On Food And Cooking Part 83

Cane and Sorghum Syrups Cane syrups may be produced directly from cane juice at sugar factories, or from raw sugar at refineries. They generally contain a combination of sucrose (2530%) and invert sugars (50%), are golden to medium brown in color, and have a mild flavor with caramel, b.u.t.terscotch, and leafy aromas. Louisiana cane syrups were traditionally made from whole cane juice, concentrated and clarified. The same basic product, with about half of its sucrose inverted by acid or enzymes, is now sometimes called "high-test mola.s.ses." It has been heated less, and so has a more aromatic, less bitter flavor than true mola.s.ses. "Golden syrup" is a refinery syrup made from raw sugar, filtered through charcoal to give it a characteristic light, crystal-clear appearance and delicate flavor. Cane syrups offer more character (though also a more intense sweetness) than corn syrup in such dishes as pecan pie. Cane syrups may be produced directly from cane juice at sugar factories, or from raw sugar at refineries. They generally contain a combination of sucrose (2530%) and invert sugars (50%), are golden to medium brown in color, and have a mild flavor with caramel, b.u.t.terscotch, and leafy aromas. Louisiana cane syrups were traditionally made from whole cane juice, concentrated and clarified. The same basic product, with about half of its sucrose inverted by acid or enzymes, is now sometimes called "high-test mola.s.ses." It has been heated less, and so has a more aromatic, less bitter flavor than true mola.s.ses. "Golden syrup" is a refinery syrup made from raw sugar, filtered through charcoal to give it a characteristic light, crystal-clear appearance and delicate flavor. Cane syrups offer more character (though also a more intense sweetness) than corn syrup in such dishes as pecan pie.

Sorghum syrup is made in small quant.i.ties in the American South and Midwest from the stalk juice of sweet sorghum, specialized varieties of a cereal plant normally grown for its grain (Sorghum bicolor, p. 482). Sorghum syrup is mainly sucrose, and has a distinctive pungency. p. 482). Sorghum syrup is mainly sucrose, and has a distinctive pungency.

Fruit Syrups: Ancient Saba, Modern Fruit SweetenersIn Europe, the original sweet syrups were made not from cane, but from grapes. Italian saba saba is grape juice cooked down to a concentrated, viscous syrup. It contains about equal amounts of glucose and fructose, and in addition has a distinct tartness due to the simultaneous concentration of the grape acids. In the 16th century, Nostradamus described making various sweet preparations with saba, and noted that "in places where there is neither sugar nor honey, the sovereign sun produces and nourishes other fruits which...come to satisfy our sensuous desire...." is grape juice cooked down to a concentrated, viscous syrup. It contains about equal amounts of glucose and fructose, and in addition has a distinct tartness due to the simultaneous concentration of the grape acids. In the 16th century, Nostradamus described making various sweet preparations with saba, and noted that "in places where there is neither sugar nor honey, the sovereign sun produces and nourishes other fruits which...come to satisfy our sensuous desire...."Manufactured fruit syrups are a relatively recent version of the traditional syrups. They're made from batches of various fruits, including apples, pears, and grapes, that are in surplus, damaged, or otherwise not suitable for other uses. Both aroma and color are removed from the juice, which is concentrated to about 75% sugars, mainly glucose and fructose due to the action of the fruit acids on sucrose. The acids are also concentrated, so the pH of the syrup is around 4. Food manufacturers value these fruit syrups in part because they can be identified appealingly as "fruit sweeteners" on the label, rather than as sugar or corn syrup. They may also contain significant amounts of pectin and other cell-wall carbohydrates that help stabilize emulsions and reduce crystal size in frozen preparations.

