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

Checkpoints are blind to replication restart and recombination intermediates that result in gross chromosomal rearrangements

Replication fork inactivation can be overcome by homologous recombination, but this can cause gross chromosomal rearrangements that subsequently missegregate at mitosis, driving further chromosome instability. It is unclear when the chromosome rearrangements are generated and whether individual replication problems or the resulting recombination intermediates delay the cell cycle. Here we have investigated checkpoint activation during HR-dependent replication restart using a site-specific replication fork-arrest system. Analysis during a single cell cycle shows that HR-dependent replication intermediates arise in S phase, shortly after replication arrest, and are resolved into acentric and dicentric chromosomes in G2. Despite this, cells progress into mitosis without delay. Neither the DNA damage nor the intra-S phase checkpoints are activated in the first cell cycle, demonstrating that these checkpoints are blind to replication and recombination intermediates as well as to rearranged chromosomes. The dicentrics form anaphase bridges that subsequently break, inducing checkpoint activation in the second cell cycle

Formation and prevention of light-struck taste white wine

Light-struck taste is a defect occurring white wines bottled in clear glass and exposed to light. It is manifested by a loss of color and aroma as a result of the presence of sulfur-like smells [1]. Its appearance is due to the reduction of riboflavin (RF), a high photosensitive compound, and the oxidation of methionine (Met) to give methional which is unstable under light and decomposes to acrolein and methanethiol. Two molecules of the latter compound can yield to dimethyl disulfide [1]. Methanethiol is highly volatile, has a low perception threshold (0.3 to 3 \ub5g/L in wine) and confers rotten eggs-like or cabbage-like aromas. Dimethyl disulfide is less volatile, but the olfactory perception threshold is still low (30 \ub5g/L) and it has an aroma impression of cooked cabbage or onion. Concentrations of RF lower than 80-100 \ub5g/L can decrease the risk of light-struck taste appearance [2]. The wine treatment with charcoal can lead to a depletion of RF in white wine [3], but it can have a detrimental effect on sensory properties of white wine. In order to limit the appearance of the light-struck taste, certain antioxidants (sulfur dioxide and glutathione) and wood tannins (oak, chestnut and galla) were tested in model wine containing RF and Met and exposed to light. The concentrations of these two compounds were monitored as well as the content of volatiles. The RF was completely degraded under light independently to the presence of Met. On the contrary, this amino acid underwent to photodegradation only in presence of RF. The sulfur dioxide limited the appearance of the defect maybe due to the formation of a complex riboflavin-sulfur dioxide making the vitamin less susceptible to the photo-degradation. The molar ratio degraded RF:degraded Met ranged from 1:8 to 1:20, much higher than one previously indicated in literature [1]. As expected, the increasing concentrations of RF led to major levels of sulfur compounds. Similarly, higher amounts of Met strongly affected the formation of volatiles which content increased as Met increased. The wood tannins could exert a protective effect, the galla tannins in particular. In fact, the lowest levels of volatiles, namely methanethiol and dimethyl disulfide, were found when the gallotannins were added. Nevertheless, the volatiles were lower in presence of both chestnut and oak tannins in comparison to the model solution. The content of oxidized phenols could be the main actor against the formation of the light-struck taste since it was the highest into the galla tannins. The oxidized phenols could bind the sulfur compounds and, consequently, they could be reduced back to phenols. The protection of white wine against the appearance of the light-struck taste can be achieved by adding the wood tannins, gallotannins in particular, before bottling. As this defect can appear for higher levels not only of RF, but also of Met, low concentrations of these compounds can also play a protective effect allowing the maintenance of the wine quality during the shelf-life

Controlled release of Michelia alba oil vapour from plastic sachets to control the growth of Aspergillus flavus on brown rice and its possible mode of action

