Antimicrobial packaging of raw beef, pork and turkey using silver-zeolite incorporated into the material

Combined Effect of an Active AgIon® Absorbent Pad and a Chitosan Coating on the Preservation of Fresh Beef

In the present study, the combined effect of an AgIon® antimicrobial absorbent (Ζ) pad and a chitosan coating (C) on the preservation of fresh beef stored aerobically at 5 °C was investigated. Microbiological, physicochemical, and sensory attributes were monitored for up to 10 days of storage. The microbiological data indicated that the C and chitosan coating plus absorbent pad (CZ) treatments were the most efficient in reducing total viable counts (TVC) by 4.09 and 3.53 log cfu/g compared to the control W and Z treatments on day 4 of storage (p < 0.05). An analogous reduction in the counts of the other microbial groups monitored was recorded. pH values were ca. 5.7 for treatments W and Z and 5.45 for treatments C and CZ on day 4 of storage (p < 0.05). The total volatile basic nitrogen (TVB-N) values remained <20 mg/100 g for all treatments on day 4 and for treatments C and CZ on day 10 of storage. The total color difference values decreased (p < 0.05) during storage for treatments W and Z, but remained constant for treatments C and CZ. Based on sensory, microbiological and physico-chemical data, beef shelf life was ca ^# + 3 days for samples W and Z and at least 10 + 3 days for samples C and CZ. Between the two antimicrobial treatments, chitosan was considerably more effective than the AgIon® antimicrobial absorbent pad, which showed practically no antimicrobial activity in direct contact with beef meat.

Facile Synthesis of Fe-Doped Hydroxyapatite Nanoparticles from Waste Coal Ash: Fabrication of a Portable Sensor for the Sensitive and Selective Colorimetric Detection of Hydrogen Sulfide

In this work, a new strategy has been reported for the portable detection of H₂S based on Fe-doped hydroxyapatite nanoparticles (Fe-HA) using a colorimetric paper test strip integrated with a smartphone platform. Fe-HA NPs were fabricated successfully via recycling waste coal ash. The obtained probe response toward H₂S was through a distinct visual color change. The sensing mechanism is based on the displacement reaction, in which PO₄ ^3- is replaced by S^2-. The prepared test strip shows high selectivity, and the other compounds containing thiol and sulfur anion have a negligible effect on the detection of H₂S. The designed scheme is applied for H₂S detection in the concentration range of 0.5-130 ppm with a limit of detection of 70 ppb. Furthermore, such a disposable sensor was used as a practical system for monitoring H₂S in actual water samples, suggesting the promising potential of this platform for suitable analysis of H₂S in an aqueous environment.

The Increase of Soft Cheese Shelf-Life Packaged with Edible Films Based on Novel Hybrid Nanostructures

This study presents, the development of a green method to produce rich in thymol natural zeolite (TO@NZ) nanostructures. This material was used to prepare sodium-alginate/glycerol/xTO@NZ (ALG/G/TO@NZ) nanocomposite active films for the packaging of soft cheese to extend its shelf-life. Differential scanning calorimetry (DSC), X-ray analysis (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) instruments were used for the characterization of such nanostructures and films, to identify the thymol adsorbed amount, to investigate the thermal behaviour, and to confirm the dispersion of nanostructure powder into the polymer matrix. Water vapor transmission rate, oxygen permeation analyzer, tensile measurements, antioxidant measurements, and antimicrobial measurements were used to estimate the film's water and oxygen barrier, mechanical properties, nanostructure's nanoreinforcement activity, antioxidant and antimicrobial activity. The findings from the study revealed that ALG/G/TO@NZ nanocomposite film could be used as an active packaging film for foods with enhanced, mechanical properties, oxygen and water barrier, antioxidant and antimicrobial activity, and it is capable of extending food shelf-life.

Effect of Agar/AgNP Composite Film Packaging on Refrigerated Beef Loin Quality

Fresh beef loin was packaged with 0-2% silver nanoparticles (AgNPs) incorporated agar films to investigate the effect of antimicrobial packaging on meat quality changes in terms of microbiological and physicochemical properties. Raw beef cuts were directly inoculated with Listeria monocytogenes and Escherichia coli O157:H7 and stored in the air-sealed packages combined with the agar films at 5 °C for 15 days. Beef samples showed low susceptibility to the agar/AgNP composite films, resulting in about one log reduction of the inoculated pathogenic bacteria in viable cell count during storage. However, the composite films could partly prevent beef samples from directly contacting oxygen, maintaining the meat color and retarding oxidative rancidity. Experimental results suggested that the AgNP-incorporated agar films can potentially be applied in packaged raw meats as an active food packaging material to inhibit microbial and physicochemical quality deterioration during distribution and sale.

