Investigatory Project

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Re-utilization of Sucrose Solution Used in Apple Preservation

ABSTRACT. Osmotic dehydration, by immersion in sucrose solutions of different concentrations, is commonly used by industries in the production of candied dehydrated fruits. A refractometer is needed in order to read the concentration of the solution after each use. By doing this, the effectivity of the sugar solutions will be maximized. However, several small-scale companies cannot afford an expensive equipment such as the refractometer.

The researchers then decided to work on apple preservation in order to come up with a table of data. This is to check the changes in the concentration of the 2.5 M solution after each use and to determine if the said solution can effectively preserve the apples. Every 12 hours, the immersed apples were replaced by a new batch of sliced fruit. But befor doing so, the concentration of a sucrose solution was read using the refractometer. The results were tabulated and after six readings, the change in the concentration with respect to the number of readings were translated into a graph. This graph serves as a basis for determining the effectivity of the sucrose solution.


Candied dehydrated fruits make good export items because of their desirable flavor. Due to the wider acceptance from consumers today, many small companies have started to produce them.
Industries use osmotic dehydration by immersion on sucrose solution to preserve fruits. The refractometer, an expensive equipment, is used to deter¬mine the concentration of sugar in the solution after its use. With the absence of the refractometer, many of these enterprises do not make use of sucrose solutions again because they are not sure whether the solution is still effective or not.

This research project was therefore designed to help small-scale industries save time, energy, and expenses by accurately graphing and measuring the concentration of the sugar solutions used in dehydration and preservation of six batches of apples without necessarily obtaining an expensive refractometer.


I. Fruit Preservation

Mailard Reaction. Sugar may interact with or-ganic constituents and it is known as mailard reaction. Preserves that are stored for unduly long periods darken and lose their fresh flavor as a result of chem¬ical spoilage.

Freezing and Thawing. The purpose of freezing storage is to retain to, as great degree as possible, the properties of the fresh fruits, vegetable, or other food products. However, during freezing and thawing, certain irreversible changes occur that render the frozen and thawed products quite different from the fresh ones in texture and general appearance.

Sugar Preservation. Studies on the manufacture of candied mangoes have been conducted by re¬search agencies so as to standardize the procedure.

Local sugar preservation of fruits only require higher amount of sugar and choice fruits.
The procedure basically involves a two-step drying process: 1) osmotic dehydration by sugar or syrup solution; and 2) conventional dehydration such as the air and sun drying (Ponting, 1973). Osmosis. Osmosis is the diffusion or the move¬ment of a substance in a form of small particles (molecules or ions), under their own kinetic energy, through a differentially permeable membrane. The expression, differentially permeable, is more accu¬rate than the commonly used semipermeable, since no membrane is strictly semipermeable. A differentially permeable membrane contains pores which are large enough to allow the passage of distilled water molecules, but too small to allow the particles of a solute in water to pass through in appreciable quantity. Consequently, if two solutions of different concentrations are separated by such a membrane, unequal pressure—usually called osmotic pressure—is exerted upon its two sides (Courchaine, 1950).

Fruits contain from 70-90%...
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