Microbial Load Of Milk Research Articles

Microbiological Evaluation of Milk Beverages Produced From African Breadfruit, Tigernut, Coconut and Date Fruit

This study was carried out to extract milk from African breadfruit, tigernut, coconut and date fruit and to observe the changes in the microbial load of milk during storage. The formulated plant milk beverages were compared to conventional plant milk beverage “Vita milk” which served as the control sample. Microbial counts, characterization and identification were carried out on the beverage samples every 7 days for up to 35 days. The total viable count of the toasted breadfruit-based samples ranged from 3.7 × 102 cfu/ml to 5.1 × 102cfu/ml and the values were lower than those recorded from the cooked breadfruit-based samples which ranged from 3.95 ×102 cfu/ml to 6.10 × 102 cfu/ml. There were no presence of coliform bacteria in the formulated beverage samples and the reference sample from 1 to 21 days of storage. After these periods, coliform bacteria were recorded in 3 samples of the formulated plant milk and in all the formulated beverage samples after 35 days of storage. The percentage occurrence of Staphylococcus species according to the result was low on the 1st day of storage (18.2%), but increases with storage period up to 28.7% after 35 days of storage. The percentage occurrence of Aspergillus species which is another organism of public health concern as recorded from the beverage samples throughout the period of storage were low and below the specified tolerable set by Codex Alimentarius which is < 50ug/ml. The overall microbial qualities of the formulated beverage were safe and stable for the 1st 21 days of storage and up until 28 days for the control sample. The study revealed that milk beverages formulated from these plants gave products that are comparable to the conventional soy bean based vitamilk. The microbiological stability of the formulated plant milk samples were relatively less compared to the vitamilk.

Optical Emission Spectra Characterization of Plasma Discharge During the Processing of Milk and Evaluation of its Quality Attributes

This study characterized the optical spectra of continuous low-pressure plasma system and evaluated its effect on milk processing. Plasma was characterized at different input power levels (24.8, 58.9, and 117.6 W which corresponds to the input voltage of 1, 1.5, and 2 kV) with a 1-cm electrode distance. Based on the characterization, the input power level 117.6 W was selected to produce maximum reactive species. The system was operated at 117.6 W to decontaminate milk flowing inside the quartz tube using three different milk flow rates 3, 6, and 9 mL/min (accounting for 5-, 2.5-, and 1-min plasma exposure time). The maximum reduction in total microbial count obtained after treatment was 1.2 log CFU/mL at an exposure time of 5 min (3-mL/min milk flow rate). Significant changes were observed in the physicochemical properties of milk after treatment. However, the only adverse effects observed were the viscosity and color of milk at 5- and 2.5-min treatment, which might be because of the use of unhomogenized milk. The continuous plasma system operated at 117.6 W reduced the microbial load in milk; further optimization of the process parameters is necessary for the complete elimination of microbial load and to increase the shelf life.

Survey of the microbiological count of the milk collected from livestock ancient city of Garmsar, Semnan Province, Iran.

Milk has a high nutritional value and can affect human health. Therefore, it is important to know the factors affecting its quality. The purpose of this study was to evaluate the raw milk microbial quality and factors affecting it. A total of 4260 raw cow milk samples, which were collected from villages around Garmsar city, Iran, and their microbial load were registered at Garmsar Dairy Cow Association between 2013 and 2014, was used in the present study. The total average ± SD of microbial load concentration was 3.02 × 105 ± 2.75 × 105 (CFU/ml). The average concentration of total bacteria in 2013 was 2.73 × 105 ± 1.58 × 105 (CFU/ml) and in 2014 it was 3.32 × 105 ± 3.93 × 105(CFU/ml). Seasonally, it was 2.94 × 105 ± 1.72 × 105 (CFU/ml), 3.69 × 105 ± 4.55 × 105 (CFU/ml), 2.91 × 105 ± 1.62 × 105 (CFU/ml), and 2.63 × 105 ± 1.67 × 105 (CFU/ml) for spring, summer, autumn, and winter, respectively. There was a significant difference in seasonal average microbial concentration of milk samples (p < 0.05). The present study concludes that microbial load of milk can be affected by environmental and hygienic conditions. Ranchers need to pay more attention to hygiene especially in warm seasons. Because in case of high microbial load in raw milk, even after milk pasteurization, it is not possible to have a high-quality and desirable product. Milk producers and distributors need also awareness in order to reduce the incidence of secondary contamination. But, the main correction is to establish direct supervision of the Ministry of Health onto the health of dairy cow farmers by structural integrity of Veterinary Medical Organization as the global one health.

