Conditions Affecting the Stability of Ascorbic Acid / Vitamin C in Lemon Juice

CONDITIONS  AFFECTING  THE  STABILITY  OF  ASCORBIC ACID  /  VITAMIN  C  IN  LEMON  JUICE

GAN  WEI  NYE

LEE  WAN  JUN

BELLASARI  PERMANA  BINTI  MUHAMMAD  KEVIN  JABAR

6 ATAS SAINS

SMK  (P)  SULTAN  IBRAHIM,

JOHOR  BAHRU

ABSTRACT

        Vitamin  C  is  one  of  the  least  stable  of  all vitamins  in  solution  and  is  oxidized  readily  in  light,  air  and  when  heated.  The  stability  of  ascorbic  acid/vitamin  C  in  lemon  juice  is  affected  by  conditions  such  as   freshly  squeezed  and  sunlight. Besides  that,  the  stability  of  ascorbic  acid /vitamin C  in  lemon  juice  can  be  determined  using  volumetric  analysis.  The  vitamin C  percentage  and  concentration  of  sunlight-exposed  lemon  juice  is  lower  than  freshly squeezed  lemon  juice.  Thus,   vitamin C  in  sunlight-exposed  lemon  juice  is  less  stable  than  vitamin  C  in  freshly squeezed  lemon  juice.

CHAPTER  1

1.1                INTRODUCTION

        Vitamin  C  is  ascorbic  acid.  One  of  vitamin  C’s  chemical  properties  is  that  vitamin  C  is  a  reducing  agent  which  removes  oxygen  from  or  adds  hydrogen  to  other  chemicals. Vitamin  C  is  also  a  water  soluble  vitamin  and  supply  have  to  be  replenished  daily  since  the  vitamin  cannot  be stored  in  our  body.

        Besides  that,  vitamin  C  can  be derived  from  citrus  fruits  and  green  vegetables.  Vitamin  C  is involved  in  many  processes  in  the  human  body  including  the  collagen  production  in  connective  tissues,  synthesis  of  dopamine,  adrenaline  and  noradrenaline  in  the  nervous  system  and  also  synthesis  of  carnitine  which  is  important  in  the  transfer  of  energy  to  cell  named  mitochondria.

        Since  vitamin  C  cannot  be  manufactured  in  our  body,  the  persistant  absence  of  vitamin  C  from  an  individual’s  diet  may  lead  to  specific  vitamin  deficiency  disease.  A  deficiency  in  vitamin  C  causes  scurvy,  a  condition  where  the  gums  becomes  soft  and  teeth  grow  loose,  susceptibility  to  bruising  and  wounds  fail  to  recover  properly.

          In  New  Zealand  and  Australia,  the  recommended  daily  intake  of  vitamin  C  is  60mg.  Vitamin  C  was  proved  to  be  the  agent  which  prevent  scurvy  and this  is  why  vitamin  C’s  scientific  name  of  “ascorbic  acid”,  literally  translates  as  “anti-scurvy  acid”.

1.2                LITERATURE  REVIEW

        According  to  Claude  Yoder  [1],  the  most  accurate  and  convenient  way of  preparing  a  standard  solution is  to  weigh  the  reagent,  dissolve  it,  and  dilute the  solution  to  a  definite  volume  in  a  volumetric  flask.  This  method  can  only be  used  if  the  reagent  is  a  primary  standard.  In  order  for  a  reagent  to  be  a primary  standard,  it  must  be  obtainable  in  pure  form  (generally  at  least  99.98% pure),  stable  both  in  pure  form  and  in  solution,  easy  to  dry  and  keep  dry,  and  soluble  in  a  suitable  solvent.

        According  to  Jill  Irvin  [2],  vitamin  C  is  one  of  the  least  stable  of  all vitamins  in  solution  and  is  oxidized  readily  in  light,  air  and  when  heated.  

1.3                PROBLEM  STATEMENT

        Does  the  stability  of  ascorbic  acid/Vitamin  C  in  lemon  juice  is  affected  by  conditions  such  as   freshly  squeezed  and  sunlight?

1.4                OBJECTIVES  OF  RESEARCH

        The  first  objective  is  to  analyse  the  effect  of  freshly  squeezed  and  sunlight  on  the  stability  of  ascorbic  acid  in  lemon  juice.

        The  second  objective  is  to  determine  the  stability  of  ascorbic  acid / vitamin C  in  lemon  juice  using  volumetric  analysis.

CHAPTER  2

2.1                LIST  OF  APPARATUS  AND  MATERIALS

        The  apparatus  used  are  beakers  (50 ml),  syringe  (1 ml),  retort stand, sieve,  knife,  squeezer,  burette,  white  tile,  filter   funnel,  crucible,  electronic  balance  and  spatula.

        The  materials  used  are  1.0%  dichlorophenolindophenol  solution  (DCPIP), 0.1%  ascorbic  acid  solution,  lemon  juice  and  distilled  water.

2.2                PROCEDURES

        To  prepare  1.0%  dichlorophenolindophenol  solution  (DCPIP),  1.00 g  of    dichlorophenolindophenol  (DCPIP)  is dissolved  in  100 ml  of  distilled  water.  To  prepare  0.1%  ascorbic  acid  solution, 0.10 g  of  ascorbic  acid  is  dissolved  in 100 ml  of  distilled  water.  

        Firstly,  determine  the  volume  of  a  standard  vitamin  C  solution  needed to  decolourise  a  fixed  volume  of  DCPIP.  Then,  determine  the  volume  of  lemon  juice  of  different  conditions  needed  to  decolourise  the  same  volume  of  DCPIP.  The   vitamin  C  content  of  lemon  juice  of  different conditions  is calculated  by comparing  the   vitamin  C  content  of  lemon  juice  of  different conditions with  the  standard  vitamin  C  solution.