Aerobic Mesophilic Bacteria Counts Research Articles

Vida útil de carne fresca de res envasada al vacío a 0°C y +4°C

El objetivo de este trabajo fue determinar la vida útil de cortes cárnicos envasados al vacío y almacenados a 0°C y 4°C. Se evaluaron parámetros fisicoquímicos (pH, porcentaje de Drip, rancidez por Kreiss), aspecto del corte (estado del envase, color del corte, grasa, olor); y aspectos microbiológicos (recuentos en placa de bacterias aerobias mesófilas, enterobacterias, Escherichia coli, coliformes totales, bacterias ácido lácticas) en cortes de bife y picaña durante 5 meses.En los cortes almacenados a 4°C se observaron alteraciones fisicoquímicas y de aspecto en el tercer mes (pH <5.4, perdida de vacío y presencia de olores ácidos); mientras que a 0°C no se percibieron alteraciones hasta el quinto mes. Por otro lado, no se observó crecimiento significativo para E.coli ni coliformes totales durante el periodo en estudio.El almacenamiento de cortes envasados al vacío y mantenidos a 0°C contribuye a la calidad del producto, y mantiene sus características fisicoquímicas y sensoriales en condiciones comercialmente aceptables durante cuatro meses, permitiendo su transporte hasta destinos distantes.Producción Agropecuaria y Desarrollo Sostenible, Vol. 4, 2015: 27-45

Chemical Composition and Microbiological Properties of Tarhana Enriched with Immature Wheat Grain

In this study, the effect of immature wheat grain (IWG) supplementation on the tarhana formulation was investigated by determining color values and some chemical and microbiological properties. Flours obtained from IWG, harvested at 26 (IWG-1) and 36 days (IWG-2) after anthesis, were used in the tarhana formulation as a replacement of white wheat flour in concentrations of 10, 30 and 50%. Ash, Ca, Mg, K, P and Zn contents of tarhana samples increased by IWG-1 addition. IWG-2 addition resulted in an increase in moisture and protein contents. IWG-1 addition into the tarhana provided an increase in the antioxidant activity and total phenolic contents of the samples. The total counts of mesophilic aerobic bacteria and lactic acid bacteria of tarhana with IWG-1 were higher than those of other tarhana samples. Practical Applications Some changes occur in the physical properties and chemical composition of wheat during maturation period. These changes have an effect on the nutritional components and health benefits of wheat grain. In this study, two different immature wheat grains were used in tarhana production. Some chemical and microbiological properties of enriched tarhanas were assessed. Using immature wheat flour increased the mineral content of tarhana samples. The antioxidant activity of samples increased with immature wheat flour addition. Counts of lactic acid bacteria of enriched tarhanas was higher than the control.

Evaluation of Biogenic Amines Levels, and Biochemical and Microbiological Characterization of Italian-type Salami Sold in Rio de Janeiro, Brazil.

The objective of the present study was to evaluate the levels of biogenic amines (cadaverine, putrescine, tyramine, histamine, spermidine and spermine) by high performance liquid chromatography (HPLC) and the physicochemical (moisture, lipids, proteins, pH, water activity and fixed mineral residue) and microbiological (lactic acid bacteria and aerobic heterotrophic mesophilic bacteria count) characteristics of six Italian-type salami brands sold in the city of Niteroi (Rio de Janeiro, Brazil). The salami showed lactic acid bacteria count from 5.7 to 8.6 CFU•mL-1, and heterotrophic mesophilic bacteria count from 5.8 to 8.7 CFU•mL-1. Three brands showed moisture contents above 35% and one brand had protein content below 25%. The mean values obtained for the amines were: 197.43, 143.29, 73.02, 4.52, 90.66 and 36.17 mg•kg-1 for tyramine, putrescine, cadaverine, spermidine, histamine, and spermine respectively. Two brands presented histamine contents above the legal limit established in 100 mg•kg-1. We concluded that the evaluated salami presented a wide variation in the count of the bacterial groups with a predominance of lactic acid bacteria. The moisture contents indicate insufficient drying before commercialization and protein content had values below the minimum limit determined by the Brazilian legislation. Finally, the levels of biogenic amines found could cause adverse reactions in susceptible consumers, depending of the amount and frequency of intake of these products.

