Manufacturing of Food Packaging Based on Nanocellulose : Current Advances and Challenges

Nowadays, environmental pollution due to synthetic polymers represents one of the biggest worldwide challenges. As demonstrated in numerous scientific articles, plant-based nanocellulose (NC) is a biodegradable and nontoxic material whose mechanical, rheological, and gas barrier properties are competitive compared to those of oil-based plastics. However, the sensitivity of NC in humid ambient and lack of thermosealability have proven to be a major obstacle that hinders its breakthrough in various sectors including food packaging. In recent years, attempts have been made in order to provide a hydrophobic character to NC through chemical modifications. In addition, extensive works on nanocellulose applications in food packaging such as coating, layer-by-layer, casting, and electrospinning have been reported. Despite these enormous advances, it can easily be observed that packaging manufacturers have not yet shown a particular interest in terms of applicability and processability of the nanocellulose due to the lack of guidelines and guarantee on the success of their implementation. This review is useful for researchers and packaging manufacturers because it puts emphasis on recent works that have dealt with the nanocellulose applications and focuses on the best strategies to be adopted for swift and sustainable industrial manufacturing scale-up of high-performance bio-based/compostable packaging in replacement of the oil-based counterparts used today

Fast Production of Cellulose Nanocrystals by Hydrolytic-Oxidative Microwave-Assisted Treatment

In contrast to conventional approaches, which are considered to be energy- and time-intensive, expensive, and not green, herein, we report an alternative microwave-assisted ammonium persulfate (APS) method for cellulose nanocrystals (CNCs) production, under pressurized conditions in a closed reaction system. The aim was to optimize the hydrolytic-oxidative patented procedure (US 8,900,706), replacing the conventional heating with a faster process that would allow the industrial scale production of the nanomaterial and make it more appealing to a green economy. A microwave-assisted process was performed according to dierent time\u2013temperature programs, varying the ramp (from 5 to 40 min) and the hold heating time (from 60 to 90 min), at a fixed reagent concentration and weight ratio of the raw material/APS solution. Dierences in composition, structure, and morphology of the nanocrystals, arising fromtraditional and microwave methods, were studied by several techniques (TEM, Fourier transform infrared spectroscopy (FTIR)-attenuated total reflectance (ATR), dynamic light scattering (DLS), electrophoretic light scattering (ELS), thermogravimetric analysis (TGA), X-ray diraction (XRD)), and the extraction yields were calculated. Fine tuning the microwave treatment variables, it was possible to realize a simple, cost-eective way for faster materials\u2019 preparation, which allowed achieving high-quality CNCs, with a defined hydrodynamic diameter (150 nm) and zeta potential (0.040 V), comparable to those obtained using conventional heating, in only 90 min instead of 16 h

Are Cellulose nanocrystals ‘alien particles’ to human experience?

A wide family of cellulose-based additives are authorized worldwide as fillers and thickening agents in foods, pills and tablets, and microcrystalline cellulose (MCC) is, among these, the most important one. Since MCC manufacturing is similar to the main production route of cellulose nanocrystals (CNCs), it is reasonable to wonder whether the MCC would contain CNCs as minor components. In this Short Communications we provide first results about the occurrence of CNCs in MCC, observed by dynamic light scattering and transmission electron microscopy after serial filtrations of MCC suspensions. The incidence of cellulose nanoparticles has been proved in several different trials in our ongoing works on diverse MCC samples and the nanoparticles isolated showed shape and dimensions similar to those commonly produced by acidic hydrolysis at laboratory level. Therefore, the presence of CNCs in many products is considered as a certainty. The foods and the pharmaceuticals we have been consuming so far, do indeed contain traces of CNCs to such an extent that this wide presence in consumed products should be taken into account when considering possible limitations of the use of these nanoparticles in food contact materials manufacture

Minimally processed potatoes : part 2. Effects of high oxygen partial pressures in combination with ascorbic and citric acid on loss of some quality traits

Sliced potatoes were stored in flexible packaging under different oxygen partial pressures (10, 55 and 100 kPa) after dipping treatments with ascorbic and citric acid at different concentrations. The levels of oxygen, ascorbic and citric acid were modulated according to a Central Composite Design. The response surface methodology allowed an assessment of the effects of these variables and their interactions on the respiration rate in a closed system, on the carbon dioxide accumulation rate and the volatile metabolites production inside flexible pouches. The results showed that the respiration rate did not increase in direct linear proportion to the oxygen partial pressure and there was no significant difference in respiration between 55 and 100 kPa, even though the respiration rate was higher at these super-atmospheric oxygen levels than at 10 kPa. Citric acid did not affect the respiration significantly, while the respiration rate increased with the increase in ascorbic acid concentration. However, at the highest level of ascorbic acid tested (5%), the respiration rate decreased. During storage in a high barrier plastic pouch, a higher CO2 accumulation rate was generally observed under 55 kPa than under 10 and 100 kPa. High oxygen partial pressures (55 and 100 kPa) did not stop the production of hexanal but they had an inhibitory effect on the anaerobic volatiles productio

