The combined effects of lactoperoxidase system and whey protein coating on microbial, chemical, textural, and sensory quality of shrimp (Penaeus merguiensis) during cold storage (4 ± 1°C)

Growth and reproduction of gram-negative bacteria has a pivotal role in spoilage of seafood products. In order to identify the effect of lactoperoxidase system (LPOS), an antimicrobial activity was added to whey protein solution at the levels of 0 (control group), 1.25%, 2.5%, 5%, and 7.5%. Then, the shrimp samples were coated with immersion method and stored in the refrigerator for 16 days. In this period, the microbial tests of psychrotrophic bacteria, mesophilic bacteria, Pseudomonas fluorescens, Pseudomonas spp., and Shewanella putrefaciens, chemical tests of total volatile basic nitrogen, thiobarbituric acid, and pH, and sensory evaluation were carried out on the days of 0, 4, 8, 12, and 16. Adding LPOS in the coating resulted in a decrease in the total specific spoilage organisms and TVB-N. There was no significant effect for the TBA test. The levels of LPOS showed a positive correlation with the acceptable measurement in the sensory evaluation.

Bioemulsifiers Derived from Microorganisms: Applications in the Drug and Food Industry

Emulsifiers are a large category of compounds considered as surface active agents or surfactants. An emulsifier acts by reducing the speed of chemical reactions, and enhancing its stability. Bioemulsifiers are known as surface active biomolecule materials, due to their unique features over chemical surfactants, such as non-toxicity, biodegradability, foaming, biocompatibility, efficiency at low concentrations, high selectivity in different pH, temperatures and salinities. Emulsifiers are found in various natural resources and are synthesized by Bacteria, Fungi and Yeast. Bioemulsifier’s molecular weight is higher than that of biosurfactants. Emulsion’s function is closely related to their chemical structure. Therefore, the aim of this paper was to study the various bioemulsifiers derived from microorganisms used in the drug and food industry. In this manuscript, we studied organisms with biosurfactant producing abilities. These inexpensive substrates could be used in environmental remediation and in the petroleum industry.

The antibacterial effect of whey protein-alginate coating incorporated with the lactoperoxidase system on chicken thigh meat

Nowadays, the environmental problems due to the use of synthetic films and packages have caused the production of natural edible coatings or films. The aim of this study was to produce an edible whey protein-alginate coating with different concentrations of lactoperoxidase system to control the microbial load and increase the shelf life of chicken thigh meat stored in refrigerated condition (4 ± 1°C). So, after the provision of the alginate-whey protein coating incorporated with the lactoperoxidase system (at concentrations of 2%, 4%, and 6% in alginate-whey protein solution), microbial experiments were conducted for the period of 8 days. Three batches of organisms, including total aerobic mesophilic bacteria, Enterobacteriaceae, and Pseudomonas aeruginosa in samples, were tested by culturing in appropriate conditions. Results indicated that the coating had a substantial inhibitory effect on all lots. Also, the antimicrobial activity of coating increased with increase in lactoperoxidase system concentration in alginate-whey protein coating.

Probiotic white cheese production using coculture with Lactobacillus species isolated from traditional cheeses

Aim:

The aim of the present study was to investigate the viability of lactic acid bacteria isolated from traditional cheeses and cocultured in Iranian white cheese during ripening.

Materials and Methods:

A total of 24 samples were isolated from 8 types of traditional cheeses in West Azerbaijan, Iran. Isolated species were cocultured with starter bacteria during the production of Iranian white cheese, and their viability was investigated up to 60 days of the refrigerated storage.

Results:

Of 118 isolates of Lactobacillus, 73 isolates (62%) were confirmed as facultative heterofermentative and 45 isolates (38%) as obligate homofermentative. Of the facultative heterofermentatives, 28 isolates (24%) were Lactobacillus plantarum, 24 isolates (20%) were Lactobacillus casei, and 21 isolates (18%) were Lactobacillus agilis. Obligate homofermentatives were Lactobacillus delbrueckii (21%), Lactobacillus helveticus (14%), and Lactobacillus salivarius (3%). L. plantarum, L. casei and L. helveticus were found in high enough levels(10⁶ CFU/g).

Conclusion:

According to the obtained data, it is recommended that complex starters such as L. helveticus, L. plantarum, and L. casei can be used in industrial productions of cheese to obtain exclusive properties of traditional cheeses.

