Intelligent double-layer polymers based on carboxymethyl cellulose-cellulose nanocrystals film and poly(lactic acid)-Viola odorata petal anthocyanins nanofibers to monitor food freshness.

The present study was conducted with the aim of fabricating smart bilayer polymers based on carboxymethyl cellulose-cellulose nanocrystals film and poly(lactic acid)-Viola odorata extract nanofibers (CMC-CNC and PLA-VOE) for freshness monitoring of Pacific white shrimps, minced lamb meat, chicken fillets, and rainbow trout fillets, during refrigerated storage conditions. The fabricated indicators based on CMC-PLA-VOE 5%, CMC-CNC 1%-PLA-VOE 5%, and CMC-CNC 3%-PLA-VOE 5% presented remarkable color changes in pH 1-12 buffer solutions, including red at pH 1-6, violet at pH 7-8, green at pH 9-10, and brown at pH 11-12. Significantly lower water vapor permeability and oxygen transmission rate of prepared polymers were found in comparison with the control groups (P < 0.05). Regarding the monitoring of food samples in real-time, the samples spoiled after 3 days, evidenced by total viable count, psychrotrophic bacterial count, total volatile basic nitrogen, and pH values of 7.17-7.54 log CFU/g, 5.68-6.23 log CFU/g, 25.14-28.12 mg N/100 g, and 7.10-7.66, respectively. Meanwhile, the noticeable color change of prepared indicators from white to violet (day 3) and finally dark violet (day 7) was observed, indicating a potential application in intelligent packaging for real-time control of the freshness of perishable food samples.

Cellulose/Salep-based intelligent aerogel with red grape anthocyanins: Preparation, characterization and application in beef packaging.

The purpose of this study was to prepare a porous intelligent aerogel for food packaging applications, in particular for monitoring minced beef freshness, using cellulose extracted from grape stalk, Salep as a copolymer, and red grape anthocyanins as a pH-sensitive pigment. Aerogels based on cellulose 1% (w/v) and Salep 1% (w/v) at ratios of 1:3, 3:1, and 1:1 were prepared by lyophilization. Aerogel with high porosity, low density, and higher mean pore size was chosen for preparing intelligent colorimetric aerogel (ICA) with the addition of 0.44 mg/100 mL of anthocyanins. Based on the color parameters, the stability of ICA was satisfactory when exposed to both light and dark conditions, as well as when stored at either 4 or 25 °C. Additionally, X-ray diffraction and thermogravimetric analyses indicated that an amorphous aerogel was formed, with a thermal decomposition temperature of 320 °C. The color of the ICA changed from purple on the first and 3rd days of packaging to blue-gray on the 6th day. As the spoilage process continued, the color of the indicator became dark brown. Taken together, ICA showed a quick response to minced beef spoilage with the ability to differentiate between fresh and spoiled meat during storage at 4 °C.

Molecular detection of Coxiella burnetii in Kope cheese and cattle milk in West Azerbaijan, Iran.

There are few studies on Coxiella burnetii (Cb) as a causative agent of Q fever in dairy products in Iran. The prevalence of Cb was studied by polymerase chain reaction (PCR) method in Kope (pot) cheese and cattle milk collected from West Azerbaijan province, Iran. A total number of 240 Kope cheese and 560 milk samples were collected during the year 2020. All samples were subjected to PCR based on transposable gene IS1111. The results showed that 12.50% (95.00% confidence interval (CI): 9.00 - 16.10%) of Kope cheese and 13.00% (95.00% CI: 10.00 - 17.30%) of milk samples were positive for Cb. There was a significant difference in cheese and milk contaminations with Cb among the defined age groups as well as regional and seasonal variations. It was concluded that Kope cheese and cattle milk are important sources of Cb and should be considered as important risk factors in the epidemiology of Q fever disease in public health.

Identification of Salmonella carriers by amplification of FimA, Stn and InvA genes and bacterial culture methods in fecal samples of buffalo.

