Total Count Of Microorganisms Research Articles

Arginine and sodium fluoride affect the microbial composition and reduce biofilm metabolism and enamel mineral loss in an oral microcosm model

ObjectiveTo assess the effects of arginine, with or without sodium fluoride (NaF; 1,450 ppm), on saliva-derived microcosm biofilms and enamel demineralization. MethodsSaliva-derived biofilms were grown on bovine enamel blocks in 0.2 % sucrose-containing modified McBain medium, according to six experimental groups: control (McBain 0.2 %); 2.5 % arginine; 8 % arginine; NaF; 2.5 % arginine with NaF; and 8 % arginine with NaF. After 5 days of growth, biofilm viability was assessed by colony-forming units counting, laser scanning confocal microscopy was used to determine biofilm vitality and extracellular polysaccharide (EPS) production, while biofilm metabolism was evaluated using the resazurin assay and lactic acid quantification. Demineralization was evaluated by measuring pH in the culture medium and calcium release. Data were analyzed by Kruskal-Wallis’ and Dunn's tests (p < 0.05). Results8 % arginine with NaF showed the strongest reduction in total streptococci and total microorganism counts, with no significant difference compared to arginine without NaF. Neither 2.5 % arginine alone nor NaF alone significantly reduced microbial counts compared to the control, although in combination, a reduction in all microbial groups was observed. Similar trends were found for biofilm vitality and EPS, and calcium released to the growth medium. Conclusions8 % Arginine, with or without NaF, exhibited the strongest antimicrobial activity and reduced enamel calcium loss. Also, NaF enhanced the effects of 2.5 % arginine, yielding similar results to 8 % arginine for most parameters analyzed. Clinical significanceThe results provided further evidence on how arginine, with or without NaF, affects oral microcosm biofilms and enamel mineral loss.

Exploring the potential of melittin peptide: Expression, purification, anti-pathogenic properties, and promising applications as a bio-preservative for beef slices

Melittin peptide is a short cationic linear peptide derived from honey bee venom with 26 amino acids, demonstrates potential in controlling and eliminating pathogens. In this study, the genetic sequence of melittin was inserted into the pcDNA3.1+ plasmid and expressed in HEK-293 cells with a His-tag. Purification was done through affinity chromatography and a nickel column. In this study, the antimicrobial effect of melittin in beef sirloin was first investigated, and the minimum inhibitory concentration (MIC) was determined. Then, the effect of combining it with nanochitosan (n-CH) coating, melittin (0.1% and 0.2%v/v), and nanochitosan alone on the physicochemical, microbiological, and sensory properties of beef was examined over a 9-day at 4 °C. At the end of the storage period, the coated samples effectively prevented an increase in pH (5.75 ± 0.06) and showed a significant decrease in the peroxide value (PV) (4.50 ± 0.07). The most favorable result was observed when using the n-CH+0.2%M, which led to malondialdehyde level of 0.44 ± 0.0.05 mg/kg in the amount of thiobarbituric acid reactant. Additionally, the total volatile base nitrogen content in the treatment involving 0.2%M and n-CH+0.2% and 0.1%M was deemed acceptable. Although the total viable count (TVC) of microorganisms in samples covered with melittin increased over time (7.88 ± 0.12 CFU/g), the microbial growth rate in these samples was lower than the control sample (12.10 ± 0.13 CFU/g). Therefore, the use of nanochitosan based edible coatings in combination with melittin in meat packaging reduces microbial population and increases its shelf life.

Nectarine powder of Bulgarian origin: Physicochemical composition, antioxidant activity, microbiological and sorption characteristics