INTERACTIVE POLYPHENOLS-BASED BIOPACKAGING FOR FOOD PRESERVATION: AN IN VITRO STUDY

Producing green, sustainable and renewable materials is one of the major challenge nowadays in the food-packaging sector. In this context, the aim of our study is to develop an active cellulose-based packaging, cellulose in fact is one of the most plentiful polymer on the earth. Tetrahydrocurcumin (THC), a derivative of curcuma, chosen as antioxidant and antimicrobial natural substance, was added into a cellulose matrix (1.5% w/w) and the resulting material was then studied. In addition to this active compound, the paper also contained chitosan and carboxymethylcellulose, to improve the retention of THC and the mechanical properties. Mechanical, chemical and microbiological analyses were done to completely characterize the active papers. Grammage, dry and wet strength were determined. The polyphenol content was determined by the Folin-Ciolcalteu method. Antimicrobial activity of THC, in solution and after its incorporation into the papers, was tested against Gram negative bacteria (Escherichia coli and Pseudomonas putida), Gram positive bacteria (Staphylococcus aureus and Listeria innocua) and moulds (Penicillium chrysogenum and Aspergillus niger). Antioxidant capacity was also tested through the DPPH method. THC solution presented a good antioxidant capacity: it showed an EC50 equal to 4,49 ppm ( EC50 of Trolox was 2,86 ppm). Its minimal inhibitory concentration is 0,4 g/L for Gram positive bacteria, and higher than 0,6 g/L for Gram negative. THC solution was found effective in delaying the development of moulds. THC polyphenols were quantified as 0,8% on paper weight for the paper containing THC and these quantities together with chitosan resulted able to slow down the growth of microorganism. Pseudomonas is inhibited by the presence of chitosan and THC is able to amplify the antimicrobial activity of chitosan, by inhibiting also the growth of Staphylococcus and E. Coli. The presence of THC does neither affect the mechanical properties of papers, nor the color and the odor. Based on these results, it is possible to conclude that THC exhibits good antioxidant and moderate antimicrobial properties. Paper sheets didn’t lose their mechanical properties. These data will pave the way to the use of THC for the production of an active paper-based packaging to improve the shelf life of food items

Light-induced changes in an aqueous betha-carotene system stored under halogen and fluorescent lamps, affected by two oxygen partial pressures

The aim of this work was to investigate the reaction kinetics of beta-carotene in an aqueous medium as a function of exposure to commercial lights (halogen and fluorescent sources) and oxygen partial pressures. The evolution of the pigment concentration, the changes in color and the accumulation of a volatile compound (beta-ionone) were monitored during storage. The kinetics of degradation were mathematically modeled in order to compare the effects of lighting conditions and oxygen partial pressures. Lighting was a critical variable also in the presence of a low oxygen partial pressure (5 kPa) and in these conditions the beta-carotene degraded completely during storage, even if more slowly than at 20 kPa of O2. The pigment degradation was correlated to illuminance and UVA irradiance values but the different decay rates of the fluorescent lamps were explained by the differences in the blue region of the energy emission spectra. Halogen lamp gave the minor negative effects on beta-carotene degradation

Posidonia Oceanica And Green Tea Extract As Active Agents For Shelf Life Extension Of Fresh Cut Peach

Nowadays the reduction of food waste and the availability of food all over the world areas are priority keys for society. In this context, the shelf life extension of fresh products in a sustainable way may represent one of the main goals. The aim of the present research work was to extend the shelf life of fresh cut peach slices by using extracts of Posidonia oceanica (POS) and green tea (GT), and compared to the control. Total polyphenols content was assessed by Folin-Ciocalteu method and the antioxidant capacity by DPPH (2,2-Diphenyl-1-Picrylhydrazyl) assay. Antimicrobial activity of the two extracts was initially carried out in vitro by determining the Minimal Inhibitory Concentration (MIC) against Escherichia coli, Listeria innocua, Pseudomonas putida, Staphylococcus aureus, Saccharomyces cerevisiae, Aspergillus niger and Penicillium chrysogenum. The two extracts in vivo on peach slices by dipping were applied (only water for the control), than, slices were placed into low-density polyethylene (LDPE) bag and stored at 3 ± 1°C for up to 7 days. Microbiological analyses, color (L*,a*,b*), total soluble solid (TSS) and titratable acidity (TA) on peach slices were carried out every 3 days. POS showed the highest polyphenols content (615±45 mg Gallic Acid Equivalent/g – mg GAE/g) while GT 526 ± 28 mg GAE/g. The values of EC50, for POS, was 72.42 ± 22.90 mg/L, while for GT 3.80 ± 0.11 mg/L. Trials in vitro showed MIC values of above 2 g/L for POS and above 1 g/L in GT mainly against Gram positive bacteria. POS was also found to lead a growth delay in the case of fungi, approximately 60 h compared to the control. Results related to the Total Aerobic (TAC) and yeasts and moulds (Y&M) counts highlighted that peach slices dipped with POS maintained in the first 5 days of storage the microbiota at lower or analogous levels than those found at t0 (1.80 ± 0.09 log cfu/g respect 2.30 ± 0.11 log cfu/g and 1.80 ± 0.05 log cfu/g respect 1.70 ± 0.03 log cfu/g of the control, respectively for TAC and Y&M). Regarding pomological analysis, after seven days, lightness of the peach slices decreased 28% in POS, 24% in GT and 35% in control. During shelf life TSS increased 8% in the control, 2% in POS and remained unchanged in GT, after seven days. At the same time, TA decreased 30% in POS, 20% in GT treatment and 63% in the control. During the experiment TSS increased in all treatments, more rapidly in the control; meanwhile the TA decreased slowly in treated samples compared to the control. Concluding, Posidonia oceanica and green tea extracts were found able to delay the colour and pomological parameters decay, maintaining a good fruit quality during shelf life. Data already showed evidence a better performance of the Posidonia extract, limiting the growth of microorganisms responsible for fresh fruit deterioration

