Refrigeration Temperature Research Articles

Effect of Addition of Mango Seed Extract on Storage Stability of Chevon Meatballs at Refrigeration Temperature.

In this study, the addition of mango seed extract (MSE) in goat meatballs was assessed. The efficacy of three different levels of MSE extract, namely T1 = (2.5 mL/100 g of meat emulsion v/w), T2 = (5.0 mL/100 g of meat emulsion v/w), T3 = (7.5 mL/100 g of meat emulsion v/w), and T0 (control without mango seed extract), was conducted for evaluation of changes in water activity (aW), pH, total phenolic compounds, DPPH, peroxide value, TBARS, microbial quality, and sensory attributes of the goat meatballs stored at refrigerated temperature (4 ± 1 °C). Incorporation of the mango seed extract T3 (7.5 mL/100 g) showed that it can potentially better maintain change in pH and water activity. Total phenolic and DPPH activity decreased significantly (P0.05) among all samples throughout storage; however, the highest value was noted for T3 among all samples. The MSE-added goat meatballs (T3) group had lower significant (p < 0.05) peroxide values than the other samples. The T3 sample added with MSE exhibited significant (p < 0.05) lower TBRAS values as compared to other treatments. Comparatively lower microbial proliferation and better sensory attributes were maintained among the treated groups during the entire storage time. The results show that the inclusion of MSE extract T3 (7.5 mL/100 g) is a promising natural antioxidant that can maintain a better quality of goat meatballs at refrigerated temperature (4 ± 1 °C) under aerobic packaging conditions.

Augmenting the Oxidative Stability of Chicken Nuggets by incorporating cumin and Black cumin as natural preservatives

ABSTRACT The present research investigated the effectiveness of cumin and black cumin extracts as natural antioxidants in uncooked chicken nuggets stored at refrigeration temperature (4°C) for 12 days and compared the results with a control treatment. Seven treatments were formulated, including a control group (Tc), T1 (0.5% cumin), T2 (1% cumin), T3 (1.5% cumin), T4 (0.5% black cumin), T5 (1% black cumin), and T6 (1.5% black cumin). The product was evaluated for several physicochemical parameters on days 0, 3, 6, 9, and 12 of storage. The data was analyzed using a two-way factorial design under a completely randomized (CRD) design. Results showed that both treatments and storage significantly impacted all physicochemical properties, including DPPH, TPC, pH, POV, and TBARS (p < 0.05). The values of TBARS significantly decreased with the increase in the concentration of cumin extract whereas TBARS increases during the storage period. Moreover, the interaction effect (Treatment*storage days) did not significantly affect any of the physicochemical parameters (p > 0.05). Sensory evaluation showed that T3 (1.5% cumin) was the most pleasant and preferred treatment. Conclusively, both cumin and black cumin have good antioxidant properties and can be used as natural antioxidants to increase the shelf life of food products.

Large reversible multicaloric effects over a broad refrigeration temperature range in Co and B co-doped Ni–Mn–Ti alloys

Solid-state refrigeration is considered a promising alternative to traditional vapor compression refrigeration technology. Researchers demonstrated that Ni–Mn–Ti alloys have a remarkable elastocaloric effect. However, the Ni–Mn–Ti alloy can only operate under a uniaxial stress field due to its antiferromagnetic austenite, which narrows its range of refrigeration temperatures. Here, we activated the magnetism of the alloy by replacing some Ni atoms with Co atoms. The Ni–Co–Mn–Ti–B alloy demonstrates a reversible maximum magnetic entropy change(ΔSm) of 24.9 J kg−1 K−1 and achieves an adiabatic temperature change of 7.8 K under a 7 T magnetic field. Additionally, we demonstrate that adding boron (0.2%) can improve the mechanical properties and cyclic stability in Ni–Mn–Ti alloys. The elastocaloric effect of 21.3 K with high cycle stability (1013 cycles) were successfully achieved in the directionally solidified (Ni35Co15Mn35Ti15)99.8B0.2 alloy. Furthermore, we have demonstrated that the magnetoelastic coupling effect can effectively extend the refrigeration temperature range. The alloys achieved large caloric effects in the temperature range of 240 K–340 K. This provides a new strategy for designing high-performance materials for wide-temperature-domain refrigeration.

