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JAMS - FRUIT PRESERVES
Fruit preserves are preparations of fruits, vegetables and sugar, often canned or sealed for long-term storage. The preparation of fruit preserves today often involves adding commercial or natural pectin as a gelling agent, although sugar or honey may be used as well. The ingredients used and how they are prepared determine the type of preserves; jams, jellies, and marmalades are all examples of different styles of fruit preserves that vary based upon the fruit used.
Many varieties of fruit preserves are made globally, including sweet fruit preserves, such as strawberry, as well as savoury preserves of vegetables, such as tomatoes or squash. In American, the plural form "preserves" is used to describe all types of jams and jellies. In all other English speaking countries most fruit preserves are simply called jam, with the singular preserve being applied to high fruit content jam, often for marketing purposes. Additionally, the name of the type of fruit preserves will also vary depending on the regional variant of English being used.
A conserve, or whole fruit jam, is a jam made of fruit stewed in sugar. Traditional whole fruit preserves are especially popular in Eastern Europe where they are called varenye, as well as in Western, Central and Southern Asia, where they are referred to as murabba.
Often the making of conserves can be trickier than making a standard jam; it requires cooking or sometimes steeping in the hot sugar mixture for just enough time to allow the flavour to be extracted from the fruit, and sugar to penetrate the fruit; and not cooking too long such that the fruit will break down and liquefy. This process can also be achieved by spreading the dry sugar over raw fruit in layers, and leaving for several hours to steep into the fruit, then just heating the resulting mixture only to bring to the setting point. As a result of this minimal cooking, some fruits are not particularly suitable for making into conserves, because they require cooking for longer periods to avoid issues such as tough skins. Currants and gooseberries, and a number of plums are among these fruits.
Because of this shorter cooking period, not as much pectin will be released from the fruit, and as such, conserves (particularly home-made conserves) will sometimes be slightly softer set than some jams.
An alternative definition holds that conserves are preserves made from a mixture of fruits and/or vegetables. Conserves may also include dried fruit or nuts.
"Fruit butters are generally made from larger fruits, such as apples, plums, peaches or grapes. Cook until softened and run through a sieve to give a smooth consistency. After sieving, cook the pulp … add sugar and cook as rapidly as possible with constant stirring.… The finished product should mound up when dropped from a spoon, but should not cut like jelly. Neither should there be any free liquid."—Berolzheimer R (ed) et al. (1959)
The term "jam" refers to a product made of whole fruit cut into pieces or crushed then heated with water and sugar to activate its pectin before being put into containers:
"Jams are usually made from pulp and juice of one fruit, rather than a combination of several fruits. Berries and other small fruits are most frequently used, though larger fruits such as apricots, peaches, or plums cut into small pieces or crushed are also used for jams. Good jam has a soft even consistency without distinct pieces of fruit, a bright colour, a good fruit flavour and a semi-jellied texture that is easy to spread but has no free liquid." – Berolzheimer R (ed) et al. (1959).
Freezer jam is uncooked (or cooked less than 5 minutes), then stored frozen. It is popular in parts of North America for its very fresh taste.
"Good jelly is clear and sparkling and has a fresh flavour of the fruit from which it is made. It is tender enough to quiver when moved, but holds angles when cut."
EXTRACTING JUICE — Pectin is best extracted from the fruit by heat, therefore cook the fruit until soft before straining to obtain the juice ... Pour cooked fruit into a jelly bag which has been wrung out of cold water. Hang up and let drain. When dripping has ceased the bag may be squeezed to remove remaining juice, but this may cause cloudy jelly." – Berolzheimer R (ed) et al. (1959).
The benchmark citrus fruit for marmalade production in Britain is the Spanish Seville orange, Citrus aurantium var. aurantium, prized for its high pectin content, which gives a good set. The peel has a distinctive bitter taste which it imparts to the preserve. In America marmalade is sweet.
Marmalade is generally distinguished from jam by its fruit peel.
The term 'preserves' is usually interchangeable with 'jams'. Some cookbooks define preserves as cooked and gelled whole fruit (or vegetable), which includes a significant portion of the fruit. In the English speaking world, the two terms are more strictly differentiated and, when this is not the case, the more usual generic term is 'jam'.
In general, jam is produced by taking mashed or chopped fruit or vegetable pulp and boiling it with sugar and water. The proportion of sugar and fruit varies according to the type of fruit and its ripeness, but a rough starting point is equal weights of each. When the mixture reaches a temperature of 104 °C (219 °F), the acid and the pectin in the fruit react with the sugar, and the jam will set on cooling. However, most cooks work by trial and error, bringing the mixture to a "fast rolling boil", watching to see if the seething mass changes texture, and dropping small samples on a plate to see if they run or set.
Commercially produced jams are usually produced using one of two methods. The first is the open pan method, which is essentially a larger scale version of the method a home jam maker would use. This gives a traditional flavour, with some caramelization of the sugars. The second commercial process involves the use of a vacuum vessel, where the jam is placed under a vacuum, which has the effect of reducing its boiling temperature to anywhere between 65 and 80 °C depending on the recipe and the end result desired. The lower boiling temperature enables the water to be driven off as it would be when using the traditional open pan method, but with the added benefit of retaining more of the volatile flavour compounds from the fruit, preventing caramelization of the sugars, and of course reducing the overall energy required to make the product. However, once the desired amount of water has been driven off, the jam still needs to be heated briefly to 95 to 100 °C (203 to 212 °F) to kill off any micro-organisms that may be present; the vacuum pan method does not kill them all.
During commercial filling it is common to use a flame to sterilize the rim and lid of jars to destroy any yeasts and moulds which may cause spoilage during storage. Steam is commonly injected immediately prior to lidding to create a vacuum, which both helps prevent spoilage and pulls down tamper-evident safety button when used.
Glass or plastic jars are an efficient method of storing and preserving jam. Though sugar can keep for exceedingly long times, containing it in a jar is far more useful than older methods. Other methods of packaging jam, especially for industrially produced products, include cans and plastic packets, especially used in the food service industry for individual servings. Fruit preserves typically are of low water activity and can be stored at room temperature after opening, if used within a short period of time.
US FDA definitions
European Union directives on jam
Extra jam is subject to somewhat stricter rules that set higher standards for the minimum fruit content (45% instead of 35% as a general rule, but lower for some fruits such as redcurrants and blackcurrants), as well specifying as the use of unconcentrated fruit pulp, and forbidding the mixture of certain fruits and vegetables with others.
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