Effects of Gaseous Ozone on Microbiological Quality of Andean Blackberries (Rubus glaucus Benth)

Andean blackberries are highly perishable due to their susceptibility to water loss, softening, mechanical injuries, and postharvest diseases. In this study, the antimicrobial efficacy of gaseous ozone against spoilage (mesophiles, psychrotrophs, and yeasts and molds) and pathogenic (E. coli, S. enterica, and B. cinerea) microorganisms was evaluated during 10 days of storage at 6 ± 1 °C. Respiration rate and mass loss were also determined. Ozone was applied prior to storage at 0.4, 0.5, 0.6, and 0.7 ppm, for 3 min. The best results were observed with the higher ozone dose, with initial maximum reductions of ~0.5, 1.09, and 0.46 log units for E. coli, S. enterica, and B. cinerea, respectively. For the native microflora, maximum reductions of 1.85, 1.89, and 2.24 log units were achieved on day 1 for the mesophiles, psychrotrophs, and yeasts and molds, respectively, and this effect was maintained throughout storage. In addition, the lower respiration rate and mass loss of the blackberries ozonated at 0.7 ppm indicate that this treatment did not induce physiological damage to the fruit. Gaseous O3 could be effective in maintaining the postharvest quality of blackberries throughout refrigerated storage but higher doses could be advisable to enhance its antimicrobial activity.

Chemometric Comparison of High-Pressure Processing and Thermal Pasteurization: The Nutritive, Sensory, and Microbial Quality of Smoothies

This study investigated the status of bioactive compounds (phenolic compounds, carotenoids, and vitamin C), changes in color performance, and microbiological quality in smoothies preserved by high-pressure processing (HP) and thermal pasteurization (P) during cold storage at 4 °C for 21 days. Chemometric tools were used to select relevant variables that represent the most useful information for the fast and accurate quality assessment of smoothies. HP was performed at 350 and 450 MPa for 5 and 15 min at room temperature, respectively, while P was performed at 85 °C for 7 min. Smoothies were prepared by blending juices of apple (50%, v/v), carrot (20%, v/v), chokeberry (5%, v/v), Indian banana puree (10%, w/v), and almond drink (15%, v/v). The results obtained indicated that lower pressures with a shorter duration of HP showed higher levels of bioactive compounds in the smoothies, compared to the control samples. Compared to P, the HP samples exhibited a greater stability of bioactive compounds during shelf life. HP was found to be highly effective in reducing the native microflora of the smoothies, without subsequent microbial activation during storage. This study demonstrated the usefulness of the chemometric approach in interpreting complex datasets for the effective quality assessment of smoothies treated with different preservation technologies.

Isolation and Molecular Identification of the Native Microflora on Flammulina velutipes Fruiting Bodies and Modeling the Growth of Dominant Microbiota (Lactococcus lactis)

The objectives of this study were to isolate and identify the dominant microorganism in Flammulina velutipes fruiting bodies (FVFB) and to develop kinetic models for describing its growth. The native microflora community on FVFB was isolated and identified using morphological examination and high-throughput sequencing analysis. FVFB presented complex microbial communities with dominant microorganisms being Lactococcus lactis. Irradiated FVFB were inoculated with the isolated strain of L. lactis and cultivated at various temperatures (4, 10, 16, 20, 25, 32, and 37°C). Three primary models, namely the Huang, Baranyi and Roberts, and reparameterized Gompertz models, and three secondary models, namely the Huang square-root, Ratkowsky square-root, and Arrhenius-type models, were developed and evaluated. With the lowest values of mean square error (MSE, 0.023–0.161) and root mean square error (RMSE, 0.152–0.401) values, the reparameterized Gompertz model was more suitable to describe the growth of L. lactis on FVFB than both Huang and Baranyi and Roberts models. The Ratkowsky square-root model provided more accurate estimation for the effect of temperature on the specific growth rate of L. lactis. The minimum growth temperature predicted by the Ratkowsky square-root model was −7.1°C. The kinetic models developed in this study could be used to evaluate the growth behavior of L. lactis on FVFB and estimate the shelf-life of FVFB.

