Fat replacers are fats which provide few calories than natural fat from 0 to 9 kcal/g. These are classified as fat mimetics e.g. protein and carbohydrate based and fat substitutes e.g. fat based fat replacer.
Due to health conscious consumers demand of functional food products have been increased because they interested to intake low fat diet. These nutritional concerns are linked to lower consumption of fat and sugar due to the risk of high blood pressure, obesity, cancer, cardiovascular diseases and diabetes. It was become the major priority to develop the low fat content products with same characteristics of fat and give same texture, mouthfeel, appearance, aroma and flavor like fat.
Fat mimetics consist on carbohydrate and protein based material so these are commonly used in cheese products. However emulsified fat enhance quality and mouth-feel by increasing fullness, smoothness and creaminess in various food products. Fat gives much energy than proteins and sugar so fat content reduced in food products for health concern to prevent from obesity and overweigh. Different ingredients are used to replace fat in food products. Emulsified fat act as filler and used to increase viscosity by improving sensory properties.
Polysaccharide thickeners are used for this purpose. An ideal fat replacer should be non-toxic and partially or completely undigested. It is difficult to reduce saturated and trans-fatty acids from the diet. In bakery products shortening ability of hard stock fats effect physical properties like plasticity and elasticity. Bread belongs to that kind of foods which make the foundation to develop new products by using primary dietary cereals which is cost effective, nutritious. Bread is a good source of carbohydrates, fats, proteins and fibers. It is also rich in vitamin B complex and minerals i.e. magnesium, phosphorus and potassium. These components are present in bread which is made up of whole wheat flour. So due to its essential nutritive values bread becomes the basic part of food guide pyramid and considered as staple food.
Sesame oil
Sesame oil is extracted from sesame i.e. cultured in temperate and tropic areas. It ranks 12th among all vegetable oils. Sesame oil is a rich source of essential fatty acids like it contains 35% linoleic acid, 43% oleic acid, 7% stearic acid and 11% palmitic acid which give 96% of total fatty acid profile. This oil is used in cosmetics, varnishes, paints and as insecticides. Sesame oil act as antioxidant because it is very stable to oxidation, these antioxidants are sesamin, sesamol and sesamolin with tocopherols. Sesamolin in converted into sesamol after frying, this sesamol act as anti-oxidant to promote apoptosis of cancer cells .Sesamin and sesamolin are non-glycerol, although it prevent from oxidation so high quality products are produced.
Emulsion
An emulsion is a suspension of two immiscible liquids i.e. oil and water, in which one phase is suspended in another phase. Emulsion has two types these are oil in water (O/W) emulsion and water in oil (W/O) emulsion. In the case of oil in water emulsions, dispersed phase is oil and continuous phase is water e.g. sauces, milk, mayonnaise and salad dressings while in the case of water in oil emulsions, water is dispersed phase and oil is continuous phase e.g. margarine and butter. For emulsion preparation high pressure homogenizers are used. Emulsion stability depends upon both chemical forces and physical forces. Physical forces which include to make emulsion unstable are Ostwald ripening, partial coalescence, coalescence, flocculation, creaming and phase inversion. The chemical forces include hydrolysis of lipids and oxidation.
However three phases are used to make a stable emulsion these are emulsifiers, suspended phase and continuous phase. Emulsion stability also affected by pH, ionic strength and temperature. Emulsifiers play an important role to stable and prepare emulsion. They reduce the interfacial surface tensions of water and oil and coated droplets of emulsion. Intensive agitation requires distorting and breaking down the droplets of emulsion. So higher energy used for this purpose.
Conclusion
Many fat replacers are used for this purpose which is inexpensive and easily accessible. Emulsion stability has major concern to prepare emulsion because emulsion is not thermodynamic stable. Emulsifiers are used to prepare emulsion and stabilize it. Emulsifiers are used as fat substitutes. Bread is a basic product which is prepared by baking in oven and a basic part of food guide pyramid. It is perishable and considered as staple food and balanced diet. These were used to prepare bread with fewer calories. Composition of emulsion includes sesame oil, moisture, stabilizer and emulsifier. Compositional analysis of wheat flour includes ash, moisture, crude fat, crude fiber and protein.
In second step of research wheat flour, fat replacers and other ingredients were mixed at different concentration levels. Then their rheological properties were determined and used in various other food products. Different concentration of emulsion reduced water absorption which is helpful to increase the shelf life of product. To determine rheological properties farinographic studies done. It results that water absorption is highly significant. It is noticed from data of different treatments that absorption of water ranged from 61.58-58.86%. It was noticed that absorption of water is maximum in To and minimum in T5.When amount of emulsion enhance it decrease water absorption level.
Data obtained from different treatments indicated that development time was highly significant. It was observed that minimum development time found in To and maximum in T5. Results got from mean values range from 11.51-16.74 minutes. It was determined from results that dough stability time highly significant among different treatments. Results get from mean values range from 10.50-13.60 minutes. It was noticed that stability is minimum in To and maximum in T5. Present results obtained for mixing tolerance index indicated that it is highly significant with various treatments. Results get from mean values range from 32-76.33BU. It was noticed that is minimum in To and maximum in T5.
Different concentrations of fat replacers improved functional properties and nutritional characteristics to prepare low fat bread. Compositional analysis of bread showed that nutritional quality of bread improved by adding different concentration of fat replacers. It was prescribed that the maximum value of fat contents obtained in T0 i.e. 5.42% and minimum in T5 i.e. 3.71%. It was showed from results that fiber contents increased in T5 i.e. 0.54% and decreased in T0 i.e. 0.49%. It was described from results that moisture content’s maximum value obtained for T5 treatment i.e. 36.42% and minimum value for the To treatment i.e. 32.26%, ash contents for T5 is 1.64% and T0 is 1.44%, protein contents maximum value obtained for T5 treatment i.e. 14.42% and minimum value for the T0 treatment i.e. 14.02%. Results obtained from physical analysis of bread showed that there was highly significant relation among all parameters. By increasing amount of fat replacer colour of bread improved. It was also obtained that hardness of bread was highly significant among different treatments.
The sensory parameters of bread prepared by using wheat flour with sesame oil emulsion noticed a highly significant effect on volume, evenness of bake, color of crumb, aroma, mastication, taste and texture and non-significant results noticed on color of crust, symmetry of form, character of crust, grain size.These parameters values increased by increasing concentration of emulsion. Emulsion also increased the quality and shelf life of product. It is prescribed that up to 40% fat replacer based emulsion show improvement in functional and nutritional properties of bread. Nutritional support programs should be launched to develop fat replacer to reduce calories in products.