Study Of Physico Chemical And Microbiological Quality And Adulteration In Processed Dairy Products
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Publisher: 2010 Dissertation 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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Study On Chemical Composition Of Nili Ravi Buffalo Milk
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Publisher: 2010 Dissertation note: Milk is a complete food and contains all the nutritional components in balanced form. It helps to meet important nutritional needs of the human body. Vitamins, minerals, sugar, Fat, and protein are present in milk. Among the established breeds of buffalo in Pakistan. the Nili-Ravi breed originated in the valleys of Sutlej and Ravi rivers is dominant in the Punjab province. The purpose of the study is to determine the chemical composition and fatty acid profile of buffalo milk.
The milk animals, Buffaloes were divided into 3 groups on the basis of lactation period i.e early, middle and late lactation. Five animals were present in each group. Six milk samples. 3 in the morning and 3 in the evening from each animal was collected. A total of 90 milk samples were obtained for analysis. Milk in bottles of 500 ml capacity was transported to lab. [he samples were analyzed in Livestock Production Research Laboratory, Livestock Production Research Institute Bahadurnagar (Okara). Temperature, Density, Conductivity and freezing point was determined by using Milkoscan.
Buffalo samples were analyzed for proximate analysis, parameters like fat, crude protein, lactose, ash, solids not fat, total solids, pH and acidity were determined. Fatty acid profile of buffalo milk was determined by the method of AOAC (2000). Milk fat content (%)was Ihund to be significantly (p<0.05) lower in the early (6.52) and mid lactation (6.61) stages than the late lactation stage (6.85). The content of TS (%) was found to be significantly (p<O.05) higher in the late lactation (14.62 and 15.45) stage than the early (12.94 and 13.65) and mid lactation (13.76 and 14.14) stages. In contrast, the content of total protein (4.31 to 4.78%), SNF (X.4() to8.70%), lactose (4.36 to 4.74%), and ash (0.l8to 0.19%) did not vary significantly among the different lactation stages.
Fatty acids profile also checked from Cl to C20. The values of Butyric acid, Caproic acid. Myristic acid, Stearic acid, and Oleic acid showed significant increase towards end of lactation. 'lhcse values of fatty acids also revealed that there is significant difference among the animals and between the lactation stages of Nih- Ravi buffalo milk. Results showed that Capric acid, Laurie acid, Palmitic acid, Palmitoleic acid, Linoleic and Linolenic acid decreased in early to middle and increased towards end of lactation.
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Effect Of Various Concen Trayious Of Hydrogen Pereoxide On Chemical And Microbiogical Quality Of Raw Buffalo Milk
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Publisher: 2011 Dissertation 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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Survival Of Probiotic Bacteria In Commercial Infant Foods And Their Antimcrobial Activity Against Food Borne
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Publisher: 2011 Dissertation 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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Development And Sensory Evaluation Of Flavored Probiotic Acidophilus Milk
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Publisher: 2011 Dissertation 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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Rheological And Microstructural Study Of Commercial Cheddar And Mozzarella Cheeses By Using Farinograph
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Publisher: 2012 Dissertation note: A series of five experiments were conducted using Brabender Farinograph-E to study rheological properties of different brands of cheeses. This is a computerized machine having data recording capacity. It was found that Farinograph was a use full machine for preparing cheese and studying its rheology. The data recorded in the form of Farinogram showed that torque (resistance against flow of farinograph paddles) depended on fat content, temperature employed and time given to cheese formation. Also, the texture of cheese was influenced by these factors.
Sensory tests are not capable of measuring results more accurately as compared to Instrumental tests. To study cheese properties and effects of many manufacturing factors the fundamental methods will help researchers to develop cheeses with required and persistent textural and rheological properties. The instrument most frequently used all over the world for determining water absorption and mixing characteristics of wheat and rye flour in baking industry is Brabender Farinograph®. The present study was conducted by using Farinograph-E as a major tool to measure rheology of cheeses. In this study cheeses of different ages, and kinds e.g., Mozzarella, medium Cheddar, mild Cheddar, old Cheddar, extra old Cheddar, Ricotta and Parmesan were included. The parameters for operating Farinograph-E were developed and initial trials were conducted in various directions to finalize the procedure. Farinograph-E (Brabender GmbH, Duisburg, Germany) was used in this study by using its bowl W-50.
