Psychrotrophic Bacterial Counts Research Articles

Characterization of psychrotrophic and thermoduric bacteria in raw milk using a multi-omics approach.

Psychrotrophic and thermoduric bacteria are the main reasons for the spoilage of dairy products. This study aims to address the composition and function of psychrotrophic and thermoduric bacteria in eight groups of raw milk samples obtained from Heilongjiang Province and Inner Mongolia (China). Microbial enumeration showed an average total bacterial count of 4.63 log c.f.u. ml-1 and psychrotrophic bacterial counts of 4.82 log c.f.u. ml-1. The mean counts of mesophilic and thermophilic thermoduric bacteria were 3.68 log and 1.81 log c.f.u. ml-1, respectively. Isolated psychrotrophic bacteria (26 genera and 50 species) and mesophilic thermoduric bacteria (20 genera and 32 species) showed high microbial diversity. Through metagenomic and proteomic analyses, significant disparities in the concentration and community structure of psychrotrophic and thermoduric bacteria were observed among different locations. A large number of peptidases were annotated by metagenomics, which may result in milk spoilage. They mainly come from some typical psychrotrophic and thermoduric bacteria, such as Chryseobacterium, Epilithonimonas, Pseudomonas, Psychrobacter, Acinetobacter, Lactococcus, Escherichia and Bacillus. However, the main proteins detected in fresh raw milk were associated with bacterial growth, reproduction and adaptation to cold environments. This investigation provides valuable insights into the microbial communities and protein profiles of raw milk, shedding light on the microbial factors contributing to milk deterioration.

Synthesis and Characterization of Janus fenugreek Seed Gum-based Film for Food Packaging and Wound Dressing Applications

The use of plant-derived natural gum polysaccharides in food packaging and biomedicine is growing due to their biocompatibility, biodegradability, film-forming ability, abundant functional groups, and potential for chemical or physical modification to develop novel materials. In this study, fenugreek (Trigonella foenum-graecum) seed gum (FSG)-based Janus films with glycerol (GLY) as a plasticizer in varying concentrations (2%, 5%, 7%, and 10% w/w) were synthesized for potential food packaging and biomedical applications. The glycerol concentration significantly affected the stability, microstructure, moisture content, and solubility of the film, with 5% GLY yielding the most stable films. The water solubility was gradually increased with increasing the GLY content in the film sample. The film exhibited strong radical scavenging activity against DPPH assays, with an IC50 value of 158.73±0.013 µg/mL. The total phenolic content (TPC) and total flavonoid content (TFC) of the film were found to be 88.21±0.012 mg/g in gallic acid equivalents (GAE) and 9.36±0.018 mg/g in quercetin equivalents (QE), respectively. The pristine FSG film exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, and the fungal strain Candida albicans, which was significantly enhanced by incorporating the antibacterial drug penicillin. Additionally, we examined the impact of different films on chicken meat and cheese by monitoring changes in weight loss, color, pH, total aerobic mesophilic counts (TAMC), and psychrotrophic bacterial counts (PBC) during storage. Our results demonstrated that the samples packaged with pristine FSG film exhibited significantly lower TAMC and PBC values and slowed down the increase in pH values compared to the control samples, which further decreased by incorporating antimicrobial drug. These findings indicated that the Janus pristine FSG film is suitable for food packaging. Further, antimicrobial drugs incorporated into FSG film could be potential candidates for wound dressing applications.

Electrospun fiber mats based on chitosan-carrageenan containing Malva sylvestris anthocyanins: Physic-mechanical, thermal, and barrier properties along with application as intelligent food packaging materials