Effect of active-modified atmosphere packaging on the respiration rate and quality of pomegranate arils (cv. Wonderful)

Two experiments were conducted to investigate the effects of active- and passive-modified atmosphere packaging (MAP) on respiration rate (RR) and quality attributes of minimally processed pomegranate arils (cv. Wonderful) stored at 5°C for 12d. In experiment 1, pomegranate arils were packaged in low barrier bi-axially oriented polyester (BOP) film under active-MA (5kPaO2+10kPaCO2, 30kPaO2+40kPaCO2), passive-MA and in clamshell trays. In experiment 2, a high barrier Polylid® film was used with arils packaged under three active-MAs (5kPaO2+10kPaCO2+85kPaN2; 30kPaO2+10kPaO2+60kPaN2; 100kPa N2) and passive-MA. Arils packed in clamshell trays had lowest RR (RCO2) compared to the other MA treatments in experiment 1, ranging from 41.1nmolkg−1s−1 on day 3 to 238.8nmolkg−1s−1 on day 12. Respiration rate of arils packaged in the high barrier polylid film was significantly affected by MA treatments. At the end of 12d storage, total anthocyanin content (TAC) in arils was highest for clamshell packages (0.31±0.01gL−1) and lowest in passive-MAP (0.27±0.02gL−1). Packaging arils in high O2 atmosphere and 100kPa N2 significantly lower aerobic mesophilic bacteria counts throughout the storage duration. Based on sensory scores obtained and microbial load, the shelf life for arils packaged in clamshell trays, passive-MA, and high O2 level MA was 6, 9 and 12d, respectively.

Effect of perforation-mediated modified atmosphere packaging and storage duration on physicochemical properties and microbial quality of fresh minimally processed ‘Acco’ pomegranate arils

This study investigated the effects of number of perforations (P-0, -3, -6 and -9 per 160.1 cm2) and storage duration on the physicochemical quality attributes and microbiological quality of fresh minimally processed pomegranate (Punica granatum L., cv. Acco) arils stored at 5 °C for 15 days. Arils were analysed for physicochemical quality attributes on day 0, 3, 6, 9, 12 and 15. Microbial analyses for aerobic mesophilic bacteria, yeast and moulds were made on 0, 6, 10 and 14 day, and the presence of Escherichia coli was tested before and at the end of storage. Headspace gas composition was significantly influenced by number of perforation. Highest CO2 accumulation was observed in non-perforated MAP, while O2 concentration increased with increase in number of perforations in PM-MAP. Highest decrease in total soluble solids (TSS) from 15.4 to 13.1°Brix was observed in P-9 PM-MAP arils. Highest counts of aerobic mesophilic bacteria (5.5 log CFU g−1) and yeast and moulds (5.3 log CFU g−1) were observed in P-0 and P-9 PM-MAP. No E. coli were detected before and at the end of storage. Overall, P-3 and P-6 PM-MAPs better maintained quality attributes of pomegranate arils than P-0 and P-9.

Effects of lactic acid and lemongrass oil treatment on the pre-existing microorganisms and foodborne pathogens in Tatsoi (Brassica rapa var. rosularis) baby leaves

The effects of lactic acid and lemongrass oil treatments on microbial growth in Tatsoi baby leaves were investigated to ensure microbial safety. To determine the optimal concentrations of lactic acid and lemongrass oil as a sanitizer, the effects of several concentrations of lactic acid (0.25, 0.5, 1, and 2 %) and lemongrass oil (0.1, 0.3, 0.5, and 1 %) on aerobic mesophilic bacteria, Salmonella Typhimurium, and Listeria monocytogenes in Tatsoi baby leaves were evaluated. The results showed that the 1 % lactic acid and 1 % lemongrass oil treatment reduced the populations of the microorganisms to the greatest extent. In particular, after the combined treatment with 1 % lactic acid and 1 % lemongrass oil, the count of aerobic mesophilic bacteria was reduced from 7.63 to 2.45 log colony forming unit (CFU) · g−1, and L. monocytogenes was reduced from 6.71 to 1.96 log CFU · g . In addition, S. Typhimurium was not detected in the Tatsoi baby leaves during 7 days of storage. These results suggest that a combined treatment using 1 % lactic acid and l % lemongrass oil could be an effective method for the inactivation of bacteria on the surfaces of Tatsoi baby leaves.