Comparison of Viability of the Preserved Autologous Aspirated Fat Tissue Transfer in Refrigerated and Frozen Specimens.

Fat graft surgery is one of the most effective procedures in plastic surgery, and since some patients request multiple surgeries and these cases sometimes take hours, it endangers the viability of the fat graft. In this study, we intend to evaluate the viability of adipose tissue aspirated with a syringe at refrigerator (4°C) and freezer (-20 °C) temperatures. This was a cross-sectional study. After receiving the ethics committee's approval (IR.MUMS.MEDICAL.REC.1401.423), 17 volunteers entered the study. The harvested fat tissue sample was divided into 3 parts, and each of them was transferred to 3 separate sterile tubes. The first tube was sent to the laboratory for preliminary examination of fresh fat, and the second tube was transferred to a 4°C refrigerator for 72 hours. The sample from the third tube was first passed through a strainer and after drying, it was transferred to a -20°C freezer for 72 hours. After treatment with trypsin, we placed the sample inside the centrifuge using the Coleman method. Finally, 3 layers were formed, and the white middle layer was extracted as a fat cell suspension. Tissue samples were stained with trypan blue, and the percentage of viable cells was calculated using an optical microscope. There was a significant difference between the mean number and percentage of viable cells in all 3 groups. Samples in the 4°C refrigerator had significantly more cellular viability than those in the -20°C freezer (mean difference, 72.842%; P < 0.001). Our findings showed that after 72 hours at 4°C, adipose tissue has significantly higher survival than at -20°C (98.93% vs 75.31%). Since the survival of fat cells is one of the direct determinants of fat retention, it can affect the results after surgery. The present study recommends fresh adipose tissue for immediate transplantation unless there is an urgent need for cold storage.

Profiling of microbial populations present in ground beef and plant-based meat analogues

Plant-based meat analogues have gained significant popularity in recent years. Different from ground beef, plant-based meat analogues are derived from a broader range of raw ingredients and undergo more complex manufacturing processes. In this study, 16S rRNA and internal transcribed spacer sequencing techniques were employed to profile and compare the microbial populations present in ground beef (GB), soy-, and pea-based meat analogues (SBM and PBM), and their changes during refrigeration (4 °C) and ambient temperature storage (22 °C). The sequencing results illustrated remarkable microbial differences among GB, PBM, and SBM. Pseudomonas, Brochothrix, and Lactobacillus were the top dominate bacterial genera, Cladosporium, Candida, and Komagataella were the top dominant fungal genera present in GB, PBM, and SBM respectively. At the end of storage, dominant microorganisms present in meat samples, in general, were determined by meat types and storage temperatures, except for SBM. For example, in PBM, refrigeration favored the proliferation of Leuconostoc, while Lactococcus emerged as the primary genus at ambient temperature. For SBM, Lactobacillus and Komagataella were dominate bacterial and fungal species regardless of the storage temperatures. These findings provide crucial information for the development of preventive measures to ensure the microbial safety and quality of plant-based meat analogues.

Effect of temperature, 1-methylcyclopropene, and modified atmosphere packaging on the post-harvest behavior of lulo (Solanum quitoense Lam)

Lulo (Solanum quitoense Lam) is a tropical fruit with high market potential but short shelf life. In this work, the effect of temperature, the application of 1-methylcyclopropene (1-MCP), and the use of modified atmosphere packaging (MAP) were evaluated on the preservation of fresh lulo fruits. Three independent experiments were made sequentially: in the first one, an adequate refrigeration temperature was established (between 5 and 18 °C), then in the second experiment, a suitable dose and application time of 1-MCP (0.35–1.0 μL L−1 and 10–15 min) were found and finally, the combined effect of refrigeration, 1-MCP, and MAP were determined in the last experiment. In the experiments with 1-MCP and MAP, some fruits were stored at refrigeration (5 °C) and then at room temperature (23 °C) while others were kept at room temperature the whole test. Different properties such as respiration, ethylene production, color index, and gas level were evaluated in the samples to determine post-harvest changes. Given the fruit behavior during cold storage, 5 °C proved to be more favorable for preservation. Likewise, samples treated with 0.70 μL L−1 1-MCP + 15 min immersion showed lower CO2 and ethylene production throughout cold storage and shelf time compared with other 1-MCP treatments. For the tests with MAP, the combined treatment with 1-MCP and at 5 °C resulted in a lower respiratory rate, ethylene production, and physicochemical changes during the evaluation (24 days of cold storage + 16 days of shelf time). The results obtained can contribute to increasing the possibilities of lulo commercialization and marketing.