The tests were performed by cutting whole cheese bars into small pieces and shifted into air tight containers. The grated cheese was loaded with the help of spatula into Farinograph bowl. Water bath was adjusted at various temperatures like 20, 30, 40, 50 and 60°C. The temperature was continuously monitored through a temperature probe, inserted into the bowl contained cheese sample. The speed of paddles/ spindles was fixed in Newton meters (Nm) and was kept as constant for all the trials. The lid was closed after filling the bowl and clamped in order to avoid any disturbance. The test was allowed to run for specified time for 35 and 60 minutes. After completion of time durations the test was stopped automatically. The readings were recorded in the form of a graph (torque, time and temperature) of cheese dough resistance over mixing time.
Besides Farinographic studies, the results of Mozzarella and medium Cheddar Farinographic samples of (brand No name) were examined through Cryo-scanning electron microscopy and Fluorescence microscopy to study their microstructure at different stages and their relationship with quality of cheeses. The present study revealed that temperature, time and different fat percentages of different cheese brands shows significant effects on torque values. The results indicated that by increasing fat percentage the torques value decreases.
Cryo-scanning electron microscopy revealed finer details of cheeses. Shape, size and distribution of fat globules were observed through fluorescence microscopy. The changes in globule sizes and their interaction with casein matrix was also observed. Size of globule was estimated using image analysis technique. Aggregation of globules and their rupture was also observed. These changes in fat globules shape and sizes affected flowability, meltability and viscosity of cheeses and thus affected production of torques which were observed in graphs produced by Farinographs.
By studying microstructure it was obvious from micrographs that Stage 1 showed smaller fat globules in large numbers. In Stage 2 the globules became larger in size and lesser in number and like bubbles in shape, as shown in plates. At stage 3, there was no particular change from Stage 2 texture, except slight change in colour. The same changes are depicted in the shape of curve, that moved up and downwards and then upwards.
Full fats at stage 1, showed smaller fat globules those enlarged at stage 2. In stage 3, only enlarged globules were observed, and the resistance increased against paddles of farinograph and sharp increase was seen in the slope of graph. Globules retained their features at next stage and slope in graph became horizontal to x-axis after reaching maximum value.
These results suggest that size distribution of fat globules tended to impose influence on Farinographic results. Overall it is indicated that Farinograph is a suitable instrument for measuring rheology of cheeses.
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Qualitative Comparison Of Yoghurt Prepared From Conventional And Probiotic Culture
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Publisher: 2013 Dissertation note: Abstract
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Isolation And Molecular Characteracterization Of Staphylococcus Aureus From Raw Milk
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Publisher: 2013 Dissertation note: Abstract
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Fractions Of Milk Fat On Lipolysis In Cheddar Cheese
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Publisher: 2014 Dissertation note: Lipids are heterogeneous group of biological compounds, soluble in fat and insoluble in water. Oils and fats mainly comprise of triglycerides and has great importance in Food systems. Fats and oils are completed through ester of three fatty acids and a glycerol molecule (Stolyhmo, 2007; McClement and Decker, 2010; Nichols et al. 2011). Fats have a primary importance for the texture of Foods (Rao, 2003).
Fat has more energy values as compared to other Foods nutrients (Wu et al. 2013), presently, one of the major developments is declining the cholesterol contents and fat in the Foodstuffs (Ma and Boye, 2013). Sensory attributes like appearance, flavor, texture and physicochemical properties of the Foods depend upon the fat because it is very important for the Foodstuffs improvement. For these properties, there should be practical strategies which can reduce fat contents only in the Foodstuff (Wu et al. 2013) and should not effect on nutritious and sensory properties (Boff et al. 2013).