Effect of ultraviolet-C light and mild thermal treatment on the storage life of orange juice

This study aimed to evaluate the effect of low-dosage treatment with ultraviolet-C light (19.75 J L^–1 for 5 min), mild thermal treatment (40 °C for 5 min), or their combination on the native microflora (mesophiles and moulds plus yeast) and consumer acceptance of orange juice at the beginning and after storage (5 or 22 °C). Results indicated that UV-C light and mild thermal treatments reduce 0.19 ± 0.03 and 0.25 ± 0.02 log cycles (both kinds of microorganisms), respectively. The combination of treatments displays an additive effect against mesophiles (0.47 ± 0.01 log) and moulds plus yeasts (0.42 ± 0.02 log). After 9 days of storage at 5 °C, combined treatment did not present any microbial increases (P > 0.05), while consumer acceptance was similar (P > 0.05) to the fresh orange juice. Although several studies about the use of hurdle technology using UV-C light in orange juice have to be conducted, the results obtained in this study are promising, and they can be used for further studies.

The possibility of increasing the shelf life of dried apricot with application of uv radiation

The use of physical methods of processing, in particular ultraviolet radiation, is used in the food industry for the purpose of disinfection of raw materials, semi-finished products and finished products, which increases the storage time. The process of processing food products with ultraviolet light quickly proved itself. This method does not change the taste of the product, increases the shelf life and sales, and is a non-thermal method of deactivating pathogens. The wide use of the bactericidal effect of UV rays for food products is limited by their low penetration capacity, so the UV spectrum can be used mainly for sur-face sterilization, provided that the deep layers of the material do not contain microflora. The effectiveness of UV radiation depends on the following factors: the source and the UV dose; the sensitivity of microorganisms to UV light; the composition and physical properties of the product. Object of research: model media containing native microflora of dried fruit raw materials "dried Apri-cots". The research was carried out using model media simulating the proper-ties of the raw material surface, excluding its protective mechanisms and allow-ing to reveal the true dynamics of inhibition of native microflora. Native micro-flora of dried fruits implies a set of microorganisms. Literature sources have shown the possibility of the presence of such types of microorganisms as E. coli, Salmonella, Candida, Pseudomonas, spore forms of microorganisms on the surface of raw materials. During the experiment it was determined that the treatment duration of 5 min reduced the initial contamination of 2 order pro-cessing in 10 minutes – 2.6 the order in 15 minutes – 2.7 order and 20 minutes for 3 orders of magnitude.

The study of patterns of inhibition native microflora of raw materials under the influence of ultraviolet radiation with different processing intensity

Ultraviolet radiation has long proven itself as a technological process that allows you to reduce a significant amount or completely inhibit unwanted microorganisms, however, this technology is mainly used for disinfection of air and surfaces in industrial enterprises. The use of food processing with ultraviolet light is poorly developed, this is due to a number of limitations, one of which is the small depth of penetration of ultraviolet radiation. This circumstance introduces a number of restrictions and requires additional research for the active introduction of UV radiation in the food industry. The aim of the work: to study the dynamics of inhibition of native microflora of raw materials during UV treatment with various doses; to determine the degree of development of residual microflora during storage of UV-treated food products. Objects of research: model media containing native microflora of raw materials and fresh mushrooms. An improved UV treatment mode is proposed to reduce the surface injury of fresh mushrooms and ensure their microbiological stability of champignons during storage. The obtained results allowed us to establish the regularities of inhibition of native microflora on the surface of model media and fresh mushrooms depending on the distance to the UV radiation source, the time of irradiation, and the accumulated dose. It is noted that the dynamics of inhibition of native microflora on the surface of model media is not linear, and "Plateau" zones are marked. When developing a technology for processing fresh mushrooms, it is recommended to use a UV source with an accumulated radiation dose of 500 Dg/m2.

Selection and valorization of arbuscular mycorrhizal fungi isolated from phosphate sludge basins in promoting of citrus and carob seedlings

Accumulation of phosphate sludge (PS) generated from phosphate treatment process in the open air represent an environment risk and a problem in terms of storage capacities. The use of this by-products in agriculture, is an alternative recovery technique for the phosphate. Moreover, selection of symbionts and their inoculation into the soil whether in the nursery or at field were strongly encouraged. These inoculants were selected not only for their impact on the plant, but also for their ability to persist in the soil at the expense of the residual native microflora. This can be performed to the microorganisms which could occur in the solid sludges deriving the exploitation of phosphates in a pilot site of Khouribga area. In this context, the indigenous mycorrhizal resources have been exploited through better exploration of the local floristic diversity and then a series of mycorrhizal fungi selection and production tests have been made. The mycorrhizal complex was prepared and their effect was tested in Citrus and carob plants growth in the nursery. Two mixtures of PS were carried out: 10% (S2) and 40% (S5) for Citrus plants and 20% (S3) and 40% (S5) for carob plants. The sandy soil of Maamora forest was used as a control (S1). The results shown three dominant morphotypes were detected: Rhizophagus irregularis, Funnileformis constrictum and Scutellospora calospora. The effect of the PS with the AMF-based inoculum indicate that mycorrhizal inoculation of the substrates by a raw inoculum stimulates the growth of plants specially S2, S5 and S3 for Citrus volkameriana, Carrizo citrange and carob respectively. Based on these results, this combination between PS and mycorrhizal fungi had a great effect on Citrus and carob plant in the nursery.

