1.
Effect Of Various Levels Of Probiotics(Lactobacillus Acidophilus And Bifidobacterium Bifidum) On Physicochemical, Microbiological And Sensory Characteristics Of Ice Cream
by Aliya Javed | Dr. Muhammad Ayaz | Dr. Saima | Muhammad Nadeem.
Material type: ; Format:
print
Publisher: 2010Dissertation note: Ice-cream is a frozen mixture of combination of components, such as milk, sweeteners, stabilizers, emulsifiers and flavoring agents. Ice-creams are food products which show excellent potential for delivering probiotics to consumer. Probiotics are basically health promoting gut friendly bacteria. Minimum viable quantity of probiotics which is beneficial for human beings is 106 or 107 cfu/g. Benefits are strain specific and cannot be extrapolated. Keeping in view the importance of probiotics the present research study was planned to determine the influence of various levels of probiotics (Lactobacillus acidophilus and Bifidobacterium bifidum) on physicochemical and sensory characteristics of ice cream, assessing the viability of probiotics at different storage periods and to give innovative and value added product to commercial ice cream manufacturers. In order to carry out the study, Freeze dried cultures of two probiotic bacteria i.e., Lactobacilus acidophilus (DVS LA-5 Probio-Tec®) and Bifidobacterium bifidum (DVS BB-12® Probio-Tec®) were obtained from Chr. Hansen (Hørsholm Denmark). The probiotic cultures were stored at - 18? C in freezer.
These two probiotic strains were inoculated alone and in combination in ice cream mix at three different inclusion levels. Hence there were total nine experimental treatments. A regular or control ice cream i.e., without any probiotic culture was also used along with treatments. Probiotic ice cream preparation and physical tests were performed at walls Ice Cream factory, Lahore, Pakistan. Chemical analysis were performed at department of Food and Nutrition laboratory, whereas, Microbiological tests were conducted at department of Microbiology, University of Veterinary and Animal Sciences, Lahore.
Probiotic ice cream was manufactured in the pilot plant of the research and development department, Unilever Walls Ice Cream factory Lahore. Ice cream mix was prepared by following standard procedure. After mixing, homogenization and pasteurization of ice cream mix, it was cooled to 41°C and was divided into ten equal parts. Probiotics cultures alone and in combination, according to experimental design, were added in ice cream mix. Then it was fermented for two hours at 41°C. Then mix was aged at 4°C for a period of 2 hours followed by freezing and hardening. Ice cream samples were packed in one liter plastic tubs and were stored at - 18°C in freezer.
Ice cream samples were analyzed after every fifteen days interval during storage period of three months. Physicochemical tests including overrun, viscosity, melting resistance, pH, acidity, fat, protein, total solids were performed by following the methods of AOAC (2000). As far as results of physicochemical tests are concerned, it was observed that both Lactobacillus acidophilus and Bifidobacterium bifidum are able to produce acid in ice cream. Acidity tended to increase as a result of increase in the number of bacteria. Highest pH was observed in control (R) sample, whereas, lowest pH was observed for samples having mixed culture. pH tended to decrease throughout storage. Lactobacillus acidophilus found more acid producing than Bifidobacterium bifidum. Ice cream samples containing high levels of probiotic bacteria showed decreased value of overrun. Whereas no effect was found in case of viscosity. Samples with increased level of bacteria showed significantly less melting resistance. Also, melting resistance tended to decrease significantly with increase in storage. Total solids and fat contents remained constant throughout storage and effect of treatments was statistically non significant. In case of protein contents, a positive correlation was observed .Increase in level of bacteria , increased the protein contents of ice cream, but it remained constant throughout the storage.
Viable probiotic bacteria were enumerated by using the technique of spread plate method by using RCA media. In present study, cell count of viable bacteria, after fermentation, showed increase number of colonies. Samples inoculated with B3 were excellent in regard of exhibiting probiotic property followed by treatments B2 and A3. Treatments in combination i.e., C1, C2 and C3 showed results close to treatments having single cultur , which might be due to nutrients competency with each other. Furthermore, it was quite difficult to count colonies in mixed culture. Ice cream samples prepared from mixed culture were more acidic in taste and flavour and were least liked by sensory evaluators.
Probiotic ice cream was subjected for sensory evaluation by five panel of judges. They rated ice cream by using nine point hedonic scale. Color of ice cream did not show any change throughout storage and was not affected by various levels of probiotics. No surface spots were found in any treatment at any storage period. Due to acid producing nature of probiotics, slight acidic changes were observed in thickness, flavour and taste of ice cream. However, overall acceptability for all probiotic ice cream was good. The data were analyzed according to analysis of variance technique under factorial arrangement. Significance of means was compared by using Duncan's multiple range test.