Corn Syrups, Glucose and Fructose Syrups, Malt Syrup Sugars from Starch We come now to a source of sugar that is relatively new, but today rivals cane and beet sugars in commercial importance. In 1811, a Russian chemist, K. S. Kirchof, found that if he heated potato starch in the presence of sulfuric acid, the starch was transformed into sweet crystals and a viscous syrup. A few years later, he discovered that malted barley had the same effect as the acid (and thereby laid the foundations for a scientific understanding of beer brewing). We now know that starch consists of long chains of glucose molecules, and that both acids and certain plant, animal, and microbial enzymes will break these long chains down into smaller pieces and eventually into individual glucose molecules. The sugars make the syrup sweet, and the remaining fragments of glucose chains give the solution a thick, viscous consistency. In the United States, the acid technique was used to produce syrup from potato starch in the 1840s, and from corn starch beginning in the 1860s. We come now to a source of sugar that is relatively new, but today rivals cane and beet sugars in commercial importance. In 1811, a Russian chemist, K. S. Kirchof, found that if he heated potato starch in the presence of sulfuric acid, the starch was transformed into sweet crystals and a viscous syrup. A few years later, he discovered that malted barley had the same effect as the acid (and thereby laid the foundations for a scientific understanding of beer brewing). We now know that starch consists of long chains of glucose molecules, and that both acids and certain plant, animal, and microbial enzymes will break these long chains down into smaller pieces and eventually into individual glucose molecules. The sugars make the syrup sweet, and the remaining fragments of glucose chains give the solution a thick, viscous consistency. In the United States, the acid technique was used to produce syrup from potato starch in the 1840s, and from corn starch beginning in the 1860s.

High-Fructose Corn Syrups The 1960s brought the invention of fructose syrups. These start out as plain corn or potato syrups, but an additional enzyme process converts some of the glucose sugars into fructose, which is much sweeter and therefore gives the syrups a higher sweetening power. The solids in standard high-fructose corn syrup are around 53% glucose and 42% fructose, and provide the same sweetness as the syrup's equivalent weight in table sugar. Because high-fructose syrups are relatively cheap, soft-drink manufacturers began to replace cane and beet sugars with them in the 1980s, and Americans began to consume more corn syrups than cane and beet sugar. Today they're a very important sweetener in food manufacturing. The 1960s brought the invention of fructose syrups. These start out as plain corn or potato syrups, but an additional enzyme process converts some of the glucose sugars into fructose, which is much sweeter and therefore gives the syrups a higher sweetening power. The solids in standard high-fructose corn syrup are around 53% glucose and 42% fructose, and provide the same sweetness as the syrup's equivalent weight in table sugar. Because high-fructose syrups are relatively cheap, soft-drink manufacturers began to replace cane and beet sugars with them in the 1980s, and Americans began to consume more corn syrups than cane and beet sugar. Today they're a very important sweetener in food manufacturing.

Making Corn Syrups To make corn syrups, manufacturers extract starch granules from the kernels of common dent corn (p. 477), and then treat them with acid and/or with microbial or malt enzymes to develop a sweet syrup that is then clarified, decolorized, and evaporated to the desired concentration. Nowadays, enzymes from the easily cultured molds To make corn syrups, manufacturers extract starch granules from the kernels of common dent corn (p. 477), and then treat them with acid and/or with microbial or malt enzymes to develop a sweet syrup that is then clarified, decolorized, and evaporated to the desired concentration. Nowadays, enzymes from the easily cultured molds Aspergillus oryzae Aspergillus oryzae (also used in j.a.pan to break rice starch down into fermentable sugars for (also used in j.a.pan to break rice starch down into fermentable sugars for sake sake) and A. niger A. niger are used almost exclusively. In Europe, potato and wheat starch are the main sources for making what is called "glucose" or "glucose syrup," which is essentially the same as American corn syrup. are used almost exclusively. In Europe, potato and wheat starch are the main sources for making what is called "glucose" or "glucose syrup," which is essentially the same as American corn syrup.

