جستجوی مقالات مرتبط با کلیدواژه "cream" در نشریات گروه "دامپزشکی"

Cream enabled the growth of most microorganisms due to the adequate moisture, pH close to neutral, and nutrient rich. The major cause of bitter flavour in cream is degradation of proteins to the hydrophobic peptides by protease enzyme derived from the thermostable bacteria resistant to the pasteurization temperature. The present study was aimed to investigate and molecular identify of bacteria spp. causing bitter flavour in pasteurized cream. The pasteurized cream samples were collected, then microbiological tests such as total count of microorganisms, psychrotrophic bacteria count, coliform bacteria count, thermostable bacteria count, sporogen bacteria count and also chemical tests such as acidity and pH measurement were carried out. The tests were fulfilled with three repetitions at 4ºC and 15ºC in first, third, fifth, seventh, ninth, and eleventh days after the cream production. The isolates causing bitter flavour in creams were identified by physiological, biochemical, phylogenetical, and molecular methods. The bacterial isolates were inoculated into the pasteurized creams and assayed for changing in flavour. The two species of bacteria causing bitter flavor were isolated from the pasteurized creams. The sequencing of 16S rRNA gene of isolates indicated that they were Bacillus cereus and Bacillus subtilis. The temperature of preservation is one of the most important agents of microorganisms’ activity and dairy product durability. Keeping raw milk for a long time before the pasteurization leads to increasing proteolytic bacteria resistant to the pasteurization temperature, producing protease by the organisms and finally, changing the product flavour.

Measuring total microbial count of ice-cream with conventional pour plate count method and comparing the results with standard limits is one of the routine tests in ice-cream manufacturer factories. Achieving the results of total microbial count in minimum time is really important for confidence from the hygienic quality of products. So impedance-splitting method as a new technique for this purpose was considered in order to receiving the results in less time and as soon as possible. The main purpose of this study was to evaluate the correlation between impedance detection time (IDT in hrs.) and total microbial population (log 10 N) of industrial and traditional ice-cream in order to design the predictive microbial model according to impedance technique. During 6 months, 120 samples (60 samples for industrial and 60 samples for traditional ice-cream) were collected from different areas of Ahvaz. Half of samples in both industrial and traditional ice-creams were Vanilla and the other half were cocoa. Samples examined under sterile conditions. The total microbial count by pour plate technique and impedance splitting method were carried out based on the recommendations of Iran's Standard Institute and Industrial Investigation. Then the calibration curves of 2 methods and their equations were obtained by using Excel software. The calibration curves of methods were elaborated for total microbial count and impedance detection time, demonstrating a good correlation between the two methods in industrial ice-cream 96.55% and 95.31% for Vanilla or plain and cocoa ice-creams respectively). According to the calibration curves, the correlation between two methods was 89.07% and 87.37% for plain and cocoa traditional ice-creams respectively. In general the correlation between two methods was 94.61% for industrial and 87.92% for traditional ice-cream. Therefore, impedance measurement which is a more rapid, automated and less laborious method than conventional total microbial count technique could be used like some developed countries as an alternative method for the rapid measuring the total microbial loads in foods instead of conventional methods.

Origin of contamination for traditional ice cream consist of using of using primarilycontaminated or unpasteurized ingredients (i.e., milk or cream). Determination of coliform-Enterococcns ratio is among methods used for investigation of fecal coliform's origin. Thisstudy aims to enumerate fecal coliform and Enterococci as well as their ratio, in order to findout the origin of contamination in traditional ice cream. Consequently, 21 traditional icecream samples were collected throughout Tabriz. Samples were prepared and then enumationof fecal coliforms and Enterococci were performed according to the Iranian standards (No.356, 2946 and 2198 respectively). Mean level of contamination for fecal coliforms was 6.67and for Enterococci was 307.1. on the other hand, the fecal coliforms-Enterococci ratio wasdetermined as 0.0217. Regarding the normal mean ratio of coliforms and Enterococci incow's intestine, therefore the origin of contamination for traditional ice creams weredistinguished as cow's feces which could enter cow's milk direct and lor indirectly.

In this study, survival of Lactobacillus acidophilus and Bacillus coagulans after freezing and during 90 days of storage at -18○C in probiotic and low-fat synbiotic ice-cream was evaluated. Addition to a control group (which was ordinary ice-cream), two probiotic ice-creams were formulated using L. acidophilus and B. coagulans and two synbiotic ice-creams were prepared using the aforementioned microorganisms but replacing 5% of milk-fat with inulin. The total solids of the ice-cream mixes did not differ significantly, however there was a significant difference (p<0.01) between their fat contents. The viable counts of L. acidophilus and B. coagulans were higher than the recommended minimum limit of 6 log cfu/g in all probiotic and synbiotic ice-creams during the 90-days of frozen storage. The survival rate either after freezing or at the end of frozen storage was higher in the samples with B. coagulans. Inulin had not preservative effect on probiotic microorganisms during frozen storage. Moreover, survival of high populations of probiotic microorganisms for a long time revealed that ice-cream has a great potential to be a functional food.

Origin of contamination for traditional ice cream consist of using of using primarily contaminated or unpasteurized ingredients (i.e., milk or cream). Determination of coliform- Enterococcns ratio is among methods used for investigation of fecal coliform's origin. This study aims to enumerate fecal coliform and Enterococci as well as their ratio, in order to find out the origin of contamination in traditional ice cream. Consequently, 21 traditional ice cream samples were collected throughout Tabriz. Samples were prepared and then enumation of fecal coliforms and Enterococci were performed according to the Iranian standards (No. 356, 2946 and 2198 respectively). Mean level of contamination for fecal coliforms was 6.67 and for Enterococci was 307.1. on the other hand, the fecal coliforms-Enterococci ratio was determined as 0.0217. Regarding the normal mean ratio of coliforms and Enterococci in cow's intestine, therefore the origin of contamination for traditional ice creams were distinguished as cow's feces which could enter cow's milk direct and lor indirectly.