Measurement of Off-Flavoring Volatile Compounds and Microbial Load as a Probable Marker for Keeping Quality of Pasteurized Milk

(1) Background: Multiple attempts have been conducted to correlate milk keeping quality with chemical, physical or bacteriological parameters. These methods only measure the chemical changes in milk produced by bacteria. Headspace solid-phase micro-extraction (HS-SPME) is an economic and recent method used to measure both volatile compounds and microbial load in milk, also allowing to keep the quality of the milk product. (2) Methods: The present study was conducted to identify and measure the off-flavoring volatile compounds through gas chromatography coupled with flame ionization detector (GC-FID) and the microbial load of pasteurized fluid milk stored at different temperatures, as a possible indicator of its keeping quality. (3) Results: The highest results were obtained to acetone, followed by butanone, pentanal and ethanol. These mean values were significantly enhanced from the 0 to 19th day of storage, at 10 °C. At day 19th, the minimum score for aroma, flavor and overall acceptability were also recorded as 4.33 ± 0.17, 4.02 ± 0.06, 4.00 ± 0.04, respectively. Likewise, maximum values for standard plate count (Log10 CFU 15.54 ± 0.40 mL−1) and total psychotroph count (Log10 CFU 11.67 ± 0.30mL−1) were reported at 10 °C and 4 °C. (4) Conclusion: HS-SPME/GC-FID methodology revealed to be very sensitive and capable to be applied in volatile compounds quantification in pasteurized milk produced during the storage period at different temperatures.

Evaluation of the quality of cow milk consumed by children in and around Bahir Dar

The safety of dairy products with respect to food-borne diseases is a great public health concern around the world. The microbial load of milk is a major factor in determining its quality. Hence, this study was aimed to evaluate of the quality and hygienic practices of cow milk consumed by children in and around Bahir Dar. A total of 79 milk samples were collected and analyzed using standard bacteriological examination. The study revealed that the proportions of respondents who practice udder washing prior to milking were 56%, 22% and 2% in urban, periurban and rural areas, respectively. Moreover, 88.7%, 67.3% and 45.2% of respondents has a practice of milk boiling before feeding the milk to their children in the urban, peri-urban and rural areas of the study, respectively. The majority of respondents in the urban (88%) and peri-urban (50%) areas wash milking, milk feeding and storing containers with detergents and boiled water. Higher (SPC/ml) was found in the rural 5x105 areas of the study compared to the urban and peri-urban sites. Likewise, of SPC, higher CC (2.2x105) was obtained in the rural area of the study without significant (p &gt; 0.05) difference in mean SPC across location. Therefore, milk collected from all study sites does not meet the minimum quality standard as the coliform population was much higher than the value indicated. Therefore, further research works to address constraints and to improve child milk consumption are imperative.Keywords: Bahir Dar, child milk consumption, milk quality

Microbial Quality of Cow Milk in Dawa Chefa District, Amhara Region, Ethiopia

Background: The microbial load of milk is a major factor in determining its quality, which is indicates the cleanliness of the milking utensils, condition of storage, manner of transport as well as the cleanliness of the udder of the individual animal. The aim of this study was to determine microbial quality of cow’s milk. Methodology: The study was conducted in Dawa Chefa District, Oromia Zone of the Amhara National regional state. A total of 50 samples of raw cow's milk were collected at morning from hotels (27 samples), cooperative (3 samples) and household producers (20 samples). The farmers (producers) that involve in the study were selected based on potential of milk production, market orientation and willingness of households. Samples of raw morning milk were taken from each sampling point twice in a month. During collection, approximately 250 ml raw milk sample were taken aseptically from the owner’s container then placed into sterile glass bottles. Result: The average total plate counts of milk sampled from farmers, dairy cooperatives and hotels were 6.88 log10, 7.10 log10 and 7.54 log10, respectively. The average coliform counts were 5.57 log10 at farm level, 5.63 log10 for dairy cooperative and 5.37 log10 for hotels. The average yeast and mould counts at farmer, dairy cooperative and hotel were 0.46 log10, 0.62 log10, and 0.74 log10 cfu/ml, respectively. The indirect tests and the actual bacterial count indicated that the microbial quality of milk produced by farmer and collected by dairy cooperatives in the study area was poor and this calls for scrupulous hygienic measure during production and handling of milk. Conclusion: The result showed that the microbial quality of raw milk obtained from local dairy farmer was very low. This was due to the unhygienic condition of milking; unclean milk handling equipment and the use of contaminated water. Therefore, Proper hygienic practice will become a useful parameter and model for other dairy farmers within the district to improve and upgrade their dairy production.

