Microbiological Quality Indicators Research Articles

The effect of functional additives on the indicator “water activity” of biscuit semi-finished products

Among different segments of the population of the Russian Federation, flour confectionery from biscuit dough is one of the most popular. In order to give them functional properties to increase the biological value, we used pumpkin in this work. Such an additive enriches the finished product with pectins, carotenoids and minerals. The introduction of pumpkin puree also has a positive effect on organoleptic characteristics, but increases the humidity of the finished product. Introduction to the recipe for biscuit pumpkin puree helps to increase the value of the indicator “water activity”. Researching the microbiological quality indicators in the products developed showed that between Aw and microbiological quality indicators such as QMAFAnM and the content of yeast and molds, a straightforward relationship is observed: an increase in the proportion of water in the finished biscuit cake mix leads to increasing in a total number of microorganisms and also increasing the microorganisms of spoilage. In the sample with 20% replacement of wheat flour with pumpkin puree, the value of Aw approaches the value characteristic of products with high humidity (0.9). Therefore, enriched biscuit semi-finished products have a shorter shelf life, it is advisable to produce them at public catering facilities.

The effect of dihydroquercetin on the stability of consumer properties of chopped semi-finished meat

The steadily increasing demand for semi-finished meat products is provided by the constantly expanding product range and improving its quality. In turn, quality stability is an important criterion for increasing sales. The article presents data on the effect of a natural antioxidant-dihydroquercetin on the stability of consumer properties of chopped semi-finished moose meat with the addition of beet fiber when stored at a negative temperature for 216 days. Dihydroquercetin was added in an amount of 0.05% by weight of the raw material. In the course of the work, generally accepted methods of studying organoleptic and microbiological quality indicators were used. The degree of oxidative deterioration of the product was checked by determining the acid, peroxide and thiobarbituric numbers. The conducted studies allowed us to conclude that the use of this food additive allows us to preserve the organoleptic and microbiological properties of the semi-finished product for a longer period by inhibiting the formation of oxidation products. The use of dihydroquercetin contributed to a decrease in the experimental sample of the semi-finished product on day 216 of the peroxide and acid number by 2 times, and the thiobarbituric number by 1.8 times in relation to the control. Thus, by reducing the oxidative damage of the semi-finished product, it is possible to influence its characteristics during storage.

Quality and safety ensuring in the development of flavored spices based on greated cereals using the HACCP principles

The object of research is the production of a new flavor seasoning of increased nutritional value based on sprouted green buckwheat using the HACCP (Hazard Analysis and Critical Control Points) principles. Research is aimed at drawing up a HACCP plan in order to control the safety of flavoring condiments of increased nutritional value. The new flavor seasoning is developed on the basis of sprouted green buckwheat of the «Bogatyr» variety, dried vegetables (carrots, pumpkin, garlic), dried herbs (celery, basil, oregano, dill), spices (ginger, turmeric, curry, paprika, coriander).For a flavoring seasoning with the addition of 30 % sprouted green buckwheat, technical conditions have been developed, where the requirements for organoleptic, physico-chemical and microbiological quality indicators are normalized.The paper describes the method of germination of green buckwheat grain, as well as the standards used for drawing up the HACCP plan at the enterprise.As a result of the analysis of the production process of flavoring seasoning, dangerous factors and management measures were identified. Three critical control points have been identified: in the process sprouted, in the process disinfection under grain germination, and in the process packaging of the finished product. Biological, chemical and physical hazards that can occur at each stage of seasoning production are identified. Once the risk factor was identified, critical limits were identified and monitoring procedures were established, as well as corrective actions were developed. During the research, a HACCP plan was developed for a new type of flavor seasoning with increased nutritional value in order to improve the safety and quality of products. The application of the HACCP plan will allow to effectively manage processes, use preventive measures, and accurately identify critical processes.