One way to improve the quality of food products is by conducting more thorough research on regional foods. This approach has several benefits, such as promoting human health, supporting the local economy, and preserving cultural food traditions. In this regard, our study investigated the potential of nectarine powder as a regional fruit product that could be developed into a global innovation. The present study examined: the physicochemical composition, antioxidant activity, microbiological load, and adsorption and desorption characteristics of the nectarine powder. The fruit powder was acquired through the use of a heat pump dryer, where drying took place at 42 °C for a duration of 8 h until achieving a moisture content ranging from 13.5 % to 14.5 %. The approximate physicochemical values are as follows: proteins, total carbohydrates, crude fiber, ash content and total lipids. Microbiological parameters, namely the total count of mesophilic aerobic and facultative anaerobic microorganisms, yeasts and molds, Escherichia coli, Salmonella spp., coagulase-positive staphylococci, and coliforms were checked and found to be within the acceptable limits as stipulated by the relevant state standards. Antioxidant activity was demonstrated through the utilization of various methods, including DPPH (33.19 ± 0.09mMTE/g extract), ABRS (2.55 ± 0.05mMTE/g extract), FRAP (1.43 ± 0.03mMTE/g extract) and CUPRAC (0.83 ± 0.01mMTE/g extract) methods. Investigation of the mass transfer sorption characteristics is performed using the gravimetric-static method. The conditions of the experiment were selected according to the usual conditions in which the food products are found in the commercial depot. The equilibrium and monolayer moisture data are investigated at 10 °C, 25 °C and 40 °C and relative air humidity in the wide range from 11 % to 87 %, achieved by the salts saturated solutions. To depict the adsorption and desorption isotherms, the modified models of Halsey, Chung-Pfost, Henderson, and Oswin were selected.

Modifiye atmosfer ile paketlemenin etli mantının raf ömrü ve kalite özelliklerine etkisi

This study aimed to evaluate the effects of modified atmosphere packaging on the shelf-life and quality characteristics of mantı (a meat-filled pasta product) stored in refrigerator conditions. In this direction, mantı, whose humidity value is reduced to 34% with the pre-drying process, were packaged with different gas mixtures (ambient air, 80% CO2 + 20% N2, 60% CO2 + 40% N2, 40% CO2 + 60% N2, 20% O2 + 40% CO2 + 40% N2) and kept in cold storage for 90 days. In this process, mantı samples were analysed regarding physico-chemical, microbiological, colour and sensory parameters. According to the findings, Escherichia coli, sulfide-reducing anaerobic bacteria and Salmonella spp. were not detected. While total aerobic mesophilic microorganism and mould yeast counts increased throughout storage, they were lowest in packages containing 80% CO2. The high count of microorganisms in the samples packaged with ambient air also showed parallelism with the lipid oxidation values, causing the products to remain below acceptable sensory levels starting from the 60th day of storage. In the modified atmosphere packaging application, the increased amount of carbon dioxide in the package ensured that the texture and flavour properties of the mantı were preserved close to the first day during their shelf life. As a result, the modified atmosphere packaging application preserved the quality characteristics of mantı for a long time, increased their stay in the aisle and allowed them to be acceptable to consumers. While the protective effect increased, especially with the increasing amount of CO2 in the gas composition, the product's sensory properties were also preserved during storage, and economic losses could be prevented.

Гідроекологічна характеристика сучасного стану Запорізького (Дніпровського) водосховища та його приток

Purpose: to determine the hydroecological condition of the different areas of the Zaporizhzhia (Dnipro) reservoir and its tributaries (Samara River, Konoplyanka River), which are under technogenic pressure. Methodology: classical methods of determining hydrochemical indicators (pH, dissolved oxygen, carbon dioxide, permanganate oxidizability, anions and cations of organic and inorganic compounds) and microbiological parameters (total count of microorganisms and count of saprophytes) were used during the study. The content of heavy metals was determined by atomic absorption spectrophotometry. Findings: The study of the current hydroecological state of the Zaporizhzhia (Dnipro) reservoir in the summer period showed that, according to most parameters, the water quality did not exceed the MAC (maximum allowable concentration) for fish farming. The exception was the reduced oxygen dissolved concentration (by 10-25%) in almost all areas of the reservoir, and the high mineralization of water in the Samara Bay (2 MAC), due to the discharge of highly mineralized waters of the Samara River. In the long-term aspect, there is an increase in the total mineralization of the Samara River (4 MAC, which is under the influence of the discharge mine waters of the coal mining industry of Western Donbas. The analysis of the content of heavy metals in the reservoir indicated an increase in the concentration of copper - from 13 MAC in the Samara Bay to 21 MAC in the lower part of the reservoir. The Samara River was characterized by a high content of cadmium (1.5 MAC), copper (13 MAC), and nickel (2.3 MAC). Indicators of the ecological state of the Konoplyanka River had significant differences in its different areas: in the upper reaches of the river, where the economic and domestic effluents of the city of Kamianske and the tailings storage facilities for radioactive waste are located, water did not meet the MAC for oxygen content, carbon dioxide, nitrites, nitrates, mineral ions (Ca2+, Mg2+, Cl’, SO4-2), general mineralization and the count of saprophytic microorganisms; at the mouth of the river, exceeding the MAC for nitrate content and saprophytic microflora was recorded. Originality: data on the hydroecological state of the Zaporizhzhia (Dnipro) reservoir and its tributaries in the conditions of the war have been obtained. Practical value: the results of the conducted study can be used to develop a strategic program for the restoration of the ecosystem of the Dnipro reservoirs in the post-war period. Key words: Zaporizhzhia (Dnipro) reservoir, tributaries, hydrochemical parameters, count of microorganisms, heavy metals.