This study aimed to create antifungal volatile-releasing sachets, from various commercially available synthetics (Tyvek®; high density polyethylene; HDPE, polypropylene/polyethylene; PP/PE and polyamide/polyethylene; PA/PE) and bio-based plastic sachet materials (Polylactic acid; PLA and cellophane), containing Michelia alba (MA) essential oil to be used against A. flavus on malt extract agar (MEA) and brown rice. In addition, the bioactive compounds (total phenolic content 32 and total flavonoid content) and antioxidant activity (DPPH, ABTS, and FRAP) of brown rice after treatment by the active sachets were examined. Results indicated that different sachet materials affected the release of the linalool and caryophyllene as antifungal volatiles. Tyvek® and PP/PE had a suitable permeability for controlling the release of the volatiles, which could be matched with the maximum concentration within 48 h, whereas PA/PE, PLA and cellophane had lower permeability. The antifungal volatiles released from Tyvek® and PP/PE sachets containing MA essential oil at 300 μl could completely inhibit the growth of A. flavus on MEA and brown rice for at least 20 days using accelerated conditions at 25°C and 80%RH. No spore germination or deformed hyphae of A. flavus could be observed in the treated brown rice when compared to the control which showed swelling spores and regular structure with uniformity. In addition, the bioactive compounds and antioxidant activity of brown rice treated with MA essential oil in the Tyvek® and PP/PE sachets were higher than in the control. Therefore, this study demonstrates a good opportunity to implement antifungal volatile-releasing sachets containing MA for shelf-life extension and improving the antioxidant activity of brown rice

An essential function for the ATR-Activation-Domain (AAD) of TopBP1 in mouse development and cellular senescence

ATR activation is dependent on temporal and spatial interactions with partner proteins. In the budding yeast model, three proteins – Dpb11TopBP1, Ddc1Rad9 and Dna2 - all interact with and activate Mec1ATR. Each contains an ATR activation domain (ADD) that interacts directly with the Mec1ATR:Ddc2ATRIP complex. Any of the Dpb11TopBP1, Ddc1Rad9 or Dna2 ADDs is sufficient to activate Mec1ATR in vitro. All three can also independently activate Mec1ATR in vivo: the checkpoint is lost only when all three AADs are absent. In metazoans, only TopBP1 has been identified as a direct ATR activator. Depletion-replacement approaches suggest the TopBP1-AAD is both sufficient and necessary for ATR activation. The physiological function of the TopBP1 AAD is, however, unknown. We created a knock-in point mutation (W1147R) that ablates mouse TopBP1-AAD function. TopBP1-W1147R is early embryonic lethal. To analyse TopBP1-W1147R cellular function in vivo, we silenced the wild type TopBP1 allele in heterozygous MEFs. AAD inactivation impaired cell proliferation, promoted premature senescence and compromised Chk1 signalling following UV irradiation. We also show enforced TopBP1 dimerization promotes ATR-dependent Chk1 phosphorylation. Our data suggest that, unlike the yeast models, the TopBP1-AAD is the major activator of ATR, sustaining cell proliferation and embryonic development

Antimicrobial agents and packaging systems in antimicrobial active food packaging: An overview of approaches and interactions

tMost of the scientific studies and innovations in food packaging have focused on the inhi-bition or prevention of microbial growth as well as avoiding further microbial deteriorationof food products. Among current food packaging techniques, active packaging, particular-ity antimicrobial active packaging, has attracted much attention due to the diversity in thematerials used, the methods of application, and the variety of food products that can be pro-tected. Direct and indirect techniques can be utilized to introduce antimicrobial compoundsinto food packaging materials. The increasing importance of the application of antimicrobialpackaging has inspired a better understanding of these materials and the factors influenc-ing the effectiveness of antimicrobial systems. This article is a review on the materials usedfor delivering antimicrobial substances with a focus on their main mechanisms of actionand release when used for food contact applications. In this regard, the effects of antimi-crobial agents on packaging properties will be discussed. Many challenges, including thecontrolled release of antimicrobial agents and the development of active packaging mate-rials (mainly bio-based materials) with adequate barrier properties, transparency, tensilestrength and other characteristics to meet the requirements of food protection and foodsafety, still remain to be solved in these new approaches to antimicrobial active packaging