Shelf Life of Chicken Meat Balls Submitted to Sous Vide Treatment

The objective of this study was to investigate the appropriate temperature for processing storage of chicken meatballs made of minced chicken meat with the sous vide method. The chicken meatballs were prepared and separated into four experimental groups according to the application of heat treatment (10 and 20 minutes) and storage time (+2 and +10°C). Sensory, microbiological (total aerobic mesophilic bacteria, total psychrotrophs, lactic acidbacteria, Enterobacteriaceae, Clostridiumperfringens, Listeria spp.), chemical (pH, thiobarbituric acid), color (L*, a*, b* values), and texture profile analyses were performed on meatball samples. Cl. perfringens and Listeria spp. were not detected in meatball samples during the storage period. Samples cooked at 10 minute and stored at +2°C the highest count of total aerobic mesophilic bacteria (p<0.05). For lipid oxidation, interaction was observed between cooking time and storage temperature, with higher TBARs values for samples stored at 10 °C, while cooking time and storage temperature showed no influence on the color and textural analysis parameters. For the treatments evaluated, cooking time x storage temperature seem affect more microbiological and chemical parameters than color and textural parameters of chicken meatballs.

Chemical, Physicochemical, Nutritional, Microbiological, Sensory and Rehydration Characteristics of Instant Whole Beans (Phaseolus vulgaris).

Instant whole beans obtained by drying at 25 °C were evaluated for their chemical, physicochemical, nutritional, microbiological, sensory and rehydration characteristics. The proximal composition of instant whole beans was typical of this kind of food, whereas aw and L*, a* and b* values were 0.639, 98.55, -0.28 and -1.52, respectively. In instant whole beans, 75% of the essential amino acids had a value greater or equal to the reference standard for adult humans; the protein quality in terms of chemical score was 95%. Microbiological counts of aerobic mesophilic bacteria, moulds, yeasts and total coliforms of rehydrated instant whole beans were <10 CFU/g, whereas the scores for colour, flavour, texture and overall acceptability were 7.22, 7.68, 7.24 and 7.34, respectively, on a 1-9 hedonic scale. The logarithmic and Pilosof models showed close fits (R2>0.99) to the experimental data for drying of cooked beans and rehydration of instant whole beans, respectively. In the light of the chemical, physicochemical, nutritional, microbiological, sensory and rehydration characteristics of instant whole beans found in this study, drying at 25 °C is recommended for the production of such food.

English

The Amazon offers great potential for fishery activities but the fish fauna&rsquo;s specific microbiota is not yet known. This paper identified the bacterial flora composition and the influence of this process on the microbiological spoilage in economically important fish species in the Amazon region: butterfly peacock bass (Cichla ocellaris) and piramutaba (Brachyplatystoma vailantii). To this end, microbiological characterization was performed: counts of total mesophilic aerobic bacteria, psychrotrophic bacteria and coliforms at 35 and 45&deg;C. Bacteria were also isolated through seeding in agar surface using violet red bile glucose (VRBG) for enterobacteria strains and Baird-Parker Agar with egg-yolk tellurite for Staphylococcus species, both with incubation at 36&deg;C for 48 h. The bacteria isolated were identified using the API 20E kit (Enterobacteria), and Gram-positive with API Staph (Staphylococci). Finally, the limit temperature for strain growth was tested using spectrophotometry readings at 554 nm at 10 and 15&deg;C at three different times: 0, 3 and 6 h. The mesophilic aerobic bacteria counts for fresh fish samples ranged from 6.03 - 8.23 log CFU/g for piramutaba and 4.52 - 7.24 log CFU/g for butterfly peacock bass. The count ranges of psychrotrophic aerobic bacteria found were 6.14 - 8.56 log CFU/g and 4.52 - 7.24 log CFU/g for piramutaba and butterfly peacock bass, respectively. They also had an average score above 103 MPN/g for total coliforms. Sixteen different strains were isolated. The most predominant were Staphylococcus hominis, Staphylococcus aureus, Stenotrophomonas maltophilia and Enterobacter intermedius. When subjected to temperatures of 10 and 15&deg;C, the strains did not achieve growth for 6 h at a 95% significance level. Key words: Fish, Cichla ocellaris, Brachyplatystoma vailantii, microflora.

