CC BY
23
Научни трудове на Съюза на учените в България-Пловдив. Серия В. Техника и технологии, т. XV, ISSN 1311 -9419 (Print), ISSN 2534-9384 (On- line), 2017. Scientific Works of the Union of Scientists in Bulgaria-Plovdiv, series C. Technics and Technologies, Vol. XV., ISSN 1311 -9419 (Print), ISSN 2534-9384 (On- line), 2017.
IMPACT OF DAIRY FAT ON CHEESE Monika Karabeleska* , Julijana Tomovska, Stefche Presilski University ,, St. КЗimentOhridski,, - Bitola, Faculty of Biotecnical Seienceo a Bitola
Abstract
Fat content affects several aspects of cheese, including the composition, biochemistry, microstructure, yield, rheological properties and textural features. The process of creating milk gel occurs through hydrolysis of casein micelles, acidification to isoelectric point, acidification at pH 5.4 to 5.6. Networking fat globules occupy the space between the protein chains and can be considered physically difficult aggregation paracasein matrix. Milk fat contributes directly or indirectly on the yield of cheese. Proteolysis directly affect the level of intact casein, which is the main determinant of fragility and functional properties. Primary proteolysis was investigated indicates that the effect depends on the level of MNFS in cheese. Secondary proteolysis plays a role in forming taste FFa also participate as precursors for a number of volatile compounds aromatic. The dependence of the strength of the cheese by the presence of fat has been shown that there is no meaning. Keywords: cheese, dairy fat, proteolysis, milk fat
1. Introduction
Fat is the main ingredient in most kinds of cheese, but its content and meaning varies considerably between species. Within species and between species are differences in fat content which are influenced by many factors, including the composition of milk (especially the ratio of protein / fat), the processes of production of cheese (recipe, production process and technology) that affect levels of milk fat and moisture that keeps the rennet and the moisture content of the cheese. Fat contributes to the formation of flavor directly and indirectly via lipolysis. Fat content affects several aspects of cheese, including the composition, biochemistry, microstructure, yield, rheological properties and textural features.
2. The influence of fat composition on the cheese
2.1 Fat content
Fat is the main ingredients of most types of cheese and significant changes in its composition and representation results in concurrent changes in moisture levels and protein, and the yield of cheese. In a study where conditions in cheese production is kept constant, reducing the fat content in cheese is simultaneously associated with an increase in the concentration of moisture, protein, and reduction in the content of fat in dry matter, moisture not fatty substances and pH.
2.2 Contribution of fat on the microstructure of cheese
Basically cheese represents a concentrated protein gel that captures fat, moisture and other substances. The process of creating milk gel occurs through:
• Hydrolysis of casein micelles stabilized in K-casein by the action selected acidic proteinases (rennet)
• Acidification to an isoelectric point (pH value) of the application of casein with lactic acid bacteria or food acids,
• Acidification at a pH of 5.4 to 5.6 at high temperature (89-90°C)
Differences in the composition of the cheese between the inside and surface of particles arising as a result of cutting or interrupting the coagulum particles that further lead to loss of fatty globules from freshly cut surfaces surrounding medium consisting of whey, said surfaces covered with fat become of the internal structure of the cheese.
2.3 Microstructure for the fat phase
Networking fat globules occupy the space between the protein chains and can be considered physically difficult aggregation paracasein matrix, to the extent related to their volume fraction and distribution by size. As a result, higher levels of fat leads to slower development of syneresis during the manufacturing process and higher levels of MNFS in cheese, a dominant influence on the yield of cheese and its quality. The temperature applied during the manufacturing process of cheese (30-55oC), most or almost all milk fat is in the form of liquid and as a result, she has the ability to run and aggregates, allowing implementation of the process of symbiosis in changing external force. The significant part of the fat (about 20-30%) that can be at the liquid form at the temperature of maturation applied in the production of cheddar and mozzarella (about 6-7o C), it is further extended aggregation, leading to symbiosis. For these reasons, an increase of the liquid versus solid by increasing the ratio of the fraction with low melting point (fat, oleic fraction) vs. fraction with high melting point (stearic fraction), resulting in higher levels of free oil in mozzarella cheese which gets to rekombination milk, which in turn is produced by homogenization of skimmed milk and fat fraction. Homogenization of milk for cheese production, at a pressure in the range of 2.6 - 30 MPa causes more even dispersion of fat globules and a significant reduction in size and degree of association and symbiosis fat globules in Cheddar and mozzarella.