Milk fat can be transformed into various fractions such as very high melting fraction (>50°C), high melting fraction (35-50°C), middle melting fraction (25-35°C), low melting fraction (10-25°C) and very low melting fraction (<10°C). Low melting fraction (<15°C) has strong butter flavor and can be incorporated into milk powder to improve functionality. It can be used in confectionery products and can increase spread ability of butter at low melting temperature (Gunstone, 2001).
It has been investigated that melting point of butter oil decreased with C18:2 and increased with C16:0 and C14:0 fatty acids. It has also been investigated that melting point is negatively correlated to C40, C38, C30 and C28 tri-acylglyceride while positively correlated with C48, C46 and C44 tri-acylglycerides (Ortiz-Gonzalez et al. 2007).
The anhydrous milk fat has a higher fraction of low melting tri-acylglycerids due to more unsaturated fatty acids (Smet et al. 2010).
Fatty acids are composed of carbon and hydrogen atoms having one carboxyl (COOH) group at one side of the chain (Ghatak and Bandyopadhyay, 2007). Fatty acids are divided into short, middle, long chain fatty acids and also in saturated and unsaturated fatty acids. Unsaturated fatty acids are further categorized as monounsaturated, poly unsaturated fatty acids and saturated fatty acids. Almost 65-68% saturated fatty acids of milk fat possess many health concerns (Richmond, 2007). More than 4 hundred types of fatty acids are present in milk fat of different bovine breeds. Plasma cholesterol and incidence of coronary heart disease is increased by medium chain saturated fatty acids of milk fat lauric acid (C12:0), myristic acid (C14:0) and palmitic acid (C16:0) (Jensen, 2002). Fatty acid composition of diet has a great impact on health. Considerable attention has been given on the saturated fatty acids present in diet (Astrup et al. 2011). Nutritionists recommend that saturated fatty acids should be replaced by unsaturated fatty acids to decrease the incidence of cardiovascular disease (Erkkila et al. 2008).
Medium chain fatty acids C12:0, C14:0 and C16:0 are atherogenic (Parodi, 2004; Kris-Etherton and Innis, 2007). The coronary heart diseases and atherogenic fatty acids are highly correlated (Moss and Reed, 2003; MacRae et al. 2005; Mensink, 2006). As compared to other lipids sources dairy products are well known to increase the cardiovascular diseases in human beings, because dairy products contain lower proportion of unsaturated fatty acids and higher proportion of saturated fatty acids especially palmitic and myristic fatty acids (Sacks and Katan, 2002). Dairy Foodstuffs are the sources of dietary cholesterol which increases the serum cholesterol (Collins et al. 2003).
Modification in milk fat can be carried out by chemical and enzymatic interesterification (Pal et al. 2000). Physical modiﬁcation (fractionating of bovine milk fat into different fractions) of milk fat can be carried out by fractionation (Ali and Dimick, 1994). Commercial dairy industries commonly use dry fractionations to improve the texture and flavour properties of dairy products (Grall and Hartel, 1992). Nadeem et al. (2013) found in a study that long chain and short-chain fatty acids can be increased by fractionation of milk fat. Fractionation improves the functional properties of milk fat. Low melting fractions of milk fat can be used in a wide range of functional dairy products.
Cheese is worldwide extensively used dairy product. Researchers have tried to improve the unsaturated fatty acid composition of milk fat by blending with vegetable oil but the use of vegetable oils in cheese has a negative impact on texture, functional properties, excessive lipolysis and flavor characteristics of cheese (Wijesundera and Watkins, 2000;Yli-Jokipii et al. 2001; Dinkci et al. 2011). There are many factors which affect the texture and rheological properties of the cheese. These factors also effect the appearance, functional properties of the cheese and also effect the flavor of the cheese which are very important for consumer. On the base of texture varieties of cheeses are differentiated. Important property for the determination of differences in the cheeses is texture as compared to other flavor and taste property (Wendin et al. 2000)
Free fatty acids of cheddar cheese produced in the result of lipolysis are the precursors of flavor compounds (Smit et al. 2002; McSweeny, 2004). The suitability of low melting fractions of milk fat as a substrate in the manufacturing of cheddar cheese has not been previously investigated.
