- Functional properties of food
- General Properties of Major Food Components
- Functional Properties of Food Components
- Chemical and Functional Properties of Food Components - Semantic Scholar
Phytates, oxalates, and tannates can interfere with the absorption of a number of minerals. Certain medications such as tetracycline can also inhibit absorption of minerals, whereas others such as jodoquinol function as antibacterial agent by chelating trace metals at bacterial surface, thereby inhibiting their growth. The possible competition mechanisms of some min- erals have already been discussed. Finally, to participate in a nutritionally relevant process for the organism as a whole, a mineral must be transported away from the intestine.
The concentration of circulating binding proteins and the degree of saturation of their metallic binding sites may influence the rate and magnitude of transport of the absorbed minerals. Minerals require a suitable mucosal surface across which they enter the body. Excessive mucosal damage due to mesenteric infarction or inflammatory bowel disease, or major diversion by jejunoileal bypass procedures, reduces the available surface area.
Minerals whose absorption occurs primarily in the proximal intestine, e. In addition, the integrity of the epithelium, uptake of fluids and electrolytes, intracellular protein synthesis, energy-dependent pumps, and hormone receptors must be intact. Intrinsic diseases of the small intestinal mucosa may impair mineral absorption. Conditions such as celiac sprue, dermatitis herpetiformis, infiltrative lymphomas and, occasionally, inflammatory bowel disease produce diffuse mucosal damage.
Protein energy malnutrition causes similar damage, and tropical enteropathy affects part of the population of developing countries living under adverse nutritional and hygienic conditions. The roles of each group in the human body are summarized in Table 5. Potassium, sulfur, phosphorus, iron, and other minerals are structural components of soft tissues.
Sodium is principally found in extracellular fluid bone is an exception , where it is the chief cation, and thus it is considered mainly as a primary determinant of body fluid osmolarity as well as the maintainer of body fluid pH. Intracellular fluid contains much smaller amounts of sodium though these stores, and perhaps the sodium of the bone also serve in this capacity.
It is also important to mention that the energy for impulse transmission in the nerve and its action potential derive from the potential energy represented by the separation of sodium and potassium across the cell wall. On the other hand, calcium, together with phosphorus, magnesium, and fluorine, are com- ponents of bone and teeth. Deficiencies during the growing years cause growth to be stunted and bone tissue to be of poor quality.
A continual intake of minerals is essential for the maintenance of skeletal tissue in good condition. Minerals are an integral part of many hormones, enzymes, and other compounds that regulate physiological functions in the organism. For example, iodine is required to produce the hormone thyroxine, chromium is involved in the production of insulin, and hemoglobin is an iron-containing compound. Thus, the production of these substances in the organism depends on adequate intake of the involved minerals.
A knowledge of the chemical and physical properties of the constituents of foods is important to your understanding of how food systems behave under the various conditions encountered in preservation, storage and preparation for consumption. Food systems vary in their chemical composition and physical properties, ranging from chemically simple systems such as sugar syrups to the chemically complex food systems such as milk, muscle food systems, and plant tissue systems.
In Colloidal Dispersions , the particles of one substance are distributed, dispersed, in another substance without dissolving. The substance that is dispersed within another is called the dispersed phase. The substance that extends throughout the system and surrounds the dispersed phase is called the continuous phase. Table 2. For example, a sol is a suspension of large molecules dispersed in a liquid, generally water.
An emulsion is a suspension of liquid droplets fat or water within a liquid medium fat or water. Homogenized milk is a dispersion of milk fat droplets in a liquid medium skim milk portion of milk , while skim milk itself is a suspension of milk protein particles, the casein micelles, within a water-based medium. A solid emulsion is a dispersion of liquid droplets within a solid phase. Margarine and butter are examples of water in oil emulsions, in which the continuous phase is solid under refrigerator or low ambient temperatures.
Figure 2. A gel is a dispersion of water held within a continuous matrix of polysaccharides starch gels or proteins gelatin gels. Some scientists consider the water in gels to be a second continuous phase rather than a dispersed phase. A foam is a dispersion of gas bubbles distributed within a liquid phase.
A typical foam is created when egg whites are beaten and air is incorporated within the liquid by the action of the egg white proteins which stabilize the bubbles by forming a film around the gas. A solid foam is created when gas bubbles are dispersed within a solid phase ice cream.
