1.
Effect Of Various Concen Trayious Of Hydrogen Pereoxide On Chemical And Microbiogical Quality Of Raw Buffalo Milk
by Muhammad Ilyas Alam | Prof. Dr. Muhammad Ayaz | Dr. Aftab Ahmed Anjum | Dr. Imran Javed.
Material type: ; Format:
print
Publisher: 2011Dissertation note: Milk is a complex mixture of fat, proteins, carbohydrates, minerals, vitamins and other miscellaneous constituents dispersed in water. Milk production in flush season is much more than in the normal. Milk production and supply fluctuate through out the year and during winter it is surplus to its demand. Surplus milk is available in winter due to new calving, less consumption of milk by the consumer. In winter season ample amount of green fodder is available to the animals which in turn increase the milk production.
Milk and milk products being very delicate and perishable food require special handling prior to the consumption and further treatment. Pakistan due to its harsh climatic conditions people are using different methods, for the preservation of milk. They are using different chemicals, additives and antibiotics to enhance the keeping quality of milk. Present study was planned to investigate the various concentration of hydrogen peroxide or raw buffalo milk and its effect on chemical and microbiological quality of raw buffalo milk.
Raw buffalo milk samples were collected from Dairy Animal Training and Research Centre, University of Veterinary and Animal Sciences, Ravi campus Pattoki Fifty samples of raw buffalo milk (100ml each) were collected to studied the nutritional composition and microbiological quality of the milk after adding the hydrogen peroxide. The hydrogen peroxide of different concentration i.e. 0.025%, 0.05%, 0.075%and 0.1% were used in this study. There was no significant change in the result regarding various nutritional composition of raw buffalo milk after adding the various concentrations of hydrogen peroxide. There is a slight change in the lactose % during study of 48 h storage of milk at different temperature. Statistically the change which occurred in lactose during storage is significant whereas over all decrease in Solid Not Fat is non significant
Mean value of TPC of raw buffalo milk treated with different concentrations of hydrogen peroxide storage at the three different temperatures indicated that at 10° C TPC was very less as compared to control. TPC at 30° C after 48 h was 9.83x106.Which was very less as compared to TPC of control i.e. 1.195 x107.
The effect of H2O2 on the quality of the milk is negligible as compared to the losses suffered without it. The hydrogen peroxide definitely have its effect as a preservative.. The use of preservative in milk and dairy products are not new in the countries where ambient temperature remains quite high. Our study suggests that the concentration of hydrogen peroxide to be used for the preservation of raw milk is 0.05 % to 0.1 %
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2.
Survival Of Probiotic Bacteria In Commercial Infant Foods And Their Antimcrobial Activity Against Food Borne
by Rana Faheem Sakhawat Ali | Prof. Dr. Muhammad Ayaz | Dr. Imran Javed | Dr. Muhammad Nasir.
Material type: ; Format:
print
; Literary form:
not fiction
Publisher: 2011Dissertation note: Novel bio-therapeutic agents (Probiotics) are live microorganisms that, when administered in adequate number provide health benefits to the consumer. Functional foods contain viable probiotic bacteria in sufficient population. Some manufacturing companies of multi national fame claim the presence of probiotics in their dairy and cereal products especially for the consumption of infants and growing children of different age groups. But neither a legal definition nor specific regulations governing probiotic food exist. There is no approved list of human foods and any bacterial strain of a known species that is traditionally used can be added. Pakistani parents spent huge amount to purchase the different infant formulas for the better nourishment of their children. Any information basing on scientific grounds which confirms the presence or absence of gut friendly bacteria will be of great value for the general consumers. It is important to ensure a high survival rate of these bacteria during the product shelf life to maintain consumer confidence in probiotic products.
This study is presented to assess the viability, label correctness and diversity of Lactobacillus and Bifidobacterium species in powder milk and cereals recommended for infants. The viability of the probiotic microorganisms was evaluated throughout the shelf life. Antibacterial activity of the recovered strains was also measured against the common food borne pathogens. Isolation, identification and count of micro-organisms was carried out by serial ten fold dilutions prepared in PBS solution using the pour plate technique. Strains were propagated by inoculating the Lactobacillus in de Man Rogosa-Sharpe (MRS) and Bifidobacterium species in Reinforced Clostridium Agar under anaerobic conditions at 42°C.Typical cell morphology, colony characteristics and biochemical tests are used for the identification of isolates. Survival rate of the microorganisms was calculated by the viable cell count which represents the original concentration of probiotics in the infant formulation. Out of the total 45 analyses it is concluded that cereal food contains Bifidobacterium species only and the number of Bifidobacterium species in all three products is more than the Lactobacillus species. Moreover, survival rate of both organisms showed a decline pattern in the terminal stage of shelf life.
Lactobacillus and Bifidobacterium species were identified and differentiated by the application of various biochemical tests including Catalase test, Carbohydrate fermentation profile and growth response at different temperature and NaCl concentration. Gram positive and catalase negative isolates fermented the glucose without the production of CO2.
