1.
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).
2.
Enhancement Of Omega Fatty Acids In Margarine Through Chia (Salvia Hispanica L.) Oil
by Hafiza Anam Baig (2010-VA-355) | Dr. Muhammad Nadeem | Dr. Saima Inayat | Dr. Muhammad Hayat Jaspal.
Material type: ; Literary form:
not fiction
Publisher: 2016Dissertation note: The higher incidents of deaths from cardiovascular diseases have led to the identification
and modification of risk factors for atherogenesis; it is regarded as the number one reason of
deaths in developed and underdeveloped countries. Chia contains about 40% edible oil, with
fairly high content of unsaturated fatty acids, oil contains about 60% omega-3 fatty acids on
weight basis. Margarine will be prepared from palm oil, palm kernel oil, butter and chia oil
blends by varying the concentration from 5% to 20%.
Margarine was prepared by blending butter, palm oil and Chia seed oil in various
proportions. Market margarine (Blue Band) was used as a positive control. Butter, Palm oil and
Chia Seed oil was characterized for free fatty acids, moisture content, saponification value,
unsaponifiable matter, 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. Colour, free fatty acids, iodine value, peroxide value, anisidine value,
conjugated dienes and trienes was determined. Fatty acids composition of margarines was
determined by the transformation into fatty acid methyl esters. Margarine was stored at 6±1oC,
for 2 months, iodine value, peroxide anisidine values, free fatty acids, conjugated dienes and
trienes was determined. 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.
Peroxide value of 60 days old control and T4 (12% chia oil) were 7.06 and 12.10
(MeqO2/kg). After 60 days of storage period, peroxide value was in the order of T4> T3> T2>
T1> control. Free fatty acids increased with the storage period in all the treatments. They are
also increasing with the treatments having higher concentration of chia oil. At 60 day, control
Summary
68
and T4 are 0.16 and 0.19% respectively. Anisidine value trend is considerably accelerating
along the treatments as well as with the storage time. At 60 day, control and T4 is 24.42 and
44.78 respectively. Conjugated Dienes have the increasing trend throughout the treatments.
They also have higher values from 0 to 60 days of time period. At 6o day, the control and T4
are 2.47 and 3.34 respectively. Conjugated Trienes of all the samples increased throughout the
storage period of 60 days. At 60 day, the control and T4 are 2.60 and 3.28 respectively. Iodine
value is in the decreasing trend throughout the storage period and the treatments. They are in the
order of T0>T1>T2>T3>T4. Fat content of all the treatments and the control went on decreasing
throughout the storage period of 60 days. At 60 day, control and T4 were 68.61 and 90.91
respectively. The order of the fat content in all the treatments were T0>T1>T2>T3>T4. Moisture
content of all the treatments and the control went on decreasing throughout the storage period of
60 days. At 0 day, Moisture content of all the treatments were virtually the same. At 60 day,
control and T4 were 27.52 and 7.64 respectively. Salt content of all the treatments at the end of
the storage period were increased. At 60 day, control and T4 were 4.18 and 1.42 respectively.
The taste score of all the treatments along the treatments having different concentrations of
unsaturated fatty acids and also along with the storage period of time is decreased. The taste
score of the control and T4 were 8.06 and 6.90 respectively. The order of the taste score is in the
descending order of T0>T1>T2>T3>T4. Results of this evidenced that concentration of omega
fatty acids can be enhanced in margarine through chia oil with acceptable sensory
characteristics. Major changes in fatty acid composition were observed around C18:2 and C18:3
(omega 6 and 3). Concentration of trans fatty acids in control, T1, T2, T3 and T4 was 24.75%,
6.67%, 5.49%, 4.71% and 3.19%. Availability: Items available for loan: UVAS Library [Call number: 2578-T] (1).