This study aimed to encapsulate Malva sylvestris extract (MSE) into chitosan-carrageenan (CH-KC) fibers using the electrospinning technique and monitor the freshness of silver carp fillets during the refrigerated storage conditions for 8 days. The CH-KC + MSE 4 % fiber mats were red at pH values lower than 3, purple at pH 4–6, dark blue at pH 7, green at pH 8–10, and brown at pH 11–12. The tensile strength, elongation at break, water vapor permeability, oxygen transmission rate, moisture content, and water solubility of fabricated fiber mats were 7.71–11.02 MPa, 13.12 %–30.00 %, 7.35–20.01 × 10−4 g mm/m2 h Pa, 3.81–8.23 cm3/m2 h, 15.74 %–27.34 %, and 3.90 %–7.56 %, respectively. Regarding the potential application of a fabricated indicator for freshness monitoring of silver carp fillets, total viable count, psychrotrophic bacterial count, pH, and total volatile basic nitrogen reached 8.91 log CFU/g, 8.03 log CFU/g, 8.10, and 40.18 mg N/100 g at the end of the study, respectively. Meanwhile, the CH-KC + MSE 4 % fiber mat color changed from white to green. These findings suggest that CH-KC + MSE 4 % fiber mats can be further utilized in the food industry to control the freshness of refrigerated silver carp fillets.

Shelf life extending of probiotic beef patties with polylactic acid-ajwain essential oil films and stress effects on Bacillus coagulans.

Meat and meat products are prone to the microbial and chemical spoilage, due to the high nutritional content. This study investigated the effect of polylactic acid (PLA) films incorporated with ajwain essential oil (AEO) on microbial (total viable count [TVC], psychrotrophic bacterial count [PTC], Enterobacteriaceae, Pseudomonas spp., yeast and mold (Y&M), and also Bacillus coagulans [BCG]), chemical (pH, peroxide value [PV], thiobarbituric acid-reactive substance [TBARS], and TVN values), and sensorial properties of beef patties, as well as survivability of BCG during refrigerated storage. Results showed that all microbial counts of samples were significantly increased, except BCG, during storage but the lowest TVC of samples was achieved in samples wrapped with PLA-1% AEO (8logcolony forming units per gram [CFU/g]) at 12th of storage, which is significantly lower than control treatments (10.66logCFU/g). The best results in all treatments are those wrapped by PLA-1% AEO in all evaluated characteristics. At the final day of storage, PTC (8.82logCFU/g), Enterobacteriaceae (5.05logCFU/g), Pseudomonas spp. (9.08logCFU/g), Y&M (4.69logCFU/g), and also pH (4.5), PV (5.12meq/kg), TBARS (2.92MDA/kg), and TVN (14.43mgN/100g) values of PLA-1% AEO treatments were significantly lower than control samples. AEO-PLA films reduce the survival of BCG in raw patties, which reached 6.19logCFU/g in PLA-1% AEO treatments, although increasing the concentration of AEO in packaging PLA films led to the maintenance of BCG viability during the cooking process by increasing the AEO in PLA films. Overall, results showed shelf life of beef patties is extended 3 days more (150%) by wrapping with PLA films incorporated with 1% AEO.

The effect of different cooking methods on sensory attributes, physicochemical properties, and microbial safety of ostrich meat (Struthio camelus).

The present work aimed to determine the impact of various cooking methods on sensory attributes, microbial safety, and physicochemical characteristics of ostrich meat to specify the best cooking method that guarantees the microbial safety of the meat as well as maintains nutritional values and is highly attractive to consumers. One hundred fresh leg muscles of ostriches were divided into five groups. Different cooking techniques were used for each group, as follows: roasting, boiling, grilling, frying, and microwaving. Each method was examined by evaluating the impact of various cooking methods on sensory attributes, proximate chemical analysis, protein and fat oxidation parameters, microbial load, changes in color, and the shear force of ostrich meat. The oven-roasting and grilling methods are highly recommended and more appealing to consumers since they produce tenderer and juicier meat, cause less cooking loss (CL), and maintain the nutritive value of ostrich meat; however, they have the highest protein and fat oxidation rates. On the other hand, boiling and frying methods revealed good fat oxidation parameters, the highest CL, and preserved nutritional value, but unfortunately, they were not highly preferred by consumers. From a hygienic point of view, grilling and microwave cooking are the methods that ensure the microbiological safety of cooked ostrich meat, as they significantly reduce Enterobacteriaceae and psychrotrophic bacterial counts, among other cooking methods. The oven roasting and grilling methods were the most preferable thermal cooking techniques, as they achieved the highest acceptability to consumers and maintained the nutritive values of ostrich meat.