Combining Feature Selection Techniques and Neurofuzzy Systems for the Prediction of Total Viable Counts in Beef Fillets Using Multispectral Imaging

In the food industry, quality and safety issues are associated with consumers’ health condition. There is a growing interest in applying various noninvasive sensorial techniques to obtain quickly quality attributes. One of them, hyperspectral/multispectral imaging technique has been extensively used for inspection of various food products. In this paper, a stacking-based ensemble prediction system has been developed for the prediction of total viable counts of microorganisms in beef fillet samples, an essential cause to meat spoilage, utilizing multispectral imaging information. As the selection of important wavelengths from the multispectral imaging system is considered as an essential stage to the prediction scheme, a features fusion approach has been also explored, by combining wavelengths extracted from various feature selection techniques. Ensemble sub-components include two advanced clustering-based neuro-fuzzy network prediction models, one utilizing information from average reflectance values, while the other one from the standard deviation of the pixels’ intensity per wavelength. The performances of neurofuzzy models were compared against established regression algorithms such as multilayer perceptron, support vector machines and partial least squares. Obtained results confirmed the validity of the proposed hypothesis to utilize a combination of feature selection methods with neurofuzzy models in order to assess the microbiological quality of meat products.

Bacillus Cereus prevalence in human milk donations in a North Italy human milk bank

Abstract Background The importance of human milk in infants’ diets is well-known in the medical community. Unfortunately, breastfeeding isn't always possible for various reasons, human milk donation represents the main solution to this problem. The donated milk goes through a pasteurization treatment (62.5 °C for 30 minutes). Before consumption, the milk is tested to analyze the microbiological safety aspect, specifically: the protocol of a North Italian bank, provides for the total count of microorganisms and of Bacillus Cereus. The presence of B. Cereus in pasteurized milk samples has been witnessed in the last few years. B. Cereus infections in infants have consistently been reported and banked human milk could be one of the possible sources. This work aims to study the prevalence of B. Cereus in banked human milk sampled before and after pasteurization treatment. Methods Between 2020 and 2023 we tested 1055 samples, before and after the pasteurization treatment. The enumeration of B. cereus is performed in accordance with ISO 7932:2004. 100 µL of pure raw milk and two consecutive decimal dilutions in buffered peptone water were seeded on Bacillus cereus Agar (BCA) at 30° for 24h-48h. B. Cereus strains isolated were typed using the hemolysis test and BCA. Results We found 46 samples positives for B. Cereus from 1055 samples analyzed before the heat treatment. The number increased to 57 in the pasteurized samples. These data are confirmed by the typing of the isolated strains from the human milk. Conclusions The 4% of not pasteurized milk is discarded due to B. Cereus presence, and the rate increase to 5% in pasteurized milk. This information suggests that the heat treatment isn't capable to inhibit all the B. Cereus, and the increase of B. Cereus from not pasteurized to pasteurized need to be studied. Key messages • B. Cereus represents one of the main causes of noncompliance in banked human milk. • Implementation of preventive/corrective actions is needed to prevent the contaminations led by the operators.