Effect of packaging on volatile profiles of mulberry tea

This research aimed to investigate the effect of packaging materials and storage time on volatile profiles of mulberry tea. The mulberry tea samples were packaged in linear lowdensity polyethylene laminated aluminum (AL) bag and polypropylene (PP) bag and stored at 30\ub11\ub0C for 18 months. The volatile profiles were monitored using a headspace solid phase microextraction/gas chromatography-mass spectrometry. The results showed that storage time had no significant impact on the key volatile compounds of the AL packaged samples. However, some volatiles associated with lipid oxidation like hexanal and 4-oxo-2-nonenal were observed to significantly (p<0.05) increase in the PP packaged samples with storage time

Application of UV-C light for preventing the light-struck taste in white wine

The light-struck taste is a fault occurring in white wine bottled in clear bottles and exposed to light. The defect is due to the formation of methanethiol and dimethyl sulphide responsible for like-cabbage aroma arising from the reaction between riboflavin (RF), a highly light-sensitive compound, and methionine (Met). The light-struck taste is limited for RF concentration lower than 50 \ub5g/L achieved through the choice of a Saccharomyces strain low RF-producer and the RF removal with charcoal and bentonite as fining agents [1]. Moreover, the protective effect of wood tannins has been recently showed, especially galla tannins [2]. Due to the RF sensibility to light, the UV-C light treatment was assayed. A synthetic wine solution spiked with RF (200 \ub5g/L) and Met (3 mg/L) was irradiated with UV-C light up to 2000 J/L and RF decay was monitored. A linear decrease as UV-C light intensity increase was observed. RF was lower than 50 \ub5g/L and 20 \ub5g/L for 1500 J/L and 2000 J/L treatments, respectively. The addition of tannins (40 mg/L) led to a limited RF decrease (73%) maybe due to their shading properties [3]. Even though the UV-C light treatment is not admitted by the International Organization of Vine and Wine, its application could represent a tool for avoid the risk of light-struck taste development in bottled wine. The light exposure when the redox potential is high and the combined use of tannins could limit the appearance of this fault after the wine bottling preserving the wine quality during the shelf-life

Novel technologies for extending the shelf life of drinking milk : Concepts, research trends and current applications

Drinking milk with longer shelf-life is nowadays required to have access to markets of distant countries. Novel technologies for milk processing, alternative to conventional heat-treatments, may provide milk industry with reliable, efficient and clean equipment for drinking milk manufacture. This review addresses the most promising of these technologies, either under experimental examination or already commercially available. In particular, scientific literature documenting the performances of ohmic heating, microwaves, radio frequency, microfiltration, high pressure, pulsed electric field, and ultrasounds is presented. Attention is given to the respective effectiveness in destroying microorganisms, inactivating enzymes, and avoiding damage to milk components, as well as to the consequent microbiological and physicochemical stability of the processed milk during storage. Although most technologies allow to destroy or remove vegetative bacterial cells, so far none proves to represent a comprehensive alternative to conventional heat treatments. The combination of an alternative technology with mild thermal treatments represents, at the moment, the sole realistic approach to produce fresh-like/high quality pasteurized milk

Performance comparison of coatings based on cellulose nanocrystals and microfibrillated cellulose for food packaging

This article aimed at comparing gas barrier performance of plastic films coated with both cellulose nanocrystals (CNCs) and microfibrillated cellulose (MFC) obtained from cotton linters. CNCs were chemically isolated by ammonium persulfate (APS) hydrolysis, while the MFC was obtained mechanically either by APS-assisted pretreatment (MFCaps) or without pretreatment (MFC). Initially, mechanical tests of the three samples were performed and their properties were characterized by dynamic light scattering, TEM, FTIR, TGA and WAXS. Subsequently, coated PET films were characterized by water contact angle, transparency and opacity evaluation following by water vapor and oxygen transmission rates assessment performed at 25 °C/ 90% RH and 25 °C/ [0%–80% RH] respectively. Finally, oxygen diffusion and solubility coefficients were calculated by using half-time method. The findings showed that, coated films based on MFCaps display a much better oxygen barrier under higher RH and a higher level of residue when submitted to 700 °C degradation compared to CNCs