Microbial inactivation and shelf life comparison of ‘cold’ hurdle processing with pulsed electric fields and microfiltration, and conventional thermal pasteurisation in skim milk

Thermal pasteurisation (TP) is the established food technology for commercial processing of milk. However, degradation of valuable nutrients in milk and its sensory characteristics occurs during TP due to substantial heat exposure. Pulsed electric fields (PEF) and microfiltration (MF) both represent emerging food processing technologies allowing gentle milk preservation at lower temperatures and shorter treatment times for similar, or better, microbial inactivation and shelf stability when applied in a hurdle approach compared to TP. Incubated raw milk was used as an inoculum for the enrichment of skim milk with native microorganisms before PEF, MF, and TP processing. Inoculated milk was PEF-processed at electric field strengths between 16 and 42kV/cm for treatment times from 612 to 2105μs; accounting for energy densities between 407 and 815kJ/L, while MF was applied with a transmembrane flux of 660L/h m2. Milk was TP-treated at 75°C for 24s. Comparing PEF, MF, and TP for the reduction of the native microbial load in milk led to a 4.6 log10 CFU/mL reduction in count for TP, which was similar to 3.7 log10 CFU/mL obtained by MF (P≥0.05), and more effective than the 2.5 log10 CFU/mL inactivation achieved by PEF inactivation (at 815kJ/L (P<0.05)). Combined processing with MF followed by PEF (MF/PEF) produced a 4.1 (at 407 and 632kJ/L), 4.4 (at 668kJ/L) and 4.8 (at 815kJ/L) log10 CFU/mL reduction in count of the milk microorganisms, which was comparable to that of TP (P≥0.05). Reversed processing (PEF/MF) achieved comparable reductions of 4.9, 5.3 and 5.7 log10 CFU/mL (at 407, 632 and 668kJ/L, respectively (P≥0.05)) and a higher inactivation of 7.1 log10 (at 815kJ/mL (P<0.05)) in milk than for TP. Microbial shelf life of PEF/MF-treated (815kJ/L) and TP-treated milk stored at 4°C was analysed over 35days for total aerobic; enterobacteria; yeasts and moulds; lactobacilli; psychrotroph; thermoduric psychrotroph, mesophilic, and thermophilic; and staphylococci counts. For both PEF/MF and TP-treated milk an overall shelf stability of 7days was observed based on total aerobic counts (P≥0.05). Milk hurdle processing with PEF/MF at its most effective treatment parameters produced greater microbial inactivation and overall similar shelf stability at lower processing temperatures compared to TP. With higher field strength, shorter treatment time, larger energy density, and rising temperature the efficacy of PEF/MF increased contrary to MF/PEF. Thus, PEF/MF represents a potential alternative for ‘cold’ pasteurisation of milk with improved quality.

Supporting the extensive dairy sheep smallholders of the semi-arid region of Crete through technical intervention

The objective of this field study was to depict the extensive system of dairy sheep farming in the semi-arid environment of the island of Crete and to assess the potential margins of improvement through technical intervention. Forty-three family-run farms keeping a total of 13,870 sheep were surveyed in seven representative areas of the island. Several parameters were dealt with, concerning socio-economy, flock management and productivity. Study areas differed widely regarding feeds supplied per sheep, land cultivated for feeds, grazing land utilized and housing space. A range of parameters were recorded on flock size and their production characteristics such as births, fertility and number of lambs weaned. Milk yield and parameters associated with milk quality, such as somatic cell counts and total microbial flora, were also recorded. Technical intervention was directed towards removal of non-productive animals, programming of matings, balancing of diets, management of grazing lands and health care. Ewe fertility and numbers of lambs weaned per ewe, as well as harvested milk and milk quality (based on somatic cell counts and microbial load of milk) were also significantly improved. Information derived from this study stresses the important role of extension services to small farm sustainability and contributes to our knowledge of the dairy sheep farming systems in countries around the Mediterranean and elsewhere.