Salmonellosis is one of the most important bacterial diseases in human and animals. Rapid diagnosis and sub sequence accurate treatment of Salmonella carriers help reduce the salmonellosis in human and livestock animals. In this study, 420 fecal samples were taken during year 2019 from buffalo in the Urmia, Khoy and Piranshahr regions in west Azerbaijan province, Iran. Samplings were carried out in different seasons. Presence of Salmonella invasion genes (FimA, Stn and InvA) were evaluated by polymerase chain reaction. The bacterial culture and biochemical tests were performed on feces samples for isolation of bacterium Salmonella; however, all samples were negative in culture method. PCR findings showed that, 50 (11.90%) fecal samples were positive to the genes. The analysis of results showed that frequency of salmonellosis outbreak in different parts of west Azerbaijan province followed a similar pattern and the incidence of salmonellosis according to forecast in the warm seasons (spring and summer) was more than in cold seasons (autumn and winter). The prevalence of Salmonella in buffalo's feces based on warm and cold seasons were 32 (64.00%) and 18 (36.00%), respectively. The results showed significant difference between cold and warm season in the prevalence of salmonellosis. Therefore, the application of molecular technics is essential for the prevention and treatment of salmonellosis. The results also showed that specificity of PCR method was better than culture method for detection of Salmonella in feces sample.

Development and characterization of active packaging nanofiber mats based on gelatin­sodium alginate containing probiotic microorganisms to improve the shelf-life and safety quality of silver carp fillets.

The current study aimed to incorporate Lactobacillus acidophilus, Limosilactobacillus reuteri, Lacticaseibacillus casei, and Lacticaseibacillus rhamnosus (~10 log CFU/ml) into gelatin­sodium alginate nanofibers via electrospinning process in order to investigate the influence of fabricated mats on the growth of food-related pathogenic bacteria and shelf-life extension of refrigerated silver carp fillets in a two-week period. The strain-loaded nanofibers exhibited lower water vapor permeability, swelling index, moisture content, and tensile strength than the straight nanofibers (P < 0.05). The survival order of probiotics in nanofibers stored at 4, 25, and 37 °C for 14 days are as follows: L. acidophilus (8.15-9.35 log CFU/g) > L. reuteri (7.42-9.24 log CFU/g) > L. casei (7.41-9.13 log CFU/g) > L. rhamnosus (7.37-8.92 log CFU/g). The probiotic mats significantly delayed the growth of Vibrio parahaemolyticus, Salmonella Typhimurium, Staphylococcus aureus, and Listeria monocytogenes in silver carp fillets in comparison with the unpackaged sample (P < 0.05). Moreover, the designated nanofibers improved the bacterial, chemical, and sensory properties of treated samples in comparison with the unpackaged samples throughout the study period. Our findings indicate that gelatin­sodium alginate nanofibers are a suitable platform for the protection of living probiotics and present an alternative procedure for retarding the growth of food-borne pathogens and extending the shelf-life of fresh carp fillets under refrigerated storage conditions.

Antibacterial interactions of pulegone and 1,8-cineole with monolaurin ornisin against Staphylococcus aureus.

The aim of this study was to investigate the antibacterial interactions of pulegone and 1,8-cineole with monolaurin ornisin against Staphylococcus aureus. The individual and combined antibacterial activities of the compounds were evaluated using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), fractional inhibitory concentration index (FICi), and time-kill methods. Furthermore, the mechanism of the antibacterial action of the compounds was tested by measuring the release of cell constituents. The MIC values of pulegone, 1,8-cineole, nisin, and monolaurin were 5.85 µl/ml, 23.43 µl/ml, 6.25 µg/ml, and 0.031 mg/ml, respectively. A synergistic antibacterial activity (FICi = 0.5) was found between 1,8-cineole and nisin. The time-kill assay showed that the populations of S. aureus exposed to 1,8-cineole, nisin, and their combination were decreased by 5.9, 5.3, and 7.1 log CFU (colony-forming units)/mL, respectively. The combination of 1,8-cineole and nisin also induced the highest release of cell constituents. It was concluded that the combination of 1,8-cineole and nisin could be considered as a novel and promising combination which may reduce the required dose of each antibacterial compound.

Potential application of postbiotics metabolites from bioprotective culture to fabricate bacterial nanocellulose based antimicrobial packaging material.

