This page describes the properties of milk carbohydrate. Over there is a brief introduction to general Carbohydrate Chemistry, adhered to by sections on Milk Carbohydrate (Lactose) Chemistry, Lactose physics Properties, and the influence of heat Treatments top top Lactose Properties. For an ext details ~ above lactose properties see referrals by Fox and McSweeney (1998), Holsinger (1988, 1997), and also O"Brien (1995, 1997).
General Carbohydrate Chemistry
Carbohydrates are made up of molecules referred to as saccharides. Simple saccharides contain 1 or 2 molecules and also are referred to as monosaccharides or disaccharides, or, an ext commonly, sugars. Oligosaccharides and polysaccharides space chains the contain a few to numerous sugar molecules and also may be described as starches.
The monosaccharides essential in food and also health room glucose (sometimes called dextrose), fructose, and galactose. The disaccharides space sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose). The 2 sugar molecules in disaccharides are bonded together and this bond need to be broken prior to the sugars have the right to be used by the body because that energy and also other human body functions. Starches are lengthy chains that glucose that have the right to be directly or have actually branches, and there space several means in which the molecules in ~ starches have the right to bond to every other. Starches from different sources, such as wheat or corn, have unique functional properties. The framework of starches deserve to be amendment to enhance their functional properties and increase their use in foods.
Milk Carbohydrate Chemistry
Milk contains about 4.9% carbohydrate that is predominately lactose v trace quantities of monosaccharides and also oligosaccharides. Lactose is a disaccharide that glucose and galactose. The structure of lactose is:
Lactose physical Properties
Lactose is dissolved in the serum (whey) step of liquid milk. Lactose liquified in solution is uncovered in 2 forms, dubbed the α-anomer and ß-anomer, that deserve to convert earlier and forth between each other. The solubility that the 2 anomers is temperature dependent and therefore the equilibrium concentration that the 2 creates will be different at various temperatures. At room temperature (70°F, 20°C) the equilibrium ratio is roughly 37% α- and also 63% ß-lactose. At temperatures over 200°F (93.5°C) the ß-anomer is less soluble so there is a higher ratio the α- come ß-lactose. The form of anomer current does not impact the nutritional properties of lactose.
Lactose crystallization occurs as soon as the concentration the lactose exceeds its solubility. The physical properties of lactose crystals room dependent on the crystal form and can considerably influence their use in foods. Temperature affects the equilibrium ratio of the α- and also ß-lactose anomers, as defined above. Lactose crystals developed at temperatures listed below 70°F (20°C) are mostly α-lactose crystals. The α-monohydrate lactose crystals are an extremely hard and also form, because that example, as soon as ice cream goes through plenty of warming and also freezing cycles. This results in an undesirable gritty, sandy structure in the ice cream. Gums are often used in ice cream to inhibit lactose crystallization. The crystal kind of ß-lactose is sweeter and much more soluble 보다 the α-monohydrate lactose and may be desired in some bakery applications. When a lactose solution is rapidly dried it does not have actually time come crystallize and forms a form of glass. Lactose glass exist in milk powders and causes clumping. The clumping is desirable due to the fact that it results in a milk powder the dissolves instantly in water.
Influence of warmth Treatments on Lactose Properties
The typical pasteurization conditions used for fluid milk have actually no far-reaching effect ~ above lactose. The greater temperatures offered for ultra high temperature (UHT) pasteurization of extended shelf life products and spray drying can cause browning and isomerization reactions, i beg your pardon may impact product quality and nutritional properties. The browning reaction, dubbed the Maillard reaction, occurs between the lactose and protein in milk and produces undesirable flavors and color, and decreases the obtainable content that the amino mountain lysine in milk protein. The isomerization reaction is a molecule rearrangement the lactose to lactulose.
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Lactulose is created for usage by the pharmaceutical industry in pill production.