In the case of whipped egg whites, the foam is converted to a solid foam by the action of heat on the egg proteins. Some of these phenomena are discussed in more detail later in this lesson. The major food components of food systems are carbohydrates, fats, proteins and water. There are also minor food components, organic acids, pigments, aroma compounds, vitamins and minerals. In this section we will discuss the important functional properties of these components and how those properties influence the chemical and physical properties of foods.
Carbohydrate is an example of major food components of food systems. Other major components are fats, proteins and water. In this section we will discuss the important functional properties of these components and how those properties influence the chemical and physical properties of foods Carbohydrates are one of the three main classes of nutrients the other two being fats and proteins. They occur in foods as sugars and starches. Digestible carbohydrates contribute 4 Calories kilocalories of metabolized energy per gram.
The main monosaccharides found in foods are glucose, fructose and galactose. These are referred to as simple sugars because one of their main functions is their ability to impart a sensation of sweetness; however, sugars vary in their sweetening power. The sweetness of various sugars in comparison to sucrose table sugar is shown in Table 2. Disaccharides are formed by the union of two monosaccharide molecules. Disaccharides are also considered as "simple" sugars.
Functional properties of food
Disaccharides are split into their component monosaccharides by enzymes or by boiling with dilute acids. The most important disaccharides in foods are sucrose, lactose and maltose. These disaccharides differ from one another in solubility, sweetness, and other properties. Table sugar, obtained from sugar-cane or sugar-beet, is mainly pure sucrose. It is formed from glucose and fructose linked together. Sucrose can be found in a variety of fruits, grasses and roots. One of the recent trends in the food industry, particularly for carbonated beverages, is the use of invert sugar in place of sucrose because of the inherently greater sweetening power per unit weight of the fructose containing sweetening systems see Table 2.
Incidentally, the primary sugars in honey are glucose and fructose in a ratio. Most of the nectar collected by the honey bee contains sucrose which is hydrolyzed by invertase in the saliva of the honey bee. Some of the glucose is converted to gluconic acid and hydrogen peroxide by glucose oxidase, another enzyme secreted into the collected nectar by the honey bee. The gluconic acid and hydrogen peroxide act as preservatives in the nectar.
Honey also contains minute quantities of other complex sugars. Adapted from: Desrosier, N.https://evzosupmina.tk/map3.php
General Properties of Major Food Components
Elements of Food Technology. AVI Publishing Company. Westport, CT. Pomeranz, Y. Functional Properties of Food Components.
Functional Properties of Food Components
Academic Press Inc. Lactose, also known as milk sugar, occurs in the milk of all animals. Lactose is formed by linking glucose and galactose together. The hydrolysis of lactose found in dairy products into its component monosaccharides is catalyzed by the enzyme lactase. Breaking down lactose substantially increases the sweetness. Lactose can also be fermented by lactic acid-producing bacteria, into lactic acid.
This is the acidulant and preservative agent in yogurt and numerous cheeses. Have you seen lactose-free products in the market or have you met someone who is "lactose intolerant"? Lactose intolerant people are those who do not have the enzyme lactase necessary to digest breakdown lactose milk sugar. People who are lactose intolerant can suffer from minor cramps to extreme intestinal discomfort. Lactose-free products have had the enzyme lactase usually isolated from yeast added to them.
Alternatively, lactose intolerant individuals can take tablets containing the enzyme, prior to eating or drinking dairy or other food products with lactose or milk solids. The sugar maltose contains two glucose units linked together.
Chemical and Functional Properties of Food Components - Semantic Scholar
It is obtained when starch e. Many soft drinks are now sweetened with HFCS especially when cost of these syrups is lower than the cost of sucrose or even invert sugar. Food Technology, 40 8 Another important property of the simple sugars is their ability to serve as reactants in non-enzymatic browning reactions, namely caramelization and the Maillard browning reaction.
The brown pigments formed during the heating of sugars contributes to the colour of caramel candies and toffees. The pigments are not the same as the melanoidins formed during the Maillard reaction. The Maillard browning reaction occurs when reducing sugars react with nitrogenous compounds such as amino acids, proteins or amines. A reducing sugar contains a free aldehyde or ketone group.
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Glucose, fructose, galactose and lactose are examples of reducing sugars. Sucrose does not have this "free" OH, therefore is not a reducing sugar. The Maillard browning reaction is responsible for the formation of the brown pigments that appear on bread slices when they are toasted in the toaster. Many low molecular weight intermediate compounds are formed and these often are aroma and flavour compounds that contribute to the desirable or undesirable flavours produced in a food by the Maillard reaction.