Postbiotics (P) of FreshQ, a food protective culture, was prepared and used to develop an antimicrobial membrane by bacterial nanocellulose (BNC). Postbiotics were prepared in de Man, Rogosa and Sharpe medium and freeze-dried. The chemical composition was investigated by GC-MS and the antibacterial activity of postbiotics on different bacterial and fungal strains was investigated. Finally, postbiotics were included in wet and lyophilized BNC by ex-situ method, and their antibacterial activity and FTIR specifications were studied. The GC-MS analysis of postbiotics revealed the presence of fatty acids, alkanes, aldehydes, hydrocarbones fatty acid esters, propionic acid, and certain antibacterial and antifungal compounds such as 2,4-Di-tert-butyl phenol and dotriacontane. Postbiotics revealed antibacterial activity on all investigated strains in a concentration-dependent manner and as the concentation decreased, there was a significant reduction in antimicrobial effects. The zone of inhibition for all bacterial pathogens exceeded 20 mm, then they were classified as "extremely sensitive microorganisms" to the postbiotics at 50 % concentration, while fungal strains revealed a lower zone of inhibition (<17 mm). The order of antimicrobial susceptibility was as follows: Listeria monocytogenes > Staphylococcus aureus > Escherichia coli > Salmonella Typhimurium > Aspergillus flavus > Penicillium citrinum. We also recognized that P-BNC in wet form has significant antimicrobial activity than lyophilized form due to the high adsorption capacity and open 3D structure of BNC in wet form. The fabricated material can serve as an antimicrobial membrane for food applications.

The concentration of the potentially toxic elements (PTEs) in the muscle of fishes collected from Caspian Sea: A health risk assessment study.

In the present study, the concentration of (potentially toxic element) PTEs in the five fish species from the Caspian Sea (from five coastal areas) was measured and compared. The target hazard quotient (THQ) and total THQ (TTHQ) were calculated using Monte Carlo simulations to determine the non-carcinogenic risk in both children and adults consumers. The highest concentration of PTEs was associated with chromium (Cr) measured in Cyprinus carpio, sampled from Bandar Anzali (1.56 ± 0.14 µg/g dw), and the minimum PTEs level was nickel (Ni) in Vimba from Astara (0.02 ± 0.01 µg/g d w). The rank order for PTEs based on THQ was mercury (Hg) > cadmium (Cd) > lead (Pb)> Ni > tin (Sn) > Total Cr. For adults, the fishes rank order based on TTHQ was: Cyprinus carpio (3.268) > Chelon saliens (2.89) > Rutilus frisii kutum kanesky (2.28) > Oncorhynchus mykis (1.39) > Vimba (0.25); and for children was Cyprinus carpio (15.25) > Chelon saliens (13.47) > Rutilus frisii kutum kanesky (10.63) > Oncorhynchus mykis (6.48) > Vimba (1.16). Overall this study showed that the levels of PTEs in investigated fish species had a potential non-carcinogenic risk for both children and adults (TTHQ>1).

Optimization and characterization of eco-friendly antimicrobial nanocellulose sheet prepared using carbon dots of white mulberry (Morus alba L.).

BACKGROUND: Carbon dots (C-dots) with antimicrobial activity were synthesized from the white mulberry extract with the aim of fabricating anti-listeria nanopaper using bacterial nanocellulose (BNC). Highly dispersed synthesized C-dots with a size smaller than 10 nm (approximately 4.9 nm) were impregnated into BNC by an ex situ coating method and then mechanical, morphological, UV-protectant and antibacterial activity were assessed. Randomized response surface methodology using a central composite design was applied to investigate the optimized concentration of C-dots in the BNC membrane. RESULTS: An optimized nanopaper including C-dots at a concentration of 530 g L-1 and an impregnation time of 14 h at 30 °C with significant antimicrobial activity on Listeria monocytogenes was designed. The addition of C-dots into BNC significantly increased ultimate tensile strength and decreased strain with respect to breaking BNC. A BNC sheet with high-efficient UV-blocking property was prepared using C-dots. CONCLUSION: Based on the results, the designed nanopaper shows a substantial capacity with respect to the fabrication of antimicrobial/UV-blocking sheets for food active packaging. © 2020 Society of Chemical Industry.

Preparation of on-package halochromic freshness/spoilage nanocellulose label for the visual shelf life estimation of meat.