Investigating the microbial properties of sodium alginate/chitosan edible film containing red beetroot anthocyanin extract for smart packaging in chicken fillet as a pH indicator

The current trend in the production of smart films involves the use of pH-responsive color indicators derived from natural sources. In line with this trend, the aim of this research is to produce edible films from sodium alginate (A) and chitosan (Ch) incorporating red beet anthocyanin (Ac) extract, and to assess the properties of these films and their use as coatings for chicken fillets. The study employed a factorial design to evaluate the effects of treatments C (control), A25%-ch75% (films consisting of 25% sodium alginate and 75% chitosan), and A25%-ch75%-Ac (films consisting of 25% sodium alginate, 75% chitosan, and red beet anthocyanin). The findings indicate that the inclusion of red beet anthocyanin extract did not result in any discernible differences in the FTIR spectra of the film samples. Analysis of the XRD results revealed that the addition of the extract led to a reduction in the crystal structure of the film. Moreover, SEM results demonstrated that the extract caused alterations in the polymer chains and an increase in the porosity of the film matrix. With regard to the chicken fillet samples coated with the film, over time, there was an increase in microbial analysis (total microorganism count and Staphylococcus aureus coagulase-positive) and chemical properties (pH, peroxide, thiobarbituric acid, and nitrogen compounds) for all samples. However, this trend was significantly lower in the samples coated with the Ac extract (P < 0.05). Texture analysis results revealed that the hardness parameter of all samples decreased over the storage period, while the samples containing the Ac extract demonstrated a significant increase in this parameter (P < 0.05). Additionally, the color changes of the pH sensor corresponded to the anthocyanin structure. Based on the results, the smart film composed of sodium alginate/chitosan incorporating red beet anthocyanin extract has the potential to enhance the quality, prolong the shelf life, and decrease the microbial load of chicken fillet when used as a coating. Furthermore, red beet anthocyanin can serve as a suitable indicator for spoilage changes in packaged food products.

Analysis of antimicrobial efficacy of sodium hypochlorite and ozonated water against biofilm in oval canals.

This in vitro study compared the antimicrobial efficacy of 2.5% sodium hypochlorite (NaOCl) and 8 µg/mL ozonated water agitated by passive ultrasonic irrigation (PUI) or PUI combined with EndoActivator (EA) against mature multispecies biofilm. One hundred and five oval-shaped mandibular premolars were instrumented, sterilized, and inoculated with Enterococcus faecalis, Candida albicans, and Staphylococcus aureus, divided into: control group - saline; O3 group - ozonated water; O3 PUI group - ozonated water with PUI agitation; O3 PUI+EA group - ozonated water with PUI+EA agitation; NaOCl group - NaOCl; NaOCl PUI group - NaOCl with PUI agitation; and NaOCl PUI+EA group - NaOCl with PUI+EA agitation. Microbiological samples were collected before (S1) and after (S2) the disinfection procedures and the data were statistically analyzed using the Kruskal-Wallis test. In the culture method, there was significant disinfection in the O3 PUI+EA, NaOCl, NaOCl PUI, and NaOCl PUI+EA groups (p˂0.05). The combination of NaOCl with PUI+EA reduced microbial counts to zero (p˂0.05). In the qPCR method, there was a significant reduction in the total count of viable microorganisms in the O3 PUI, O3 PUI+EA, NaOCl, NaOCl PUI, and NaOCl PUI+EA groups (p˂0.05). It can be concluded that 2.5% NaOCl with and without agitation, as well as 8 µg/mL ozonated water with its action enhanced by the agitation techniques, were effective in root canal disinfection, and their antimicrobial efficacy is related to the microorganisms present in the biofilm.

Red beetroot betalains as a novel source of colorent in ice-cream as compared with Red Dye 40 (E129)

Background: Although there is an increasing need for eco-friendly and non-toxic food colorants, plant-based colors have shown to be a promising alternative to synthetic food colors. The natural pigment (betalain) was extracted from red beetroot utilizing a magnetic stirrer shaking apparatus in the current study. Objective: The purpose of this study was to evaluate the effect of betalain (natural pigment) and red dye 40 (synthetic pigment), on the chemical, microbiological, and sensory properties of ice cream. Materials and Methods: Betalain and red dye 40 were added into ice cream at variable concentrations of 50 mg/mL, 100 mg/mL, and 200 mg/mL. Specimens were stored for 70 days and evaluated every ten days. Results: The values of titratable acidity, PH, fat, protein, total count of microorganisms, and sensory characteristics were gave higher scores samples than than in ice cream with red dye 40. Nevertheless, betalain doses of 50, 100, and 200 mg/mL have been reported to have a significant 70-day storage activity in ice cream. When compared to mixtures containing 50, 100, and 200 mg/mL of red dye 40 after 70 days. According to the findings, betalain may be utilized as a natural pigment and food preservative to boost stability during storage.Keywords: Red beetroot,Betalain, Functional foods, Red Dye 40 (E129),Antioxidants, synthetic colors, Storage stability

Intermediate Cluster Disinfection: Which Disinfection Solution Is Most Effective on Milking Liners? A Comparison of Microorganism Reduction on Liner Inner Surfaces Using Quantitative Swab Sampling Technique.