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Antimicrobial Potential Of Bovine Lactoferrin Against Foodborne Pathogens
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Publisher: 2014 Dissertation note: Health is recourse of everyday life, but not the object to live. It is positive to give special importance to personal and social resources. However, in Pakistan and other developing countries conditions are different, most people have low income and they live in un-sanitized environment. They eat un-hygienic food and also lack safe drinking water. People do not adopt any preventive measure to minimize the risk of contamination. Food storage is also un-hygienic. These conditions lead towards contamination and result in foodborne infections and gastro-enteritis. Foodborne illnesses are always a serious health issue in the Pakistan and throughout the world. Individual’s record for foodborne illnesses is impossible but it is reported that 7 out of 10 people suffer from foodborne illness caused by different microbes each year worldwide (WHO survey 2012).
Foodborne illness is caused by eating contaminated food with pathogenic bacteria. Some common pathogens are Escherichia coli, Campylobacter jejuni, Clostridium botulinum, Clostridium perfringens, Listeria monocytogens, Bacillus cereus, Staphylococcus aureus and Salmonellaspecies. Incubation period for onset of symptoms of food poisoning ranges from hours to days. Nausea, vomiting, abdominal cramps, fever and diarrhea are symptoms which appear commonly in most of food poisoning. However, foodborne illnesses if left untreated can lead severe dehydration, imbalance of intestinal micro flora, digestive disorders and even death in some cases. It was recorded that 2.2 million people killed from foodborne illness globally every year and the burden arising from foodborne diseases is larger (Kuchenmuller et al. 2009).
Antibioticsare massively used to overcome food poisoning; however, from health point of view they badly affect thenormal micro flora of gut but also microbes become antibiotic
resistance. The problem needs to be dealt with some other way like adding bio preservatives or antimicrobial agents in food.
To control microbes in foods, numerous methods have been adopted including the use of synthetic and natural antimicrobial agents. Scope of natural antimicrobial agents are increasing day by day and different natural sources are being utilized to get these agents. Among these natural sources milk is best and widely utilized source from long times. Milk contains many biologically active compounds among which lactoferrin is one of them.
Lactoferrin is a multifunctional globular glycoprotein from transferrin family, an iron-binding protein. It is part of innate immune system and has antibacterial activity known as far back as 1930. It was first isolated in 1939 from cow milk (Charrondiere et al. 2011). Lactoferrin belongs to the transferrin family having ability to bind iron two times higher than other transferrin proteins. Its molecular weight is 80 kDa and has about 700 amino acids depending upon species e.g. cow, buffalo, goat and sheep (Adlerova et al. 2008). Lactoferrin molecule consists of simple polypeptide chain folded into two symmetrical and highly homologous lobes (N and C) connected by a hinge region. Both lobes bind two metal ions in synergy with carbonate (CO32-). Not only Fe2+ and Fe3+ ions but Cu2+, Zn2+ and Mn2+ ions can also bind. Lactoferrin can bind Fe3+ reversibly so it can exist as free of Fe3+ (Apo-Lf) or in association with Fe3+ (Holo-Lf) and exhibits different three dimensional structure depending upon binding to Fe3+. Apo-Lf has an open structure and holo-Lf has closed which provide resistance to proteolysis. At iron-binding site Aspirin, two Tyrosine, and Histidine amino acids are directly involved in each lobe and Arginine is bound to CO32- ions. Number and position of Cystine-residues allows intermolecular disulfide bridges and Asparagine-residues in both lobes provide several sites for N-glycosylation (Farnaud and Evans 2003).
