1.
Study Of Physico Chemical And Microbiological Quality And Adulteration In Processed Dairy Products
by Sibghat Ullah | Prof. Dr. Muhammad Ayaz | Dr. Muhammad Nasir | Prof. Dr. Anjum.
Material type: ; Format:
print
Publisher: 2010Dissertation note: Dairy products are perishable food items and are good source of nutrients for human being as well as microorganisms. Adulteration in processed dairy products has become a very serious and alarming issue in Pakistan. The milk and milk product adulterants include water, starch, vegetable oil, yeast, Soya protein, whey powder and hazardous substances. There is a growing demand from consumers for healthy and hygienic dairy products. Keeping in view these facts, the present study was carried out to determine the physicochemical, microbiological and adulteration in various processed dairy products. The results are summarized as follows:
The highest mean values of physical tests in ice cream samples were, melting resistance 11.64 +0.030, melting quality 28.27+0.322.The highest mean values of yoghurt samples in different chemical tests were i.e. Fat 3.46 +0.140%, pH 5.67±0.01, Ash 2.63+0.208%, Total solids 14.28±0.10% and Moisture content 81.56+2.645%. The highest mean values of cheese samples in different chemical tests were i.e. Fat 31.93+0.801%, pH 4.60+0.447, Lactose 1.81+0.159%. Highest mean values for milk powder samples were i.e. Lactose 47.98+1.178%, Protein contents 23.86+1.289%, Total solids 94.82 +0.430% and Moisture content 6.34+1.72%. Highest mean values of microbiological count in yoghurt samples were i.e. Total plate count 4.60+0.627 log cfu/g, Coliform count 3.85+0.442 log cfu/g and Staph aureus count 4.52 +0.577 log cfu/g. Highest mean values of microbiological count in
cheese samples were i.e. Total plate count 4.93+1.128 log cfu/g, Coliform count 5.28+0.759 log cfu/g and Staph aureus count 4.64+1.132 log cfu/g. Highest mean values of microbiological count in butter samples were i.e. Total plate count 5.39+0.534 log cfu/g, Coliform count 5.39 +0.524 log cfu/g and Staph aureus count 5.35 +0.736 log cfu/g. Highest mean values of different microbiological tests in ice cream samples were i.e. Total plate count 5.76+0.690 log cfu/g, Coliform count 5.41+0.616 log cfu/g and Staph aureus count 6.38 +0.536 log cfu/g.
Adulteration study in different dairy products are summarized as i.e. Haleeb and Nestle yoghurt brands were negative for chemical adulterants tests i.e. Urea, Formaldehyde, Neutralizers, Starch, Boric acid, Quaternary ammonium compounds, while H2O2 was detected positive in both yoghurt samples of Haleeb and Nestle. Similarly all the chemical adulterants tests were negative for milk powder samples of Haleeb and Nurpur brands while positive for H2O2. Results about ice cream samples shows that all the ice cream samples were negative for chemical adulterants tests i.e. Urea, Formaldehyde, Neutralizers, Starch, Boric acid, Quaternary ammonium compounds, while positive for H2O2.
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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.
Physico-Chemical And Sensory Characteristics Of Feta Cheese Made From Sheep Milk Blends.
by Muhammad Adeel | Dr. Imran Javed | Dr. Muhammad Nasir | Dr. Saima Inayat.
Material type: ; Format:
print
; Literary form:
not fiction
Publisher: 2013Dissertation note: Abstract Availability: Items available for loan: UVAS Library [Call number: 1639,T] (1).
4.
Quality Enhancement Of Soy Milk And Soy Yoghurt Blender With Buffalo Milk
by Muhammad Asad Hameed | Dr. Saima Inayat | Dr. Imran Javed | Dr. Muhammad Nasir.
Material type: ; Format:
print
; Literary form:
not fiction
Publisher: 2014Dissertation note: Yoghurt is a fermented milk product, which is produced by the bacterial fermentation of milk. It is a rich source of calcium, protein and vitamin B-complex. Lactose-intolerant people can eat yoghurt without any harm as lactose is converted into lactic acid by the bacterial culture. Yoghurt is more nutritive then milk and possesses better digestibility. The benefit of yoghurt depends upon the presence of beneficial viable bacterial culture in adequate number. The bacterial cultures are used in the fermentation process to metabolize the lactose, secondly the proteolysis of protein for improving bioavailability and thirdly lactic acid bacteria for production of some B-complex vitamins and vitamin K. Yoghurt culture are responsible for the production of aromatic flavor compounds.
In Pakistan the production of soy milk and soy yoghurt isnot common because ofconsumerunawareness for such kind of products. Therefore, this study was designed to develop soy milk and soy yoghurt by using different concentrations of buffalo milk. To produce soy yoghurt, soy milk and whole milk was pasteurized at 85°C for 30 minutes to kill the pathogenic microorganism. Thencooled at 42°C. This milk was used for the production of yoghurt.Thecommercial starter culture was used for the manufacturing of soy yoghurt. This culture was imported from Italy.
During storage the prepared soy yoghurt was evaluated for its sensory qualities. A panel of judges evaluated the yoghurt samples for appearance, taste, color and overall acceptability on 9-point hedonic scale (9 = like extremely; 1 = dislike extremely). The sensory evaluation of the product at 0, 7, 14 and 21 day was carried out in the Department of Dairy Technology, University of Veterinary and Animal Sciences, Ravi Campus, Pattoki. There was significant effect of storage on sensory attributes of soy yoghurt. Highest score was awarded to T0. Soy yoghurts were evaluated for physico-chemical parameters (Fat, protein, total solid, acidity, pH and ash) during storage of 21 days with 7 days interval. Fat, pH and ash contents were continuously decreased while protein, total solid and acidity values show continuous increase in all treatments. Soy yoghurt was also evaluated for microbiological examination (total plate). Highest microbial count was observed in T0.
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