Sanitary, Hygienic and Epidemiological Aspects of Recreational Water Use of the Population of the Upper Don River Basin

Introduction: The problem of safe recreational water use is closely related to conditions of surface water bodies (rivers, reservoirs, lakes, and ponds) experiencing a significant anthropogenic load and their water quality. The purpose of the study was to assess safety of recreational water use of the population based on the results of testing water quality in the bodies of water of the Upper Don River basin. Materials and methods: In 2015–2019, surface water samples were taken at 73 water quality checkpoints of 26 water bodies and tested for chemical, microbiological and parasitological indicators. Test results were then used to assess hazards related to recreational water use of the population. Results: It was found that in 26 of 73 surveyed recreation areas (35.6 %) water quality failed to meet recreational water quality criteria. Poor microbiological water quality indicators were established at 21 of 73 sites (26.7 %) with the proportion of water samples with high thermotolerant and total coliform counts varying from 1.5 to 75.0 %. Risks of epidemic hazard posed by recreational water use were assessed to be the highest in three recreation areas (4.1 %) and moderate – in 18 areas (24.7 %). Conclusions: The estimated reliability of differences in the long-term incidence rates of infectious diseases probably related to microbiological surface water quality indicators (by Student’s t-test) confirmed the hypothesized association between poor microbiological water quality parameters and high incidence rates of acute intestinal infections and bacillary (Flexner) dysentery (p < 0.05). The findings demonstrate the necessity of implementing measures to ensure health and epidemic safety of recreational water use of the population.

Економічна ефективність санітарної обробки доїльного обладнання за використання екологічно безпечних мийно-дезінфікувальних засобів Санімол Л і Санімол К

Goal. To determine the economic efficiency of sanitation of milking and dairy equipment with the use of new detergents Sanimol L and Sanimol K. Methods. General scientific methods are used: analysis and synthesis, comparison, and theoretical generalization. A direct calculation of the difference in the cost of similar funds is also made. Results. It is determined that the total estimated economic effect per 100 lactating cows during sanitation of 5 portable milking machines three times a day and milk cooler once a day with Sanimol L and Sanimol K during the year will be UAH 21,097 compared to CircoSuper AF and Sidmax. The economic effect obtained due to the increase of microbiological indicators of milk quality as a result of sanitary treatment of milking equipment with Sanimol L and Sanimol K is calculated for 100 cows for 3 times milking with portable milking machines. The milk yield for one lactating cow was 4,500 kg/year. Before the introduction of sanitary treatment of milking equipment with Sanimol L and Sanimol K, the farm received the grade I milk which worth 8.4 UAH/kg. The use of these preparations made it possible to obtain and deliver milk to the processing plant of the extra grade for 9.8 UAH/kg. Annual economic effect — UAH 624097.2. Conclusions. The use of Sanimol L for sanitary treatment of milking equipment is 1.3–1.8 times more cost-effective compared to CircoSuper AF, and Sanimol K — 3.8–4 times more than Sidmax. The annual economic effect due to the use of Sanimol L and Sanimol K for sanitation of milking equipment and dairy equipment on dairy farms with a population of 100 cows will amount to UAH 624097.2.

Spatial cross-correlation between physicochemical and microbiological variables at superficial soil with different levels of degradation

Best soil management practices can be achieved by evaluating the spatial cross-correlation variability ofsoil microbiological and physicochemical indicators, in order to comprehend the underlying relations between these mutually dependent properties, being valuable indicators for prospective evaluation of soil resources.The purposes of this study were to measure microbiological and physicochemical variables in superficial soil, spatially cross-correlate and determine spatial causalities between these two families of variables.The spatial variability of pH, gravimetric soil water content, 238U, 232Th, 40K, 137Cs, acid phosphatase, dehydrogenase activity, microbial biomass carbon, mesophilic aerobic bacteria and filamentous fungi was studied at a 13 ha field located in Uruguay.238U and 232Th were both negatively lineally correlated with gravimetric soil water content (−0.42), 137Cs (-0.45 and −0.48 respectively) and dehydrogenase activity (-0.44 and −0.48 respectively). A semivariogram analysis revealed that the best fit model for soil variables was spherical, with moderate to strong spatial dependence. Cross-correlation results suggest that there is an influence factor from spatial interaction. In this sense, gravimetric soil water content connects physicochemical variables with soil biodiversity. Spatially, soil water content is inversely influenced by 232Th and 238U (as indicators of sub-superficial soil), and directly influenced by dehydrogenase activity (indicator of soil microbial activity), revealing soil microbial activity as a possible indicator of water retention in drying soils. The combination of spatial patterns of environmental radionuclides with microbiological indicators of soil quality could represent a valuable integrated approach to assess soil conservation status and further explain the impact of anthropogenic disturbance.

