food enzymes. what is an enzyme? a biological catalyst that promotes and speeds up a chemical...

FOOD ENZYMES

What is an enzyme?What is an enzyme?

A biological catalyst that A biological catalyst that promotes and speeds up a promotes and speeds up a chemical reaction without chemical reaction without itself being altered in the itself being altered in the process.process.

Lowers the activation Lowers the activation energies of a substanceenergies of a substance

Energy Profile

reactants

products

H

EA

T.S.

catalyst

Enzymatic ReactionsEnzymatic Reactions

Enzyme combines with a Enzyme combines with a specific substrate to a form specific substrate to a form an enzyme-substrate an enzyme-substrate complex in a lock and key complex in a lock and key concept before forming concept before forming new products.new products.

Enzyme action

enzyme

substrateproducts

Structure of an enzyme

Contains both a protein and Contains both a protein and a nonprotein.a nonprotein.

Nonprotein is either a Nonprotein is either a coenzyme (usually a coenzyme (usually a vitamin) or a cofactor vitamin) or a cofactor (usually a mineral). (usually a mineral).

Factors influencing enzyme activity Operate under optimum Operate under optimum

conditions of pH and conditions of pH and temperature. temperature.

Easily inactivated Easily inactivated (denatured) in presence of (denatured) in presence of inhibitors.inhibitors.

Enzyme Nomenclature Names usually end in –ase.Names usually end in –ase. Usually named after substrates they Usually named after substrates they

act upon e.g. urea --- urease act upon e.g. urea --- urease lactose --- lactaselactose --- lactase or the resulting type of chemical or the resulting type of chemical

reaction e.g. hydrolysis --- hydrolases reaction e.g. hydrolysis --- hydrolases oxidation --- oxidasesoxidation --- oxidases This rule does not always apply. E.g. This rule does not always apply. E.g.

ficin found in figs and papain in ficin found in figs and papain in papayas. papayas.

Enzyme Nomenclature cont. hydrolysis --- hydrolases hydrolysis --- hydrolases oxidation --- oxidasesoxidation --- oxidases This rule does not always This rule does not always

apply. E.g. ficin found in apply. E.g. ficin found in figs and papain in papayas. figs and papain in papayas.

Properties of enzymes

Control ripening.Control ripening. Cause food spoilage (rotting).Cause food spoilage (rotting). Responsible for changes in Responsible for changes in

flavor, color, texture and flavor, color, texture and nutritional properties.nutritional properties.

Can be inactivated by heat to Can be inactivated by heat to extend storage stability of extend storage stability of foods.foods.

Properties

Used for fermentation Used for fermentation purposes in foods.purposes in foods.

Can be immobilized to a Can be immobilized to a surface of a membrane or surface of a membrane or other inert object in contact other inert object in contact with the food being processed.with the food being processed.

Can be extracted and purified Can be extracted and purified to a high degree.to a high degree.

Applications in food industry Carbohydrases: production of corn Carbohydrases: production of corn

syrups from starch (glucoamylase); syrups from starch (glucoamylase); conversion of cereal starches into conversion of cereal starches into fermentable sugars in malting, fermentable sugars in malting, brewing, distillery, baking industry brewing, distillery, baking industry (amylase).(amylase).

Proteases: meat tenderizers Proteases: meat tenderizers (bromelin, papain, ficin)(bromelin, papain, ficin)

Lipases: Flavor production in Lipases: Flavor production in chocolate and cheesechocolate and cheese

Applications

Glucose oxidase: desugaring of Glucose oxidase: desugaring of eggs, flour and potatoes; eggs, flour and potatoes; preparation of salad dressings. preparation of salad dressings.

Pectinases: clarification of fruit Pectinases: clarification of fruit juices; increase of yield of juice juices; increase of yield of juice from grapes and other products; from grapes and other products; removal of excess pectin from removal of excess pectin from juices before concentration.juices before concentration.

Applications contd

Lipoxygenase: bleaching of flours.Lipoxygenase: bleaching of flours. Phosphatase: quality testing of Phosphatase: quality testing of

food productsfood products Phenol oxidase: imparts the Phenol oxidase: imparts the

characteristic dark hue to tea, characteristic dark hue to tea, cocoa, coffee and raisins.cocoa, coffee and raisins.

Renin (chymosin): cheese Renin (chymosin): cheese productionproduction

Applications Flavorases: restoration and Flavorases: restoration and

enrichment of flavor by addition enrichment of flavor by addition of enzyme preparations to food of enzyme preparations to food products e.g. fresh corn enzyme products e.g. fresh corn enzyme extracts to improve flavor of extracts to improve flavor of cannned goods or addition of cannned goods or addition of alliinase to convert alliin of alliinase to convert alliin of garlic into garlic oil.garlic into garlic oil.