Monitoring of Some Food Poisoning Bacteria in Smoked and Cured Meat Products

The aim of this study is to estimate the presence of some food poisoning bacteria in smoked and cured meat products. This study was carried-out on a total of 120 samples of smoked and cured meat products. That includes (Smoked frankfurter, pasterma. Smoked Turkish meat and Oriental sausage) (30 samples of each) were randomly collected from supermarkets in different localities at Alexandria governorate. The total weight of each sample was about 500 gm. The samples were transferred Aseptically with a minimum of delay to the laboratory in an icebox for further examination to ensure that the samples were apparently fit for human consumption. The results indicated that, the higher level of Aerobic bacterial count observed in smoked frankfurter that was 7.35 X 10 6 followed by oriental sausage that was 1.20 X 10 6 and in pasterma was 1.18 X 10 6 and the lower MAC observed in smoked Turkish meat that was 0.59 X 10 6 cfu/g, respectively. Also, the higher level of psychrotrophic bacterial counts observed in smoked frankfurter that was 7.66 X 10 8 followed by smoked Turkish meat that was 0.55 X 10. while, the Enterobacteriaceae counts showed that, the higher level of enterobacteriaeceae counts observed in pasterma that was 2.46 X 10 4 followed by smoked frankfurter that was 1.62 X 10 4 . The higher level of E. coli counts observed in pasterma that was 8.29 X 10 4 followed by smoked Turkish meat that was 3.58 X 10 4 cfu/g. In smoked frankfurter the higher incidences of E. coli observed in serotypes of EHEC 2 (6.67 %), EPEC 2 (6.67 %), O113 that was 2 (6.67),. While, in pasterma the higher incidences of E. coli observed in serotypes of O113 that was 6 (20 %), O124 that was 3 (10 %), O125 that was 3 (10 %). While,in smoked Turkish meat observed in serotypes of ETEC 1 (3.33 %), O113 that was 2 (6.67 %). While, the higher incidences of E. coli serotypes in Oriental sausage observed in serotypes of O56 that was 6 (20 %), O113 that was 3 (10 %). The higher level of Salmonella serotypes observed in pasterma were S. Enter 5 (16.67 %), S. Tsavi 4 (13.33 %), S. Haifa 3 (10 %), S. Ingind 3 (10 %) and S. Ingan 2(6.67 %). While, its level in smoked turkish meat the higher serotypes observed in S. Haifa 4 (13.33 %), S. Tsavi 4 (13.33 %), S. Enter 3 (10 %), S. Typhi 3 (10 %) and S. Ingind 3 (10 %). The higher level of S. aureus counts observed in smoked frankfurter that was 7.83 X 10 4 followed by pasterma that was 1.24 X 10 4. While, in pasterma were S. epidermidis 6 (20 %), S. homini 4 (13.33 %) . While, in Smoked frankfurter it was in S. aureus 3 (10 %), S. epidermidis 3 (10 %) and in S. and in Oriental sausage in S. aureus 3 (10 %), S. epidermidis 2 (6.67 %). While, in smoked Turkish meat , the higher Stap. Serotypes were S. aureus that was 4 (13.33 %). The higher level of Enterococci serotypes observd in Smoked frankfurter it was in Ent. Facium 7 (23.33 %), Ent. Faecal 6 (20 %), while, in Pasterma were E. facium 5 (16.67 %) and En. Faaecal 8 (26.66 %). While, in smoked Turkish meat , the higher Enterococci serotype is the Ent. Faecal 6 (20 %) and Ent. Facium 2 (6.66%) Our results concluded that, through the examined samples of cured meat and meat products as smoked frankfurter, pasterma, smoked Turkish meat and oriental sausage give an idea about sanity measures given during all the steps of processing and production of such products and which to be said that it is of high number of total microbial count present it is of poor sanitary conditions. Thus, to improve the quality of meat and meat products and to prevent consumers from doing ill, control programs to reduce diseases in beef production farms and production of disease-free primary herds by regular vaccination and correct treatment to avoid pathogens and antibiotic resistant pathogens by using nature constituents and feed additives.