Modular implant design affects metal ion release following metal-on-metal hip arthroplasty: a retrospective study on 75 cases

Metal-on-Metal (MoM) total hip arthroplasty (THA) has been associated to wear and metal-ions release, controversially related to a variety of clinical complications. Little is known about the relevant design-dependent parameters involved in this process. The present study investigated the correlation between metal ion release in blood and revision rate as a function of: (i) specific MoM implant modular design parameters, (i.e. acetabular cup and femoral head diameters, taper adapter material and size, femoral neck material and modularity and stem size); (ii) MoM bilaterality. Co and Cr ions concentration levels in blood of 75 patients were retrospectively-evaluated with a mean follow-up of 4.8 years (range: 1.8-6.3). Patients were divided in a unilateral and a bilateral group. Statistical analysis was performed to find any significant difference related to acetabular cup diameter, femoral head diameter, taper adapter material/size, neck material/size and stem size. The bilateral MoM group had 4-times higher metal ion levels in blood than the unilateral one (p=0.017 only Cr), related to a higher revision rate (30% vs 20%): differences were 10-times higher particularly with a 48 mm femoral head diameter (p=0.012) and a Ti-alloy neck (p=0.041). Within the monolateral group using a shorter taper adapter and a shorter neutrally-oriented neck demonstrated higher ion levels (p=0.038 only Cr and p=0.008 only Co, respectively). The aforementioned design-features and MoM bilaterality are important risk-factors for metal-ion release in modular MoM THA

A Superstabilizing log⁡(n)\log(n)-Approximation Algorithm for Dynamic Steiner Trees

In this paper we design and prove correct a fully dynamic distributed algorithm for maintaining an approximate Steiner tree that connects via a minimum-weight spanning tree a subset of nodes of a network (referred as Steiner members or Steiner group) . Steiner trees are good candidates to efficiently implement communication primitives such as publish/subscribe or multicast, essential building blocks for the new emergent networks (e.g. P2P, sensor or adhoc networks). The cost of the solution returned by our algorithm is at most $\log |S|$ times the cost of an optimal solution, where $S$ is the group of members. Our algorithm improves over existing solutions in several ways. First, it tolerates the dynamism of both the group members and the network. Next, our algorithm is self-stabilizing, that is, it copes with nodes memory corruption. Last but not least, our algorithm is \emph{superstabilizing}. That is, while converging to a correct configuration (i.e., a Steiner tree) after a modification of the network, it keeps offering the Steiner tree service during the stabilization time to all members that have not been affected by this modification

Shelf life of minimally processed potatoes : part 1. Effects of high oxygen partial pressures in combination with ascorbic and citric acids on enzymatic browning

The shelf life of minimally processed potatoes is limited by enzyme-catalysed browning reactions. Generally, this phenomenon is controlled by the use of chemical reagents such as ascorbic acid, citric acid, or 4-hexyl resorcinol, but it seems that "oxygen shock" treatments are also particularly effective in inhibiting enzymatic browning. The aim of this work was to study the effects of high oxygen partial pressures in combination with ascorbic and citric acid on the development of the enzymatic browning of peeled and cut potatoes ('Primura' variety) that were packaged in flexible pouches and stored at 5 degrees C for 10 days. Different treatments, chosen in according to a central composite design, were applied to the sliced potatoes. The browning development during storage was measured by a tristimulus colorimeter. Second-order polynomial models were computed for three periods of storage (3, 7 and 10 days) to relate the independent variables (oxygen partial pressure, ascorbic and citric acid concentrations) to the colour function attributes. The effectiveness of the statistical approach offered the possibility to investigate the effects of several processing conditions involved in the enzymatic browning of minimally processed potatoes, while the response surface methodology allowed the identification of the optimum range of the independent variables which prevented browning. (c) 2005 Elsevier B.V. All rights reserved