During machine milking, pathogenic microorganisms can be transmitted from cow to cow through liners. Therefore, in Germany, a spray method for the intermediate disinfection of the milking cluster is often used for prevention. This method of cluster disinfection is easy to perform, requires little time and no extra materials, and the disinfection solution is safe from outside contamination in the spray bottle. Since no data on a systematic efficacy trial are available, the aim of this study was to determine the microbial reduction effect of intermediate disinfection. Therefore, laboratory and field trials were conducted. In both trials, two sprays of 0.85 mL per burst of different disinfectant solutions were sprayed into the contaminated liners. For sampling, a quantitative swabbing method using a modified wet-dry swab (WDS) technique based on DIN 10113-1: 1997-07 was applied. Thus, the effectiveness of disinfectants based on Peracetic Acid, Hydrogen Peroxide and Plasma-Activated Buffered Solution (PABS) was compared. In the laboratory trial, the inner surfaces of liners were contaminated with pure cultures of Escherichia (E.) coli, Staphylococcus (S.) aureus, Streptococcus (Sc.) uberis and Sc. agalactiae. The disinfection of the contaminated liners with the disinfectants resulted in a significant reduction in bacteria with values averaging 1 log for E. coli, 0.7 log for S. aureus, 0.7 log for Sc. uberis and 0.8 log for Sc. agalactiae. The highest reduction was obtained for contamination with E. coli (1.3 log) and Sc. uberis (0.8 log) when PABS was applied and for contamination with S. aureus (1.1 log) and Sc. agalactiae (1 log) when Peracetic Acid Solution (PAS) was used. Treatment with sterile water only led to an average reduction of 0.4 log. In the field trial, after the milking of 575 cows, the liners were disinfected and the total microorganism count from the liner surface was performed. The reduction was measured against an untreated liner within the cluster. Although a reduction in microorganisms was achieved in the field trial, it was not significant. When using PAS, a log reduction of 0.3 was achieved; when using PABS, a log reduction of 0.2 was obtained. The difference between the two disinfection methods was also not significant. Treatment with sterile water only led to a reduction of 0.1 log. The results show that spray disinfection under these circumstances does result in a reduction in the bacteria on the milking liner surface, but for effective disinfection a higher reduction would be preferred.

Natural photosensitizer-loaded in micellar copolymer to prevent bovine mastitis: A new post-dipping protocol on milking

Good management practices such as post-dipping applications (post-milking immersion bath) contribute to the dairy cattle health during lactation and minimize the appearance of mastitis (an infection in the mammary gland). The post-dipping procedure is performed conventionally using iodine-based solutions. The search for therapeutic modalities that are not invasive and do not cause resistance to the microorganisms that cause bovine mastitis instigates the interest of the scientific community. In this regard, antimicrobial Photodynamic Therapy (aPDT) is highlighted. The aPDT is based on combining a photosensitizer (PS) compound, light of adequate wavelength, and molecular oxygen (3O2), which triggers a series of photophysical processes and photochemical reactions that generate reactive oxygen species (ROS) responsible for the inactivation of microorganisms. The present investigation explored the photodynamic efficiency of two natural PS: Chlorophyll-rich spinach extract (CHL) and Curcumin (CUR), both incorporated into the Pluronic® F127 micellar copolymer. They were applied in post-dipping procedures in two different experiments. The photoactivity of formulations mediated through aPDT was conducted against Staphylococcus aureus, and obtained a minimum inhibitory concentration (MIC) of 6.8 mg mL−1 for CHL-F127 and 0.25 mg mL−1 for CUR-F127. Only CUR-F127 inhibited Escherichia coli growth with MIC 0.50 mg mL−1. Concerning the count of microorganisms during the days of the application, a significant difference was observed between the treatments and control (Iodine) when the teat surface of cows was evaluated. For CHL-F127 there was a difference for Coliform and Staphylococcus (p < 0.05). For CUR-F127 there was a difference for aerobic mesophilic and Staphylococcus (p < 0.05). Such application decreased bacterial load and maintained the milk quality, being evaluated via total microorganism count, physical-chemical composition, and somatic cell count (SCC).

