On Food And Cooking Part 76

Corn syrup Glucose, maltose Glucose, maltose 3050 3050

High-fructose corn syrup Fructose, maltose Fructose, maltose 8090 8090

Invert sugar syrup Glucose, fructose, sucrose Glucose, fructose, sucrose 95 95.

Crystallization Sugars are wonderfully robust materials! Unlike proteins that easily denature and coagulate, unlike fats that are damaged by air and heat and go rancid, unlike starch chains that break apart into smaller chains of glucose molecules, sugars themselves are small and stable molecules. They mix easily with water, tolerate the heat of boiling, and when sufficiently concentrated in water, they readily bond to each other and collect themselves into pure, solid ma.s.ses, or crystals. This tendency to form crystals is the means by which we obtain pure sugar from plant juices, and it's the way that we make many kinds of candies. Sugar crystallization is described in detail on p. 682.

Caramelization Caramelization is the name given to the chemical reactions that occur when any sugar is heated to the point that its molecules begin to break apart. This destruction triggers a remarkable cascade of chemical creation. From a single kind of molecule in the form of colorless, odorless, simply sweet crystals, the cook generates hundreds of new and different compounds, some of them small fragments that are sour or bitter, or intensely aromatic, others large aggregates with no flavor but a deep brown color. The more the sugar is cooked, the less sugar and sweetness remain, and the darker and more bitter it gets. is the name given to the chemical reactions that occur when any sugar is heated to the point that its molecules begin to break apart. This destruction triggers a remarkable cascade of chemical creation. From a single kind of molecule in the form of colorless, odorless, simply sweet crystals, the cook generates hundreds of new and different compounds, some of them small fragments that are sour or bitter, or intensely aromatic, others large aggregates with no flavor but a deep brown color. The more the sugar is cooked, the less sugar and sweetness remain, and the darker and more bitter it gets.

Though caramel is most often made with table sugar, its sucrose molecules actually break apart into their glucose and fructose components before they begin to fragment and recombine into new molecules. Glucose and fructose are "reducing sugars," meaning that they have reactive atoms that perform the opposite of oxidation (they donate electrons to other molecules). A sucrose molecule is made from one glucose and one fructose joined by their reducing atoms, so sucrose has no reducing atoms free to react with other molecules, and is therefore less reactive than glucose and fructose. This is why sucrose requires a higher temperature for caramelization (340F/170C) than glucose (300F/150C) and especially fructose (220F/105C).

The flavors of caramelization. Heat transforms table sugar, a sweet, odorless, single kind of molecule, into hundreds of different molecules that generate a complex flavor and rich brown color. A few aromatic examples (clockwise from top left) (clockwise from top left) : alcohol, sherry-like acetaldehyde, vinegary acetic acid, b.u.t.tery diacetyl, fruity ethyl acetate, nutty furan, solvent-like benzene, and toasty maltol. : alcohol, sherry-like acetaldehyde, vinegary acetic acid, b.u.t.tery diacetyl, fruity ethyl acetate, nutty furan, solvent-like benzene, and toasty maltol.

Making Caramel The usual technique for making caramel is to mix table sugar with some water, then heat until the water has boiled off and the molten sugar colors. Why add water if the first thing you do is boil it off? Water makes it possible to cook the sugar over high heat from the very beginning without the danger of burning it. In addition, the presence of water prolongs the period during which the syrup is cooked, gives these reactions more time to proceed, and develops a stronger flavor than heating the sugar on its own very quickly. And water enhances the conversion of sucrose into its glucose and fructose components. Cooking the syrup in the microwave oven has been found to produce a somewhat different spectrum of flavors than ordinary stovetop cooking. The usual technique for making caramel is to mix table sugar with some water, then heat until the water has boiled off and the molten sugar colors. Why add water if the first thing you do is boil it off? Water makes it possible to cook the sugar over high heat from the very beginning without the danger of burning it. In addition, the presence of water prolongs the period during which the syrup is cooked, gives these reactions more time to proceed, and develops a stronger flavor than heating the sugar on its own very quickly. And water enhances the conversion of sucrose into its glucose and fructose components. Cooking the syrup in the microwave oven has been found to produce a somewhat different spectrum of flavors than ordinary stovetop cooking.

Once caramelization and color and flavor generation begin, the overall set of reactions actually gives off heat, and can run away and burn the sugar if it's not carefully controlled. It's helpful to have a bowl of cold water ready to cool the pan down as soon as the caramel is done. Excessive caramelization turns the syrup very dark, bitter, and viscous or even solid.

