No abstract

Electrical impedance, using the Bactometer 32, was evaluated as an alternative method to the Standard Plate Count (SPC) to determine the initial microbial count of raw milk samples. The raw milk samples were obtained from farm bulk tanks on commercial dairy farms. Analyses were started within 24–36 h after collection. The impedance method was used to evaluate the samples as raw milk, raw milk plus yeast extract, raw milk given preliminary incubation (18 h at 13 C) or raw milk given preliminary incubation plus yeast extract. The yeast extract (1% final concentration) was added after the milk was placed in the module wells. The geometric mean SPC of each of these four groups was 4.51, 4.37, 4.96 and 5.14, and the corresponding mean detection times with Bactometer 32 were 10.13, 8.80, 8.28 and 6.11 h, respectively. The correlation coefficient of detection time to SPC was −0.77, −0.88, −0.78 and −0.79, respectively, for the four sample groups. When specific detection cut-off times (approximately 7 h) were selected and a maximum SPC of 100,000 CFU/ml was selected, 85.2%, 97.2%, 81.0% and 83.6%ofthe samples in the above four groups were correctly classified.

The antimicrobial activities of several compounds isolated from Artemisia campestris were studied using an agar diffusion technique. At a concentration of 125 μg/ml, six of the extracted compounds inhibited growth of Staphylococcus aureus, three of the compounds inhibited Escherichia coli and two inhibited growth of Proteus vulgaris. Pseudomonas pyocyanea was resistant to all extracted compounds.

The aim of this study was to evaluate the bacteriological quality and safety of fresh white cheese sold in Tripoli, Libya. The study lasted for approximately 7 months (November 2011-May 2012), during this period 87 fresh white cheese samples were collected from seven different areas (4 to 5 factories from each area with the rate of 3 duplicates). The samples were tested for temperature at receiving, pH and acidity, total aerobic counts, total coliform counts and the detection of incidence of some pathogenic bacteria including: Escherichia coli, Escherichia coli O157:H7, Staphylococous aureus, Salmonella spp., Aeromonas hydrophila and Listeria monocytogenes. Results indicated that the average temperature, % acidity, and pH of the tested samples were (15.80°C ± 5.8, 0.21 ± 0.02% and 5.81 ± 0.06) respectively. Data indicated that 70.1% of the samples exceeded the Libyan standard for white cheese No. 366 in respect to temperature, while pH of all samples was within the limits of such standard. On the other hand, means of total aerobic counts, total coliform counts, and the numbers of Staphyloccoccus aureus were (38 × 10 7 , 74 × 10 5 , 35 × 10 4 and 53 × 10 3 cfu/g) respectively of the study. b ia l & Bioc h e m ic a l Te chno lo g y

A new alkaloid, (+)-tuberine isolated from Haplophyllum tuberculatum, had high antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Saccharomyces cerevisiae at 1 μg/ml. (+)-Tuberine was slightly inhibitory to Escherichia coli.