Fructose CrystalsCrystalline fructose has been commercially available for only a few decades. Fructose is so hygroscopic, or water-absorbing, that it's hard to get it to crystallize from a water solution. It's now made by mixing high-fructose corn syrup with alcohol, in which fructose is much less soluble. If fructose crystals are sprinkled onto a food as decoration, they'll quickly disappear into a thin, sticky syrup as they absorb moisture from the food and air and dissolve.

The Properties and Uses of Corn Syrups Among the usual sweeteners available to the cook, corn syrups are alone in providing long carbohydrate molecules that get tangled up with each other and slow down the motion of all molecules in the syrup, thus giving it a thicker consistency than any but the most concentrated sucrose syrups. It's largely these long tangly molecules that have made corn syrup increasingly important in confectionery and other prepared foods. Because the tangling interferes with molecular motion, it also has the valuable effect of preventing other sugars in candy from crystallizing and producing a grainy texture. All molecules in the syrup are flowing very slowly, and the sucrose crystal faces keep getting covered with chains that can't become part of the crystal. (The same behavior helps minimize the size of ice crystals in ice cream and fruit ices, thus encouraging a smooth, creamy consistency.) Another consequence of corn syrup's viscosity is that it imparts a thick, chewy texture to foods. And because it includes glucose, a water-binding sugar that is less sweet than table sugar, corn syrup helps prevent moisture loss and prolongs the storage life of various foods without the cloying sweetness that honey or sucrose syrup imparts. Finally, all corn syrups are somewhat acid, with a pH between 3.5 and 5.5, so in baked goods they can react with baking soda to produce carbon dioxide and thus contribute to leavening. Among the usual sweeteners available to the cook, corn syrups are alone in providing long carbohydrate molecules that get tangled up with each other and slow down the motion of all molecules in the syrup, thus giving it a thicker consistency than any but the most concentrated sucrose syrups. It's largely these long tangly molecules that have made corn syrup increasingly important in confectionery and other prepared foods. Because the tangling interferes with molecular motion, it also has the valuable effect of preventing other sugars in candy from crystallizing and producing a grainy texture. All molecules in the syrup are flowing very slowly, and the sucrose crystal faces keep getting covered with chains that can't become part of the crystal. (The same behavior helps minimize the size of ice crystals in ice cream and fruit ices, thus encouraging a smooth, creamy consistency.) Another consequence of corn syrup's viscosity is that it imparts a thick, chewy texture to foods. And because it includes glucose, a water-binding sugar that is less sweet than table sugar, corn syrup helps prevent moisture loss and prolongs the storage life of various foods without the cloying sweetness that honey or sucrose syrup imparts. Finally, all corn syrups are somewhat acid, with a pH between 3.5 and 5.5, so in baked goods they can react with baking soda to produce carbon dioxide and thus contribute to leavening.

Corn syrups. Standard corn syrup is a water solution of glucose chains of varying lengths (left). (left). One-and two-unit sugars taste sweet, while taste-free longer chains make the syrup viscous. By controlling the relative populations of different chains, the manufacturer can tailor the syrup's balance of sweetening and thickening powers. High-fructose corn syrup One-and two-unit sugars taste sweet, while taste-free longer chains make the syrup viscous. By controlling the relative populations of different chains, the manufacturer can tailor the syrup's balance of sweetening and thickening powers. High-fructose corn syrup (right) (right) has been treated with an enzyme to convert a portion of the single glucose molecules (small hexagons) into fructose molecules (small pentagons), which taste sweeter. has been treated with an enzyme to convert a portion of the single glucose molecules (small hexagons) into fructose molecules (small pentagons), which taste sweeter.