Synthesis, optimization via response surface methodology, and structural properties of carboxymethylcellulose/curcumin/graphene oxide biocomposite films/coatings for the shelf-life extension of shrimp

In this study, carboxymethylcellulose (CMC), curcumin (Cur), and graphene oxide (GO) were used to prepare a novel biocomposite film (CMC-Cur-GO). A central composite design under response surface methodology was employed to optimize the films in terms of water vapor permeability (WVP) and swelling percentage (SP). Under the optimum conditions, which the rates of CMC, GO and curcumin were found to be 1350 mg, 29.99 mg, and 0.302 g, respectively, WVP and SP of CMC-Cur-GO were obtained 0.902 × 10−8 (g/m·h·Pa) and 13.62 %, respectively. The biocomposite films (CMC, CMC-Cur, CMC-GO and CMC-Cur-GO) were characterized by Fourier transform infrared spectroscopy, field-emission scanning electron microscope, thermal gravimetric analysis, X-ray diffraction analysis, ultraviolet-vis light transmittance, moisture content, and mechanical properties. Compared with pure CMC film, the tensile strength, elongation at break and Young's modulus of CMC-Cur-GO were significantly improved by up to 75 %, 41 % and 23 %, respectively (p < 0.05). Then, CMC-Cur-GO was applied as a coating solution for the shrimps. The coated shrimps with the CMC-Cur-GO significantly (p < 0.05) showed a noteworthy improvement in microbial quality (total and psychrotrophic bacterial count), chemical deterioration and lipid oxidation (pH and total volatile basic nitrogen, peroxide value and thiobarbituric acid) and physical characteristic (weight loss) as compared to other samples. The CMC-Cur-GO coating could increase the shelf life of shrimp under refrigerated storage.

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.

Development of bacterial inactivation model and evaluation of shelf life extension of Littopenaeus vannamei using blue LED illumination

AbstractPacific white shrimps pre‐inoculated with bacterial culture were subjected to blue LED illumination at 4°C and 15°C. Mathematical modeling of bacterial inactivation from 0 to 48 h of illumination revealed that Hom and Weibull model represent the best fit. Shelf life analysis of shrimps illuminated with 1075.68 J/cm2 (I1), 2151.36 J/cm2 (I2), 3227.04 J/cm2 (I3), 4302.72 J/cm2 (I4) dosages at 4°C revealed that reduced counts for pH, trimethylamine, hypoxanthine, total plate count, psychrotrophic bacterial count and weight loss % were observed in I4 samples, whereas TBARS, color and texture were retained better in I1 and I2 samples. Bioelectrical impedance analysis (BIA) revealed that lower internal component change percentage of 7.35 and 14.85 was observed in I1 and I2 samples. Microscopic examination of shrimp muscle disclosed increased disintegration of myofibrillar structures in I4 and I3 samples. Illumination dosage ≤2200 J/cm2 extended the shrimp shelf life to 45 days at 4°C and 15 days at 15°C without changing the quality.Practical ApplicationThe demand for quality seafood products and concern for the safety aspects leads to the development of innovative preservation method. The impact of blue LED illumination on L. vannamei shrimps depicted significant increase shelf‐life and retention of quality parameters. Inactivation kinetics of LED illumination on shrimps depicted that Weibull and HOM model resulted best fit based on the R2 and AIC values helps in process scale‐up and operation at industrial level. Successful implementation of these illumination system as a processing equipment or in cold supply chain transport vessels will help the exporters to reduce the losses and conventional processing cost. It can also be employed in portable refrigerators, freezer boxes, storage shelves and ware houses with slight modifications in designs aspects to extend the shelflife of the seafood without losing its organoleptic properties. Further, it aids in effective export performance and extended distribution of shrimps in domestic market.

