The effect of fruit preservation methods on fruit quality and nutrition
Sofia Faugno, Thea Hoemberg
Stratford Hall
Floor Location : J 128 D

The objective of this experiment was to determine which preservation technique for fruit maintained the overall best quality, as measured by the deterioration in Vitamin C content and cellular structure.

Fresh grape and strawberry samples were preserved in each of 3 ways, by freezing, drying and canning. There were 8 samples in total (2 fruits x 4 conditions). It was hypothesized that freezing, relative to fresh would provide the best outcome because this process would damage the cellular structure the least and would maintain the highest vitamin C content.

During the vitamin C testing, a 25mg tablet of Vitamin C was dissolved in water and a 5% starch solution was mixed gradually, then a titration was done with iodine. As the iodine is added the vitamin C reacts with the added iodine to form iodide until all the vitamin C is used up. At this point iodine remains in the solution and the suspended starch solution turns black. This initial testing was used as a calibration to establish that it took 70 drops of iodine to fully titrate 25mg of vitamin c.

After this, sixteen 20 gm standardized fruit samples were liquefied and titrations were performed on each. the drops of iodine required to fully titrate each gave the vitamin C content in sample size. The decrease in vitamin C content compared to fresh was easy to see and supported the hypothesis that freezing maintained the best vitamin c content of all 3 preservation techniques.

The next step was to do the Microscopic and Qualitative Analysis. Each of 8 fruit samples were examined for texture and taste, then were viewed and photographed under a low power microscope for changes to the skin and overall structure. The samples were viewed and photographed under a high power microscope to examine the cellular structure of each type of preserved fruit. After testing, it was clear that freezing maintained the best cell structure, while drying maintained some cell structure and the canning procedure completely obliterated the cell walls and internal structures.

In conclusion, the results from the experiment supported the hypothesis that freezing would maintain the best cellular structure and vitamin C content. The testing also suggested how the nutritional value of fruit can best be preserved at lower cost and brought to more people around the world.