Modeling and optimization of a passive building HVAC system based on improved PSO and H-J Algorithm

Passive buildings employ the principles of active optimization and passive priority to demonstrate their energy-saving, comfortable, and cost-effective qualities, thereby addressing energy consumption in an efficient manner. However, it cannot be ignored that the Heating Ventilation Air Conditioning (HVAC) system is still the largest energy consumer, especially when it is necessary to maintain the comfort of the indoor environment. Consequently, the control and optimization of the HVAC system is a research hotspot and a challenge in the field of building energy conservation, as it is the key to achieving ultra-low energy consumption operation in passive buildings while ensuring the thermal comfort of the indoor environment. This paper presents a comprehensive modeling, control, and optimization framework for the efficient operation of HVAC systems in a passive building located in Jinan, China. Firstly, the HVAC system is modeled using the transient system simulation tool (TRNSYS), GenOpt, Java, and other software. Secondly, the HVAC system’s year-round operation is simulated using specific configurations. In order to enhance the energy-saving effect, a strategy of increasing heat storage and return air ducts was proposed, and a significant energy-saving effect (approximately 17.31%) was realized. Lastly, the data communication interface with GenOpt is established utilizing the TRNOPT module, a method for actively optimizing the refrigerant temperature is proposed, and recalculation and optimization are carried out utilizing the swarm intelligence algorithm and the pattern search algorithm (Hooker-Jeeves algorithm, H-J algorithm). The final optimization results demonstrate a 19% reduction in energy consumption relative to the baseline heat recovery model, validating the applicability of the optimization method under this strategy. The control and optimization method of the HVAC system proposed in this paper can further exploit the energy-saving potential of the passive building HVAC system and will contribute to the advancement of building energy conservation.

Tribological performance of lubricating oils with iron tribopairs under elevated temperature and pressure in carbon dioxide refrigerant

Recent interest in carbon dioxide-based refrigeration has increased. Despite the positive environmental impacts, carbon dioxide makes a complex refrigerant due to elevated pressures and temperatures inside the compressor and the reactivity of CO2 with the lubricant. Tribological experiments were performed using synthetic oils paired with ductile iron tribo-pairs under high pressure CO2. The three lubricants investigated were PAG (Polyalkylene Glycol) and two POE (Polyolester) oils of different viscosities. Elevated temperatures resulted in higher unstable COF for POE and quicker corrosion and degradation of the tribolayer on the surface. In the case of POE, corrosion is significant in causing unstable COF performance at higher temperatures as the ester groups in POE result in more reactivity with the iron surface.

Low-temperature ammonia absorption refrigeration system based on the temperature difference uniformity principle: Optimization analysis

AARS (ammonia absorption refrigeration system) is one of the effective ways to utilize low-temperature waste heat below 100 °C for industrial applications. This novel system of LT-AARS is designed based on the principle of temperature difference uniformity for improving the overall COP. The partial condenser at the distillation section is adopted to achieve the purity of ammonia to more than 99.9 % with a small reflux ratio. A thermodynamic model is established to analyze the influence of the optimized distillation process on system performance and exergy loss. These modifications reduce the temperature difference uniformity factor from 1.12 to 1.025 and improve the COP from 0.414 to 065. Meanwhile, it is proved that the LT-AARS protocol is reasonable and effective by comparing the experimental values with the theoretical model. The exergy loss of the absorber and distiller accounts for about 55 % of the total exergy losses of LT-AARS. With the increases in refrigeration temperature from −15 to 5 °C and heat source temperature from 80 to 100 ℃, the COP can reach a maximum of 0.77. ECOP first increases sharply and then decreases slowly with the increase of refrigeration and heat source temperature, and ECOP has a maximum value. The optimal range of △x for LT-AARS varies from 5 % to 10 %. The COP and ECOP of the LT-AARS are more than 0.6 and 0.3, respectively.