In this work, grape anthocyanins (GA) were embedded in bacterial nanocellulose (BNC) by ex-situ method to fabricate an easy-to-use colorimetric label. The label revealed visible color responses to the pH buffers (2-11). According to the color parameter results [L*, a*, b*, and total color difference (TCD)], the label also presented appropriate color stability during the 60-day storage. During the application in minced beef, the label was bright red on the 1st day of storage at 4 °C. In accordance with the meat quality parameters [TVB-N, total mesophilic count, and sensory attributes], the label turned into purplish-red color on the 3rd and 5th days of storage (medium freshness meat) and turned into blue on the 7th day, representing the spoilage state. All the mentioned color changes could be distinguished by naked eyes. A strong Pearson's correlation coefficient was obtained between the TCD values and meat quality parameters, confirming the capability of the pH-sensing label to correctly distinguish the fresh meat from the spoiled meat.

CMC and CNF-based alizarin incorporated reversible pH-responsive color indicator films.

Smart color-changing indicator films were prepared using two different types of cellulose (CMC and CNF) and pH-sensitive dye, alizarin. pH-responsive color indicator films were produced by ionization and deprotonation of hydroxyl groups of alizarin phenolic compounds. The X-ray diffraction pattern of the color indicator film showed a new weak diffraction peak at 2θ = 13°, indicating the semi-crystalline character of alizarin. The indicator film showed UV-vis light screening properties and radical scavenging activity with enhanced thermal stability. The indicator film showed a distinct color change of alizarin from yellow to purple in the pH range of 2-12. In addition, the color indicator film showed stable and reversible color changes even after repeated changes in environmental pH. The pH-responsive color indicator films are likely to be used as an acid or base gas sensor due to the rapid response and reversible color change to the pH change in the packaging environment.

Preparation of antimicrobial/ultraviolet protective bacterial nanocellulose film with carbon dots synthesized from lactic acid bacteria.

Microbial biomass, as an environmentally friendly resource, has drawn a lot of attention as green biomaterials for production of unique and functionalized carbon dots (CDs). However, the hydrophilicity and high porosity drive bacterial nanocellulose as a suitable matrix for CDs with antimicrobial, photoluminescent and ultraviolet blocking features. For the first time, antimicrobial CDs were synthesized by hydrothermal method from cell-free supernatant of Lactobacillus acidophilus and characterized. Antimicrobial performance of CDs was examined on Escherichia coli (Gram-negative) and Listeria monocytogenes (Gram-positive). Additionally, the as-prepared CDs embedded by ex-situ method into nanocellulose in order to fabricate antimicrobial/ultraviolet protective nanopaper. The photoluminescent CDs with an average size of 2.8 nm and high-hydroxylated groups were synthesized. The CDs at 500 mg mL-1 concentration had antibacterial activity towards both bacteria. Moreover, nanopaper displayed a fluorescence appearance under ultraviolet. Nanocellulose with CDs loading capacity of 71.74 ± 4.13 mg cm-2 represented an appropriate stretchability and flexibility in comparison to nanocellulose. The CDs incorporated nanopaper also depicted greater ultraviolet-blocking specifications and inhibitory activity on Gram-positive bacterium than Gram-negative one. CDs can be used as a novel fluorescence antimicrobial/ultraviolet protective material in the nanocellulose film in order to develop an antimicrobial and forgery-proof packaging due to their fluorescence appearance.

Development of an easy-to-use colorimetric pH label with starch and carrot anthocyanins for milk shelf life assessment.

An intelligent freshness indicator was developed by immobilizing anthocyanins of black carrot (ABC) within the starch matrix (total anthocyanins content of 10 mg/100 mL) to monitor freshness/spoilage of milk. The microstructural, spectral, swelling and solubility properties as well as color stability (as a function of time, temperature and light) of the indicator at different pHs were characterized. The incorporation of ABC did not change the swelling index and water solubility. The prepared label showed visible color changes as a function of pH and excellent color stability after one month storage at different conditions. The total color difference (TCD) value of the indicator corresponded to the pH, acidity, and microbial growth of the pasteurized milk. The Pearson correlation coefficient showed a high correlation between TCD and pH (R = -0.979), while a high and positive correlation between TCD and acidity as well as TMC (R = 0.983 and 0.968, respectively) was observed. The developed label can discriminate fresh milk form the milk entered into the initial (TCD: 7.8 after 24 h) and final (TCD: 34.8 after 48 h) steps of spoilage. The fabricated label opens a new perspective to use anthocyanins-incorporated biopolymers in the milk intelligent packaging as a simple and easy-to-use freshness indicator.