INVESTIGATION OF HISTAMINE LEVELS IN PASTEURIZED, HIGH HEAT-TREATED MILK AND TYPES OF CHEESE

Histamine is the most common and toxic biogenic amine in foods. The presence of histamine in some foods is considered as an indicator of microbiological quality and hygiene. In this study, it was aimed to investigate the amount of histamine in some milk and cheese consumed in Ankara. A total of 116 samples of 20 different pasteurized milk, 20 high heat-treated milk and 76 cheese samples (tulum cheese, white cheese, fresh kashar cheese, and labne cheese) were analyzed by enzyme-linked immunosorbent assay (ELISA) technique. As a result, In 29 (72.5%) of 40 milk samples, the presence of histamine was detected in concentrations ranging between 0.10 and 0.32 mg/L. The mean levels (±S.E) of histamine of milk samples were found to be 0.18±0.01 mg/L. In 58 (76.3 %) of 76 cheese samples, the presence of histamine was detected in concentrations ranging between 2.52 and 189.79 mg/kg. Regarding the tulum cheese, white cheese, fresh kashar cheese, and labne cheese samples, mean levels (±SE) of histamine in were found to be 56.60±12.56 mg/kg; 3.68±0.29 mg/kg; 4.88±0.35 mg/kg and 4.48±0.39 mg/kg, respectively. The mean levels of histamine of cheeses were higher than mean levels of histamine of milk. The differences between mean levels of histamine in milk samples and the mean levels of histamine in cheese samples were statistically significant (P<0.001). At present, there are no established limits on Turkish Food Codex for histamine concentrations in milk and cheeses.

Antimicrobial resistance and ESBL genes in E. coli isolated in proximity to a sewage treatment plant

This study was aimed to determine the prevalence of antibiotic-resistant Escherichia coli in the Szreniawa river with detailed aims of: (i) assessment of differences in the number of microbiological indicators of water quality in a diurnal cycle in a vicinity of the sewage treatment plant (STP); (ii) determination of prevalence of antimicrobial resistant E. coli isolated from three sites located at varying locations toward the STP; (iii) evaluation of the presence of extended-spectrum beta lactamase (ESBL)-determining genes in waterborne E. coli isolated from three sites of Szreniawa and (iv) genetic similarity assessment among the E. coli populations. Bacteriological contamination (coliforms, E. coli, E. faecalis) was assessed using membrane filtration. Fifty E. coli strains, the species of which was confirmed by MALDI-TOF analysis, were subjected to antimicrobial resistance tests using standard disk-diffusion method. Double disk synergy test was used to assess the ESBL production and PCR tests were conducted to detect the ESBL-conferring genes and evaluate the genetic diversity. A significant variation in the number of bacteriological indicators was observed both within and between the sampling sites, suggesting the effect of effluent from the STP, point discharge of household sewage and agricultural runoff on the water contamination. The resistance to amoxicillin/clavulanate (90%) and ampicillin (36%) was most prevalent. Multidrug resistance was observed in 40% of strains but no ESBL-producing strains were observed phenotypically. However, the presence of three ESBL-determining genes (TEM, OXA and CTX-M) was detected in 24, 10 and 8% of strains, respectively. A number of factors caused considerable pollution of the river and numerous multidrug resistant E. coli strains were isolated.