Grades of Corn Syrup Corn syrup is an especially versatile ingredient in food manufacturing because its sweetness and viscosity can be varied simply by controlling the thoroughness of the enzymatic digestion of starch into sugars. The most common consumer grade of corn syrup is about 20% water, 14% glucose, 11% maltose, and 55% longer glucose chains. It is only moderately sweet, and fairly viscous. Several others grades are available to manufacturers: Corn syrup is an especially versatile ingredient in food manufacturing because its sweetness and viscosity can be varied simply by controlling the thoroughness of the enzymatic digestion of starch into sugars. The most common consumer grade of corn syrup is about 20% water, 14% glucose, 11% maltose, and 55% longer glucose chains. It is only moderately sweet, and fairly viscous. Several others grades are available to manufacturers: Maltodextrins are syrups that contain less than 20% glucose plus maltose, and are used mainly to give viscosity and body with little sweetness and moisture absorption.

High-fructose corn syrups are around 75% fructose plus glucose, and give an overall sweetness around that of table sugar. They and high-glucose syrups help develop color and retain moisture in baked goods.

High-maltose syrups are valuable in ice creams, and some confections, where lowered freezing points or interference with crystallization are desired but sweetness is not; maltose is less sweet than either table sugar or glucose. In baked goods, maltose feeds yeasts and improves leavening.

Malt Syrup and Extract Malt syrup is made from a combination of germinated cereal grains, preeminently barley, and ordinary cooked grains. It's among the most ancient and versatile of sweetening agents, and was the predecessor of modern-day high-tech corn syrups. Along with honey, malt syrup was the primary sweetener in China for 2,000 years, until around 1000 Malt syrup is made from a combination of germinated cereal grains, preeminently barley, and ordinary cooked grains. It's among the most ancient and versatile of sweetening agents, and was the predecessor of modern-day high-tech corn syrups. Along with honey, malt syrup was the primary sweetener in China for 2,000 years, until around 1000 CE CE; it's still made in both China and Korea. Malt syrup had the advantage that it could be made in households from readily available and easily stored materials, the same whole grains that were grown as staple foods, including wheat, rice, and sorghum. It was therefore a far more affordable sweetener than cane sugar.

There are three stages to making malt syrup. First a portion of whole grain is malted malted: soaked in water and allowed to germinate partly, then dried again by means of carefully controlled heating (p. 744). The germinating embryo produces enzymes that will digest the grain's starch into sugars to fuel its growth; barley is preferred in malting because it produces unusually copious and active enzymes. Drying preserves these enzymes, and also develops color and flavor by means of browning reactions. In the second stage, the malted grain is mixed with some water and with unmalted but cooked grains - rice, wheat, barley - and the malt enzymes digest the cooked starch granules to produce a sweet slurry. In the final stage, the slurry is extracted with additional water, and the liquid is boiled down to concentrate it. The result is a concentrated syrup of maltose, glucose, and some longer glucose chains. Malt syrup is therefore much less sweet than a similarly viscous sucrose syrup. In Asia it is used to provide color and gloss in savory dishes - for example, it's painted onto the skin of Peking duck - as well as in confections.

The Composition of Malt Extract

% of Malt Extract by Weight

Water

20% 20%.

Protein

5 5.

Minerals

1 1.

Total sugars

60 60.

Glucose

710 710

Maltose (double-glucose chains)

40 40.

Maltotriose (triple-glucose chains)

1015 1015

Longer glucose chains

2530 2530

Malt syrup has a relatively mild malt aroma because the malted barley is a small fraction of the grain mixture. If the malted barley is soaked on its own, without any added cooked grains, then the malt flavor is much stronger. Such a preparation is usually called "malt extract." It is frequently used in baking to provide maltose and glucose for yeast growth and moisture retention (p. 530). In the United States, malted milk and malt b.a.l.l.s are made from a mixture of barley malt and powdered milk.

Sugar Candies and Confectionery All sugar candies, whether brittle or creamy or chewy, are essentially mixtures of two ingredients: sugar and water. Cooks manage to create very different textures from the same materials by varying the relative proportions of sugar and water, and the physical arrangement of the sugar molecules. They control the proportions as they cook the sugar syrup, and they control the physical arrangement as they cool it. Depending on how hot the syrup gets, how quickly it cools, and how much it's stirred, it can solidify into coa.r.s.e sugar crystals, fine sugar crystals, or a monolithic crystal-free ma.s.s. To a large extent, the art of the confectioner depends on the science of crystallization.