Einkorn (Triticum monococcum L.) and nectarine flour mixture - antioxidant activity, microbiological and sorption characteristics

The current paper presents the initial scientific research on a new enriched flour mixture with nectarine powder, comprising physicochemical parameters, antioxidant capacity, microbiological load, and sorption characteristics data. A mixture of 70% Einkorn flour and 30% fruit powder of Bulgarian origin as a functional food supplement was blended. The presence of bioactive components was proved by the in vitro analysis of antioxidant activity through DPPH, ABTS, FRAP, and CUPRAC methods. The microbiological indicators, the total count of mesophilic aerobic and facultative anaerobic microorganisms, yeasts and molds, Escherichia coli, Salmonella spp., coagulase-positive staphylococci and coliforms, were within the permissible norms and no presence of pathogenic microorganisms, were detected in the flour mixture. Adsorption and desorption processes were studied at 10, 25 and 40°C and aw = 0.112-0.868 following static gravimetric methods. The obtained S-shaped equilibrium sorption isotherms confirm the constant trend that with increasing equilibrium moisture content, the temperature decreases in conditions of constant water activity. Based on the obtained sorption capacity data, a calculation of the monolayer moisture content was made using the linearization of the BET model. One of the modified three-parametric models of Oswin, Halsey, Henderson, and Chung-Pfost was selected as a suitable model for describing all sorption isotherms.

Влияние ионизирующего облучения на пшеничную хлебопекарную муку

Radiation processing suppresses the development of microorganisms and pests in food products. This method is safe and does not affect nutritional value; however, it may change the properties of starch and proteins. The research objective was to define the effect of ionization on the baking properties and safety indicators of wheat flour.&#x0D; The study featured wheat flour subjected to gamma irradiation at 0–47.52 kGy, as well as dough and bread made from this flour. The flour samples were tested for the radioactivity of radionuclides; a set of experiments revealed their microbiological indicators and falling-number values. The dough samples were studied on an Alveograph and a Mixolab analyzer to define their structural and mechanical properties. The quality of bread was evaluated by its specific volume, shape stability, and sensory profile.&#x0D; The flour proved safe in terms of residual gamma radiation after 24 and 72 h. At the maximal dose of gamma radiation, the total viable count of mesophyll aerobic and optional-anaerobic microorganisms decreased by fifteen times, whereas the amount of mold decreased by five times. The total strain energy, elastic properties, and elasticity index of the dough declined by more than 50%. The dough had a lower stability during kneading. Its gelatinization onset started earlier by 2.3–3.3°C. The falling number decreased by more than four times, probably, due to the changes in the state of wheat starch. The bread samples had a smaller specific volume and a lower dimensional stability. They also demonstrated signs of darkening, stickiness, and crumb crushing at the maximal irradiation dose (47.52 kGy).&#x0D; The microbiological safety indicators of wheat flour increased at the maximal irradiation dose. However, the baking properties of flour decreased. The sensory and physicochemical parameters of bread quality started to deteriorate at ≥ 23 kGy. Therefore, ionization cannot be recommended as a disinfection method for baking wheat flour production.

Formulation of nanoemulsion carriers containing Pennyroyal (Mentha pulegium) and Gijavash (Froriepia subpinnata) essential oils for enriching Doogh (Iranian dairy drink).

Today, the increasing use of chemical preservatives in foods is considered one of the main problems in food industries. This study aimed to produce the pasteurised Doogh (Iranian yogurt drink) containing a nanoemulsion of essential oil (EO) with appropriate quality. A factorial test based on a completely randomised design with two treatments in three levels, including EO type (pennyroyal, Gijavash, and their equal combination) and a control sample was applied to assess the physicochemical and sensory properties of Doogh. The highest negative zeta potential and antioxidant activity percentage were observed in the sample containing the nanoemulsion of pennyroyal and enriched with a combination of two essential oils. The microbial evaluation results indicated that the total microorganism count was minimised in the Doogh containing the nanoemulsion of Gijavash. The nanoemulsions of pennyroyal and Gijavash can be added into Doogh formulation to produce a new product with maximum sensory acceptability.

