Cookbook:Fruit Preserves
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Fruit preserves are a group of sweet spreads made by cooking fruit with sugar.[1][2][3]
Production
editThe basic technique is the same for most varieties of preserve. The fruit and sugar are cooked together to reduce the water and concentrate the sugar.[4] In non-industrial settings, this is typically done by simple boiling at atmospheric pressure until the mixture reaches the 'gel stage' or about 7–8°F or 4–4.5°C above the boiling point of water at a given elevation.[2][3][5] In industrial settings, vacuum evaporators may be used, which results in water loss at a lower temperature, preserving volatile flavor and texture of the product.[5][4] As the mixture is slowly cooled, it sets to the end spreadable consistency.[2][4][5]
Once finished, the preserves may be stored in the fridge, but it is very common in modern times to sterilize them.[2][5] Canning is typically the most common method of doing so,[3] readily done by both industrial producers and home cooks. In some cases, so-called freezer jams are made without any cooking and with freeze-tolerant pectin—these are kept in the freezer for preservation.[3][4]
Characteristics
editDespite some differences, all fruit preserves share the same essential characteristics. Most take the form of a syrupy gel,[4] with attention paid to the specific ratios of fruit, sugar, and pectin needed to achieve desired gelling characteristics.[5][6] Because sugar is a preservative, preserves are quite sweet, but preserves not meant for long-term storage may be less so.[2]
Pectin
editPectin is critical to the finished texture of most preserves, as it is the gelling agent most commonly used. Naturally, it is found in fruit skins, cores, and seeds,[2] from which it is extracted during cooking.[4] When the pectin is released from the fruit, it cannot initially form a gel, and it must typically be cooked with sugar and acid in order to force it to interact with itself, forming a network that solidifies upon cooling.[1][4][5] Commercially, several types of pectin are available, each with slightly different properties and requirements for sugar, acid, and cooking of the preserves.[4] While pectin is present in most if not all fruits, not all fruits contain sufficient pectin to set the finished preserve. In these cases, it becomes necessary to supplement the preserves with pectin-rich fruits or with commercially available purified pectin.[5][6][7]
Sugar
editJust as critical to traditional preserve-making is sugar, which plays multiple roles in achieving the desired final product. At its most basic level, sugar provides desirable sweetness to preserves, especially to those made with fruits relatively low in sugar or high in acid. However, sugar is also very important as a preservative,[2][3][6] helping protect the finished product from all but the most tolerant microbes. Even then, it can take quite a while for sugar-tolerant yeasts to spoil the preserves. As a result, low-sugar preserves tend to have poorer keeping quality.[2] Finally, sugar is structurally important, as it sequesters water and helps ensure that traditional pectins can bind to each other and form the requisite gel.[4][8][9] Interestingly, while sucrose is commonly the sugar of choice for many preserves, as the mixture cooks in an acidic environment, a significant amount of the sucrose inverts to produce glucose and fructose, which impacts the texture by sequestering water and suppressing crystallization.[10] A typical sugar concentration for preserves using traditional pectin is about 60–65%.[2][4][9]
Acid
editLike sugar, acidity is critical to both flavor and texture in fruit preserves.[2] This acidity can come from the main fruit(s) in the preserve or can be added supplementally, typically through citrus juice or vinegar.[3][8] As mentioned above, the acid helps invert the sugar during the cooking process, and it also cuts through the high sugar levels required in traditional preserves. Critically, acidity helps prevent the ionization of pectin that causes the molecules to repel each other and fail to gel;[4][8][9] thus, acid is important for preserves made with traditional high-methoxyl pectin.[8] The optimal pH for preserves is generally stated to be from 2.8 to 3.5,[5][9] with 0.5% acid by weight.[4]
Flavor
editThe preparation of preserves can affect its flavor. Notably, the longer the mixture is cooked, the greater the loss of volatile aromatic compounds, and the less bright and fresh the preserve will taste. This is not necessarily a bad thing, but it is something to consider. Additionally, the texture of the final preserve can also affect its flavor—if the jam sets very firmly, the aromatic molecules will not circulate as well, and it will be less flavorful.[8]
Fruit
editJust about every fruit can be made into preserves,[2] though they will all produce preserves with different characteristics. Fruits with relatively low acidity (e.g. ) will need supplemental acid, and fruits with low pectin (e.g. strawberries, raspberries, peaches) will need to be supplemented by either pectin-rich fruits (e.g. grapes, apples, quinces, cranberries) or by commercial pectin.[3][4][8][9] While the fruit does not need to be particularly attractive, it should not be moldy or otherwise low quality.[2][3] Additionally, note that overripe fruit will have lower pectin than slightly underripe fruit.[2][3][5]
Varieties
editGenerally speaking, fruit preserves can be divided into a couple different varieties. Jam is a preserve made from whole, crushed, chopped, or puréed fruit, with the key distinction that it contain pulp, skins, and sometimes even seeds[1][3][11][12][13]—is is rarely or never strained.[1] It is cooked to the gel stage,[1] and the final consistency is thick but spreadable.[9] Unlike jam, jelly is made from the fruit juice only.[7][9][11][12] Jellies are translucent and wobbly and have a defined but delicate texture without any bits.[1][2][3][12] Marmalade is similar to jam in that it uses fruits with peel, but it is typically made from citrus fruits,[1][9] and the overall consistency is similar to that of jelly.[1] Fruit butters are made from puréed fruits cooked down until concentrated and spreadable but not particularly gelatinous.[3] Pectin is rarely added here,[3] and apple butter is one of the more common variations. Fruit compotes are typically less sweet and cooked for less time than other preserves, remaining somewhat juicier and sometimes even preserving the original shape and structure of the fruit.[2][7] In some cases, the term conserve is used to refer to chunks or pieces of fruit in a thick syrup,[1][3][9] but this term is less well-defined than the others.[1] Some people may also use the term preserve to refer to something like a conserve.[3][11][12]
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Jelly, from redcurrants -
Fruit butter, from apples -
Marmalade, from oranges -
Jam, from blackcurrants
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Selection and storage
editPreserves have a fairly long shelf life in general due to their high sugar content and acidity,[1] though they will eventually succumb to mold. To prevent this, preserves are very commonly canned, which extends their lifetime to years provided the seal stays intact. As with most foods, it's a good idea to keep them away from light and heat to optimally preserve their flavor.