Application of supercritical fluids in cholesterol extraction from foodstuffs: a review

Various innovations have so far been devised to extract cholesterol from foods. Achieving a supercritical fluid is perhaps one of the greatest human successes in the field of extraction from foodstuffs in last 2 decades. Supercritical fluid extraction (SFE) offers a rapid, environment-friendly and selective method for extracting cholesterol from foods. This review aims at investigating the application of supercritical fluids in extraction of cholesterol. Various factors affecting the SFE, collection systems, examples of cholesterol extraction and SFE benefits are some of the issues discussed in this study.

Recent Progress in the Development of Conducting Polymer-Based Nanocomposites for Electrochemical Biosensors Applications: A Mini-Review

Among various immobilizing materials, conductive polymer-based nanocomposites have been widely applied to fabricate the biosensors, because of their outstanding properties such as excellent electrocatalytic activity, high conductivity, and strong adsorptive ability compared to conventional conductive polymers. Electrochemical biosensors have played a significant role in delivering the diagnostic information and therapy monitoring in a rapid, simple, and low cost portable device. This paper reviews the recent developments in conductive polymer-based nanocomposites and their applications in electrochemical biosensors. The article starts with a general and concise comparison between the properties of conducting polymers and conducting polymer nanocomposites. Next, the current applications of conductive polymer-based nanocomposites of some important conducting polymers such as PANI, PPy, and PEDOT in enzymatic and nonenzymatic electrochemical biosensors are overviewed. This review article covers an 8-year period beginning in 2010.

Efficiency of dietary sodium alginate coating incorporated with lycopene in preserving rainbow trout

The main aim of this study was to investigate the effect of alginate coating without or with lycopene at levels of 0.5, 1, 1.5, and 3% on the quality of rainbow trout stored under refrigerated conditions for 16 days. Samples coated with alginate with or without lycopene showed significantly lower free fatty acid (FFA) and total volatile basic nitrogen (TVB-N) values compared to uncoated (control) filets, particularly after day 4. Moreover, significant differences (p < 0.05) were observed between the coated samples containing lycopene and samples not containing lycopene on the last day. In relation with pH, none of the treatments resulted in significant differences. In regard to oxidation parameters, the effect of alginate-lycopene coatings was only seen on day 16 of storage. In general, although alginate-lycopene coating had no significant effect on the reduction of thiobarbituric acid and peroxide values, it succeeded in decreasing the TVB-N and FFA values.

Enhancement of corrosion resistance of polypyrrole using metal oxide nanoparticles: Potentiodynamic and electrochemical impedance spectroscopy study

We introduce a simple and facile strategy for dispersing of nanoparticles within a p-type conducting polymer matrix by in situ electropolymerization using oxalic acid as the supporting electrolyte. Coatings prepared from polypyrrole-nano-metal oxide particles synthesized by in situ polymerization were found to exhibit excellent corrosion resistance much superior to polypyrrole (Ppy) in aggressive environments. The anti-corrosion behavior of polypyrrole films in different states and the presence of TiO₂, Mn₂O₃ and ZnO nanoparticles synthesized by electropolymerization on Al electrodes have been investigated in corrosive solutions using potentiodynamic polarization and electrochemical impedance spectroscopy. The electrochemical response of the coated electrodes in polymer and nanocomposite state was compared with bare electrodes. The use of TiO₂ nanoparticles has proved to be a great improvement in the performances of polypyrrole films for corrosion protection of Al samples. The polypyrrole synthesized in the presence of TiO₂ nanoparticles coated electrodes offered a noticeable enhancement of protection against corrosion processes. The exceptional improvement of performance of these coatings has been associated with the increase in barrier to diffusion, prevention of charge transport by the nanosize TiO₂, redox properties of polypyrrole as well as very large surface area available for the liberation of dopant due to nano-size additive.