Lactoferrin is produced by mucosal epithelial mammary cells of human, cows, buffaloes, goat, horses, many other mammals and fish. It is widely distributed in body tissues and present in mucosal surfaces, specific granules of leukocytes and in biological fluids like tears, saliva, digestive fluids, seminal fluids and most abundant in milk comprising the second highest protein in human milk after casein. Concentration of lactoferrin in different species is for cow milk (80-500 mg/L), buffalo milk (50-320 mg/L), camel milk (200-728 mg/L), goat milk (98-150 mg/L) and sheep milk (20-140 mg/L) (Krol et al. 2011).
Many physiological functions of lactoferrin have been attributed. It plays an important role in iron regulation, non-specific immune response, regulation of cells growth and differentiation, protection from cancer, anti-inflammatory, anti-oxidant and strong antimicrobial activity against bacteria, fungi, yeast, viruses and parasites (Conneely et al. 2005). Another dominant role of lactoferrin is during involution of mammary gland. Concentration of lactoferrin increased dramatically from 0.1-0.3mg/ml in normal milk to 20-30mg/ml by 30 days in dry period. It is particularly important for bacteriostatic properties and non-specific defense against invading bacteria. Lactoferrin also affects phagocyte function and limit oxidative degeneration of cell components during inflammation and involution (Welty et al. 1976).
Lactoferrin exhibits strong antimicrobial activity against different bacteria, virus, protozoa, fungi and yeast (Hancock and Janssen 2009). The antibacterial activity of lactoferrin is due to two mechanisms; by binding the iron at infection sites, making it unavailable to bacteria and direct interaction of N-terminal of lactoferrin with micro-organism (Cruz et al. 2009, Orsi 2004). Lactoferrin acts differently with Gram-positive and Gram-negative bacteria (Sharma et al. 2013). It damages Gram-positive cell wall through interaction with negatively charged lipoteichoic acid causing reduction in negative charge on cell wall and favor contact between lysozyme and inner peptidoglycan (Fayad 2012). Gram-negative bacteria are destroyed by interaction of lactoferrin with external lipopolysaccharides by preventing contact with Ca2+ and Mg2+ ions which cause release of lipopolysaccharides, increase permeability and ensures damage (Ochoa and Cleary 2009, Ekins et al. 2004).
Milk and milk products are one of main diet in Pakistan and all over the world. During manufacturing different milk products, a number of by-products are obtained. Among them, cheese whey is produced in high volumes. It is commonly dumped off into sewerage which cause serious environmental problem as it contain high organic matter as well as loss of valuable nutrients it contain. Whey has Biological Oxygen Demand (BOD) ranges from 40,000 to 60,000 ppm (Sayadi et al. 2006) while permitted limit for BOD of domestic sewerage is 200 to 300 ppm. In order to overcome this problem there is need of effective and permanent way for treatment of whey. However, conversion of whey into non-food items like biogas is unreasonable as it is rich in unique nutrients.
Now-a-days there is an interest growing on to find new ways of whey utilization throughout the world. One option is to use the whey in processes in which saleable food or pharmaceutical products can be obtained. Whey could be subjected to different techniques to isolate different components like lactose, lysozyme and immunoglobulin. Likewise, lactoferrin can be isolated from cheese whey by cation exchange chromatography without loss of its biological properties in single step method and about 90% purity (Wu et al. 2011, Moradian et al. 2014).
In this study, we anticipated to use lactoferrin from bovine milk as natural antimicrobial agent. It has been shown that lactoferrin hasstrong antimicrobial activity against different bacteria, fungi, yeast, viruses and parasites (Conneely et al. 2005). In our country, very little work has been carried out onlactoferrin as natural anti-microbial agent. In fact, all over the world, the research scenario is now changing and concentrating toward the extraction of natural agents for product safety and health improvement. The lactoferrin has a potent anti-microbial activity against common foodborne pathogens. Due to the negative health effects of synthetic anti-microbial agents, the uses of natural sources are being encouraged all over the world. Our main focus of this study is to check the anti-microbial activity of lactoferrin against three pathogenic bacteria Escherichia coli, Staphylococcus aureus and Salmonella enteritidis isolatedduring our previous study.