Screening of Adjuvants as Sunlight Protectant for NPV and Evaluation of Storage Conditions against &lt;i&gt;Spodoptera litura&lt;/i&gt;

This experimental study evaluated the effect of adjuvant supplementation on larval mortality of nuclear polyhedrosis virus under sunlight. Study revealed that Tinopal @1% provided best protection from sunlight and retained viral efficacy up to 68.75 and 66.75% in SpltNPV (native) and SpltNPV (NIPHM) respectively, against third instar larvae of Spodoptera litura (F). However, all adjutants resulted in significantly higher larval mortality as compared to control (virus alone) under sunlight. SpltNPV viral formulations stored at different storage conditions recorded minimum reduction in larval mortality, when stored in amber coloured glass bottle at refrigeration temperature (4± 2°C).

Kinetic and proteomic studies in milk show distinct patterns among major Listeria monocytogenes clones

Listeria monocytogenes, a contaminant of raw milk, includes hypervirulent clonal complexes (CC) like CC1, CC4, and CC6, highly overrepresented in dairy products when compared to other food types. Whether their higher prevalence in dairy products is the consequence of a growth advantage in this food remains unknown. We examined growth kinetics of five L. monocytogenes isolates (CC1, CC4, CC6, CC9, and CC121) at 37 and 4 °C in ultra-high temperature (UHT) milk and raw milk. At 4 °C, hypovirulent CC9 and CC121 isolates exhibit better growth parameters in UHT milk compared to the hypervirulent CC1, CC4, and CC6 isolates. CC9 isolate in raw milk at 4 °C exhibited the fastest growth and the highest final concentrations. In contrast, hypervirulent isolates (CC1, CC4, and CC6) displayed better growth rates in UHT milk at 37 °C, the mammalian host temperature. Proteomic analysis of representative hyper- (CC1) and hypovirulent (CC9) isolates showed that they respond to milk cues differently with CC-specific traits. Proteins related to metabolism (such as LysA or different phosphotransferase systems), and stress response were upregulated in both isolates during growth in UHT milk. Our results show that there is a Listeria CC-specific and a Listeria CC-common response to the milk environment. These findings shed light on the overrepresentation of hypervirulent L. monocytogenes isolates in dairy products, suggesting that CC1 and CC4 overrepresentation in dairy products made of raw milk may arise from contamination during or after milking at the farm and discard an advantage of hypervirulent isolates in milk products when stored at refrigeration temperatures.

Food Safety and Management System Audits in Food Retail Chain Stores in Greece

The present study aimed to assess the performance of food safety management systems in food retail stores via audits to reveal potential areas of improvement and to find out possible corrective actions to suggest to the top management. Two cycles of on-site audits took place in 106 stores to assess the requirements and hygiene conditions. After the first cycle of audits, improvements were suggested to the top management, and a second cycle of audits took place after a reasonable time. In the checklist, we recorded the temperatures of retail refrigerators and the scores from the inspection of hygiene and HACCP documentation. In the A′ audit, the percentage of stores that had higher temperatures than the critical limits was equal to 51%, and those temperatures occurred in the refrigerators for salads, followed by the refrigerators for deli meat, yogurts and desserts. In the B′ audit, only the refrigerators for salads exhibited percentages that were statistically significant lower (p-value &lt; 0.05), and the stores were improved after the audit. High percentages of high-scoring stores were observed in the A′ and B′ audit in the inspection of HACCP documentation, although there was not a statistically significant improvement observed (p-value &gt; 0.05). In the hygiene inspection, statistically significant improvement with 95% confidence appeared for “Refrigerator’s products appearance”, “Storage cleanliness”, and “Grocery shelf cleanliness”. The highest number of non-conformities without statistically significant improvement was found for “Checking temperatures of the receiving products” and “Labeling of fruit store products”, with the percentages being lower than 15% in both of the audit cycles. Many employees of the stores did not check and record the temperatures of receiving products from suppliers. In addition, the storage of spoiled products beneath fresh products for selling in the same refrigerator is not a good practice. Greater efforts must be made by top management and employees to maintain and distribute food products in the best and safest possible hygiene conditions.