When cooking cheese is heated to a higher temperature (80-100oC), which turn affect the application of its microstructure to a level depending on the fat content, the degree of emulsion, the nature of the membranes of the fat globules or the type of cheese. 2.4 Effects of fat on the yield of cheese
Milk fat contributes directly or indirectly on the yield of cheese. The direct link is clearly reflected in the equation who is used to calculate, making the link between the concentration and yield of milk fat and protein
Table 1. Effect of fat content of the milk on the yield of cheddar and fat of cheese a
Fat in milk (%, w/w) Actual yield (kg/100kg milk) Provided yield6 (kg/100kgmilk) Yield of dry matter (kg/100kg milk) Fat obtained from cheese (% of total )
0,54 6,37 6,47 3,43 80,84
1,5 7,49 7,58 4,29 87,84
2,00 8,09 8,21 4,79 89,48
3,33 9,50 9,61 5,92 87,84
a Collected data from Fenelon and Guine (1999) 6 Provided using modified Van Slykes formula as mentioned in the text.
The fat also indirectly affect the yield of cheese, because its presence in paracasein matrix affect the degree of contraction of the matrix, and thus the moisture content and yield of cheese. Occluded fat globules physical limit the contraction of the surrounding area paracasein network, thereby reducing the volume of syneresis. It is becoming harder to remove the moisture because the fat content of the whey is increased. As a result, the ratio of moisture versus casein increases, while the percentage of creating cheese modified in order to emphasize the casein aggregation. 2.5 The impact of fat on proteolysis
Fat contributes to the taste, through the creation of peptides and free amino acids and indirectly through catabolism of free amino acids to a variety of compounds, including amines, acids, thiols. Proteolysis directly affect the level of intact casein, which is the main determinant of fragility and functional properties.
Primary proteolysis was investigated indicates that the effect depends on the level of MNFS in cheese. * Cheese with a similar level of MNFS, Rank has studied the impacts of the fat content, within 13.5 to 30% w / w, the proteolysis of cheese flasks in which they were made certain changes in the manufacturing protocol in order to obtain content MNFS similar to that of full fat cheese. After 6-8 months storage at 40 C, concentration of aa - casein at low level fat cheese (13,5% w/w) it was only moderately lower than that of full fat cheese (30% w/w). * Cheese with variety content of MNFS. Contrary to previously stated, referring to the fact that the level of fat in the region of 6-33% w / w, has a significant impact on the level of proteolysis in Cheddar produced using identical conditions but with varying levels of MNFS. Secondary proteolysis come researchers found that the proportion of 5% phosphotungstic acid soluble N, which includes pepticite low molecular weight and free amino acids is affected very low at 40% reduction of fat content. Fatty Acid Metabolism in addition to their direct role in forming taste FFa also participate as precursors for a number of volatile compounds aromatic substances example: n-methyl ketones (alkane-2-ones), secondary alcohols, hydroxy acids, lactones, esters, and thioesters. 3. Conclusion
Change the fat content has a significant impact on its surface fragility in different types of cheese, including the Cheddar and Mozzarella. Reduce the fat content in Cheddar resulting in increased elasticity, cohesiveness, easy of chewing, as well as rubber and reduce adhesion, as a result, the texture of Cheddar with reduced fat content is much less affordable for consumers, compared with full fat Cheddar, which is much softer and has less features of rubber. According to some research scientists came to the conclusion that the strength of different cheeses generally shows an increasing tendency by reducing the fat content, the link between fat and strength proved to be not very significant. 4. References
Ardo,Y.1993 Characterizing ripening in low-fat,semi-hard-eyed cheese made with undefined mesophilic DL-starter.Ind.DairyJ.3, 343-357
Bryant. a.,Ustanol,Z.,Steffe,J. 1995.Texture of Cheeddar cheeseas influenced by fat reduction.J.Food.
Collins,Y.F McSweeney,P.L.N Wilkinson,M,G 2004.Lipolusis and catabolism od fatty acids incheese.In Cheese Chemistry,Physics and Microbiology. Vol. I,General aspects 3rdedn,pp 373-389,Elsevier. academic Prees. Amsterdam.
Curtin, a ,C.McSweeney,P.L.H.2004.Catabolism of amino acids in sheese during ripening. Drake.M. a.,Herrett,W.,Boylston,T.D.,Swanson.RG.1995a.Sensory evaluation of reduced-fat cheese.J.Food Sci.60,898-901.
Fox,P.F.,Guinee,T.P.,Cogan,T.M.,McSweeney,P.L.H.2000.Fundamentals od Cheese Science. Aspen Publishers,Inc.,Gaithersburg,MD.
Gilles.J.,Lawrence,R.C.1985.The yield of cheese.N.z.J.Dairy Sci.Technol.20,205-214. Jarrett.W.D., Aston,J.W.,Dulley,J.A simple method for estimating free amino acids in Cheddar cheese. Aus.J.Dairy Technol.37, 55-58.
Metzger,L.E.,MistryV.V.1995. A new approach using homogenization of cream in the manufacture od educed fat Cheedar cheese.1.Microstructure,fat globule sizedisrtribution, and free oil.J.Dairy Sci.84, 1348-1895.
Wright. A.J.Marang. a .G.Hartel,R.W.2002.Lipids: Rheological properties of and their modification Encyclopedia of Dairy Sciences.Vol.3pp.1577-1583, academic Prees,London academic Prees.London.
Corresponding author: [email protected]
