One way to prolong the shelf life of fruits is to store them as sugar concentrates, which also allows the use of those that are not good enough or that are too ripe.
Marmalade, a fruit jam made from citrus juice boiled with sugar and water, extends the use of fruits, especially oranges, lemons, grapefruits and limes, alone or in combination .
The bitter variety of oranges is preferred, but sweet ones and tangerines are frequently combined with lemons and grapefruit.
There are two types of marmalades that can be prepared – jelly and thick. The jelly marmalade contains finely cut peels, while the thick contains almost everything except the seeds.
Most of the pectin, the gum-like substance, in citrus fruits is found in the pips (seeds) and the white inner skin (pith). When making marmalade, it is essential to cook all the fruit to extract the pectin.
It is therefore best to divide the fruit into two parts, one part being cut directly into the baking dish, and the other tied loosely in muslin (a white cotton cloth) and placed in the dish at the same time. Both parts soften, however, the bound parts are discarded after squeezing the juice with the pectin.
As with other fruit jellies, a higher proportion of citrus is required for jelly marmalade than for the thick variety. It compares well to jam. In other respects, the rules for making jam apply. Prolonged cooking after adding the sugar should be avoided as it spoils the taste and darkens the color of the marmalade.
It can also lead to the loss of gelling properties, thus making the product runny.
Wash and scrub fruit with a kitchen brush, if necessary, to remove all dirt and soil particles. To ensure easy peeling, fruit can be scalded in hot water for about two minutes.
For jelly marmalades, thin strips of skin, without pith, are cut after the fruit has been peeled by hand. For thick types, however, thicker slices can be cut from the whole skin with the marrow.
All cuts should be uniform in size to make the product attractive. The white skin should be thinly sliced and tied together with the seeds and any excess skin in a muslin bag, then cooked with the rest of the fruit.
The fruit should be cooked to extract the pectin and soften the skin before adding sugar.
The amount of water used for cooking depends on the cooking method and type of pan used.
As a general rule, allow two liters of water for each kilogram of fruit if cooked in an open pan or one liter of water for each kilogram of fruit if cooked in a pressure pan. Preliminary cooking takes longer, usually two to three hours, unless a pressure cooker is used.
At the end of cooking, the pulp should be soft enough to fall apart when pressed between the fingers.
Once the sugar has been added and dissolved, boiling continues for about 15-20 minutes or until the setting point is reached.
Set point test
a) Splinter test
Dip the mixing spoon into the boiling mixture, then raise it at least 30cm above the pan. Hold the spoon horizontally for a few seconds, then turn it so that the marmalade flows to the side. If it falls in clear drops, it is ready. If the flow is continuous, it takes a little longer to cook.
b) Cold plate test
Pour a small amount of marmalade onto a cold plate or saucer. When it is cold, push it with your index finger. The marmalade is ready if it forms wrinkles and a skin forms on it.
Although citrus fruits are high in acid, the amount of fruit used relative to the amount of marmalade obtained is small.
For this reason, some marmalade recipes (such as orange and jelly) require additional acid which can be provided by adding juice or citric acid.
The acid is added to the pan with the pieces of fruit before boiling.
The marmalade should be skimmed off the froth as soon as it is ready to prevent the froth from sticking to the skin.
To prevent the skin from rising in the storage jars, the marmalade should be allowed to cool in the pan until a skin forms on the surface. It is then stirred gently, poured into clean, hot glass jars and covered.
Selected marmalade recipes
Jelly marmalade: one kilogram of oranges, two and a quarter liters of water, the juice of two lemons or a teaspoon of citric acid and one and a half kilograms of sugar.
Lemon or lime marmalade: One and a half kilograms of lemons or limes, two to three liters of water and three kilograms of sugar.
Orange marmalade: One and a half kilograms of oranges, two to three liters of water, three kilograms of sugar and the juice of two lemons or a teaspoon of citric acid.
The marmalade can be spread on bread or toast, or mixed with soy sauce to make a marinade that can be used on meat.