D-tryptophan, an eco-friendly natural, safe, and healthy compound with antimicrobial activity against food-borne pathogens: A systematic review.

Recently, the use of D-amino acids as food preservatives has attracted considerable attention because these natural compounds do not have adverse effects on human health. In addition, D-amino acids such as D-tryptophan can reduce the harmful effects of other treatments. For instance, the use of D-tryptophan in food reduces the requirement for high temperatures and their damaging effects on nutrients such as proteins and vitamins. The purpose of this systematic review was to investigate the antimicrobial effect of D-tryptophan on food-borne pathogens invitro and in food models. To identify related studies, scientific digital databases such as PubMed, Science Direct, and Google Scholar were searched from January 2000 to February 2023. The results of the studies showed that when D-tryptophan was used with other stresses such as using different salt concentrations, refrigeration, or high temperatures, it showed significant antimicrobial effects on Gram-positive and Gram-negative food-borne pathogens, and antibiofilm impacts were also observed with D-tryptophan. Since studies have shown that the antimicrobial activity of D-tryptophan depends on several factors, including the pathogen strain, the type of stress, and the concentration of D-tryptophan, and every article has focused on one of these factors, there is a need for a systematic review that summarizes and concludes the effect of all these factors on the antimicrobial activity of D-tryptophan against food-borne pathogens.

Functional properties of cream and butter oil from milk of Holstein cows abomasally infused with increasing amounts of high-oleic sunflower fatty acids.

This research paper addresses the hypothesis that there is an optimal amount of intestinally available oleic acid (provided via abomasal infusion) to produce higher-oleic acid milk fat with satisfactory functional characteristics of cream and butter oil. A control and four increasing doses of free fatty acids from high oleic sunflower oil (HOSFA) were infused into the abomasum of four lactating dairy cows in a crossover experimental design with 7-d periods. Treatments were: (1) control (no HOSFA infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Viscosity, overrun and whipping time as well as foam firmness and stability were evaluated in whipping creams (33% fat). Solid fat content (from 0 to 40°C), melting point and firmness were determined in butter oil. Whipping time of cream increased linearly and viscosity decreased linearly as infusion of HOSFA increased. Overrun displayed a quadratic response, decreasing when 500 g/d or more was infused. Foam firmness and stability were not affected significantly by HOSFA. For butter oil, melting point, firmness, and solid fat content decreased as HOSFA infusion increased. Changes in 21 TG fractions were statistically correlated to functional properties, with 6-10 fractions showing the highest correlations consistently. Decisions on the optimal amount of HOSFA were dependent on the dairy product to which milk fat is applied. For products handled at commercial refrigeration temperatures, such as whipping cream and butter oil, the 250 g/d level was the limit to maintain satisfactory functional qualities. Palmitic acid needed to be present in at least 20% in milk fat to keep the functional properties for the products.

Magnetic properties and large low-field cryogenic magnetocaloric effect in the divalent europium borate Eu2B2O5 compound

We herein investigated the divalent europium borate Eu2B2O5 compound regarding its structural, magnetic and magnetocaloric properties by means of experimental determinations and first principal calculations. The Eu2B2O5 compound was found to crystallize in a monoclinic structure (P21/c space group) and order ferromagnetically at ground state. A large cryogenic reversible MCE was observed in the Eu2B2O5 compound around 2.7 K. The maximum values of magnetic entropy change of Eu2B2O5 compound reach 13.7, 28.2 and 46.9 J/kgK under the magnetic field changes of 0–1, 0–2, and 0–5 T, respectively. The corresponding values of adiabatic temperature change and refrigerant capacity are obtained to be 3.3, 7.0, and 13.3 K and to be 37.8, 102.5, and 317.3 J/kg. These magnetocaloric parameters, especially under relatively low-field changes, are better than those of the reported candidate materials, which makes the Eu2B2O5 compound attractive for cryogenic MR applications.