Spray coating application for the development of nanocoated antimicrobial low-density polyethylene films to increase the shelf life of chicken breast fillets

Antimicrobial coated films were produced by an innovative method that allowed surface modification of commercial low-density polyethylene films so that well-defined antimicrobial surfaces could be prepared. A Pluronic™ surfactant and a polystyrene-polyethylene oxide block copolymer were employed to develop modified materials. The Pluronic™ surfactant provided a more readily functionalised film surface, while block copolymer provided a reactive interface which was important in providing a route to silver nanoparticles that were well adhered to the surface. Antimicrobial films containing silver were manufactured using a spray coater and the amount of silver used for coating purposes varied by the concentration of the silver precursor (silver nitrate) or the number of silver coatings applied. Potential antimicrobial activity of manufactured silver-coated low-density polyethylene films was tested against Pseudomonas fluorescens, Staphylococcus aureus and microflora isolated from raw chicken. The microbiological and physicochemical quality of chicken breast fillets wrapped with silver-coated low-density polyethylene films followed by vacuum skin packaging was also assessed during storage. Antimicrobial activity of developed silver-coated low-density polyethylene films was dependent ( p < 0.05) upon the concentrations of silver precursor and the number of silver coatings used. Better antimicrobial activity against P. fluorescens, S. aureus and chicken microflora was observed when the concentration of silver precursor was 3% and the spray coating deposition of silver was repeated four times. Use of silver-coated low-density polyethylene films extended ( p < 0.05) shelf life of chicken breast fillets and enhanced ( p < 0.05) oxidative stability compared to control films. Results indicated that silver-coated low-density polyethylene films could potentially be used as antimicrobial packaging for food applications.

Potassic zeolites from Brazilian coal ash for use as a fertilizer in agriculture

Brazilian coal has an ash content ranging from 30 to 50% by weight. Consequently, its use in coal-fired thermoelectric for power production generates a lot of waste. The construction sector is the largest consumer of coal ash, but it cannot absorb the entire amount generated. Thus, other applications for coal ash should be studied in aim to optimize the use of this industrial waste. This research had as focus to synthesize potassic zeolite from of the coal ash into on potassium fertilizer for the grown wheat plant. In this work, it was used a subbituminous coal from Mina do Leão (RS, Brazil) presenting 48.7% ash content on a dry basis. Concerning the synthesis of potassic zeolite, it was adopted the conventional method of hydrothermal treatment with potassium hydroxide. A schedule of experiments was conducted in order to define the optimum condition of zeolite synthesis that was then used an alkaline solution of 5M KOH with a reaction time of 24h at 150°C. According to this procedure, it was obtained a zeolite with a single crystalline phase, identified through X-ray diffraction as Merlinoite. Subsequently, it was performed a set of tests using potassic zeolite asa fertilizer for plants in a greenhouse. The synthesized potassic zeolite showed a good potential for its use as fertilizer in agriculture.

Influence of modified atmosphere and vacuum packaging with and without nanosilver-coated films on different quality parameters of pork

Pork is often marketed in packages with high oxygen atmosphere (MAP) or vacuum to improve shelf life and appearance. As silver ions have antibacterial effects, food contact films coated with silver might improve the shelf life of meat. In the present study, pork was wrapped in commercially available films, coated with nanosilver particles, and stored in the two packaging variants MAP and vacuum for 12 days. During storage, samples were analyzed on days 1 (before packaging), 4, 8 and 12 for microbiological contamination, meat quality (e.g., pH, color), and for the percentages of the myoglobin (Mb) redox forms. In addition, the effects of the film were examined after inoculation of the meat with high quantities of methicillin-resistant Staphylococcus aureus (MRSA) cells before vacuum storage for 8 days. MAP storage resulted in higher lightness (L*) values, lower liquid loss and higher Mb oxidation compared to vacuum. Microbiological spoilage was partly affected by the packaging variants with reducing effects of the MAP. The nanosilver-coating only affects the Mb redox form percentages of the pork cutlets and on day 4 the L* values, whereas microbiological parameters were not influenced. As the nanosilver coating had no influence on the total viable bacteria counts as well as Pseudomonas spp., Enterobacteriaceae and MRSA counts, an advantage of the nanosilver coating on the shelf life could be excluded.

Potential of the polymer poly-[2-(tert-butylamino) methylstyrene] as antimicrobial packaging material for meat products

AIMS

The objective of the study was to investigate the antimicrobial potential of a new SAM(®) polymer poly(TBAMS) as packaging material for meat products.

METHODS AND RESULTS

The influence of temperature, time and product factors on the antimicrobial activity of poly(TBAMS) against different bacteria was determined using a modified test method based on the Japanese Industrial Standard 2801:2000. Results showed a significant reduction in bacterial counts on poly(TBAMS) compared with the reference material of several meat-specific micro-organisms after 24 h at 7°C. Bacterial counts of Staphylococcus aureus, Listeria monocytogenes, Lactobacillus spp., Brochothrix thermosphacta and Escherichia coli were reduced by >4·0 log10  units. Pseudomonas fluorescens was less sensitive to poly(TBAMS) within 24 h between 2 and 7°C. Prolonging the storage time to 48 h, however, resulted in an increased reduction rate. Furthermore, antimicrobial activity was also observed if meat components in the form of meat extract, meat juice or bovine serum albumin protein were present. Antimicrobial activity was also achieved if inoculated with mixed cultures.

CONCLUSIONS

Poly(TBAMS) showed antimicrobial properties under conditions typical for meat supply chains.

SIGNIFICANCE AND IMPACT OF THE STUDY

Poly(TBAMS) bears a high potential to increase safety and shelf life of meat products.

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.