Whey protein isolate/cellulose nanofibre/TiO2 nanoparticle/rosemary essential oil nanocomposite film: Its effect on microbial and sensory quality of lamb meat and growth of common foodborne pathogenic bacteria during refrigeration

The use of biodegradable nanocomposite films in active packaging is of great importance since they can have a controlled release of antimicrobial compounds. This study was conducted to evaluate the efficacy of whey protein isolate (WPI)/cellulose nanofibre (CNF) nanocomposite films containing 1.0% (w/w) titanium dioxide (TiO₂) and 2.0% (w/v) rosemary essential oil (REO) in preserving the microbial and sensory quality of lamb meat during the storage at 4±1°C. Initially, the best concentration of each compound to be added to the film was determined by micro-dilution and disc diffusion methods. The microbial and sensory properties of lamb meat were controlled in two groups (control and treatment) over 15days of storage. Then, the samples were analysed for total viable count (TVC), Pseudomonas spp. count, Enterobacteriaceae count, Lactic acid bacteria (LAB) count, inoculated Staphylococcus aureus count, Listeria monocytogenes count, and Escherichia coli O₁₅₇:H₇ count. Microbial analysis and nine-point hedonic scale was applied for the sensory analysis. Results indicated that the use of nanocomposite films significantly reduced the bacterial counts of treatment group. Higher inhibition effect was observed on Gram-positive bacteria than on Gram-negative bacteria (P<0.05). The microbial and sensory evaluations also showed that the use of nanocomposite films significantly increased the shelf life of treated meat (15days) compared to the control meat (6days). Based on the results of this study, the edible nanocomposite films were effective in preserving the microbial and sensory qualities of lamb meat; therefore, this application is recommended in meat especially red meat.

Genome-wide association study of cell-mediated immune response in chicken

Cell-mediated immunity (CMI) causes the intracellular destruction of the antigen or elimination of the host cell to make animals resistant against exogenous antigens and cancers. In this study, a genome-wide association study (GWAS) was carried out to identify genomic regions associated with CMI in chicken using chicken 60k high-density single nucleotide polymorphism (SNP) array. Genomic relationships were taken into account to adjust for population structure. In order to account for multiple testing, chromosome-wise false discovery rate was controlled at 5% and 10% levels. Moreover, a comparison of the power of fixed and mixed linear models based on genomic inflation factor was carried out. Mixed linear model (MLM) had better inflation rate, and therefore the results from MLM were used for subsequent analysis. Three significantly associated SNPs (FDR < 0.05) on chromosome 24 and linkage group E22C19W28_E50C23, and three suggestively associated SNPs (FDR < 0.1) on chromosome 1, 5 and 16 were identified. Pathway analysis showed that two biological pathways, which are related to immune response, were strongly associated with the candidate genes surrounding identified SNPs, and their influences were mostly on antigen processing and presentation, and cellular structure.

Phytochemical, antioxidant and antibacterial properties of Melissa officinalis and Dracocephalum moldavica essential oils

Aromatic plants are rich in essential oils with considerable antimicrobial properties. The aim of this study was to investigate chemical composition, antimicrobial activity and antioxidant properties of Melissa officinalis and Deracocephalum moldavica essential oils (EOs). The identification of chemical constituents of the EOs was carried out using gas chromato-graphy-mass spectrometry analysis and antimicrobial activity of the EOs was evaluated by disc diffusion assay as well as determination of minimal inhibitory concentration (MIC) and minimal bactericidal concentration against four important food-borne bacteria: Salmonella typhimorium, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus. Antioxidant activity of the EOs was also determined by 2,2-diphenyl-1-picrylhydrazyl, 2,2-azinobis 3-ethylbenzo thiazoline-6-sulfonic acid and β-carotene bleaching tests. The major compounds of D. moldavica were geranial (28.52%), neral (21.21%), geraniol (19.60%), geranyl acetate (16.72%) and the major compounds of M. officinalis EO were citronellal (37.33%), thymol (11.96%), citral (10.10%) and β-caryophyllene (7.27%). The underlying results indicated strong antimicrobial effects of the oils against tested bacteria. Staphylococcus aureus with the lowest MIC value (0.12 mg mL^-1) for both EOs was the most sensitive bacterium, although, antibacterial effect of M. officinalis EO was stronger than D. moldavica. In addition, the results of the antioxidant activity showed that both EOs had notable antioxidant properties. In conclusion, both EOs are appropriate alternatives as potential sources of natural preservative agents with the aim of being applied in food industries.

