Food Science: Courses: FS 532

5. Apple Jelly Production

Introduction

Fruit jellies are semisolid products containing pectin as a gelling agent with high acid and sugar content. Most fruit jellies are defined by a federal standard of identity and contain as basic ingredients: fruit ingredients, pectin, acid, preservatives and saccharine ingredients (which may include sucrose and corn syrup). Pectin is a general term designating the water soluble pectinic acid (polygalacturonic acid). Gelling rate and firmness depends on pH, degree of methylation, and presence of sugar. The amount of pectin required depends on the fruit ingredient and the amount of naturally occurring pectin in the fruit.

The saccharine ingredient is generally sucrose but the standard of identity allows any other nutritive carbohydrate sweeteners. The use of sucrose and corn syrup solids combinations is popular since the corn syrup solids inhibit crystallization of the sucrose during storage.

The formation of most fruit juice jellies is established in the federal standards. The standard states that a jelly is that food which is made from a mixture composed of not less than 45 parts by weight of standard fruit juice ingredient to each 55 parts by weight of saccharine ingredient. The standard fruit juice ingredient is one with a soluble solids content of 13.33%.

The above discussion pertains to jelly made with High Methoxy (HM) pectin. Dietetic jelly is made with Low Methoxy (LM) pectin. Dietetic jelly requires neither high acid nor high sugar content. However, these jellies do require addition of sufficient calcium salt to cross-link pectin molecules during the gelling process.

In the present exercise, both HM and LM pectin jelly will be made.

Procedure
Normal Jelly
  1. Add 100 ml apple juice to a 250 ml beaker and measure percent soluble solids (%SS).
  2. Calculate Standard Fruit Juice ingredient (F), as well as the amount of sugar (S) and pectin (P) required to make the jelly.
  3. Weigh out and mix S and P in a 400 ml beaker.
  4. Adjust pH of apple juice to 3.2 with lemon juice.
  5. Pour pH adjusted juice into a 700 ml beaker, add ca. 1 g butter, and concentrate on a hot plate to ca. 13.3 % SS.
  6. Add sugar-pectin mixture slowly with mixing.
  7. Continue boiling until % SS = 65%.
  8. Pour into labeled beaker and refrigerate. Label should include group number, final value of %SS, pH, and pectin type.
Dietetic Jelly
  1. Add 150 ml apple juice to a 250 ml beaker and measure %SS.
  2. Calculate F, S, P, as well as amount of Calcium required to make the jelly.
  3. Weigh out and mix S, P and Ca in 400 ml beaker.
  4. Measure pH of apple juice.
  5. Pour juice into 700 ml beaker, add ca. 1 g butter, and concentrate on a hot plate to ca. 13.3 %SS.
  6. Add the sugar-pectin-calcium mixture slowly with mixing.
  7. Once the mixture is rendered soluble, measure %SS.
  8. Pour into labeled beaker and refrigerate. Label should include group number, final value of %SS, pH, and pectin type.
University of Wisconsin College of Agricultural & Life Sciences
Copyright © 2003, Department of Food Science,
University of Wisconsin-Madison. 		Updated March 21, 2003.
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