Design and preparation of antimicrobial meat wrapping nanopaper with bacterial cellulose and postbiotics of lactic acid bacteria.

Lyophilized postbiotics of Lactobacillus plantarum was prepared and impregnated in bacterial nanocellulose (BNC) by ex-situ method to develop an antimicrobial ground meat wrapping nanopaper. The postbiotics incorporated BNC (P-BNC) films were optimized by response surface methodology and their antimicrobial activity against Listeria monocytogenes were examined. The BNC with postbiotics at 21.21% concentration and 28 min impregnation time was chosen as an optimized P-BNC film. The FTIR results confirmed the immobilization of postbiotics in BNC. The P-BNC film represented a significant reduction (~5 log cycles) in L.monocytogenes counts in ground meat at the end of the storage period (9 days at 4 °C). Meat wrapped by P-BNC film displayed a significant decrease in total mesophilic and psychrophiles count and TBA values than the controls. BNC can be considered as a proper carrier for development of antimicrobial film using postbiotics of LAB for food application.

Chitosan-starch film containing pomegranate peel extract and Thymus kotschyanus essential oil can prolong the shelf life of beef.

The aim of the current study was to investigate the effects of pomegranate peel extract (PPE) and chitosan-starch (CH-S) composite film incorporated with Thymus kotschyanus essential oil (TEO) on the shelf-life of beef during storage period of 21 days at 4 °C. The physico-mechanical parameters, the color and Fourier Transform Infrared spectra values of the films were determined. Changes in odor, color, pH, thiobarbituric value for lipid oxidation levels and Pseudomonas spp. total viable counts, lactic acid and Listeria monocytogenes were determined during the storage time. All treated films showed lower elongation, strength and transparency values compared with chitosan - starch (CH-S) group. Results showed that CH-S-PPE 1%-TEO 2% treatment had the highest inhibition effect against L. monocytogenes. The bacterial counts and lipid oxidation were successfully inhibited using PPE and TEO. CH-S-PPE 1% group containing up to 2% TEO had the best acceptable sensory characteristic. Beef samples wrapped with CH-S film containing PPE and TEO also had longer shelf life.

Evaluation of dioxin-like polychlorinated biphenyls in fish of the Caspian Sea.

Dioxin-like polychlorinated biphenyls (DL-PCBs) have toxic properties for humans. The innovation of this study was that for the first time in Iran, 12 DL-PCBs concentration in 5 fish species: Rutilus frisii kutum kanesky, Chelon saliens, Vimba vimba, Cyprinus carpio and Oncorhynchus mykiss, from 5 coastal areas of the Caspian Sea (125 samples), were investigated. DL-PCBs extraction was in accordance to USEPA method 1668 revision A and carry out by chromatography columns modified with silica gel. DL-PCBs concentration were measured by HRGC (Agilent 6890 Series, Agilent Technologies, USA) coupled with HRMS AutoSpec Ultima NT-HRGC/HRMS (Micromass, USA), equipped with the HP-5MS 30 m × 0.25 mm × 0.25 µm column (Agilent Technologies) and helium as carrier gas. The mean concentration of DL-PCBs in samples ranged 232 ± 16-1156 ± 14 pg/g fat, that was in accordance with the Joint FAO/WHO Expert Committee on Food Additives and European Standards. The highest concentration was in Cyprinus carpio of Bandar Anzali, and lowest obtained in samples from Chalous. However, based on fish consuming and fish originating from the fishing area the health risk evaluation to estimate the potential consequences of chronic exposure to DL-PCBs for consumers is recommended and effective measure for health risk reduction.

Antimicrobial, microscopic and spectroscopic properties of cellulose paper coated with chitosan sol-gel solution formulated by epsilon-poly-l-lysine and its application in active food packaging.