COMPREHENSIVE ASSESSMENT OF QUALITY AND SAFETY OF BERRY SAUCE WITH IODINE-CONTAINING ADDITIVE

One of the acute problems of our time is iodine deficiency in human nutrition, which is typical for both countries with economies in transition and economically developed ones. Today, about a third of the world's population live in conditions of natural iodine deficiency. The most common solution to iodine deficiency is salt iodization, but this can lead to excessive iodine intake. In addition, it is much healthier to eat organic iodine, which is found in large quantities in brown algae. It is the development of new types of food products using brown algae as a biologically active additive that is a new promising direction for solving the problem of insufficient iodine consumption. Taking into account the relevance of solving the problem of iodine deficiency and the constantly growing demand for fruit and berry sauces, the technology of berry sauces based on blueberries, cranberries, dogwood, sea buckthorn and viburnum with the addition of brown algae has been developed. However, the mass introduction into production and consumption of the developed sauces will make a significant contribution to solving the global problem of insufficient consumption of organic iodine, requires research to establish their compliance with the typical quality and safety indicators for these products. The physicochemical indicators of the developed berry sauces were investigated, confirming the high quality in terms of the content of soluble solids – 25.0 ... 28.5%, the mass fraction of titratable acids – 1.9%, and indicate the complete absence of mineral, vegetable and foreign substances in the product. It was found that the developed sauces with iodine-containing algal additive have high microbiological quality indicators when stored for up to 14 days, even without adding preservatives. The complete safety of the developed berry sauces was established in terms of the content of toxic elements, as well as the absence of genetically modified organisms in the finished product

The optimization of the recipe storage of frozen pancakes with minced meat

The purpose of the article is to optimize the formulation of frozen pancake with minced meat of extra biological value. Based on the monitoring of the foodmarket, it was concluded that the range of frozen pancakes with minced meatisone of the most popular. The analysis of modern researches in this direction is carried out.It is also established the necessity for developmentof new resource-saving technologies of frozen uncooked food of highbiological value. The subject of the research is technology, semi-fi nished pancakes, minced meat, Jerusalem artichoke and eggplant food powders. It has been identifi ed the upcoming food supplements. A recipe for a semi-fi nished pancake has been developed. When working out the technological solutions for the production of coat for pancakes with Jerusalem artichoke powder, the dosage of powder varied from 1 to 5% in increments of 1%. For minced meat, the replacement of raw meat with reconstituted eggplant powder was from 2 % to 20% in increments of 4% . Based on the analysis of organoleptic quality indicators of the semi-fi nished pancake (shell), the rational dosage of Jerusalem artichoke powder, equal to 2%, was fi nally established. Based on the results of the research, a rational amount of reconstituted eggplant powder was established, that is 10% of the total weight of semi-fi nished products. We can see the quoted results of research with organoleptic, microbiological indicators of quality. It was found that the chemical composition of the developed pancakes with the addition of Jerusalem artichoke powder (shell) and eggplant (minced meat) have a more balanced composition in terms of nutrients and essential substances. It is investigated that according to microbiological indicators the developed pancake semi-fi nished product is safe. The results of the experiments prove that the chosen eggplant and Jerusalem artichoke powders, as well as other vegetable powders are eff ective products of functional nutrition. Therefore, these products can be off ered for mass use in the production of fl our products, namely pancakes. Key words: pancake semi-fi nished product, food powder, eggplant, Jerusalem artichoke, minced meat, pancakes.

Individual and combined mild heat and UV-C processes for orange juice against Escherichia coli O157:H7

This study was conducted to evaluate the individual and combined efficacies of mild heating at 53 °C and ultraviolet-C (UV–C) irradiation at 1.14 mW/cm2 (0.0114 kJ/m2 s) against E. coli O157:H7 in orange juice. Processes were calculated from inactivation parameters and applied to orange juice either individually such as heating to inactivate 5 log cycles of the organism (H5D), UV-C irradiation to inactivate the same (UV–C5D); or sequentially to achieve an additive inactivation rate of 5 log cycles, including H3D → UV-C2D, and UV-C2D → H3D. A simultaneous treatment of H3D + UV-C0.2D was also tested. Among the processes that targeted the 5-log reduction, only the H5D was able to achieve the desired population decline (5.03 ± 0.03 log CFU). The greatest population change was observed when subjected to the simultaneous H3D + UV-C0.2D process (6.35 log CFU). Microbiological quality indicators of orange juice subjected to the same set of processes were significantly improved with significant reduction in the ascorbic acid. Color space coordinates were also significantly affected by the treatments as determined by colorimetric measurements. However, color changes were not detected by consumers in samples, except for that subjected to the UV-C5D.