Sensory Attribute Properties and Shelf Life Of Chicken-Herbal Essence Functional Drinks

Chicken-herbal essence, a nutritionally rich functional beverage boasting elevated levels of proteins and amino acids, is renowned for its health-promoting attributes, notably its positive effects on lactation. Comprising an amalgamation of free-range chicken, red ginger, brown sugar, honey, sesame oil, nutmeg, salt, and water, this elixir undergoes a discernible deterioration in quality when subjected to prolonged storage. Consequently, imperative research endeavors are undertaken to elucidate the temporal constraints of storage for this esteemed functional drink. The present study is oriented towards gauging the degradation in quality and prognosticating the shelf life of chicken-herbal essence when exposed to three distinct temperatures—refrigerator temperature (10°C), ambient room temperature (25-27°C), and an elevated temperature (35°C)—utilizing the Arrhenius method as the analytical framework. Conducted over a rigorously observed four-week duration at both the Djuanda University Food Laboratory and the LPPOM MUI Laboratory, this study systematically examines diverse parameters, including pH levels, total dissolved solids, total plate count (TPC), and a comprehensive sensory evaluation. The pH testing, conducted employing a precision pH meter, yields a range of 4.676 – 5.074, while total dissolved solids ranged from 27,100 – 27,450 Brix; total plate count ranged from 0 – 20 CFU/mL. In the sensory test, samples at three temperatures were withdrawn upon panelists' arrival. Generally, refrigerated and room temperature storage showed higher acceptability than higher temperature (35°C) storage. Shelf life estimation indicated that refrigerated storage (10°C) extended to 53 days, surpassing the other temperatures.

Microbial, Physicochemical and Sensory Quality of Freshly Extracted Apple and Cucumber Juice Subjected to Preservatives and Storage Conditions

Fruit juices are commonly consumed for their refreshing attribute, nutritive values and health benefits. Fruit juice samples were treated with 0.5 g/ml garlic, 0.5 g/ml ginger, 0.25 g/ml mix of ginger and garlic and 0.05% (w/v) of sodium benzoate respectively where the ginger, garlic and sodium benzoate serve as natural and artificial preservatives. Their effects on the fruit juices were evaluated during 8 days of storage at 4°C and ambient temperature (28±2°C). Juice treated with sodium benzoate had the least microbial contamination while the untreated juice had the highest. The bacterial isolated from the samples were Staphylococcus sp, Bacillus sp. (Most occurring bacteria isolated), Micrococcus sp, and lactobacillus sp. The fungi isolated in the course of the study were Aspergillus sp, Rhizopus sp and Penicillium sp. (The highest occurred fungi isolated). There was a marginal decrease in pH values across treatments in stored juices with juice stored at 4°C showing the least change in pH compared to that stored at ambient temperature. The results obtained show that the preservatives exhibited an antimicrobial effect on the microbial load. The Total titratable acidity of all samples increased with time at ambient temperature and decreased at refrigerated temperature. The ascorbic acid content of both juices samples at storage temperatures decreased after the storage period due to the high sensitivity of vitamin C to oxygen, light, heat, etc. In conclusion, the findings of this study generally indicate that combination of chemical and natural preservation together with refrigeration is suitable for the preservation of fruit juice for a long time. Chemical preservatives can be recommended to be replaced with natural preservatives such as ginger and garlic, since the process is inexpensive and easy. However, preservation of fruit juice at ambient temperature for a long time should be discouraged to reduce microbial contamination.