Microbial Growth Dynamics in Minced Meat Enriched with Plant Powders

Plant powders with antimicrobial properties can be used in food manufacturing and must comply with the demands of consumers regarding microbiological safety, nutritional value, and sensory properties of foods. The present study aimed to assess the microbial growth inhibitory ability of different plant powders, including by-products of horticultural primary processing (e.g., pomace) in raw and cooked minced pork. The total counts of aerobic mesophilic bacteria, pseudomonads, yeasts, and moulds were studied to assess the microbial growth dynamics in meat samples. Additionally, for the plant powders, which were able to suppress the microbial growth in a total counts dynamics study, the growth potential of Listeria monocytogenes in ready-to-eat (RTE) minced meat samples was estimated by challenge testing. The results showed that the most effective combinations of plant powders in raw minced pork, in relation to the total counts of microorganisms, were 3% apple+1% onion+2% blackcurrant berries (Apple+On+BCber); 3% apple+1% garlic+2% tomato (Apple+Ga+Tom); and 3% apple+2% tomato+1% rhubarb petioles (Apple+Tom+Rhub). However, challenge tests revealed that some plant powders were unable to inhibit the growth of L. monocytogenes. The lowest L. monocytogenes growth potential (δ = 2.74 log cfu/g) was determined for cooked minced pork samples enriched with 2% rhubarb petioles, followed by Apple+On+BCber (δ = 3.63 log cfu/g) and Apple+Tom+Rhub (δ = 3.74 log cfu/g). In minced pork samples without plant additives, the L. monocytogenes growth potential was 7.30 log cfu/g. In conclusion, blends of plant powders may have good potential for developing meat products with acceptable microbiological quality.

Critical Effect of H2O2 in the Agar Plate on the Growth of Laboratory and Environmental Strains.

We previously showed that autoclaving in preparing agar media is one of the sources of hydrogen peroxide (H2O2) in the medium. This medium-embedded H2O2 was shown to lower the total colony count of environmental microorganisms. However, the critical concentrations of H2O2 detrimental to colony formation on the agar plate remain largely undetermined. Herein, we elucidated the specific effect of H2O2 on microbial colony formation on solid agar medium by external supplementation of varying amounts of H2O2. While common laboratory strains (often called domesticated microbes) formed colonies in the presence of high H2O2 concentrations (48.8 μM or higher), microbes from a freshwater sample demonstrated greatly decreased colony counts in the presence of 8.3 μM H2O2. This implies that environmental microbes are susceptible to much lower concentrations of H2O2 than laboratory strains. Among the emergent colonies on agar plates supplemented with different H2O2 concentrations, the relative abundance of betaproteobacterial colonies was found to be lower on plates containing higher amounts of H2O2. Further, the growth of the representative betaproteobacterial isolates was completely inhibited in the presence of 7.2 μM H2O2. Therefore, our study clearly demonstrates that low micromolar levels of H2O2 in agar plates critically affect growth of environmental microbes, and large portions of those are far more susceptible to the same than laboratory strains. IMPORTANCE It is well-known that most of environmental microorganisms do not form colonies on agar medium despite that agar medium is the commonly used solidified medium. We previously demonstrated the negative effects of H2O2 generation during agar medium preparation on colony formation. In the present study, we investigated the independent effect of H2O2 on microbial growth by adding different concentrations of H2O2 to agar medium. Our results demonstrate for the first time that even low micromolar levels of H2O2 in agar plates, that are far lower than previously recognized as significant, adversely affect colony number obtained from freshwater inoculum.

VARIABILITY OF SELECTED PARAMETERS OF HYGIENIC QUALITY OF FRESH, MARINATED AND GRILLED POULTRY MEAT IN RELATION TO ITS STORAGE CONDITIONS