Different amounts of sugarcane trash left on the soil: Effects on microbial and enzymatic indicators in a short‐term experiment

AbstractWhen using mechanical harvesting, the sugarcane trash can be partially recovered for use as feedstock for bioenergy. However, the amount of trash that can be removed without prejudicing the sustainability of the sugarcane production system has still been little studied. The aim of this study was to evaluate the short‐term impact of removing part of the sugarcane trash using enzymatic and microbiological soil quality indicators. We tested three rates of trash removal: 0% (T0), 50% (T50) and 100% (T100). The microbial biomass C (Cmic) and N (Nmic), β‐glucosidase activity (GA) and the ratios Cmic as a per cent of Ctot and Nmic as a per cent of Ntot were highest for T100. The urease activity decreased with an increase in trash removal. The specific activity of β‐glucosidase did not differ between the treatments, while the specific activity of urease showed the same pattern as the absolute activity. The metabolic quotients (qCO2) were higher for T50 and T100 with no significant difference between them. The principal component analysis showed that the first component, which explained 77.66% of the total variance, was significantly correlated with Nmic, basal respiration and GA and discriminated the three treatments. The results showed that the removal of part of the trash adversely affected some of the soil quality attributes. This suggests the need for monitoring over a period of years in sugarcane areas where part of the trash is removed for industrial purposes, in order to better understand the cumulative impact on soil quality and to ensure the sustainability of bioenergy production.

A Graduated Approach in the Abolition of Waterborne Diseases in Drinking Water Using an Indicator Based Approach and Nano Based Biosensors: A Review

The detection of pathogens continues to be a challenge in this present day despite the advancement in technology. The emergence of waterborne diseases is of great importance and their rapid detection and identification in water is of utmost importance. Water quality indicators and pathogen detection in environmental water samples is significant for maintaining safe drinking water. Traditional methods like the culture-based methods are laborious, time consuming and yield false-positive results. Hence, a lot of research has been put in developing rapid detection methods and quantifying water pathogens in water. These methods include the use of water quality indicators as early warning systems and nano material based biosensor detection methods. The review highlights “the state of the art” method for monitoring and detecting waterborne pathogens. The review summarizes the microbiological water quality indicators and biosensor based methods. These methods are time effective, sensitive, specific and therefore important in the diagnosis and prevention of waterborne diseases. Keywords: Waterborne Diseases, Biosensor based methods, Water quality indicators , Pathogens. DOI: 10.7176/JEES/10-3-07 Publication date: March 31 st 2020

Microbiological indicators of soil quality are related to greater coffee yield in the Brazilian Cerrado region

Abstract One of the main challenges faced by the rapidly growing human population is to increase agricultural sustainability. Soil quality is an essential aspect of agricultural sustainability, but farmers have generally assessed this based on conventional chemical and physical indicators, with little application of indicators of soil functions, such as soil microbiological attributes. These indicators may respond faster to changes in soil conditions and thus they could correlate better with the growth/yield of crops such as coffee. The aim of this study was to investigate the potential of soil microbiological indicators in assessment of soil quality for sustained coffee production, compared to or combined with conventional soil physical and chemical indicators. To accomplish that, two observational studies were performed by measuring soil microbiological, physical, and chemical attributes in coffee field areas with contrasting records of coffee yield but under similar edaphic and climatic conditions in the Cerrado (Brazilian tropical savanna) region of Minas Gerais, Brazil. In the first study, two neighboring field areas with contrasting yield were selected for each of the following three cultivars: Catuai Vermelho IAC 99, Catuai Vermelho IAC 144, and Rubi MG 1192. Samples were taken in two seasons (dry and rainy) of the year. In the second study, four neighboring field areas cropped with the cultivar Catuai Vermelho IAC 144 were chosen based on their contrasting yield records. In both studies, the experimental procedure consisted of collecting four composite soil samples (each composed of four subsamples) taken at a depth of 0–10 cm from each field area within the area of canopy projection of the coffee plant. The microbiological attributes evaluated were microbial biomass carbon; microbial basal respiration; metabolic quotient; urease, β-glucosidase, and arylsulfatase enzyme activities; and fluorescein diacetate hydrolysis. The physical and chemical attributes evaluated were texture, pH, organic matter content, and fertility. Climatic conditions affected the responses and must be considered in evaluation and elaboration of soil quality indexes. The physical and chemical attributes that were most closely related to higher coffee yields were Ca contents, organic matter content, effective cation exchange capacity, and base saturation in both studies in the rainy season. Microbial biomass carbon, metabolic quotient, and β-glucosidase and urease activities were positively related to higher coffee yields, and these attributes exhibited greater ability to discriminate the production potential of the soil than chemical and physical attributes did, in both seasons and studies.

