PINEAPPLE JAM
Sri Lanka has two varieties of pineapple, Kewpine and Mauritius. Kewpine is the cooking
pineapple, the fruits are larger and they give a better yield of juice. However, the flavour is not
as good as the Mauritius variety which being sweeter is usually eaten fresh. We found that the
Mauritius variety made a better jam (a better set, flavour and colour). The pulp from pineapple
varies (core included) from pH 3.4-4.1. This means that, to give a jam with a good set the
recipe has to be adjusted each time new pulp is used. The yield from whole fruit to usable fruit
pulp from Mauritius is approximately 30% and for Kewpine 35%. Pineapple contains little or
no pectin so pectin must be added when making jam. Pineapples contain the enzyme
bromelain, which is a proteolytic enzyme (breaks down proteins). This can cause problems for
operators’ hands which are in contact with the juice for long periods during cutting operations,
gloves should therefore be worn and washed each day. To make 200 x 1Ib jars of pineapple jam
requires approximately 62kg of sugar and 158kg of fresh pineapple.
Recipe
Sugar
Fruit pulp
Pectin (grade unknown)
Water
Citric acid
38%
49%
(starting recipe
1 % before boiling)
12%
Added as required
In most countries, preservative is not allowed to be added to the jam. Only a residue of
preservative is allowed in jam made from fruit pulp that has been stored with chemical
preservatives, (l00ppm sulphur dioxide or 500ppm benzoic acid). Citric acid is not a
preservative, it is added to adjust the pH. Jams give a gel when there is the correct ratio of
pectin to water and the pH is between 2.5-3.45. The optimum pH to give a good gel is pH 3.0.
Method
Remove stalks and tops from fruits, cut off the outer cortex and pick out the ‘eyes’. Cut the fruit
into pieces, discarding any bad fruit.
Make the pieces into fruit pulp by liquidising, or passing through a Kenwood colander/sieve
(large aperture). Liquidising the pieces gives a fruit pulp with a ‘chunky’ texture but contains a
lot of pith and hard pieces. Using the colander/sieve will give a fruit pulp of a smooth
consistency, which is good for making pineapple jelly. The residue that does not pass through
the colander/sieve can be put into a muslin cloth and the juice squeezed out to get the
maximum extraction of fruit pulp. The yield of fruit pulp from whole fruit is 30%
(colander/sieve), 35% (liquidiser).
Adjust the pH of the fruit pulp by adding citric acid until it is pH 3.0. This can be measured
with a pH meter, or less accurately with pH paper, (using Whatmans pH paper 1-5 pH range,
the colour of the juice effects the result, so that a reading 2.5 pH is in fact 3.0 pH). Mix the
pectin with a small portion of the sugar. The dry mixing of the pectin is important because
pectin powder is very difficult to dissolve in water because it clumps together. If it is still a
problem to dissolve, grind the sugar to a fine powder and then mix it with the pectin.
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