Setting the Sugar Concentration: Cooking the Syrup The first factor that influences candy texture is the concentration of sugar in the cooked syrup. Confectioners have found from long experience that certain syrup concentrations are best for making certain kinds of candy. Generally, the more water the syrup contains, the softer the final product will be. So the cook must know how to make and recognize particular syrup concentrations. This turns out to be pretty simple. When we dissolve sugar or salt in water, the boiling point of the solution becomes higher than the boiling point of pure water (see p. 785). This increase in the boiling point depends predictably on the amount of material dissolved: the more dissolved molecules in the water, the higher the boiling point. So the boiling point of a solution is an indicator of the concentration of the dissolved material. The graph in the box below shows, for example, that a sugar syrup that boils at 250F/125C is about 90% sugar by weight.

Frostings, Icings, and GlazesFrostings, icings, and glazes are sweet coatings for cakes and other baked goods. In addition to being tasty and decorative, they protect the food underneath from drying out. These preparations began in the 17th century as plain syrup glazes, and gradually evolved into more elaborate forms. Today, glazes are glossy, thin, dense coatings made with a combination of powdered sugar, a small amount of water, corn syrup, and sometimes fat (b.u.t.ter, cream). The corn syrup and fat prevent the sugar from forming coa.r.s.e crystals, and the corn syrup provides a moisture-attracting liquid phase to fill the s.p.a.ce between sugar particles and create a smooth, gla.s.s-like surface. A warm fondant (around 100F/38C) poured over the cake or pastry produces a similar effect. Simple frostings are made by whipping sugar and air into a solid fat - b.u.t.ter, cream cheese, or vegetable shortening - to make a sweet, creamy, light ma.s.s. The sugar particles must be small enough not to make the frosting seem grainy, so fine grades of powdered sugar are the usual choice. Cooked frostings and icings include eggs or flour and owe their body in part to the egg proteins or flour starch. Because the sugar dissolves during the cooking, its particle size is unimportant.

Cooking the Syrup Raises the Sugar Concentration As a sugar solution boils, water molecules evaporate from the liquid phase into the air, while the sugar molecules stay behind. The sugar molecules therefore account for a larger and larger proportion of all the molecules in the solution. So as it boils, the syrup gets more and more concentrated: and this in turn causes its boiling point to continue to rise. In order to make a syrup of a given sugar concentration, all the candy maker has to do is heat a mixture of sugar and water until it boils, and then keep it at the boil and watch its temperature. At 235F/113C, or about 85% sugar, the cook can stop the concentration process and make fudge; at 270F/132C, or 90%, taffy; at 300F/149C and above, nearing 100% sugar, brittles and hard candies. As a sugar solution boils, water molecules evaporate from the liquid phase into the air, while the sugar molecules stay behind. The sugar molecules therefore account for a larger and larger proportion of all the molecules in the solution. So as it boils, the syrup gets more and more concentrated: and this in turn causes its boiling point to continue to rise. In order to make a syrup of a given sugar concentration, all the candy maker has to do is heat a mixture of sugar and water until it boils, and then keep it at the boil and watch its temperature. At 235F/113C, or about 85% sugar, the cook can stop the concentration process and make fudge; at 270F/132C, or 90%, taffy; at 300F/149C and above, nearing 100% sugar, brittles and hard candies.

