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SAI INTERNATIONAL SCHOOL
                                                      CLASS-VII
                                             SUBJECT- CHEMISTRY
                              TOPIC-PHYSICAL AND CHEMICAL CHANGES
                       SUB TOPIC- BROWNING OF FRUITS AND VEGETABLES




                                                  LESSON NOTES


               Browning of fruits and vegetables

               It has been observed that fruits and vegetables turn brown in colour when we cut
               and keep them open.


                The change of the colour of the cut fruits is caused due to some chemical reaction.

               Open surface of cut fruit and vegetables react with the oxygen of air and oxidised.
               This oxidation decreases the nutritional value of the food items.

               If they exposed to air for longer time, lesser will be the vitamins. This change is
               irreversible in nature.

               To prevent fruits and vegetables from getting oxidised, these steps can be taken.


                 Fruits such as banana, apple, pear etc can be brushed with lemon juice.
                 Soaking the cut vegetables and fruits in plain water.
                 Adding some preservative.
                 Cooking the vegetables


               Reaction between Vinegar and Baking soda

               Vinegar is the dilute solution(4-5%)  of acetic acid and baking soda is sodium
               bicarbonate. When both are added to each other , bubbles of gas come out. This is a
               chemical reaction where new substance is produced and it is an irreversible change.
               The equation for the reaction is as follows.

               Vinegar   + baking soda         Carbon dioxide  + sodium accetate + Water


               CH3COOH  NaHCO3                       CO2                 CH3COONa             H2O





               ACTIVITY:-


               AIM- To observe the formation of a new substance on adding baking soda to vinegar




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