Techniques
editChecking set
editHow to know when preserves are done cooking? With jam and jelly at least, there are a couple ways to make sure the mixture has reached the gel point. In the cold dish test, dollop a little jam onto a cold plate and allow it to cool; when you push your finger through it, it should leave a clear trail with a little surface wrinkling and no flowing.[2][3] Alternatively, you can dip a metal spoon into the preserves and let the mixture run off it; when it is ready, the mixture should slide off in thick sheets and not small individual drops.[2][3]
Troubleshooting
editThe main issue that occurs with preserves is failure to set as desired. If not enough pectin is present, there will obviously not be a good set, and insufficient sugar and acid will also cause failure to set.[4] On the other hand, too much acid can make an over-firm gel that weeps liquid.[4] And, excessive cooking can eventually cause the pectin to degrade.[4] Make sure to allow the fruit to cook for a bit and soften before adding the sugar, since sugar will slow the release of pectin.[2] To prevent soft centers, don't pack the preserves in very large volumes.[5]
To preserve flavor, cook gently in a wide pot without stirring too much.[4][8]
Use
editPreserves are used for a variety of purposes, usually in sweet dishes. As spreads, they are applied to bread, pancakes, scones, cakes, and cookies.[7][9] They are also used as fillings in tarts, cakes, pastries, and donuts.[1][7][9] Seedless jams and jellies may be heated and brushed onto desserts to give a clear, shiny coating.[1][12][13] As a less-sweet and saucier preserve, compote Make sure the product you select has the correct texture for the application, firm enough to hold its shape if necessary and stable enough not to leak during baking if applicable.[11]
Substitution
editRecipes
editRecipes for preserves
editRecipes using preserves
editReferences
edit- ↑ a b c d e f g h i j k l m Friberg, Bo (2016-09-13). The Professional Pastry Chef: Fundamentals of Baking and Pastry. Wiley. ISBN 978-0-470-46629-2.
- ↑ a b c d e f g h i j k l m n o p q r Goldstein, Darra (2015-01-01). The Oxford Companion to Sugar and Sweets. Oxford University Press. doi:10.1093/acref/9780199313396.001.0001. ISBN 978-0-19-931339-6.
- ↑ a b c d e f g h i j k l m n o p q Chesman, Andrea (2015-09-19). The Backyard Homestead Book of Kitchen Know-How: Field-to-Table Cooking Skills. Storey Publishing, LLC. ISBN 978-1-61212-205-2.
- ↑ a b c d e f g h i j k l m n o p q McGee, Harold (2007-03-20). On Food and Cooking: The Science and Lore of the Kitchen. Simon and Schuster. ISBN 978-1-4165-5637-4.
- ↑ a b c d e f g h i j Research Chefs Association (2016-02-29). Culinology: The Intersection of Culinary Art and Food Science. John Wiley & Sons. ISBN 978-0-470-48134-9.
- ↑ a b c Labensky, Sarah R.; Hause, Alan M.; Martel, Priscilla (2018-01-18). On Cooking: A Textbook of Culinary Fundamentals. Pearson. ISBN 978-0-13-444190-0.
- ↑ a b c d e Rinsky, Glenn; Rinsky, Laura Halpin (2008-02-28). The Pastry Chef's Companion: A Comprehensive Resource Guide for the Baking and Pastry Professional. John Wiley & Sons. ISBN 978-0-470-00955-0.
- ↑ a b c d e f g This, Hervé (2007-11-15). Kitchen Mysteries: Revealing the Science of Cooking. Columbia University Press. ISBN 978-0-231-51203-9.
- ↑ a b c d e f g h i j k Davidson, Alan (2014-01-01). Jaine, Tom (ed.). The Oxford Companion to Food. Oxford University Press. doi:10.1093/acref/9780199677337.001.0001. ISBN 978-0-19-967733-7.
- ↑ Provost, Joseph J.; Colabroy, Keri L.; Kelly, Brenda S.; Wallert, Mark A. (2016-05-02). The Science of Cooking: Understanding the Biology and Chemistry Behind Food and Cooking. John Wiley & Sons. ISBN 978-1-118-67420-8.
- ↑ a b c d Labensky, Sarah; Martel, Priscilla; Damme, Eddy Van (2015-01-06). On Baking: A Textbook of Baking and Pastry Fundamentals, Updated Edition. Pearson Education. ISBN 978-0-13-388675-7.
- ↑ a b c d e Kipfer, Barbara Ann (2012-04-11). The Culinarian: A Kitchen Desk Reference. Houghton Mifflin Harcourt. ISBN 978-0-544-18603-3.
- ↑ a b Ruhlman, Michael (2008). The Elements of Cooking: Translating the Chef's Craft for Every Kitchen. Black Incorporated. ISBN 978-1-86395-143-2.