Examples of desirable compounds are the aroma and flavour of baked bread, toasted bread and roasted coffee, while undesirable aromas and flavours are those that form in skim milk powder during storage or during the browning of canned peaches during long-term storage. The brown colours are high molecular weight pigments, melanoidins, formed as a result of polymerization of some of the low molecular weight intermediate fractions.
Polysaccharides are high molecular weight, long chains of monosaccharide units i. They differ from simple sugars by being insoluble in water and generally tasteless. Most of the polysaccharides used in food products are derived from plant or seaweed sources; a few are from microbial origin.
They contribute to the thickness or viscosity and textural properties of food products. In foods such as cereals and tubers starch exists in the form of starch granules Figure 2. Starch molecules amylose, a straight chain starch molecule and amylopectin, a branched starch molecule are tightly packed within starch granules. The starch granule is not soluble in cold water but will imbibe large quantities of water when it is heated in water.
The starch granules absorb water, swell and become soft and pliable, by a phenomenon known as gelatinization. This is the phenomenon that occurs when puddings are made or when flour is used as a thickening agent when making gravies. Starch gelatinization is the phenomenon that leads to the conversion of hard, unchewable, raw rice kernels to the soft, easily chewed, cooked rice. Starches can be partially hydrolysed by acids or enzymes to produce products of intermediate chain length dextrins that have a numerous uses in food products.
Some of the dextrin products are used to create foods that provide the sensation of containing fat but that are low in fat more of this in Lesson Starch gels can lose some of their water holding capacity during refrigerated storage. This phenomenon is known as retrogradation , and involves re-association of starch molecules, especially amylose polymers, into an ordered structure.
The linear amylose molecules orient themselves in crystalline regions, leading to a squeezing out "syneresis" of water and a loss of tenderness of the food e. Retrogradation can be reversed by heating the food e. Instead of reading: Schneeman, "Fats in the diet: Why and where? Based on the reading, please answer the following questions:.
Fats play many important nutritional functions in the human body. Fats contribute energy, aim in the absorption of fat soluble vitamins, and are precursors of many essential hormones. Fats play important functional properties in foods too. The required reading talked about fats the important functional properties they have by influencing the flavour and texture of foods. These functional properties of fats and oils in foods are summarized below:. You will recall that there are two types of emulsions see colloidal dispersions and Figure 2.
Homogenization or other high-energy mixing processes may be used to disperse one liquid phase into another. Nevertheless, after two liquid phases such as oil and water are mixed and then left to stand, the natural tendency is for the two phases to separate. Emulsifiers are compounds that promote the formation of emulsions, i. Certain type of fat molecules called phospholipids , can function as emulsifiers.
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- Chemical & Functional Properties of Food Components;
Phospholipids are structurally similar to triglycerides, except that only two fatty acids are linked to the glycerol making it a diglyceride , and a charged group negatively charged phosphoric acid esterified with positively charged choline group is linked to the third position of glycerol.
Emulsifiers are amphiphillic molecules that have a hydrophilic [water loving] portion and a hydrophobic [water hating] portion. Emulsifiers assist in formation of an emulsion by orienting themselves at the interface between the two phases, with their hydrophilic and hydrophobic portions facing water and oil, respectively, thereby reducing the interfacial tension between oil and water phases. This can also help to stabilize the emulsion by preventing the dispersed oil droplets or water droplets from coalescing together.
Other factors that affect emulsion stability are droplet size, and the viscosity of the continuous phase.
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Droplet size must be such that, the downward pull of gravity, is balanced by the upward forces of buoyancy. This will reduce the tendency for "creaming" floating to the top of the less dense oil phase. Note the difference between Emulsifiers and Stabilizers. Stabilizers are compounds that increase the viscosity of the continuous phase, keeping the droplets suspended or dispersed and thus reducing the rate of creaming. Something to think about: Are any emulsifiers or stabilizers added to assist in the formation of a stable emulsion in:. Check out the label of these foods to find the answer!
The major function of milk homogenization is the formation of a stable emulsion to prevent fat separation, such as that which occurs in unhomogenized milk. Protein molecules are made up of long chains of hundreds or even thousands of amino acid units joined together. See figure on right: There are 20 different amino acids in proteins found in food systems and in the human body.