1. Browning Compiled by: Mrs. Vandana Mahajani

2. What is browning? Browning is a common colour change seen in food during prepreperation, processing or storage of food. Browning is a common colour change seen in food during prepreperation, processing or storage of food. Colour may range from cream or pale yellow to brown and black. Colour may range from cream or pale yellow to brown and black.

3. Browning –desirable or undesirable In some cases the brown colour may add to aroma,flavour and colour as brown crust of bread, roasted nuts, coffee beans, caramel peanut brittle etc. In some cases the brown colour may add to aroma,flavour and colour as brown crust of bread, roasted nuts, coffee beans, caramel peanut brittle etc. Undesirable effects are seen in milk, cream, eggs dry fruits, coconut,citrus fruits and canned juice concentrates and milk Undesirable effects are seen in milk, cream, eggs dry fruits, coconut,citrus fruits and canned juice concentrates and milk

4. Types of browning Enzymatic browning occurs in fruits when cells are disturbed when cut or bruised. This is due to the oxidative enzymes present on phenolic substances present in plant tissues. Enzymatic browning occurs in fruits when cells are disturbed when cut or bruised. This is due to the oxidative enzymes present on phenolic substances present in plant tissues. Eg. Apples, brinjals, bananas, pears and potatoes Eg. Apples, brinjals, bananas, pears and potatoes Phenolic compounds------oxygen---------- Quonines Phenolic compounds------oxygen---------- Quonines Enzymatic browning reaction Enzymatic browning reaction Prevention of EB Prevention of EB -by inactivating enzymes by heat, salt, ph levels, and low temp. -by inactivating enzymes by heat, salt, ph levels, and low temp. -by avoiding contact with oxygen -by avoiding contact with oxygen

5. Non enzymatic browning Maillard was the first tp observe browning. The reaction is also called protein sugar reaction. Maillard was the first tp observe browning. The reaction is also called protein sugar reaction. Conditions favouring millard reaction Conditions favouring millard reaction High temperature High temperature Increase in alkalinity Increase in alkalinity Concentration and type of amino acid and sugar present (lysine and glucose) Concentration and type of amino acid and sugar present (lysine and glucose) Presence of catalyst (such as copper and iron) Presence of catalyst (such as copper and iron) Desirable changes are seen as in roasting of coffee beans and nuts and quality of baking bread Desirable changes are seen as in roasting of coffee beans and nuts and quality of baking bread Undesirable changes like off-odour, off-colour, off-flavour can be prevented by low temp and low ph. Undesirable changes like off-odour, off-colour, off-flavour can be prevented by low temp and low ph.

6. Caramalization Sugars are caramalized at 163 deg C to 170 deg C. Sugars are caramalized at 163 deg C to 170 deg C. This reaction occurs in sugar alone. This reaction occurs in sugar alone. high temp high temp Sucrose---------------------------------------- caramel * acid Sucrose---------------------------------------- caramel * acid decomposition decomposition dehydration dehydration polymerization polymerization

7. Ascorbic acid browning and lipid browning Ascorbic acid browning occurs in strawberry and cocum where original red colour changes to brown. The ascorbic acid present in these fruits undergoes oxidation causing browning. Ascorbic acid browning occurs in strawberry and cocum where original red colour changes to brown. The ascorbic acid present in these fruits undergoes oxidation causing browning. Lime juice cordial and other preserves see this kind of browning. Lime juice cordial and other preserves see this kind of browning. Lipid browning occurs when amino acids present in fats react with aldehydes and reducing sugars causing browning. Lipid browning occurs when amino acids present in fats react with aldehydes and reducing sugars causing browning. It is an undesirable reaction It is an undesirable reaction

8. Role of browning in food preperation All browning reactions can be controlled. All browning reactions can be controlled. Enzymatic browning is undesirable especially in cut fruits and salads. Enzymatic browning is undesirable especially in cut fruits and salads. Natural browning during preparation of food is desirable. Natural browning during preparation of food is desirable. Brown colour, aroma and right texture imparted to food while browning occurs, is desirable. Brown colour, aroma and right texture imparted to food while browning occurs, is desirable. Detrimental effects of browning Detrimental effects of browning. Poor colour. loss of nutrients loss of ascorbic acid.