Effect of antimicrobial packaging on physicochemical and microbial quality of chicken drumsticks

The effects of antimicrobial agents (nisin, chitosan, potassium sorbate (PS) or silver substituted zeolite (AgZeo)) incorporated into low density polyethylene (LDPE) on the physicochemical and microbial quality of chicken drumsticks stored at 5 °C for 6 days were investigated. Active multilayer bags (LDPE/polyamide/LDPE-containing 2% antimicrobial agent) were used to pack chicken drumsticks under vacuum. Their efficiency in inhibiting total aerobic mesophilic bacteria (APC), total coliforms and total molds and yeasts were evaluated by comparison with control bag (LDPE-polyamide-LDPE). APC counts of samples packed in bags containing chitosan, nisin, AgZeo and PS were 1.03, 0.98, 0.51, and 0.17 log respectively were lower than those of samples packed in control bags. Samples packaged in active bags had lower microbial counts and thiobarbituric acid reactive substance (TBARS) values than those of samples packed in control bags. The pH, color and hardness of the samples were not affected significantly by use of different packaging films (p > 0.05). Therefore, the bag including chitosan or nisin can be suggested as a suitable packaging material for chicken drumstick to increase safety and quality.

Microbiological quality of selected spices and herbs including the presence of Cronobacter spp.

The cultivation of spices and herbs in parts of the world characterized by warm climate and high humidity provides excellent conditions for the development of microorganisms, including the undesirable ones. The aim of this study was to determine the microbiological quality of spices and herbs available on the Polish market, considering the occurrence of Cronobacter species bacteria.Analyses covered 60 samples of commercial spices and herbs, including 38 samples of dried herbs (basil, bay leaves, thyme, oregano, tarragon, marjoram, dill, parsley, rosemary, lovage) and 16 samples of seasoning blends as well as 6 samples of spices seeds and fruits (pimento, black pepper, coriander). All samples were tested for the total count of aerobic mesophilic bacteria (TAMB) and for the presence of Cronobacter spp.In most of the samples of spices and herbs (60.0%), the TAMB did not exceed 104 CFU/g, and the level regarded as unacceptable (>106 CFU/g) was not identified in any of the samples. The presence of Cronobacter spp. was demonstrated in 10 (16.7%) samples of the analyzed products, however these were mainly samples of herbs (basil, tarragon, parsley) and one sample of a seasoning blend (Provence herbs). The highest microbiological contamination (TAMB) was found in samples of herbs (oregano, tarragon, basil) and in ready seasoning blends, in 21.1% and 25.0% of which the total count of aerobic mesophiles was in the range of 105–106 CFU/g. In all samples of spices seeds and fruits (coriander, black pepper and pimento), the total count of aerobic bacteria reached <104 CFU/g.Results achieved in the study indicate good hygienic conditions in the production process of spices and herbs available on the Polish market. The study demonstrated also that dried spices and herbs may be carriers of Cronobacter species bacteria, though their presence in not often detected in products of this type.