Cellulose paper-chitosan (CC) double-layer films containing epsilon-poly-l-lysine (ε-PL) (0.5 and 1% w/v) were developed. FTIR analysis showed a strong association between the ε-PL and CC film. Antimicrobial activity against Listeria monocytogenes was investigated both in vitro and in the chicken breast meat. The CC films without ε-PL showed no antimicrobial activity, while the addition of ε-PL induced significant (p < 0.05) effects. During the 28 days of storage at 4 °C, no significant difference was found on the anti-listeria activity of films. When storage temperature was raised from 4 to 22 °C, the antimicrobial activity was reduced. Films containing 1% ε-PL exhibited 1.5 log10 CFU/g reduction in L. monocytogenes population during 12 days storage of meat at 4 °C, while no significant reduction was found in CC films with 0.5% ε-PL (p > 0.05). This study revealed an antimicrobial activity for CC films impregnated with ε-PL, to control foodborne pathogens in meat.

Comparing dioxin-like polychlorinated biphenyls in most consumed fish species of the Caspian Sea.

Among polychlorinated biphenyls (PCBs), dioxin-like PCBs (DL-PCBs) are of the most concern for human health. In this study, the levels of 12 DL-PCBs congeners were measured in 125 fish samples of the Caspian Sea, Iran. Five fish species (Oncorhynchus mykiss, Vimba vimba, Cyprinus carpio, Rutilus frisii kutum and Chelon saliens) were collected from 5 coastal cities of the Caspian Sea (25 samples per each city). Duncan's multi-scope test was used to compare the mean of DL-PCBs in different fish species and different cities. Probabilistic risk of exposure to DL-PCBs and sensitivity analysis were assessed using Monte Carlo simulation approach. The average (standard deviation) of DL-PCBs in fish samples ranged from 232 (16) to 1156 (14) pg/g lipids. The total maximum concentration was detected in Cyprinus carpio from Bandar Anzali, the minimum in Vimba vimba from Chalos. In all samples, non-carcinogenic risk of exposure to DL-PCBs was in safe level (Hazard Quotient < 1). In contrast, the lifetime cancer risk estimated for Bandar Anzali, Bandar Torkaman, and Rasht exceeded the threshold value of 1 × 10-6 suggested by United States Environmental Protection Agency. Sensitivity analysis indicated that the concentration of DL-PCBs and exposure frequency were the most effective parameters in increasing carcinogenic risk.

Effect of Salvia officinalis L. extract on chemical, microbial, sensory and shelf life of rainbow trout fillet.

The present study aimed at extending shelf life of rainbow trout fillet. Fish and seafoods are the most valuable nutrients, however, high levels of moisture, free amino acids, unsaturated fatty acids, and the content of nutrients make them to be categorized as spoilable and unstable foods. The objective of this research was to study of the shelf life of rainbow trout fillets using Salvia officinalis L. extract. Chemical and microbial analyses were performed on treatments. The usage of hydro-ethanol extract of S. officinalis L. significantly decreased microbial growth in fish fillet and there were significant differences among concentrations of the extract (p ≤ 0.05). The presence of extract of S. officinalis L. resulted in an inhibitory effect on the formation of TVB-N and FFA in comparison with the control group at all analytical times. In conclusion, the shelf life of fish fillets was increased noticeably using extract at 4 ± 1 °C.

Efficacy of lyophilized cell-free supernatant of Lactobacillus salivarius (Ls-BU2) on Escherichia coli and shelf life of ground beef.

In the present study, the effect of different concentrations of cell-free supernatant (CFS; 10.00 and 35.00 mg g-1) of Lactobacillus salivarius (Ls-BU2) on chemical, microbial and sensorial specifications of ground beef stored under the refrigerated condition was investigated. The antibacterial activity of CFS on Escherichia coli was also assessed. According to agar-disk diffusion method, CFS of Ls-BU2 revealed a promising antibacterial activity against E. coli in culture media compared to CFS of a well-known probiotic (L. acidophilus LA-5). In meat, CFS of Ls-BU2 showed a minimal effective concentration (MEC) of 35.00 mg g-1 on E. coli, while CFS of L. acidophilus represented a MEC of 45.00 mg g-1. The CFS of Ls-BU2 at 35.00 mg g-1 concentration retained psychrophilic counts of meat at a lower value than maximum accepted level (7 log10 CFU g-1). In a similar trend, CFS of Ls-BU2 at 35.00 mg g-1 concentration was also displayed high sensorial scores compared to other CFS-treated samples. In conclusion, we demonstrated that CFS of Ls-BU2 and to some extent CFS of L. acidophilus could act as a safe food additive for the control of bacterial pathogens and to extend the shelf life of ground beef.