Unraveling the effect of the combination of modified atmosphere packaging and ε-polylysine on the physicochemical properties and bacterial community of greater amberjack (Seriola dumerili).

The combined effect of ε-polylysine (PL) and modified atmosphere packaging (MAP; 60% CO2/40% N2) on the bacterial community of greater amberjack filets and their physicochemical properties was evaluated at 4°C. The total viable counts (TVC), psychrotrophic bacterial count, sensory index, texture analysis, and total volatile basic nitrogen (TVB-N) revealed that PL, MAP, and MAP + PL treatment delayed the deterioration of greater amberjack filets. These treatment groups also showed decreased accumulation of biogenic amines. High-throughput 16S rRNA gene sequencing results indicated that these treatments suppressed the growth of Pseudomonas in greater amberjack filets. Furthermore, the MAP + PL treatment group was observed to be more effective than the PL and MAP groups, extending the shelf life of greater amberjack filets by 6 days. This investigation showed that the combination of PL and MAP has the potential to retain the quality and extend the shelf life of greater amberjack.

Application of the Hurdle Technology Concept to the Fresh Za'atar (Origanum syriacum) Preservation.

Oregano (Origanum syriacum) is popularly called za’atar in the Middle East region. It is widely used in the Mediterranean diet as an aromatic herb. This study aimed to evaluate the preservation effect of natural additives, vacuum packaging, and refrigeration on the quality traits of fresh oregano. In total, 132 fresh oregano samples were formulated and split into 4 groups (n = 33) labeled group A (100% fresh oregano leaves, Control), group B (fresh oregano 63.2%, 15% fresh onion, 20% oil, 1.8% salt), group C (fresh oregano 61.91%, 15% fresh Allium cepa, 20% oil, 1.8% salt, 1.29% sumac), and group D (fresh oregano 59.2%, 15% fresh Allium cepa, 20% corn oil, 1.8% salt, 4% lactic acid, ultimate pH 4.4). Different quality traits such as color index (L*a*b*), microbiological analysis (total aerobic, anaerobic, and psychrotrophic bacteria and yeasts and molds), and sensory features (taste, flavor, appearance, saltiness, and overall acceptance) were assessed during the storage period (42 days) for all groups. Our study showed that the addition of lactic acid (group D) exhibited a strong preservation effect against aerobic and anaerobic bacteria. In this context, group D had significantly lower aerobic and anaerobic bacterial counts (5.12 vs. 6.7, 6, and 6.7 log (cfu/g); p < 0.05) and (4.75 vs. 6.6, 6.1, 6.77 (cfu/g); p < 0.05) than group A, B, and C; respectively. Group D exhibited significantly (p < 0.05) lower psychrotrophic bacterial count (3.6 log (cfu/g)) during the whole period of storage compared with control. Group B had a lower redness index (a*) (−3.3 vs. −1.8, −1.65, −1.23; p < 0.05) than groups A, C, and D; respectively. In conclusion, our study showed that there is a possibility of improving the preservation of oregano (Origanum syriacum) by using lactic acid and sumac combined with vacuum packaging under refrigeration conditions.

Preservation Effect of Ice-Glazing Using Pullulan and Bay Laurel Extract on the Quality Characteristics of Caspian Trout (Salmo trutta caspius) during Frozen Storage

ABSTRACT The effect of ice-glazing using pullulan (IGP) and bay laurel extract (BLE) was examined on the shelf life of Caspian trout (Salmo trutta caspius) under storage conditions in the freezer (−20 ± 2 °C). Four treatments, including 1) control (without coating), 2) IGP, 3) IGP + BLE at 750 ppm, and 4) IGP + BLE at 1500 ppm were periodically evaluated in terms of microbiological (total amounts of bacteria and psychrotrophic bacterial count) and chemical (peroxide value, thiobarbituric acid amounts, total volatile basic nitrogen) parameters, color index, texture, and fatty acid profile of Caspian trout fillet placed in the freezer for four months. The highest levels for saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid were palmitic acid (12.29%), oleic acid (60.98%), and linoleic acid (9.55%), respectively. IGP with the BLE decelerated the increasing trend of oxidative and microbial spoilage compared to the control treatment. Changes in texture, color index, and fatty acids were less in these treatments. Thus, ice-glazing with pullulan edible coating incorporated with BLE maintains the quality of Caspian trout fillet during storage in the freezer.

