Reducing sugars react with proteins and amino compounds to produce flavours and

Reducing sugars react with proteins and amino

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-Reducing sugars react with proteins and amino compounds to produce flavours and colours in foods (Maillard browning) Caramelization Rxn involves reaction of sugars when heated at high temperature (200 o C) to produce caramel and butterscotch flavors Maillard Browning Reaction -Rxn occurs when reducing sugars react with nitrogenous compounds such as Aas, proteins or amines -Reducing Sugar + amino compound (NH 2 ) -> Maillard reaction products -Reducing sugars contain a free aldehyde or ketone group (free "OH" on the position next to the O in the ring structure) -Glucose, fructose, galactose, and lactose are reducing sugars -Sucrose does not have the free "OH" and is not reducing -Responsible for brown pigments appear on toast -Low molecular weight intermediate compounds are formed and these are often aroma or flavour compounds contribute to desirable or undesirable flavours produced by this rxn -High molecular weight - brown colour, melanoidins formed by polymerization of some low molecular weight intermediate compounds Polysaccharides -High molecular weight, long chains of monosaccharide units, insoluble in water and generally tasteless -Derived from plant or seaweed sources -Contribute to thickness or viscosity and textural properties of food products Agar -extracted from seaweed (kelp), used as a thickener agent Alginates -extracted from certain types of seaweed,used as gelling agents, keep solids and liquids in suspension in fruit juices Carrageenan -extracted from certain types of seaweed (red algae), used as a suspending agent to keep cocoa particles in suspension in chocolate milk Cellulose and Hemicellulose -are present in many plant tissues as supporting structures (e.g. the fibres in celery), are polymers of glucose that are indigestible, along with pectin and the other carbohydrate gums form the indigestible portion of our carbohydrate intake that is known as dietary fibre Gum Arabic or Gum Acacia -is a plant exudate from the bark of the acacia trees, used as thickener and stabilizer in products like beer, soft drinks, ice cream Pectins -are structural polymers in plants, form the cementing material between individual plant cells, pectin affects texture of plant tissues, used in jams and jellies as gelling agents in the presence of sufficient sugar and acid, contribute to viscosity of tomato paste and ketchup, contribute to the mouth feel and maintenance of particles in suspension (e.g. orange juice, unclarified apple juice) Starch - are polymers of glucose, digestible when cooked (e.g. rice, potatoes, etc.), used as thickening, suspending and gelling agents(read text below for more information on starch) Xanthan Gum -produced by bacteria, first isolated from rotting cabbage, now cultured in large fermentation tanks and purified, used in salad dressings as a thickening agent, which enables the dressing to cling to the salad components, used as a suspending agent to maintain pieces of onion, red pepper, spices in a stable suspension Starch -Foods such as cereal and tuber starch exist as starch granules

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