Availability: Items available for loan: UVAS Library [Call number: 1205,T] (1).
2.
Study On Chemical Composition Of Nili Ravi Buffalo Milk
by Yasir Abrar | Prof. Dr. Muhammad Ayaz | Dr. Jaleed | Mr. Muhammad Nadeem.
Material type: ; Format:
print
; Literary form:
not fiction
Publisher: 2010Dissertation 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.
Availability: Items available for loan: UVAS Library [Call number: 1220,T] (1).
3.
Improving Nutritional Value And Acceptability Of Dairy Products With Lower Contents Of Saturated Fatty
by Muhammad Nadeem | Dr. Muhammad Ayaz | Dr. Imran Javed | Prof. Dr. Muhammad.
Material type: ; Format:
print
Publisher: 2013Dissertation note: Abstract Availability: Items available for loan: UVAS Library [Call number: 1742,T] (1).
4.
Fractions Of Milk Fat On Lipolysis In Cheddar Cheese
by Shakeel Ahmad (2008-VA-426) | Prof. Dr. Muhammad Ayaz | Dr. Muhammad Nadeem | Dr. Muhammad Hayat Jaspal.
Material type: ; Literary form:
not fiction
Publisher: 2014Dissertation 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.
Availability: Items available for loan: UVAS Library [Call number: 2205,T] (1).
5.
Chemical Characteristics Of Trans Free Margarine Enriched With Omega Fatty Acids Through Chia (Salvia Hispanica L.) Oil
by Muhammad Ajmal (2009-VA-495) | Prof. Dr. Muhammad Ayaz | Dr. Muhammad Nadeem | Dr. Muhammad Hayat Jaspal.
Material type: ; Format:
print
; Literary form:
not fiction
Publisher: 2015Dissertation 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.
Availability: Items available for loan: UVAS Library [Call number: 2301-T] (1).
6.
Antioxidant Charactristics And Lipolysis Of Gouda Cheese Fortified With Mango (Mangifera Indica L.) Kernel Oil
by Sadaqat Ali (2010-VA-374) | Dr. Muhammad Nadeem | Dr. Muhammad Ayaz | Dr. Naveed ul Haq.
Material type: ; Literary form:
not fiction
Publisher: 2016Dissertation note: Oil from mango kernels was extracted by mechanical expression and solvent extraction (nhexane).
Mechanically expressed and solvent extracted oil was pooled for using in Gouda
cheese. Mango kernel oil was added in cheese milk at 5%, 10%, 15% and 20% concentration;
control was comprised of 100% milk fat. Mango kernel oil and freshly prepared Gouda cheese
fortified with mango kernel oil was characterized for total phenolic contents, DPPH free radical
scavenging activity, antioxidant activity in linoleic acid, nitric oxide free radical scavenging
activity and total flavonoids. Ripening of Gouda cheese was carried out for 3 months at 8±2oC;
fat, protein, ash, moisture content were estimated at 0, 45 and 90 days of ripening Fat, protein
and moisture content in cheese were determined at 0, 45 and 90 days of ripening. Free fatty
acids, peroxide value, iodine value and cholesterol in Gouda samples were analyzed for interval
of 45 days by using the standard methods. Fatty acid composition of fresh and 3 months stored
Gouda cheese was determined on a Gas Chromatograph.
Each treatment was replicated three times, each sample was analyzed three times and Experiment
was planned in a completely randomized design, two ways analysis of variance technique was
used to determine the effect of treatment, storage and their interaction. Duncan Multiple Range
Test was used to denote the significant difference among the treatments (Steel et al. 1997).
This novel research work opened a new strategy for the development of functional foods,
application of mango kernel oil in complex food substrates with efficient waste utilization.
Fortification of Gouda cheese with mango kernel oil significantly improved the 2, 2-diphenyl-1-
picrylhydrazyl free radical scavenging activity and total phenolic contents, increased total
flavonoids. Cheese fortified with mango kernel oil revealed the existence of mangiferin,
Sammary
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catechin, quercetin caffeic acid and chlorogenic acid. Lipolytic changes in the cheese fortified
with mango kernel oil up to 10% concentration was similar to that of control with no difference
in sensory attributes. So Antioxidant characteristics of cheese can be improved through mango
kernel oil fortification. Availability: Items available for loan: UVAS Library [Call number: 2638-T] (1).