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Development Of Cheddar Cheese By Using Crude Flowers Extract Of Citrus Aurantium (Sour Orange) As A Milk Coagulant
Material type: Book ; Format:
; Literary form:
Publisher: 2015 Dissertation note: Presently in Pakistan a few dairy companies are producing Cheddar cheese. Several
alternative proteases obtained from different vegetable and fruit sources such as fruits,
roots, latex and flowers have been recommended as rennet coagulant replacer in cheeses
processing. As there is now decrease in slaughtering of young calves, natural rennet
shortage occurs, so to fill it, sometimes alternates of rennet used in cheese production
This research project was designed to implement and introduce the use of Citrus
aurantium crude flower extracts (CFE) as an economical, easily available and rennet
substitute in Cheddar cheese production. CFE was evaluated for its first time usage as
coagulant in Cheddar cheese production and compared with rennet for its physicochemical
characteristics and sensory evaluation.
Cheddar cheese was made from buffalo milk. Standardized buffalo milk was pasteurized
and then cooled to inoculation temperature. It was inoculated with addition of 2% of
starter culture and given stay of 20-50 minutes. Then control sample was coagulated with
0.002% rennet and other samples were coagulated by Citrus aurantium crude flower
extracts (CFE) at different levels of 1%, 2 %, 3% and 4% at coagulation time. After
curdling, curd was cut, stirred and whey was drained. Then milling and cheddaring of
cheese blocks was done. Salting was done at the rate of 2.5%. After pressing, cheese was
stored in hygienic packaging and left for ripening at 10°C for 2 to 3 months.
Acceptability of newly developed Cheddar cheese using crude flower extracts (CFE) as a
coagulant was evaluated by sensory evaluation using criteria of color, Cheddar cheese
samples were analyzed for physico-chemical characteristics and sensory evaluation at 63
days of storage. The statistical analysis was carried out by using one way Analysis of
Variance (ANOVA) techniques under (CRD) Completely Randomized Design (Steel et
al. 1987). Duncan’s Multiple Range (DMR) Test was used for significant difference
comparisons (SAS 9.1 Statistical Software).
The cheese prepared from using 1% and 4% CFE cheese showed higher fat contents from
0 to 63 days while CFE cheese prepared with 1% and 3% have significant fat contents
and less than control sample prepared with rennet. Cheddar cheese with %, 2% and 3%
showed similar 25% protein content respectively but less than 4% and rennet coagulated
standard Cheddar cheese. Cheddar cheese made from 2% and 1% CFE showed slightly
higher moisture content while 3% and 4% showed moisture content of 33% almost
similar to the rennet coagulated Cheddar cheese which showed 32% of moisture content.
The cheese prepared from using 4% CFE cheese showed highest pH of 5.57 at 0 days
while after storage at 63 days pH decreased to 5.52. CFE Cheddar cheese prepared with
1%, 2% and 3% showed pH of 5.55 at 0 days and decreased to 5.52 which is standard pH
of the Cheddar cheese. Salting of all cheese samples was done at the rate of 2.5%. The
cheese prepared from using 2% and 3% CFE showed decrease in salt but it was higher
than 1% and controlled Cheddar cheese. While 4% showed lower salt contents than all
cheeses. Results showed that cheeses were made with 1% and 2% of CFE had a longer
and slightly softer texture. While cheeses contained 3% and 4% CFE had semi-hard
textural properties of curd similar to rennet added cheese which is similar to the standard
Cheddar cheese made with rennet. Cheddar cheese with 3% and 1% were preferred by
consumers instead of 2% and 4% for their better taste, texture/appearance and overall
acceptability but it was less preferred over standard Cheddar cheese (controlled) due to
the presence of bitter and intense aroma compounds of Citrus aurantium flowers.