Isolates were tested for their antimicrobial activity using the Stab overlay, Cross streak and Agar well diffusion method against the common food borne pathogenic bacteria i.e. E.coli, Staphylococcs aureus, Salmonella species and Bacillus subtilus. After the completion of experiments it is concluded that Bifidobacterium species have more inhibition effect against the pathogens as compare to Lactobacillus species. Overall effect of isolates was mild to strong inhibition. Bacillus subtilus was resistant to probiotics as compare to the rest of three pathogenic bacteria.
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3.
Development And Sensory Evaluation Of Flavored Probiotic Acidophilus Milk
by Muhammad Junaid | Dr. Imran Javed | Prof. Dr. Muhammad Ayaz.
Material type: ; Format:
print
Publisher: 2011Dissertation note: Fermented milk products are the foods that have been fermented with lactic acid bacteria includes Lactobacillus, Lactococcus, Leuconostoc, bifidobacterium etc. These are of great significance as they not only preserve the surplus milk but also provide vast quantities of nutritious and healthy foods in a wide variation of flavors, aromas and textures. Acidophilus milk is one of the fermented milk products in which probiotic starter culture is used for fermentation. This probiotic product not only adds to the taste but also improves the digestibility of milk. This value added product helps in maintaining the normal mocroflora of GIT by boosting the number of friendly intestinal bacteria. Decreasing the incidence of pediatric diarrhea, reducing serum cholesterol concentration, reducing the risk of coronary heart diseases are some of health promoting benefits of this value added product.
Presently in Pakistan none of the dairy company is producing value added flavored acidophilus milk product using probiotic culture so the research project was designed in a way to develop flavored probiotic acidophilus milk which has its health benefits along with fulfilling the nutritional requirement with acceptable organoleptic characteristics. Consumer acceptability was found to be important for product development and its marketing.
The aim of the present study was the development the probiotic acidophilus milk having health promoting benefits of probiotics and to appeal its consumer recognition by flavoring the product. For flavoring purpose different food grade flavors like strawberry, chocolate and vanilla at different levels was used with the purpose of providing our people with good, nutritional, healthy and value added product through research and development. Flavored probiotic acidophilus milk is a product in which the milk a perishable commodity was fermented using the pure culture of Lactobacillus acidophilus as a starter culture.
The freshly drawn raw milk used in the study was obtained from Dairy Animal Training and Research Center (DAT&RC), UVAS, Ravi campus, Pattoki. The whole milk was pasteurized at 72 °C for 15 minutes to kill the pathogenic microorganism and ensuring the safety of consumer. It was then standardized to 3.5% fat and 8.5% SNF and cooled at 4 ±1°C. This standardized milk was used for preparation of flavored probiotic acidophilus milk.
The microbiological identification and confirmation of Lactobacillus acidophilus starter culture procured from starter culture collection center (Danisco) was carried out in the postgraduate laboratory of Department of Dairy Technology UVAS, Ravi campus, Pattoki. The freeze dried culture was activated by inoculating and growing it in sterile whole milk at 40 ±1ºC and then maintained at 4 ± 1ºC.
Preliminary studies were performed to optimize and standardize the conditions like culture concentration (to be added in the milk for acidification and fermentation), temperature of incubation and time duration for incubation during the preparation of probiotic acidophilus milk. This task was accomplished by using culture varying in concentration form 1-5%. Similarly temperature variations were studied at 30°C, 35 °C and 40 °C. Time for incubation was given 04hrs and 08hrs for each culture concentration at different temperatures. The results of preliminary studies showed the development of probiotic acidophilus milk by inoculating with Lactobacillus acidophilus culture at 01% concentration incubated at 40 °C for 04hrs as the best choice.
The actual product development phase started after finding the best combination of culture concentration with temperature of incubation and time for incubation. During this phase the standardized and pasteurized milk (200ml) equilibrated for one hour at the fermentation temperature (40ºC) in a water bath was inoculated with overnight fresh culture of Lactobacillus acidophilus at the rate of 1%. Thereafter it was flavored using three different flavors e.g., mango, strawberry, and pineapple. Fermentation time was given 4hrs and the temperature of milk was maintained at 40ºC. The flavored probiotic acidophilus milk after its development was cooled and stored at 4±1 °C up to six days.
During storage the prepared flavored Probiotic acidophilus milk was evaluated for its sensory attributes. A panel of 10 judges evaluated the product for color, taste, aroma, appearance, acidic flavor and overall acceptability on 9-point hedonic scale (9 = like very much; 1 = dislike very much). The sensory evaluation of the product at day-1 and day-6 of its production was carried out in the Department of Dairy Technology University of Veterinary and Animal Sciences, Ravi Campus, Pattoki. The sensory evaluation performa was prepared and distributed to the panelist along with the consent form to participate in this sensory evaluation.
The flavored probiotic acidophilus milk, prepared, was evaluated regularly for physico-chemical analysis, based on pH and titrateable acidity (expressed as lactic acid %) during its storage up to six days with one day interval. The total viable count of the product was also determined microbiologically at day-1 and day-6 to study the viability of culture in the probiotic product.
All the results obtained were analyzed thorough analysis of variance technique (ANOVA). The significant differences were compared using Duncan's Multiple Range (DMR) test with a probability P ? 0.05.
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