactobacillus, Leuconostoc, and Carnobacterium species, among which the most frequently detected were Latilactobacillus sakei, Latilactobacillus sakei carnosum, Leuconostoc mesenteroides, and Carnobacterium divergens. Some products presented more complex communities that encompassed Proteobacteria such as Moellerella wisconsensis, Proteus hauseri, Brochothrix thermosphacta, and less frequently Pseudomonas, Erwinia, and Massilia. Opportunistic pathogenic bacteria such as Escherichia coli and Vibrio sp. were found in small quantities. The yeasts Kazachstania servazzii and Debaryomyces hansenii occurred already at 0 days, whereas various species of Candida (Candida zeylanoides, Candida sake, Candida norvegica, and Candida glaebosa) were abundant only after 12 days. These results indicated that the microbiological contaminants overgrowing during the secondary shelf life did not derive from environmental cross-contamination at the opening of the tray but were already present when the packages were opened, highlighting the phases of production up to the packaging as those crucial in managing the safety risk associated to this product

Exploring the Microbial Community of Traditional Sourdoughs to Select Yeasts and Lactic Acid Bacteria

Sourdoughs represent an awesome example of ecosystem in which yeasts and lactic acid bacteria (LAB) interact with each other, defining the characteristics of the final product in terms of composition, texture, taste and flavor. Therefore, the identification of dominant yeasts and LAB involved in the fermentation process can lead to the selection of starters with suitable fermentation aptitude and capable of producing desired aromas and/or aromatic precursors. In this work, two sourdoughs samples (A and B) for Panettone production were collected from an artisan bakery. Yeasts and bacteria were isolated at different fermentation steps on selective agar media. A total of 120 isolates were obtained and firstly characterized by conventional microbiological methods. Afterward, genomic DNA was extracted from the cultures, and (GTG)5-PCR fingerprinting analysis was carried out to reduce the redundance among the isolates. Representative yeasts and LAB strains, having a unique profile, were identified by sequencing the D1/D2 domain of the 26S rRNA and the 16S rRNA genes, respectively. The results highlighted the occurrence of Kazachstania humilis and Fructilactobacillus sanfranciscensis in both sourdoughs. Among LAB, also some other strains belonging to Lactobacillus genus were found. Moreover, Saccharomyces cerevisiae and Staphylococcus spp. strains were detected in sample B. In this study, a pool of yeasts and LAB strains for producing starter cultures with specific technological traits for sourdoughs production was obtained

Biological control of peach fungal pathogens by commercial products and indigenous yeasts.

The potential use of the commercial biocontrol products Serenade (Bacillus subtilis QST-713) and Trichodex (Trichoderma harzianum Rifai strain T39) to inhibit the postharvest pathogenic molds Penicillium crustosum and Mucor circinelloides was investigated. Both products exhibited antagonistic activity in vitro against the pathogens, reducing their growth at different levels. In addition, epiphytic yeasts isolated from peaches were identified as Candida maltosa, Pichia fermentans, and Pichia kluyveri by PCR-restriction fragment length polymorphism of internal transcribed spacer regions and screened for antagonistic activity against the same molds. The efficacy of biocontrol in vitro was dependent on the concentration of the yeast cells. Optimal yeast concentrations were above 10(7) CFU ml(-1). However, C. maltosa and P. fermentans were more effective than P. kluyveri in inhibiting molds. The exclusion of antifungal metabolite production and direct competition for nutrients or space with the pathogens was proposed as the mechanism of biocontrol. Application of biocontrol agents directly on artificially wounded peach fruits significantly reduced the incidence of mold rot during storage at 20 degrees C

Waste Orange Peels as a Source of Cellulose Nanocrystals and Their Use for the Development of Nanocomposite Films

