Method for routine density measurement of sublimating solid carbon dioxide (dry ice) for cold-chain quality control

With recent development of vaccines and biologics, interest in dry ice for cold chain shipping has increased. However, understanding of how dry ice properties relate to performance is not well understood. This study introduces a simple method for measuring a key property of dry ice that has been shown to correlate to performance. The method involves a variant of the water displacement method for determining volume, where dense solid particles are used in place of water for volume determination. Three particle types (sieved sand, glass beads, and stainless-steel shot) were tested for suitability with the particle displacement method. Items of known mass and volume were used to validate the method. Direct volume measurements of dry ice cut samples using digital calipers were conducted in parallel for relative comparison. Results showed that the proposed particle displacement method using sieved sand produced density readings with an accuracy of 97-99%, whereas digital calipers underestimated density values. The sand and glass particles were less successful due to high thermal conductivity (stainless-steel shot), which led to errors due to condensation, and particles that were too fine and not sufficiently dense to prevent fluidization doe to sublimation gas flow. Sieved sand provided a good combination of particle size, density, thermal conductivity, and heat capacity for routine measurement of density of dry ice regardless of shape

Morphological, Thermal and Oxygen Barrier Properties Plasticized Film Polylactic Acid

Introducing plasticizer poly(ethylene glycol) (PEG400) was applied into poly(lactic acid) (PLA) to produce film matrix packaging by direct casting. Non mechanical properties were carried out plasticized PLA including morphology, crystallinity structure and degree, thermal properties and oxygen barrier properties. Plasticized PLA revealed improving surface structure of PLA film matrix form fractures and homogenous film were achieved at 5% PEG 400. Chromatogram PLA and plasticized PLA were categorized crystal structure an α-form crystal. Intercalated and exfoliated structure did not occur significantly due to dispersion PEG 400 in the matrix but indicated dispersion structure. Thermal properties did not improve plasticized PLA significantly for both glass temperature and melting temperature. PEG 400 accelerated crystal formation that increased the crystallinity degree from 17.71% to 34.64%. Plasticized PLA enhanced permeability value about 20% while largest fraction PEG400 reduced ability to prevent from oxygen through pass the film. The oxygen barrier properties was significantly affected degree of crystalline in the film with a correlation number 0.85

Predictive Modeling of Oxygen Transmission Through Micro-Perforations for Packaging Applications

Methods for creating precise perforations in respiring produce packaging are being increasingly adopted. Knowledge of oxygen transfer through perforated packaging and oxygen distribution in packages is necessary for successful packaging design of fresh produce. An approach to modeling perforated packaging performance was developed using a cylindrical chamber with precision perforations using Fick’s second law. The model was simulated using two techniques including Finite Element Method (FEM) using commercially available software and Finite Volume Method (FVM) through programming. Perforations were approximated as a source term in the second method. Both simulation techniques showed trends similar to experimental data

Review of Challenges and Advances in Modification of Food Package Headspace Gases

Modified Atmosphere Packaging (MAP) has been widely used as an effective way to preserve foods. Fresh produce, meat and meat products, seafood, and dairy products can benefit from modified gaseous atmospheres, which are usually achieved by reducing oxygen and increasing carbon dioxide concentrations, within limits, defined by product tolerances. MAP of fresh produce is particularly challenging because products are living and respiring. Respiration rates depend on several factors including temperature, oxygen, and carbon dioxide concentrations. Balancing package permeation with respiration is challenging, often due to limited selection of practical packaging materials. Failing to remain within tolerance limits of products leads to rapid quality loss. Gas barrier properties of packages determined rate of gas exchange with the external environment and is a critical factor for achieving tolerable levels. Availability of packaging materials that meet requirement of specific produce is essential. Relative permeability of common films to carbon dioxide is about 3 to 6 times of that to oxygen, often leading to package collapse for package atmospheres that benefit from carbon dioxide. Films often fail to provide desired oxygen transmission rates, high carbon dioxide to oxygen selectivity and desired mechanical properties simultaneously. Despite advances, minimal availability and high cost of selective barrier films limit applications of MAP for fresh produce packaging. Therefore, active packaging components and films are being developed and designed to overcome these limitations. Inserts or films that contain active mixtures as gas emitters and/or scavengers are now commercially available. “Clean label” trends are motivating alternative approaches using active packaging components

Effect of Plasticizer on Oxygen Permeability of Cast Polylactic Acid (PLA) Films Determined Using Dynamic Accumulation Method

Polylactic acid (PLA) is becoming an increasingly important biopolymer for packaging applications. PLA brittleness limits its applicability. This study evaluated PLA properties with increasing amounts of added polyethylene glycol (PEG) plasticizer. Oxygen transmission rate (OTR) of cast films was determined using the newly available Dynamic Accumulation (DA) method. Arrhenius temperature sensitivity of OTR and polymer Permeability was also determined. Permeability of neat PLA is 4.848 ml mm (STP)/m2 s kPa; hence, 4.84 ml mm (STP)/m2 s kPa, 4.07 ml mm (STP)/m2 s kPa and 5.42 ml mm (STP)/m2 s kPa by adding PEG 1 %, 5% and 10% respectively. The main conclusion from this work is increasing PEG will enhance the PLA permeability number but excess PEG in PLA film will decrease the permeability number