THE MICROBIOLOGICAL STATUS OF (READY TO EAT) LETTUCE BEFORE AND AFTER STANDARD WASHING

Lettuce is a vegetable that is always consumed raw. The number and types of microorganisms that may be found on the lettuce leaves depend on growing, harvesting, and particularly on handling practices, like proper washing and preparing lettuce before eating. The aim of this study was to investigate the effect that washing under running water has on the microbiological status of lettuce leaves purchased from the local market place in Banja Luka. Smears were taken from the obverse and reverse sides of lettuce leaves, and the total count of aerobic mesophilic bacteria, yeasts and molds was determined as well as the presence of sulphite-reducing clostridia, the coagulase positive staphylococci, Salmonella species, and Escherichia coli. The analysis showed that the washing reduced the total count of aerobic mesophilic bacteria by approximately 10 times, and the total count of yeasts and molds by approximately 8 times. Of the lettuce samples examined, 66,67% contained sulphite-reducing clostridia and 13,33% Salmonella species, before the washing. The number of samples with sulphite-reducing clostridia was reduced by five times after the washing, but the number of samples contaminated with Salmonella species remained the same.

Microbial load and safety of paper currencies from some food vendors in Jimma Town, Southwest Ethiopia.

BackgroundPaper currency is used for every type of commerce and plays an important role in the life of human beings. However, the combination of its widespread use and constant exchange make paper currency a likely agent for disease transmission. Thus, the aim of this study was to evaluate the microbial load and safety of Ethiopian paper currencies collected from some food vendors in Jimma town.MethodsStandard microbiological methods were used for the enumeration of various microbial groups, isolation and characterization of pathogenic bacteria and their growth potential in selected weaning foods. A total of 100 samples of Ethiopian paper currencies, consisting of five denominations, from street food venders, hotels and cafeterias in Jimma town were collected aseptically. Sterile cotton swabs moistened with buffered peptone water solution were used for swabbing and the swabs were separately soaked into 10 ml sterile buffered peptone water solution.ResultsMean microbial counts of Aerobic mesophilic bacteria, Staphylococci, Enterobacteriaceae, coliforms and Aerobic bacterial spores were (log CFU/cm2) 6.32, 4.43, 3.14, 2.98 and 3.78, respectively. However, mean counts of Yeasts and Moulds were below detectable levels. There was statistically significant variation (p < 0.05) among the mean counts of microbes isolated from samples of paper currencies. The predominantly isolated microbial groups were Staphylococcus spp. (34.06%) followed by Bacillus spp. (31.88%), Enterobacteraceae (13.39%), Micrococcus spp. (9.55%) and Streptococcus spp. (9.03%). Overall, 25% and 10% of the samples were positive for S. aureus and Salmonella spp, respectively. In challenge study, Salmonella spp. and S. aureus reached the infective dose within 12 to 18 hours of inoculation.ConclusionThus, paper currencies could be considered as one of the possible vehicles for transmission of disease causing microorganisms. Poor handling practices and personal hygiene of the food vendors could contribute to the observed microbial counts. Thus, it calls for awareness development on the potential risks associated with poor handling of paper currencies at all level of the food establishments.

Effect of date palm coproducts and annatto extract on lipid oxidation and microbial quality in a pork liver pâté.

Dates are an interesting source of bioactive compounds, and coproducts from the date industry are of potential use in the manufacturing of meat products. In the present research, spreadable pork liver pâtés were made using fresh date coproducts (2.5% and 7.5%) as a potential functional ingredient and an ethanolic annatto extract (128 mg/kg) as colorant. The effect of these 2 ingredients on the lipid oxidation and microbial quality of the pâtés was assessed during 21 d of storage. The pâtés containing 7.5% date paste were seen to have the highest content of phenolic compounds during storage. The combination of 2.5% date paste and annatto protected pâtés against lipid oxidation throughout the 21 d of storage, thiobarbituric acid-reactive substances values being 0.47 mg MDA/kg at the end of this period, while other combinations increased oxidation compared to the control pâté. The control and those made with 2.5% date paste alone showed the highest counts of mesophilic aerobic bacteria, while the addition of annatto and/or 7.5% date paste reduced this count. The results suggest that a combination of both ingredients is necessary to reduce oxidation and microbial growth, but whereas the concentration of 2.5% is more appropriate to reduce oxidation, the combination with 7.5% date paste reduces the microbial counts. Both ingredients could have an opportunity of valorization in the meat industry for improving the quality.