The aim of research was to verify scientifically variability of selected parameters of hygienic quality of fresh (A), marinated (B-E) and grilled (G) poultry meat in relation to its storage conditions. Marinated meat was kept under various conditions (12 hours and 48 hours at a temperature of 0 to 4 °C and 5 to 8 °C) until it was heat-treated. Using microbiological and physico-chemical methods, poultry meat was analysed in fresh, marinated, as well as grilled state. During the experiment period, water activity, pH, salt, and fat content, but also TVC - total viable count of microorganisms, coliforms, MFF - microscopic filamentous fungi and yeast were analysed. The value of aw ranged from 0.92 (EG) to 0.99 (AG and D). The range of mean pH values ranged from 5.82 to 6.15. The salt content was lowest in fresh meat (0.16 g/100g), in samples of marinated meat it ranged from 0.38 to 0.47 g/100g. Thus, in neither case was the maximum permitted salt content (1.3 g/100g) exceeded. The difference between the lowest and the highest fat content was very observable. The lowest value of fat content 3.40 g/100g was obtained in the sample AG. On the contrary, the highest fat content (10.24 g/100g) was detected in the sample D. The average TVC value in fresh poultry meat was 4.01 log CFU/g. In marinating process, the value increased to 4.21 log CFU/g (12 hours, 0 to 4 °C) and to 4.65 log CFU/g (48 hours, 5 to 8 °C). Microorganisms were present in number of less than 1.101 CFU/g in grilled meat. The number of microscopic filamentous fungi and yeasts was low in fresh meat and marinated meat (&lt;4.101 CFU/g). After grilling they were not detected. Coliforms indicating the cross contamination were not present in the samples. All the obtained results were statistically evaluated. The data were processed to the analysis of variance (ANOVA) in the general linear models (GLM), Scheffe’s test and Pearson correlation coefficients (rxy).

Incorporating ε-Polylysine Hydrochloride, Tea Polyphenols, Nisin, and Ascorbic Acid into Edible Coating Solutions: Effect on Quality and Shelf Life of Marinated Eggs

This study aimed to develop and characterize the chitosan-edible coating solution (CS-NH-TC) incorporated with ε-polylysine hydrochloride, tea polyphenols, nisin, and ascorbic acid and then investigate their effect on physicochemical, antibacterial, and sensory properties of marinated eggs stored at 4 °C for 24 days; marinated eggs without coating were set as control. The CS-NH-TC edible coating solution exhibited the lowest particle size (582.6 ± 16.6 nm) and polydispersity index (0.49) and highest zeta potential (30.96) among the coatings. The FT-IR spectra showed that TP, VC, nisin, and ε-PLH were successfully encapsulated in the CS edible coating solution. The moisture content and water-holding capacity of the marinated eggs coated with CS-NH-TC remained stable up to 20 days. Marinated eggs coated with CS-NH-TC edible coating solution exhibited lower total viable counts of microorganisms and more stable color and pH values compared to the control during the entire storage time. Furthermore, the texture and sensory evaluation results demonstrated that marinated eggs coated with CS-NH-TC edible coating solution had low degradation rate and improved overall acceptability scores. This study confirmed that CS-NH-TC edible coating solution was a promising coating for improving the quality and shelf life of marinated egg products and may have a broad application prospect in the preservation of other food products.

Are the apocarotenoids content and colorimetric traits of saffron (Crocus sativus L.) affected by some post harvesting operations?

Saffron quality is strongly affected by post-harvest practices. In this regard, an experiment was conducted to evaluate the effect of flowers storage temperature (2, 8, and 21 °C) and storage duration (1, 2, 3, and 4 days) on color traits (L, a, b, oh, and C), apocarotenoids content (crocin, picrocrocin, and safranal, determined by HPLC and spectrophotometry methods), antioxidant compounds (anthocyanin and total phenol) and microbial load of dried stigmas and petals. The color quality of the stigma (L, a, C, and oh) improved by one day storing at two °C. HPLC analysis revealed that the highest contents of crocin, picrocrocin, and safranal in stigma were gained by one day storing at 2 °C, although the stigma quality was even acceptable in longer storing when storage temperature was low. A positive correlation between crocin and picrocrocin contents with color parameters (L, a, and C) suggests that colorimetry can be possibly used as a fast, easy, and cheap method for stigma quality assessment. The highest amounts of anthocyanin in stigma and petal (4167 and 9663 g 100 g−1 dry weight, respectively) were obtained at two °C and three days storing. Petal had more anthocyanin content than stigma in all storage duration and temperature combinations. The total count of microorganisms in stigma and petals decreased by reducing storage duration and temperature. Overall, lower storage temperature and shorter storage duration were more favorable for improving stigma and petals quality, but low storage temperature can compensate for the negative effect of longer storage duration.