The influence of barley weed impurities on the microbiological quality indicators

Currently, malting barley is one of the most important crops that form the basis of the food business in the Russian Federation. Malting barley is imported to Europe, Asia, Africa and South America. While storing and transporting grain, its microbiological quality indicators play a very important role. Grain seeded with various microorganisms quickly loses its functional and technological properties, which negatively affects the quality of beer produced from it. According to the results of the studies, it was found that the contamination of barley with microorganisms is greatly influenced by various impurities that enter the grain mass during harvest. As well as various impurities in the grain mass of malting barley, the grains of other plants wheat, rye and oats were found in some samples in quantity of about 4%. There were also a lot of beaten barley grains, in some samples more than 2%. The moisture content of the grain mass also affects the seeding by microorganisms. Impurities had a higher humidity than grain, purified from impurities. To reduce the microbial contamination of brewing barley grains, it is necessary to thoroughly clean and refine the grain mass immediately after harvesting.

The possibility of using lactic additives and sonochemical technology in the production of preserves

The priority in improving the existing methods of processing fish is salting with the use of food additives with different functional orientations. The aim of the study was the development of preserves with the introduction of lactate-containing additives and using sonochemical technologies; examination of the quality of the products obtained according to organoleptic and microbiological safety indicators. The article proposes a resource-saving technology for the production of fish products with prolonged shelf life due to the use of a complex food additive consisting of lactic, acetic, propionic acids and their salts in different proportions with subsequent ultrasonic treatment using the ultrasonic generator of the Wave series model UZTA-0 2/22-OM. There was established the optimal mode of using the ultrasonic processing power of 75 W / m2 in the manufacture of fish preserves from herring. Organoleptic and microbiological quality indicators were studied during storage of preserved products with the addition of additives and ultrasonic treatment compared to the control. Organoleptic assessment was carried out on a five-point scale, microbiological indicators were studied by standard methods. The Dilactin Forte Plus dietary supplement in the composition of preserves in the amount of 3% and in combination with the use of sonochemical technologies makes it possible to obtain a safe high-quality fish product. Manufactured preserves at a storage temperature of 0 ± 2 ° C can maintain their high quality for 5 months.

ПРОБЛЕМЫ КАЧЕСТВА ПИТЬЕВОЙ ВОДЫ ЗАПАДНОЙ ЧАСТИ КРЫМА

Introduction. Until 2014, water supply in Sevastopol city and its municipal districts was combined due to its own surface and underground waters as well as a water conduit running from the Mezhgornoye reservoir located in the Saksky district and filled with the Dnieper waters of the North Crimean Canal. After 2014, this source was shut off. Therefore, it became important to conduct a comparative analysis of the quality of drinking water supplied to the settlements of this territorial entity. Purpose of the study: The study is aimed to assess the quality of drinking water and perform its analysis in Sevastopol city and nearby settlements, taking into account the increase in water intake from rivers and underground sources in recent years. Methods. Objects of the study are surface and underground water supply points, and drinking water for consumers. We used standard methods for the analysis of drinking water with an assessment of its physical, chemical and sanitary-bacteriological indicators using analysis of variance (AoV) methods. Water quality was assessed by the specific combinatorial index of water pollution. Using GIS technologies, maps were built to visualize a number of indicators: chemical oxygen consumption and data on the water pollution complexity coefficient at the stage when consumers receive water from the central water supply system (for all municipal districts). Results. It was established that sanitary and microbiological indicators of tap water quality — by the total microbial count, total coliform bacteria and thermo-tolerant coliform bacteria — immediately before being fed to the central water supply system in the Southern and Northern districts of Sevastopol, did not exceed sanitary standards. Due to the considerable length of the distribution networks and their high deterioration, secondary pollution of drinking water is currently taking place. In a number of municipal districts, it was revealed that the key indicators being assessed exceeded the norms of the State Sanitary Rules and Regulations. For the first time, with the help of GIS technologies in the ArcGis 10.4 software shell, specific ranks of drinking water pollution levels were distinguished for individual municipal districts, which made it possible to visualize the dynamic characteristics of polluting ingredients taking into account their territorial affiliation.