INFLUENCE OF THE MODIFIED WOOD BARK "UNISORB-BIO" ON THE RESTORATION OF SOILS CONTAMI-NATED WITH OIL

The article examines the effect of the "Unisorb-Bio" carbamide sorbent modified with wood bark on the biodegradation of fuel oil using the example of artificially contaminated soil. It is shown that for 100 days of exposure "Unisorb-Bio" and actinomycetes immobilized on it (Streptomyces exfoliatus strain) are able to effectively decompose fuel oil. The maximum value of the degree of destruction of fuel oil was 82.7% in soil samples with a sorbent modified with birch bark. In the samples with larch bark, this figure is 7.3% lower. The degree of destruction of fuel oil in the control soil sample (soil with fuel oil) for the entire exposure period was – 27.4%. If this figure is taken as the background, then only the direct contribution to the degradation of fuel oil biosorbent is 45.1%; biosorbent with 0.2% diammofoska – 55%; sorbent without microorganisms – 33.8%. The results showed that the used carbamide sorbent with immobilized and native microflora is capable of effectively decomposing fuel oil to concentrations that allow the transition to agrotechnical measures. Thus, sowing watercress on soils after the end of the experiment showed that seed germination is 50–60%, which suggests that residual concentrations of fuel oil are relatively harmless to the root system of plants and the completion of the bioremidation process can be carried out by growing plants that are resistant to residual concentrations of pollutants. In general, the result confirms the effectiveness of the applied method in accelerating bioremidation processes, but further development is required in the direction of creating mixed associations of UVOM.

Population Dynamics of Listeria monocytogenes, Escherichia coli O157:H7, and Native Microflora During Manufacture and Aging of Gouda Cheese Made with Unpasteurized Milk

ABSTRACT Cheeses made with unpasteurized milk are a safety concern due to possible contamination with foodborne pathogens. Listeria monocytogenes and Escherichia coli O157:H7 have been implicated in several outbreaks and recalls linked to Gouda cheese made with unpasteurized milk. The U.S. Food and Drug Administration Code of Federal Regulations requires cheeses made with unpasteurized milk to be aged at a minimum of 1.7°C for at least 60 days before entering interstate commerce. The goal of this study was (i) to assess the population dynamics of L. monocytogenes and E. coli O157:H7 during aging of Gouda cheese when the pathogens were inoculated into the unpasteurized milk used for manufacture and (ii) to compare the native microbial populations throughout manufacture and aging. Unpasteurized milk was inoculated with L. monocytogenes at 1 or 3 log CFU/mL or with E. coli O157:H7 at 1 log CFU/mL, and Gouda cheese was manufactured in laboratory-scale or pilot plant–scale settings. Cheeses were stored at 10°C for at least 90 days, and some cheeses were stored up to 163 days. Initial native microflora populations in unpasteurized milk did not differ significantly for laboratory-scale or pilot plant–scale trials, and population dynamics trended similarly throughout cheese manufacture and aging. During manufacture, approximately 81% of the total L. monocytogenes and E. coli O157:H7 populations was found in the curd samples. At an inoculation level of 1 log CFU/mL, L. monocytogenes survived in the cheese beyond 60 days in four of five trials. In contrast, E. coli O157:H7 was detected beyond 60 days in only one trial. At the higher 3-log inoculation level, the population of L. monocytogenes increased significantly from 3.96 ± 0.07 log CFU/g at the beginning of aging to 6.00 ± 0.73 log CFU/g after 150 days, corresponding to a growth rate of 0.04 ± 0.02 log CFU/g/day. The types of native microflora assessed included Enterobacteriaceae, lactic acid bacteria, mesophilic bacteria, and yeasts and molds. Generally, lactic acid and mesophilic bacterial populations remained consistent at approximately 8 to 9 log CFU/g during aging, whereas yeast and mold populations steadily increased. The data from this study will contribute to knowledge about survival of these pathogens during Gouda cheese production and will help researchers assess the risks of illness from consumption of Gouda cheese made with unpasteurized milk. HIGHLIGHTS