The Cold-Water Test Although it was invented 400 years ago by Sanctorius, the thermometer has been a common household appliance for only a few decades. Beginning in the 16th century and continuing to this day, confectioners have used a more direct means of sampling the syrup's fitness for different candies: they scoop out a small amount, cool it quickly, and note its behavior. Thin syrups will simply form a thread in the air. Somewhat more concentrated syrups form a ball when dropped into cold water, and the ball will be soft and malleable between the fingers; as the concentration increases, the cooled ball becomes harder. The most concentrated syrups make a cracking sound as they turn into hard, brittle threads. Each of these stages indicates a particular temperature range and suitability for a particular kind of candy (see box below). Although it was invented 400 years ago by Sanctorius, the thermometer has been a common household appliance for only a few decades. Beginning in the 16th century and continuing to this day, confectioners have used a more direct means of sampling the syrup's fitness for different candies: they scoop out a small amount, cool it quickly, and note its behavior. Thin syrups will simply form a thread in the air. Somewhat more concentrated syrups form a ball when dropped into cold water, and the ball will be soft and malleable between the fingers; as the concentration increases, the cooled ball becomes harder. The most concentrated syrups make a cracking sound as they turn into hard, brittle threads. Each of these stages indicates a particular temperature range and suitability for a particular kind of candy (see box below).

Syrup Boiling Points Depend on Sugar Concentration The boiling point of a sugar solution increases as the concentration of sugar increases. This graph shows the relationship between boiling point and sugar concentration at sea level. The boiling point of a sugar solution increases as the concentration of sugar increases. This graph shows the relationship between boiling point and sugar concentration at sea level.

The Heating Rate Accelerates During Cooking As we cook a sugar syrup, most of the heat goes into the work of evaporating water molecules from the syrup, and less into actually raising the temperature of the syrup; so the syrup temperature rises only gradually. But as the sugar concentration pa.s.ses 80%, there's so little water left that both the temperature of the syrup and its boiling point rise more rapidly. As the concentration approaches 100%, the temperature rises very fast, and can easily overshoot the desired range and brown or scorch the sugar. To avoid this, the cook should reduce the heat toward the end of cooking and keep a careful eye on the syrup temperature. As we cook a sugar syrup, most of the heat goes into the work of evaporating water molecules from the syrup, and less into actually raising the temperature of the syrup; so the syrup temperature rises only gradually. But as the sugar concentration pa.s.ses 80%, there's so little water left that both the temperature of the syrup and its boiling point rise more rapidly. As the concentration approaches 100%, the temperature rises very fast, and can easily overshoot the desired range and brown or scorch the sugar. To avoid this, the cook should reduce the heat toward the end of cooking and keep a careful eye on the syrup temperature.

Setting the Sugar Structure: Cooling and Crystallization The final texture of a candy is determined by the way in which the sugar molecules in the cooked syrup cool and settle into a solid structure. If the sugar forms a few large crystals, then the candy texture will be coa.r.s.e and grainy. If it forms many millions of microscopic crystals that are lubricated by just the right amount of syrup, then the candy will be smooth and creamy. And if it forms no crystals at all, then it will be a hard, monolithic ma.s.s. The trickiest stage of candy making thus comes after after the cooking, when the syrup cools from 250350F/ 120175C down to room temperature. The rate of cooling, the movement of the syrup, and the presence of the smallest particles of dust or sugar can have drastic effects on the candy's structure and texture. the cooking, when the syrup cools from 250350F/ 120175C down to room temperature. The rate of cooling, the movement of the syrup, and the presence of the smallest particles of dust or sugar can have drastic effects on the candy's structure and texture.

Confections and the Sugar Syrups They're Made fromSugar confections are made from syrups with particular sugar concentrations. This chart lists some common confections and two distinguishing qualities of their syrups.

Syrup Behavior in Cold-Water Test

Syrup Boiling Point* F/C Syrup Boiling Point* F/C

Confection Confection

Thread

215235/102113 215235/102113

Syrups, preserves Syrups, preserves

Soft ball

235240/113116 235240/113116

Fondant, fudge Fondant, fudge

Firm ball

245250/118121 245250/118121

Caramel candies Caramel candies

Hard ball

240265/121130 240265/121130

Marshmallows, nougat Marshmallows, nougat

Soft crack

270290/132143 270290/132143