Effect of Red Cabbage Extract on Minced Nile Perch Fish Patties Vacuum Packaged in High and Low Oxygen Barrier Films

Oxidation of polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish causes loss of product quality. Oxidative rancidity causes loss of nutritional value and undesirable color changes. Therefore, powerful antioxidant extracts may provide a relatively low cost and natural means to reduce oxidation, resulting in longer, higher quality and higher value shelf life of foods. In this study, we measured synergistic effects of red cabbage antioxidant and vacuum packaging on lipid oxidation in fresh tilapia patties using thiobarbituric acid reactive substances (TBARS) assay, peroxide value (PV), pH and color analysis. Concentrated red cabbage extract was obtained using an efficient freeze/thawed method developed in our laboratory (citation). Fresh tilapia patties were prepared with solutions containing 68 ppm of extract concentrate for each 50 gr of fish patties. Samples were stored for 15 days at refrigeration conditions (4±1°C) and analyzed interval between two days for pH, color analysis, and lipid oxidation assessments. Results show that treated and vacuum packaged samples had lower oxidation levels than controls. Lipid peroxide values on treated samples showed benefits through day 12. This work shows that synergistic effect of red cabbage antioxidant extracts and vacuum packaging may represent an inexpensive and natural method for retarding oxidative spoilage of fresh fish

Robust gasification trial results for a variety of difficult-to-recycle packaging-related materials

Currently, recycling requires nearly absolute sorting of materials to accommodate the limited capabilities of existing recycling infrastructure. Whether a material is “recyclable” depends more on the method of recycling than the material itself. Our dependence upon sorting has limited success of recycling and has stifled our ability to achieve circular economy sustainability with plastic packaging materials. Our dependence upon sorting is rooted in our material-specific recycling processes. However, newer robust recycling processes are commercially available that reduce or eliminate the need to sort waste, and can convert mixed waste into primary feedstock chemicals, such as methanol for subsequent manufacture of new products, plastics, and packaging. China is one country with significant plastics production capacity using methanol as the primary feedstock. Distributed production of waste-derived Eco-Methanol™ has the potential to significantly improve plastic recycling rates while synergistically improving purity of material-specific recycling processes, resulting in greater availability of post-consumer recycled-content (PCR) materials for manufacturers. In this study, a variety of materials associated with waste from consumer-packaged goods was treated using a state-of-the-art, commercially available, robust gasification system. For all materials studied, the process proved capable of generating high-quality synthesis gas (syngas) with high yield. Syngas is already being produced commercially on a global scale, often from coal and natural gas. Syngas is often converted into methanol using proven commercial technologies. These proven commercial processes open a clear pathway for true plastics circularity. Mixed waste conversion to syngas, methanol and then to new products, plastics, and packaging represents a rational pathway to circularity while providing a market-based approach for extended producer responsibility (EPR) by sourcing materials produced from post-consumer waste derived Eco-Methanol

Elevated Test Pressure Significantly Reduces Dynamic Accumulation Oxygen Transmission Rate (ASTM F3136) Measurement Time for Barrier Packaging Films

Measurement of gas transmission rates of materials is important for successful package design. The dynamic accumulation (DA) method (ASTM F3136) is becoming increasingly popular for measuring oxygen transmission rate (OTR) due to its simplicity and low cost. However, measurement time increases with barrier properties of materials, limiting measurement throughput. A dynamic accumulation measurement prototype capable of operating up to 1,000 psig was developed in order to accelerate gas transfer by boosting concentration gradients via elevated absolute pressures. Results show that measurement results were independent of test pressure while measurement times were substantially reduced. These results also suggest that gas transmission rate testing using the steady state approach (e.g. ASTM D3985) will also benefit from tests performed at elevated pressures by boosting signal and/or expanding the range of measurement, permitting measurement of higher barrier films than are currentlyt possible

Biosynthesis of Red Cabbage Extract Directed Ag NPS and Their Effect on the Loss of Antioxidant Activity

Plant extracts contain sources of antimicrobial and antioxidant compounds that have been used as a reducing and stabilizing agents for biosynthesis of nanoparticles (NPs). Some studies suggest that plant extracts incorporating directed NPs, such as Ag, enhanced antioxidant activity, this study suggests the opposite. Red cabbage extract with silver NPs (Ag NPs) was prepared to study and how silver ions (Ag+) and Ag NPs influence antioxidant activity of red cabbage anthocyanin. Synthesized Ag NPs were characterized by UV-vis spectra, scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). We studied Ag NPs formation as a function of Ag+ and anthocyanin concentrations. Results show that Ag+ and Ag NPs decreased antioxidant activity of anthocyanin towards DPPH. (C) 2016 Elsevier B.V. All rights reserved