Effects of Soaking with Natural Additives in Combinations with Vacuum or Modified Atmosphere Packaging on Microbial Populations and Shelf Life of Fresh Truffles (ChineseTuber Indicum)

The objective of this study was to evaluate the relative effects and interactions of combined soaking treatment using citric acid (CTA) and apple polyphenol (APP) at mild heating temperatures for the inactivation of the external and internal microflora (mesophilic aerobic bacteria, mesophilic anaerobic bacteria, and fungi) in Chinese Tuber indicum, as well as to analyze the microbiological and sensory changes under modified atmosphere packaging (MAP)- and vacuum atmosphere packaging (VAC)-packed Chinese T. indicum stored at 4 °C for up to 55 d. Chinese T. indicum was soaked with CTA and APP alone or in combination for 10, 20, and 30 min at 35, 45, and 55 °C. A disinfection method using CTA and APP (3% CTA + 3% APP for 20 min at 45 °C) was obtained. Under this set of combination, the experimental values of microbial counts of mesophilic aerobic bacteria, mesophilic anaerobic bacteria, and fungi were 2.31 ± 0.4 log CFU/g, <1.0 log CFU/g, and <1.0 log CFU/g, respectively. Through the analysis of sensory qualities and microbial populations for MAP- or VAC-packed Chinese T. indicum, the shelf life of soaked truffles was prolonged to 45 or 40 d, respectively. The synergistic effect of CTA and APP may provide valuable insight into the reduction of microorganisms on fresh truffles.

Quantitative detection of tetracycline-resistant microorganisms in conventional and organic beef, pork and chicken meat

The use of antimicrobials has increased the number of resistant bacteria to these drugs; however, the organic production has restricted the use of these compounds. The objectives of this work were to assess counts of tetracycline-resistant bacteria using conventional microbiology, to compare these results with those obtained for tet(A) and tet(B) genes by qPCR and to investigate both genes in conventional and organic meat. Counts of mesophilic aerobic bacteria were higher in organic beef, while chicken meat obtained higher counts for Enterobacteriaceae. Only tet(B) was higher in conventional pork and chicken meat than in their organic counterparts. The tet(A) gene was found in almost 100% of samples and tet(B) gene changed according to the type of meat. The presence of tet genes suggests that they are widely distributed, especially tet(A), in food of animal origin, even in organic meat samples obtained from animals in which the use of antimicrobials is restricted.

Effects of UV-C treatment on inactivation of Salmonella enterica and Escherichia coli O157:H7 on grape tomato surface and stem scars, microbial loads, and quality

The purpose of this study was to investigate the effectiveness of ultraviolet-C (UV-C) light inactivation as affected by the location of pathogens on the surface and at stem scars of whole grape tomatoes. A mixed bacterial cocktail containing a three strain mixture of Escherichia coli O157:H7 (C9490, E02128 and F00475) and a three serotype mixture of Salmonella enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) were used. Tomatoes were spot inoculated using approximately 100 μL of inocula to achieve a population of about 107±1 CFU/tomato. Additionally, the effects of treatment on color, texture, lycopene content, and background microbial loads during post UV-C storage at 4 °C for 21 days were determined. Results showed that UV-C doses of 0.60–6.0 kJ/m2 resulted in 2.3–3.5 log CFU per fruit reduction of E. coli O157:H7 compared to 2.15–3.1 log CFU per fruit reduction for Salmonella on the surfaces. Under the same conditions, log reductions achieved at stem scar were 1.7–3.2 logs CFU for E. coli O157:H7 and 1.9–2.8 logs CFU for Salmonella. The treatment was effective in controlling native microbial loads during storage at 4 °C as the total aerobic mesophilic organisms (PCA) and anaerobic lactic acid bacteria (LAB) counts of treated tomatoes were significantly (p < 0.05) lower during storage compared to the control group and the yeast and mold populations were reduced significantly below the detection limit. Furthermore, the firmness of tomato and its color was not affected by the UV-C doses during storage. UV-C radiation could potentially be used for sanitizing fresh tomatoes and extending shelf-life. The results of this study indicate that the specific location of pathogens on the produce influences the effectiveness of UV-C treatment, which should be taken into consideration for the design of UV-C systems for produce sanitization.