first_page settings Order Article Reprints Open AccessArticle Waste Orange Peels as a Source of Cellulose Nanocrystals and Their Use for the Development of Nanocomposite Films by Francesco Bigi 1 [ORCID] , Enrico Maurizzi 1 [ORCID] , Hossein Haghighi 1 [ORCID] , Heinz Wilhelm Siesler 2 [ORCID] , Fabio Licciardello 1,3 [ORCID] and Andrea Pulvirenti 1,3,* [ORCID] 1 Department of Life Sciences, University of Modena and Reggio Emilia, 42015 Reggio Emilia, Italy 2 Department of Physical Chemistry, University of Duisburg-Essen, 45141 Essen, Germany 3 Interdepartmental Research Centre for the Improvement of Agri-Food Biological Resources (BIOGEST-SITEIA), University of Modena and Reggio Emilia, 42015 Reggio Emilia, Italy * Author to whom correspondence should be addressed. Foods 2023, 12(5), 960; https://doi.org/10.3390/foods12050960 Received: 19 January 2023 / Revised: 16 February 2023 / Accepted: 21 February 2023 / Published: 24 February 2023 (This article belongs to the Special Issue Scientific Breakthroughs to Fruit and Vegetable By-Product Valorization in Food Sector) Download Browse Figures Versions Notes Abstract To date, approximately 30–50% of food is wasted from post-harvesting to consumer usage. Typical examples of food by-products are fruit peels and pomace, seeds, and others. A large part of these matrices is still discarded in landfills, while a small portion is valorized for bioprocessing. In this context, a feasible strategy to valorize food by-products consists of their use for the production of bioactive compounds and nanofillers, which can be further used to functionalize biobased packaging materials. The focus of this research was to create an efficient methodology for the extraction of cellulose from leftover orange peel after juice processing and for its conversion into cellulose nanocrystals (CNCs) for use in bionanocomposite films for packaging materials. Orange CNCs were characterized by TEM and XRD analyses and added as reinforcing agents into chitosan/hydroxypropyl methylcellulose (CS/HPMC) films enriched with lauroyl arginate ethyl (LAE). It was evaluated how CNCs and LAE affected the technical and functional characteristics of CS/HPMC films. CNCs revealed needle-like shapes with an aspect ratio of 12.5, and average length and width of 500 nm and 40 nm, respectively. Scanning electron microscopy and infrared spectroscopy confirmed the high compatibility of the CS/HPMC blend with CNCs and LAE. The inclusion of CNCs increased the films’ tensile strength, light barrier, and water vapor barrier properties while reducing their water solubility. The addition of LAE improved the films’ flexibility and gave them biocidal efficacy against the main bacterial pathogens that cause foodborne illness, such as Escherichia coli, Pseudomonas fluorescens, Listeria monocytogenes, and Salmonella enterica

Development of antimicrobial films based on chitosan-polyvinyl alcohol blend enriched with ethyl lauroyl arginate (LAE) for food packaging applications

The main aim of this study was to characterize microstructural, physical, optical, mechanical, water barrier and antimicrobial properties of chitosan-polyvinyl alcohol blend films (CS-PVA) enriched with ethyl lauroyl arginate (LAE) (1–10% w/v) for food packaging applications. The film microstructure was determined by scanning electron microscopy. Active films containing 10% LAE showed cracks on the surface with irregular shape in the cross-section indicating a weaker cohesion of the CS-PVA polymer blend at high LAE concentrations. The possible interaction of CS-PVA blend film with incorporated LAE was also investigated using Fourier-transform infrared (FT-IR) spectroscopy in the attenuated total reflection (ATR) mode. FT-IR/ATR spectra showed a low molecular interaction between the CS-PVA and LAE up to 2.5% while for films containing 5 and 10% LAE such interactions between the functional groups of the CS-PVA matrix and LAE have been detected. The active films were transparent and showed barrier properties against UV and visible light. The incorporation of LAE into the CS-PVA increased the thickness, water solubility, water vapor permeability, and the b* and ΔE* values, while it decreased mechanical properties and transparency (p < 0.05). Active films inhibited the growth of four major food bacterial pathogens including Campylobacter jejuni, Escherichia coli, Listeria monocytogenes and Salmonella typhimurium. Particularly, films containing 5 and 10% LAE were the most effective (p < 0.05). Overall, the characterization of functional properties revealed that CS-PVA blend film incorporated with LAE could be used as an environmentally friendly antimicrobial packaging material to extend the shelf life of food products

Comprehensive characterization of active chitosan-gelatin blend films enriched with different essential oils

Natural extracts and plant essential oils (EOs) have long been recognized as valid alternatives to synthetic food additives owing to their proved wide-spectrum antimicrobial capacity. The main aim of this study was to characterize the physical, mechanical, water barrier, microstructural and antimicrobial properties of chitosan-gelatin blend films enriched with cinnamon, citronella, pink clove, nutmeg and thyme EOs. The film microstructure determined by scanning electron microscopy, showed that all active films had heterogeneous surface: in particular, films including cinnamon, nutmeg and thyme EOs showed remarkable pores on the surface. The possible interaction of chitosan-gelatin blend film with incorporated EOs was investigated using Fourier-transform infrared (FT-IR) spectroscopy. Presence of new bands and changes in the FT-IR spectra confirmed intermolecular interactions between the chitosan-gelatin matrix and the EOs. The antimicrobial activity of films was determined using the disk diffusion assay. Active films inhibited the growth of four major food bacterial pathogens including Campylobacter jejuni, Escherichia coli, Listeria monocytogenes and Salmonella typhimurium and, among the tested EOs, thyme was the most effective (p < 0.05). The active films can be considered as effective barriers against UV light. The incorporation of EOs to the chitosan-gelatin film increased thickness, moisture content, water vapor permeability, b* and ΔE* values (p < 0.05) while it decreased L* value, light transparency and opacity (p < 0.05). Overall, the characterization of functional properties revealed that chitosan-gelatin films incorporated with EOs could be used as environmentally friendly active food packaging with antimicrobial properties and potential to extend the shelf-life of food products