Productive feeding of rainbow trout: properties, effects on physiological state and interior indicators

It is advisable to use secondary resources of the fish industry with high protein content as a raw material for the development of biologically complete feeds in aquaculture. The work uses standard and original research methods. A complex studies of the chemical composition, physico-chemical and microbiological quality indicators of the experimental feed proved its balance in amino acid composition. The degree of essential amino acids was 91.5 to 107.3%. The biological value of feed protein is 95.18%. It was proved that the amount of free ammonia released through the fish gills is directly proportional to the amount of feed eaten, inversely proportional to the feed coefficient and equal to 0.05. The pH value changed on the 42nd day from 7.6 to 7.7 but remained within the range of pH 6-9, which is optimal for the life support of fish. The absolute increase in the amount of individuals in the control group was 1.2% higher compared with the experimental one. At the same time, feed costs for the entire feeding period were 0.99. Fish survival was 98%. In both cases, bifidobacteria were isolated from the resistant microflora. Notably, the bifidobacteria titer was 3 lg units higher in the trout of the experimental group in comparison with the control group, which does not exceed permissible norms. Thus, the obtained feeding is not inferior in quality to the imported feeding. Therefore, it can be recommended for feeding rainbow trout grown in recirculating aquaculture systems.

Determination of the utility of ultraviolet-C irradiation for dried bay leaves microbial decontamination through safety and quality evaluations

This study was conducted to determine the efficacy of UV-C irradiation for safety and quality of dried bay leaves. Cocktails of microorganisms of the same species were prepared and inoculated onto the leaves, which were thereafter subjected to UV-C irradiation. Results showed that all tested organisms, which included Escherichia coli O157:H7, Salmonella enterica, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus, exhibited inactivation behaviors in the irradiated leaves that are characterized by initial log-linear population decline, followed by inactivation tail. The Total Log Reductions in the organisms after exposure to 3942 mJ/cm2 UV-C dose ranged from 2.70 to 3.93 log CFU/g. Furthermore, subjecting the bay leaves to UV-C of as much as 13662 mJ/cm2 did not significantly alter color, and visual sensory properties, and did not result in mercury deposition. Microbiological quality indicators of the bay leaves, including Total Plate Count and Yeast and Molds Count were improved by the UV-C irradiation. These results contribute in further understanding the scope and limitations of using UV-C as a decontamination technique for specific food product such as dried bay leaves.

Microbiological indicators of tropical soils quality in ecosystems of the north-east area of Peru

Tropical soils withstand heavy pressure due to deforestation as a result of the change in land use, decreasing their quality. Traditionally, the quality of soil has been based on physical and chemical indicators; however, the biological ones can predict variations in the quality, in an early and effective way. In this research, the microbiological quality of soils from two ecosystems was evaluated, one from the Cumbaza Sub-Basin (CSB) and the other from Degraded Pastures at Cunumbuque (DPC), both in San Martin, Peru. The physicochemical characteristics were studied and the microbial populations of Total Bacteria (TB), Sporulated Bacteria (SB), Total Fungi (TF), Actinobacteria (ACT), and parameters of microbial activity such as Basal Respiration (BR), Microbial Biomass (MB), Metabolic Quotient (qCO2) and Microbial Quotient (qMIC). According to the Principal Component Analysis (PCA), the soils of the CSB had on average a lower biological quality compared to the DPC soils. The PCA discriminated that the microbial populations of TB, SB, ACT and MB represented effective microbiological indicators to evaluate the quality of the soils, in this respect the soils of Shapumba, Chontal, Aucaloma and Vista Alegre are degraded and require the application of new technologies and public policies for their recovery.