Psychrotrophic count influence on oxidative stability and aflatoxins in milk and cooking butter

Milk and butter are among the precious foods susceptible to spoilage and rancidity due to psychrotrophic microorganisms' activities, which grow in abundance due to the richness of milk and butter in the nutrients and their ability to resist the cold environment milk and butter are stored. In this study, the total psychrotrophic bacterial and fungal counts were recorded. The rancidity represented by the Thiobarbituric acid reactive substances value and aflatoxins B1 and M1 levels were also measured by high-performance liquid chromatography. The results reflected a strong correlation between the total number of psychrotrophic bacteria, the rate of rancidity and the total number of molds, and the levels of the aflatoxins in the milk and butter. In conclusion, the psychrotrophic bacterial and mold counts in the milk and butter must be monitored carefully and be added as a routine examination to the list of the butter examinations.

Assessment of the potential of algae phycobiliprotein nanoliposome for extending the shelf life of common carp burgers during refrigerated storage

This study is focused on the effect of phycobiliprotein extraction of Gracilaria on the quality of common carp burgers, and the application of nanoliposomes containing pigment in the improvement of its antimicrobial and antioxidant activity of burgers during refrigerated storage in 18 days. Burgers were incorporated with phycobiliprotein and liposomal phycobiliprotein (2.5% and 5% w/w), and their chemical and microbial changes in terms of pH, peroxide value (PV), thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N), total viable counts (TVC), psychrotrophic bacterial counts (PTC), and sensory characteristics were evaluated. Results presented a nanoliposome size of about 515.5 nm with capable encapsulation efficiency (83.98%). Our results showed non-encapsulated phycobiliprotein could delay the deterioration of common carp burgers, as a reduction in PV, TBA, and TVB-N, TVC, and PTC values in burgers treated with free and nano encapsulated phycobiliprotein. Moreover, the potential of phycobiliprotein was improved when it was encapsulated into chitosan coated liposomes. Burgers treated with 5% nanoliposomes displayed the lowest amount of lipid oxidation and microbial deterioration in comparison to others during storage. According to chemical, microbial and sensory evaluation, the shelf life of common carp burgers was increased in samples treated with encapsulated phycobiliprotein at 2.5% and 5%, as compared to the control (p ≤ 0.05).

A natural approach, the use of killer toxin produced by Metschnikowia pulcherrima in fresh ground beef patties for shelf life extention

A novel killer toxin produced by yeast Metschnikowia pulcherrima was purified and added into ready to cook meatballs to enhance their microbial safety and extension of their shelf life. The agent was added into ready to cook meatballs at two different concentrations (1%-K1 and 2%-K2). The results of those two groups were compared to the control group (K0) lacking the killer toxin. Physical, chemical and microbiological analyses were carried out in meat dough and all analyses were repeated at two day intervals during 10 day-storage at +4 °C. Addition of inhibitor compound in meat dough decreased the numbers of total aerobic mesophillic bacteria, yeast and molds and lactic acid bacteria. Staphylococci/Micrococci, coliform bacteria and total psychrotrophic bacterial counts of the samples were determined as well. Results showed that all indicators of microbial deterioration were found to be higher in K1 group than K2 group, revealing that there was an inverse correlation between the concentration of killer toxin and the number of microorganisms causing spoilage. In addition to 1 log decrease in the number of microorganisms in toxin added groups, the high TBARS values of the control group also showed the effectiveness of the toxin. Toxic effect analysis results showed that the killer toxin had no toxic effect on L929 mouse fibroblast cells after 24h exposure.