Facile electrosynthesis of nano flower like metal-organic framework and its nanocomposite with conjugated polymer as a novel and hybrid electrode material for highly capacitive pseudocapacitors

The [Cu(btec)_0.5DMF] (H₄btec=1,2,4,5-benzenetetracarboxylate acid) was electrosynthesized on the graphite working electrode by applying catholic potential. The [Cu(btec)_0.5DMF] grows on a graphite surface which results from the coordination of 1,2,4,5-benzenetetracarboxylate anions with Cu²⁺ cations. The electrosynthesized [Cu(btec)_0.5DMF] was characterized by X-ray diffraction, scanning electron microscopy. Furthermore, POAP/Cu(btec)_0.5DMF nanocomposite film electrosynthesized on the surface of the carbon paste electrode by cyclic voltammetry. Different electrochemical methods including galvanostatic charge-discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy are carried out in order to investigate the performance of the system. This work introduces new nanocomposite materials for electrochemical redox capacitors with advantages including ease synthesis, high active surface area and stability in an aqueous electrolyte.

Effect of Echinophora platyloba DC. essential oil and lycopene on the stability of pasteurized cream obtained from cow milk

The present study was carried out to enhance shelf life of pasteurized cream using Echinophora platyloba essential oil (EEO) and lycopene. For this purpose, two concentrations of EEO (0.10% and 0.50%) and lycopene (20 and 50 ppm) alone and together as combinations were added in pasteurized creams and analyzed for microbial characteristics, sensorial properties and lipid stability during storage at 4 ˚C and 25 ˚C for 14 days. Results of microbial and chemical analyses of experimental pasteurized creams showed that pasteurized creams treated with combinations of the EEO and lycopene in their higher concentrations had the best microbial and chemical properties and the most stability than control during storage (p < 0.05). Results of sensorial evaluation demonstrated that all treatments had favorable overall acceptability, even though, the best sensorial properties were observed in creams with combinations of EEO and lycopene in their lower concentrations. Therefore, based on the results of the present study, application of EEO and lycopene as natural preservatives is especially recommend in high fat dairy products such as butter and cream.

Facile electrosynthesis, characterisation and electrochemical performance of poly ortho aminophenol/Al5Y3O12 nanocomposite as a new high efficient supercapacitor

In this paper, firstly Al₅Y₃O₁₂ has been synthesized without any impurities using pulse electrochemical deposition and then fabricated POAP/YAG films to serve as the active electrode for the electrochemical supercapacitor.

Physicoelectrochemical properties of facilely electrosynthesized reduced graphene oxide/p-type conductive polymer nanocomposite film

As electro-active electrodes, composites of reduced graphene oxide and poly ortho aminophenol (POAP) with good uniformity are prepared by electropolymerization. In comparison with Ni-POAP, the Ni-rGO/POAP-modified electrode shows a higher response for methanol oxidation.

Decomposing genomic variance using information from GWA, GWE and eQTL analysis

A commonly used procedure in genome-wide association (GWA), genome-wide expression (GWE) and expression quantitative trait locus (eQTL) analyses is based on a bottom-up experimental approach that attempts to individually associate molecular variants with complex traits. Top-down modeling of the entire set of genomic data and partitioning of the overall variance into subcomponents may provide further insight into the genetic basis of complex traits. To test this approach, we performed a whole-genome variance components analysis and partitioned the genomic variance using information from GWA, GWE and eQTL analyses of growth-related traits in a mouse F2 population. We characterized the mouse trait genetic architecture by ordering single nucleotide polymorphisms (SNPs) based on their P-values and studying the areas under the curve (AUCs). The observed traits were found to have a genomic variance profile that differed significantly from that expected of a trait under an infinitesimal model. This situation was particularly true for both body weight and body fat, for which the AUCs were much higher compared with that of glucose. In addition, SNPs with a high degree of trait-specific regulatory potential (SNPs associated with subset of transcripts that significantly associated with a specific trait) explained a larger proportion of the genomic variance than did SNPs with high overall regulatory potential (SNPs associated with transcripts using traditional eQTL analysis). We introduced AUC measures of genomic variance profiles that can be used to quantify relative importance of SNPs as well as degree of deviation of a trait's inheritance from an infinitesimal model. The shape of the curve aids global understanding of traits: The steeper the left-hand side of the curve, the fewer the number of SNPs controlling most of the phenotypic variance.