Quality characteristics of pork burger added with albedo-fiber powder obtained from yellow passion fruit (Passiflora edulis var. flavicarpa) co-products

The aim of this work determined the technological, nutritional and sensory characteristics of pork burgers, added with different concentrations (2.5 and 5%) of passion fruit albedo (PFA) co-product, obtained from passion fruit juice processing. The addition of PFA on pork burgers improves their nutritional value (higher fiber content). In raw and cooked burger, all textural parameters, except springiness and cohesiveness, were affected by the incorporation of PFA. PFA addition was found to be effective improving the cooking yield, moisture retention and fat retention. The raw and cooked pork burgers added with PFA had lower TBA values and lower counts of aerobic mesophilic bacteria and enterobacteria than the control samples. No Escherichia coli and molds were found in the samples. The overall acceptability scores showed that the most appreciated sample was the one containing 2.5% PFA. According to the results obtained, 2.5 and 5% of PFA addition can be recommended in pork burger production as a new dietary fiber source.

Impact of shortwave ultraviolet (UV-C) radiation on the antioxidant activity of thyme (Thymus vulgaris L.)

Thyme is a good source of antioxidant compounds but it can be contaminated by microorganisms. An experimental fluid bed ultraviolet (UV) reactor was designed for microbial decontamination of thyme samples and the effect of shortwave ultraviolet light (UV-C) radiation on antioxidant properties of thyme was studied. Samples were exposed to UV-C radiation for 16 or 64min. UV-C treatment led to 1.04 and 1.38logCFU/g reduction of total aerobic mesophilic bacteria (TAMB) counts. Hunter a∗ value was the most sensitive colour parameter during UV-C treatment. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of extracts was not significantly affected by UV-C. Addition of thyme extracts at 0.15 and 0.3μmolGAE/ml emulsion delayed the formation of lipid hydroperoxides and headspace hexanal in the 5.0%(wt) corn oil-in-water emulsion from 4 to 9 and 14days, respectively. No significant changes in oxidation rates were observed between UV-C treated and untreated samples at same concentrations.

Fermenter Technology Modification Changes Microbiological and Physicochemical Parameters, Improves Sensory Characteristics in the ermentation of Tella: An Ethiopian Traditional Fermented Alcoholic Beverage

Tella is an indigenous, a home processed and commercially available traditional fermented alcoholic beverage in Ethiopia. It is a main source of income for low-income women in Ethiopia. Tella gets easily spoiled and causes economic loss, as result; brewed in small amount while there are many users. This study investigated effects of fermenter technology modification on microbiological, pshysicochemical parameters and sensory characteristic of tella brewed in modified and traditional fermenters. Experiments were conducted using modified and traditional fermenters. Microbiological analysis was done for the fermenting mashes at 12 h interval. The physicochemical parameters consisted of pH, TA, Mash and environmental temperatures, Total carbohydrate, reducing sugar and ethanol content were determined. Sensory evaluation was performed for tella brewed in modified and traditional fermenters using Sensory attributes such as appearance and color, aroma, taste, strength (alcoholic) and overall acceptability. The counts of lactobacillus, lactococcus, yeasts and aerobic mesophilic bacteria showed increment during the first two phases in both fermenters but gradually decreased at phase IV in both fermenters. The counts of Enterobacteriaceae were high at day zero and not detected at phase II in both fermenters. Acetic acid bacteria were detected at the beginning of phase II in traditional fermenter but at phase III in modified fermenter.Total carbohydrate was 26.4 mg/ ml and 25.7 mg/ml at day zero in modified and traditional fermenters respectively and reached 77 mg/ml at phase III in modified and 78.1 mg/ml in traditional fermenter and then has shown decrement in next phases. Ethanol was detected at phase II in both fermenters and showed gradual increment with fermentation period. Aroma, taste and alcoholic strength were superior for tella brewed in modified fermenter. Using appropriate fermenter technology is important to brew tella with preferable sensory attributes, to make its brewing continuous, and generate continuous income.