It will give a benefit to the cheese industry by introducing a new economical, nutritional
and easily available rennet substitute source of milk coagulation. Pakistan is producing
largest amount of Citrus aurantium, so it will improve its export in other countries for
usage as an alternate of rennet and to provide economic benefits to our country.
Furthermore, it will open new ways for researchers to find out the characterization of
extract and enzyme of CFE.
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Chemical Characteristics Of Trans Free Margarine Enriched With Omega Fatty Acids Through Chia (Salvia Hispanica L.) Oil
Material type: Book ; Format:
; Literary form:
Publisher: 2015 Dissertation note: Omega fatty acids has been related with low cholesterol level in blood, reduce the blood pressure, decreases the risk of heart attacks. Omega-3 PUFA is anti-carcinogenic, anti-atherogenic, anti-lipogenic, prevent the hypertension. Margarine was prepared by blending milk fat 70%, palm oil different concentration 30%, 27.5%, 25%, 22.5% and 20% T0 to T4 respectively .Chia seed oil in various proportions 0%, 2.5%, 5%, 7.5% and 10% T0 to T4 respectively. Milk fat, Palm oil and chia Seed oil was characterized for free fatty acids, moisture content, saponification value, iodine value, refractive index. Solid fat index was determined at 0, 10, 20, 30 and 40˚C by the dilatometric method, melting point was determined by open capillary tube technique.Color, peroxide value, anisidine value, conjugated dienes and trienes was determined. Fatty acids composition of margarines were determined by the transformation into fatty acid methyl esters. Margarine was stored at -6±1oC, for 60-days, iodine value, peroxide anisidine values, free fatty acids, conjugated dienes and trienes was determined. Induction period of margarine was determined by oxidizing the samples under a steady stream of oxygen (20L/hour) at 120oC, on a Rancimat. Sensory evaluation was performed by a panel of ten trained panel of judges, samples was evaluated for color, smell, taste and overall acceptability on a 9-point Hedonic scale.All treatments were replicated three times, every sample was analyzed three times and data were expressed as Mean ± SD. The data was analyze by one way and two way analysis of variance technique, the difference among the treatments was made by Duncan Multiple Range Test
Free fatty acids increased in all the treatments during the entire storage period from 0 day to 60 days, the content of fatty acid during storage period depend upon the degree of unsaturation. . Peroxide value increased in trans free margarine enriched with omega fatty acids through chia oil the during the storage of margarine. The rise in peroxide value at all the
determination frequencies was in the order of T4> T3> T2> T1> control. Iodine value increases in trans free margarine enriched with omega fatty acids through chia oil during the storage time. The decline in iodine value of all the treatments and control was in the order of T4> T3 > T2 > T1 > control. The treatment having more unsaturated fatty acids, underwent more oxidation and yielded the higher extents of oxidation products. Anisidine value of all the treatments and control increased throughout the storage period, all the determination frequencies revealed an increasing trend, however, the rise in magnitude of oxidation products was different in all the treatments and control.Values of conjugated dienes and trienes numerically increased during the storage period, all the measurement intervals revealed an increasing trend, however, the rise in extent of oxidation products was mainly dependent upon the fatty acid composition and treatments having higher concentration of unsaturated fatty acids suffered more oxidation.Addition of chia oil in margarine did not have any impact on moisture content of margarine, moisture content of all the treatments and control was not different from each other (P>0.05). Non-significant changes melting point during storage time in margarine. Color of all the experimental margarines and control were not different from each other (P>0.05). Saponification value non-significant in treatments during storage time from 0 day to 60 days. Analysis of variance indicated that treatments had significant effect on SFI, whereas, the effect of storage and the interaction between treatments and storage was non-significant. The content of C18:3 (omega fatty acid) in margarine is significantly increased from T1 to T4 due to chia oil because it contain 68 % alpha linolenic acid.
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