The effect of carboxymethyl cellulose coating incorporated with clove oil nanoemulsion on quality of shrimp (Litopenaeus vannamei) during refrigerated storage.

The quality of shrimp, as high perishable seafood, can readily be effected by microbial, chemical, and physical alterations during storage. In this study, carboxymethyl cellulose (CMC) coating either alone or incorporated with variable levels of clove oil nanoemulsion (CNE) (10, 20, and 30 mg/ml) was developed to sustain the quality of shrimp during refrigerated storage. Changes in microbial, chemical, textural, color (L*, a*, b*), and sensory parameters of the studied groups evaluated through distinct experimental approaches. Based on our results, the pattern of increase in the aerobic plate count (APC) and psychrotrophic bacterial count (PBC) in different groups were reported as the following order: CMC + CNE < CMC < control. Also, CMC and CNE integration decreased the upward trend of total volatile basic nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS) compared to that of the control group during storage at 4°C for 10 days (P<0.05). During the storage period, the decrease of the L* value in the control group was greater than the others; whereas, the lowest a* and b* values were observed in this group (P<0.05). Besides, the textural and sensory properties of coated shrimp were significantly more acceptable (P<0.05). Integration of CNE in CMC coating promisingly improves the quality of shrimp during refrigerated storage.

Phenotypic and genotypic characterization of pseudomonas species isolated from frozen meat.

Imported frozen meat is often more heavily contaminated with different bacterial species than home slaughtered one. . In addition, meat is a good environment for spoilage due to chemical and enzymatic activities. One hundred samples of imported Brazilian frozen (50 frozen cubic meat and 50 minced meat) were collected from different supermarkets in El-Menoufia Governorate, Egypt to be examined bacteriologically for detection of phenotypic and genotypic of Pseudomonas species. The incidence of Pseudomonas species were (35/50) 70% in frozen cubic meat. While, the incidence of such organism in the examined frozen minced meat samples was 80% (40/50). Psychrotrophic bacterial count in the examined frozen cubic meat ranged from 6 x 10 2 to 1.9 x 10 5 with mean value 2.24 x 10 4 cfu/g .In addition Psychrotrophic bacterial count in frozen minced meat ranged from 7x102 to 9 x 10 5 with mean value 1.7 x 10 5 cfu/g .The incidence of identified Pseudomonas species (number and percentages) detected in the examined samples of frozen meat represented by Ps. areuginosa , Ps. fluorescence , Ps. diminuta , Ps putida and Ps. fragi were 15(30%), 40(80%), 8(16%), 5(10% )and 4(8%), respectively. Regarding the minced meat samples , The incidence of identified Ps. areuginosa , Ps. fluorescence , Ps. diminuta , Ps. putida , Ps. fragi were 20(40%), 45(90%), 5(10%) ,7(14%) and 8(16%), respectively. The Pseudomonas species were resistant to Oxacillin. They were sensitive to Gentamycin except Ps. fluorescence. PCR is rapid and reliable tool for identification of different bacterial species

Effect of gamma irradiation on physico-mechanical and structural properties of active Farsi gum-CMC films containing Ziziphora clinopodioides essential oil and lignocellulose nanofibers for meat packaging.

The objective of this study was to examine the effect of gamma irradiation (0, 2.5, and 5 kGy) on physico-mechanical and structural characteristics of films based on Farsi gum-carboxymethyl cellulose supplemented with Ziziphora clinopodioides essential oil (ZEO; 0%, 1%, and 2%) and lignocellulose nanofibers (LCNF; 0%, 1%, and 2%), and their application on fresh minced beef meat's shelf-life during refrigerated temperature (4± 1°C) for 16 days. Gamma irradiation under the 60 Co source at 2.5 and 5 kGy doses did not have a significant effect on thickness, tensile strength, swelling index, oxygen permeability, and water vapor transmission rate of prepared films (P >0.05). The best microbiological (total viable count, psychrotrophic bacterial count, Pseudomonas spp., Brochothrix thermosphacta, lactic acid bacteria, and Enterobacteriaceae) and chemical (thiobarbituric acid reactive substances, total volatile base nitrogen content, and peroxide value) properties were recorded for samples packaged with ZEO 2% + LCNF 2%, followed by ZEO 2% + LCNF 1%, ZEO 1% + LCNF 2%, and ZEO 1% + LCNF 1%. These results indicate acceptable extensions of hurdle technology for prolonged refrigeration of minced beef meat. PRACTICAL APPLICATION: The application of active packaging films has received considerable interest in extending the shelf-life of perishable foods during prolonged chilled storage. The effects of active Farsi gum-carboxymethyl cellulose films supplemented with Ziziphora clinopodioides essential oil 2% + lignocellulose nanofibers 2% resulted in delaying lipid oxidation and microbial spoilage growth of refrigerated minced beef meat and consequently extending the shelf-life during storage for at least 16 days.