Effect of storage temperature on the bacterial flora and sensory quality of vacuum packaged smoked catfish (&lt;i&gt;Clarias anguillaris&lt;/i&gt;)

This study evaluated the effect of two storage temperatures on the bacterial flora and sensory quality of vacuum packaged smoked catfish (Clarias anguillaris). The catfish was hot smoked using a traditional kiln, with mangrove wood as the source of heat. Total bacterial count (TBC) and sensory parameters (colour, smell. dryness and general appearance) were determined during storage at ambient (28 ± 2°C) and refrigeration (4°C) temperatures for 0-8 weeks. Bacteria were enumerated, isolated and identified using standard methods. Vacuum packaged smoked catfish stored at 4°C (VPCR) had the lowest TBC which increased from 3.23 – 3.58 log10 cfu/g within 2 weeks of storage and stabilized at 3.44 log10 cfu/g for 4 – 8 weeks. The TBC of the vacuum packaged smoked catfish stored at ambient temperature (28 ± 2°C) ranged from 3.32 – 6.88 log10 cfu/g within 6 weeks of storage. The bacteria isolated from fresh catfish belonged to nine genera, namely, Bacillus, Chryseobacterium, Escherichia, Lysinibacillus, Proteus, Pseudomonas, Staphylococcus, Streptococcus and Vibrio. Only Bacillus and Proteus species were isolated from freshly smoked catfish. Isolates from vacuum packaged samples were Bacillus, Lactobacillus, Proteus and Staphylococcus. Molecular characterization of three isolates from fresh catfish revealed that the species were Chryseobacterium aquifridigense, Lysinibacillus mycoides and Vibrio parahaemolyticus. The sensory scores for sample VPCR stored for 8 weeks did not differ significantly (P ≥ 0.05) from freshly smoked catfish, except for the colour. Non-packaged and vacuum packaged smoked catfish samples were of good quality during storage at ambient temperature for 4 weeks, and 4 – 6 weeks, respectively.

Development of novel carboxymethyl cellulose/gelatin-based edible films with pomegranate peel extract as antibacterial/antioxidant agents for beef preservation

Novel antioxidant and antibacterial composite films were fabricated by incorporating pomegranate peel extract (PPE) into gelatin and carboxymethyl cellulose matrices. Increasing PPE concentration significantly (p < 0.05) altered physical properties and improved UV (decrease in light transmission 87.30 % to 9.89 % at 400 nm) and water resistance, while FTIR and molecular docking results revealed hydrogen bonding between PPE and film matrix. PPE incorporation enhanced antioxidant activity up to 84.15 ± 0.12 % and also restricted gram-positive and gram-negative bacterial growth by 72.4 % and 65.9 % respectively after 24 h, measured by antimicrobial absorption assays. For beef packaging applications at refrigeration temperatures, PPE films were most effective at extending shelf-life up to 3 days, as evidenced by reduced total viable counts, total volatile basic nitrogen, weight loss, and pH changes compared to control films. Therefore, these antioxidant and antibacterial films have potential applications in food packaging to protect against mechanical stress, light exposure, microbial spoilage, and oxidative free radicals.

Intestinal pathogens detected in cockroach species within different food-related environment in Pudong, China

Cockroaches are considered mechanical transmitters of infectious diseases, posing a threat to human health. This study assessed the potential of cockroaches in food-related environments to mechanically transmit intestinal pathogens. Cockroaches captured with traps were placed together into a low temperature refrigerator at − 80° for 2 h. Standard taxonomic keys and Fluorescent quantitative PCR techniques were applied for species identification and digestive tract etiological examination. A total of 360 cockroach traps were placed, with a positive rate of 20.8%, and 266 cockroaches were captured. In general, compared with other places and areas, the degree of infestation of cockroaches was more serious in catering places and kitchens. Blattella germanica were most found in catering places (40.2%), followed by Periplaneta fuliginosa in schools (22.2%). According to the life stage, among the 128 cockroach samples, 23 were positive for nymphs and 13 were positive for adults. There were statistically significant differences in the intestinal pathogen detection rates between nymphs and adults (P < 0.05). A total of eight intestinal pathogens were detected, and enterovirus infections were the main ones, with sapovirus being the most detected in Blattella germanica or nymph. Shiga toxin-producing Escherichia coli (STEC) was the most frequently isolated bacterium. Blastocystis hominis had the highest isolation rate. In contrast, 12 diarrhoeal disease pathogens were isolated, and the viruses and bacteria with the highest frequencies were norovirus and E. coli, respectively; no parasites were found. Blattella germanica and Periplaneta fuliginosa in food-related environments can act as potential vectors for the spread of intestinal pathogens and may pose a significant threat to public health.