Activation of the Lactoperoxidase System as a Method of Preserving Raw Milk in Areas Without Cooling Facilities

Milk spoilage is a major problem to the dairy sector of tropical countries. High temperatures hasten spoilage, which is worsened by the absence of cooling facilities and adequate transportation means. Some chemicals have been tried as milk preservatives in rural areas, but are now forbidden due to toxicological reasons. The use of the lactoperoxidase system (LPS) might offer a solution to milk preservation in such areas. The lactoperoxidase system is a natural antibiotic system in milk, which could be activated to boost its effectiveness. This study focused on the effects of the lactoperoxidase system on raw bovine milk produced in the Western Highlands of Cameroon during the rainy season. Milk was collected from 17 - 31 farmers in Santa village, bulked and activated with thiocyanate and peroxide. The LPS was activated by addition of 10 ppm thiocyanate and 8.5 ppm peroxide to milk, followed by thorough mixing. Part of the milk was left untreated (control). Treated and control samples were kept under three storage conditions: ambient temperature (22 – 25 o C), water bath (20 o C) and refrigeration (6 – 8 o C). Samples were monitored for spoilage at hourly intervals, except for those in the refrigerator, which were monitored after every 6 hours. Microbial population was also estimated at intervals, using the standard plate count method. The average increase in shelf life of treated milk with respect to the control milk was +7.1 (SD 2.4) hours under ambient temperatures, +8.1 (SD 3.0) hours in a water bath and +46.2 (SD 21.2) hours in the refrigerator. The LPS limited th e activity of lactic acid bacteria, which cause spoilage in milk. Treatment reduced the lactic acid content in milk by 29% under ambient temperature and 15% in water bath after 16 hours. The LPS reduced the microbial load in milk stored under ambient temperature by more than one log cycle, after 8 hours of storage. Treated evening milk could remain in good condition for the next day's use without refrigeration. Therefore LPS treatment can improve on income generation from dairying as it enab les farmers sell milk in far-off markets.

Pre-processed bovine milk quality in Trinidad: Prevalence and characteristics of bacterial pathogens and occurrence of antimicrobial residues in milk from collection centres

The study was conducted to assess the impact of the changes in the milk collection system in Trinidad (from twice daily collection to once, introduction of chilling facilities to the collection centres and transportation of milk to the processing plant in insulated truck instead of in metal churns at ambient temperature) on the microbial load and antimicrobial residue quality of the milk as well as the temperature and pH of milk, using standard methods. The presence of antimicrobial residues was detected using the Delvo test kit. Of a total of 266 milk samples from churns, the mean ± sd temperature and log 10 ± sd TAPC per ml was 20.36 ± 7.91 °C and 6.3 ± 1.09 respectively. For 20 milk samples from the chillers, the mean temperature and log 10 ± sd TAPC per ml was 15.10 ± 2.73 °C and 7.04 ± 0.33 respectively compared with corresponding values for 36 samples collected from the truck, 11.64 ± 4.22 °C and 7.11 ± 0.62 respectively ( P < 0.05; X 2). The mean TAPC, staphylococcal and E. coli counts per ml of milk from churns were significantly ( P < 0.05; X 2) higher for milk at low temperature (0–20 °C) compared with milk at high temperature (>30 °C). Eight (4.2%) of 192 milk samples tested contained antimicrobial residues. Of 168 S. aureus isolates tested, 24 (14.3%) were enterotoxigenic while 53 (45.3%) of 117 isolates tested exhibited resistance to various antimicrobial agents while of 386 isolates of E. coli tested, 3 (0.8%) were O157 strain and 129 (64.5%) of 200 isolates exhibited resistance to antimicrobial agents. It was concluded that despite the changes, the microbial load of milk was still high suggesting poor sanitary practices at the farm level. The detection of antimicrobial residues agents coupled with toxigenic S. aureus and E. coli isolates could pose health hazards to consumers.

Catalase Activity for Rapid Assessment of High Level Total Mesophilic Microbial Load in Milk

ABSTRACT: Total mesophilic microbial load (APC) is an important index for milk quality. It takes 48 h to enumerate APC with conventional plating methods. This report presents a rapid catalase activity test for monitoring APC in milk. Most aerobic microorganisms have strong catalase activities. Catalase activity in milk was monitored with a Pasteur pipette method in 5 min. The correlation between high APC numbers (&gt; 4.0 log CFU/ml) and catalase activities was strongly correlated with r2=0.89. Classifying the APC into eight contamination groups was found to be a sound means of utilizing the resultant catalase activities to predict APC.