Development of edible bioactive coating based on mucilages for increasing the shelf life of strawberries

In the present study, the okra mucilage-quince seed mucilage (OM-QSM) coatings containing bacterial cellulose nanofibers (CN; 0, 0.5, and 1%) and Eryngium planum extract (EPE; 0, 0.25, and 0.5%) were prepared. The effects of designated coatings were evaluated in extending the shelf-life of fresh strawberries under refrigerated temperature (4 ± 1 oC) for 12 days. Samples packaged with OM-QSM + EPE 0.5% + CN 1% coating presented the best physico-chemical (weight loss, pH, titratable acidity, L*, and ho), microbial (total viable count, psychrotrophic bacterial count, and yeasts and molds count), and barrier (thickness, water vapor resistance, and O2 permeability) properties. The highest sensory attributes (odor, color, and overall acceptability) were observed in strawberries packaged with EPE 0.5% + CN 1%, EPE 0.5% + CN 0.5%, EPE 0.25% + CN 1%, and EPE 0.25% + CN 0.5% coatings. These results indicate that OM-QSM coatings supplemented with EPE 0.5% + CN 1% and EPE 0.5% + CN 0.5% can be considered as promising packaging materials for fresh strawberries during cold storage.

Catfish Glycoprotein, a Highly Powerful Safe Preservative of Minced Beef Stored at 4 °C for 15 Days.

Minced beef is a very perishable food product, due to its vulnerability to microbial contamination and its fast quality deterioration. In the current study, the biological efficiency of different concentrations (0, 50 and 100 µg g−1) of the antibacterial catfish glycoprotein (CFG) was estimated as a possible improver of the storability and safety of minced beef preserved at 4 °C for 15 days. CFG (50 and 100 µg g−1) could efficiently control the changes in meat pH during 15 days storage at 4 °C to be within the normal, acceptable levels (6.4 and 6.2, respectively), equalizing the level of the control for minced beef after 6 days of storage under similar conditions. Likewise, the level of metmyoglobin in minced beef stored at the same conditions was maintained at 53.67 and 46.67% by CFG supplementation at 50 and 100 µg g−1, respectively, at the 15th day of storage, which is comparable to the 6th day in case of the control samples. However, the antioxidant effect of CFG against lipid peroxidation was less effective. The antibacterial action of CFG was most pronouncedly powerful and efficient. Supplementation of minced beef with CFG at 50 and 100 µg g−1 significantly (p < 0.05) decreased the bacterial counts at all the time inspection points as compared to the control. After 15 days of storage, the total viable bacteria, psychrotrophic bacterial count and coliforms count were reduced to 3.12, 2.65 and 0.0 log CFU g−1, respectively, in response to CFG (50 µg g−1), and 2.41, 2.04 and 0.0 log CFU g−1, respectively, in response to CFG (100 µg g−1); this compared to 5.13, 4.78 and 2.5 in the control samples after only six days cold storage. Using CFG at 50, 100 and 200 µg g−1 in rat diets did not affect their liver or kidney functions, reflecting the non-toxicity of this substance. Substantiating the antioxidant and antimicrobial potential of CFG in minced beef storage may support its use as a naturally powerful and safe food preservative, as well as a shelf-life extender.