Investigating the Relationship Between Acid Concentration in Solution and the Onset of Enzymatic Browning in Granny Smith Apples


  • Ari Kim
  • Christine Magdaleno
  • Melanie Tan
  • Stephanie Chen
  • Chenyang Luo


Finding an anti-browning agent for apples is crucial for preserving the look of a freshly cut apple, and is known to be correlated with acidity. This study investigated the effect of a solution’s citric acid concentration on the browning of apples. There were five sample groups for the sliced apples, two controls and three treatments. The apples were soaked in the solutions with different levels of lemon juice and then observed for browning over a 24 hour period and the area of browning was measured with a 1x1cm2 grid. We hypothesized that increasing lemon juice will decrease the area of browning because the juice pH is more acidic than the optimal pH needed for polyphenol oxidase (PPO) to oxidize the apple flesh. This experiment concluded that there was a significant difference in the area of browning between the five sample groups (p < 0.05) with the highest lemon juice concentration sample group having the least area of browning and the lowest lemon juice concentration sample group having the most. The results of this study showed the effectiveness of lemon juice as an anti-browning agent and provide insight for future studies on preventing the browning of different food substances.