Immobilized enzyme, methods of immobilization, Immobilized enzymes in food industry

Immobilized enzyme

INTRODUCTION

  1. Immobilization is defined as the imprisonment of cell in distinct matrix. Those matrix allows the exchange of medium containing substrate or inhibitor molecules.
  2. The practice of immobilization of cells is very old. The first immobilized enzyme was Amino acylase of Aspergillus oryzae for the production of L-amino acid in Japan.
  3. The matrix immobilizes the enzyme by holding it permanently or temporarily for a short period of time.
  4. The matrix should be cheap and easily available.
  5. Their reaction with the enzyme should be minimum.
  6. The enzyme has the ability to catalyse the reaction under very mild condition with high degree of substrate specificity thus decreasing the formation of by-product.
  7. These enzymes can be used repeatedly and continuously.


METHODS OF IMMOBILIZATION


There are Five different methods of immobilization of enzyme: -

  • Adsorption: In this method enzyme is adsorbed to external surface of the support. The support used may be of different types such as:
    1. Mineral support (e.g. Aluminium oxide, clay)
    2. Organic support (e.g. starch)
  • Covalent bonding: It involves the formation of covalent bonds between the chemical groups in enzyme and to the chemical groups on the support.
    1. Carbohydrates (e.g. cellulose, agarose)
    2. Synthetic agents (e.g. polyacrylamide)
  • Entrapment: In this method enzyme are physically entrapped inside a porous matrix. E.g. polyacrylamide gels, agar, gelatin etc
  • Copolymerization: In this method of immobilization enzymes are directly linked by covalent bonds between various groups of enzymes via polyfunctional reagents e.g. glutaraldehyde, diazonium salt.)
  • Encapsulation: In this method the enzyme are enclosed in a membrane capsule.

Immobilized enzymes in food industry

Enzymes are intimately involved in a wide variety of traditional food processes, such as Cheese making, beer making, wine making.
Application of immobilized Protease:
  1. In general protease are very expensive enzymes.
  2. The practical applicability of immobilized proteases in food processing such as the chill- proofing of beer, coagulation of Milk, oxidative rancidity of Milk.
Application of immobilized Amino acylase:
  1. In the production of amino acids by microbial fermentation, a racemic mixture of acyl amino acids is produced.
  2. The desired product is the L- amino acid which is used to supplement proteins in foods and in pharmaceutical preparations.
Application of Immobilized Glucose isomerase:
  1. Used in corn syrup industry for producing HFCS.
  2. It also enhances the sweetening powder of the syrup.
Application of Immobilized enzyme in the Flavour Industry:
  1. Apart from protease and carbohydrate, Lipases are used for the enzymic modification of flavour of foods.
  2. Naringen is a glycoside of the flavonoid family which impart bitterness to fruits, such as Grapes and orange.
Application of Immobilized Lactase:
  1. In this lactase breaks down lactose in milk into glucose and galactose. This makes milk drinkable.

Immobilized enzyme

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