Fruits That Contain Enough Pectin - A Jelly Forming Substance
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Fruits That Contain Enough Pectin - A Jelly Forming Substance

Fruits that contain enough pectin-a jelly forming substance.

Fruits That Contain Enough Pectin - A Jelly Forming Substance

Pectin is used to denote collectively pectic acid and protopectin.  Pectin substances are plant components

present abundantly in some fruits which make them important in jelly-making.  Pectic substances include:

1.  Pectic acid

2.  Pectinic acid

3.  Protopectin

Only pectinic acid and protopectin have the ability to form gels and are collectively called pectins.

The pectinic acid requires the presence of the proper proportion of sugar and acid in order to gel.  Pectic acid which is predominant in overripe fruits generally does not form a gel and is usually not considered as pectin.  Protopectin whch is predominant in unique fruits is insoluble hence it does not have the ability to form a gel but it can be converted to a thick gel by the action of heat and acid as in jely-making.  Ripe fruits are rich in pectinic acids making the fruit sap gel as it is.

Factors necessary to form a gel:

1.  Sugar

Sugar dehydrates the pectin gel hence making it more firm.  Most jellies are saturated sugar solutions containing about 65% sugar.  In excess of this crystallization is likely to occur which will make the jelly grippy and unclear.  Crystallization is commonly prevented by the addition of a weak acid such as calamansi juice or citric acid.  This procedure is based on the fact that this weak acids convert sucrose to glucose and fructose.  The latter simple sugars collectively called invert sugar are less prone to crystallization.

2. Acidity

The more acidic the fruit juice, the better is its gel-forming ability.  This is part of the reason why fully ripe fruits don't make good jellies.  Th lower the pH, the less sugar is necessary.

3.  A desirable jelly is formed from 1% pectin.

Some organic acids identified in fruits and vegetables are:

  • citric acid
  • iso citric acid
  • cis aconitic acid
  • alpha-malic acid
  • alpha-tartaric acid
  • succinic acid
  • oxalo-acetic acid
  • oxalic acid
  • shikimic acid

Fruits Used For Jelly

For a fruit juice to make a good jelly by boiling with the addition of sugar only, the juice must contain a sufficient amount of a substance called pectin and also sufficient acid. Some fruit juices will not make acceptable jelly by this method because they are deficient in pectin, whereas others do not contain enough acid. In the middle states west of the Mississippi River the fruits most commonly used to make jelly without addition of pectin are apples, crab-apples, blackberries, sour plums, grapes, currants, and gooseberries. During the winter months cranberries are used extensively.

Cruess and McNair have reported that the following fruit juices contain sufficient acid and pectin to produce good jelly: blackberries, loganberries, Isabella grapes, Tokay grapes, cranberries, currants, whole lemons, and pomelos. They state that oranges have enough pectin but not always enough acid. Apricots and cherries sometimes make jelly but are usually deficient in pectin. Pomegranates and strawberries have enough acid but lack pectin, and pears, peaches, and huckleberries lack both pectin and acid. Citron melons and mission figs have enough pectin but lack acid. They state that lemon is too high in acid to produce a good jelly, but that two whole oranges and one whole lemon make a good combination, the acidity of the lemon allowing for the deficiency in the orange.

By the addition of pectin and sugar, all fruit juices, so far as the author knows, can be used for jelly.

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