The use of pectinase in fruit juice production

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02/05/2007                Claudia King

The use of pectinase in fruit juice production

  • Pectinase is a mixture of enzymes which is used in the fruit juice industry where they extract, clarify and modify fruit juices. (Cellulose also does this).

      Pectins are large polysaccharide molecules. They are made of hundreds of chains of galacturonic acid residues. The pectin chain is held together by a bond between carbon 1 of one galacturonic acid and carbon 4 of the next one and so on. The diagram shows where the pectin comes from in a plant. It is gel like and forms in the primary cell walls and in the middle lamella layer which sticks adjacent cells together.

     The pectin is broken down by enzymes in the pectinase group, which include polygalacturonases, pectin methyl esterase and pectin lyases. All three contribute to the breakdown of pectins from a variety of plant materials. Pectinase enzymes are produced during the ripening of some fruits and are also secreted by plant pathogens such as the fungus: Monilinia fructigena and the bacteria: Erwinia carotovora or the fungi: Aspergillus niger. The pectinase enzymes act in different ways on the pectins, for example they help soften their cell walls (they break down the cell walls). (The products of such enzyme assaults also act as a signal which causes uninfected cells to defend themselves.)

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     The way pectinase enzymes break down the pectin is as follows: pectinase splits the bonds between these galacturonic acids to shorten the pectin chain. Water is produced so pectinase is known as a hydrolytic enzyme. It splits a water molecule and adds -H to one carbon in the bond and an -OH to the other one.

      The enzymes use the common key and lock theory, where the pectin is the substrate and binds into the active site of the pectinase enzyme and the enzyme breaks down the substrate and gives ...

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*** Relevant information sources have been used and there is some good biological content. However, in general there is a lack of detail, and further explanation of points made would make a big difference to the quality.