The Flavor of Caramelized Sugar The aroma of a simple caramelized sugar has several different notes, among them b.u.t.tery and milky (from diacetyl), fruity (esters and lactones), flowery, sweet, rum-like, and roasted. As the reactions proceed, the taste of the mixture becomes less sweet as more of the original sugar is destroyed, with more p.r.o.nounced acidity and eventually bitterness and an irritating, burning sensation. Some of the chemical products in caramel are effective antioxidants and can help protect food flavors from damage during storage. The aroma of a simple caramelized sugar has several different notes, among them b.u.t.tery and milky (from diacetyl), fruity (esters and lactones), flowery, sweet, rum-like, and roasted. As the reactions proceed, the taste of the mixture becomes less sweet as more of the original sugar is destroyed, with more p.r.o.nounced acidity and eventually bitterness and an irritating, burning sensation. Some of the chemical products in caramel are effective antioxidants and can help protect food flavors from damage during storage.

When sugars are cooked with ingredients that include proteins or amino acids - milk or cream, for example - then in addition to true caramelization, some of the sugars partic.i.p.ate with the proteins and amino acids in the Maillard browning reactions (p. 778), which produce a larger range of compounds and a richer aroma.

Sugars and Health "Empty Calories" In one sense, sugars are highly nouris.h.i.+ng. Pure sugars are pure energy. After fats and oils, they're the most concentrated source of calories we have. The problem is that most people in the developed world consume more energy than they need to fuel their activity, and less than they need of hundreds of other nutrients and plant substances that contribute to long-term health (p. 253). To the extent that sugar-rich foods displace more broadly nouris.h.i.+ng foods from our diet, they are detrimental to human health, a source of calories "empty" of any other nutritional value, and a major contributor to the modern epidemic of obesity and a.s.sociated health problems, including diabetes (p. 659). In one sense, sugars are highly nouris.h.i.+ng. Pure sugars are pure energy. After fats and oils, they're the most concentrated source of calories we have. The problem is that most people in the developed world consume more energy than they need to fuel their activity, and less than they need of hundreds of other nutrients and plant substances that contribute to long-term health (p. 253). To the extent that sugar-rich foods displace more broadly nouris.h.i.+ng foods from our diet, they are detrimental to human health, a source of calories "empty" of any other nutritional value, and a major contributor to the modern epidemic of obesity and a.s.sociated health problems, including diabetes (p. 659).

People in the developed world, particularly in the United States, consume large amounts of refined sugars. Adults in the United States get about 20% of their calories from refined sugars, children between 20% and 40%. Most of this sugar intake comes not from candies and confections, but from soft drinks. Significant amounts of sugar also find their way into most processed foods, including many savory sauces, dressings, meats, and baked goods. The total sugar content in processed foods is often unclear from the ingredients list, where different sugars can be listed separately as sucrose, dextrose, levulose, fructose, corn syrup, high-fructose corn syrup, etc.

Food Words: Caramel CaramelOur word for browned sugar may come from its resemblance in color to straw. Caramel Caramel first appears in French in the 17th century as a borrowing via Spanish from the Portuguese first appears in French in the 17th century as a borrowing via Spanish from the Portuguese caramel, caramel, which meant both the elongated sugar loaf and "icicle," perhaps because they shared a similar shape and sparkly appearance. The Portuguese in turn seems to derive from the Latin which meant both the elongated sugar loaf and "icicle," perhaps because they shared a similar shape and sparkly appearance. The Portuguese in turn seems to derive from the Latin calamus, calamus, meaning "reed." The Greek meaning "reed." The Greek kalamos kalamos meant "straw," and the original Indo-European root meant "gra.s.s." The Italian meant "straw," and the original Indo-European root meant "gra.s.s." The Italian calamari, calamari, "squid," comes from the same root! Perhaps the common element is the brown color of dry gra.s.s, partly refined sugar, cooked sugar syrup, and camouflaging squid skin. "squid," comes from the same root! Perhaps the common element is the brown color of dry gra.s.s, partly refined sugar, cooked sugar syrup, and camouflaging squid skin.

Sugars and Tooth Decay It has been common knowledge for thousands of years that sweet foods encourage tooth decay. In the Greek book of It has been common knowledge for thousands of years that sweet foods encourage tooth decay. In the Greek book of Problems Problems attributed to Aristotle, the question is asked, "Why do figs, which are soft and sweet, destroy the teeth?" Nearly 2,000 years later, as sugar cane was being established in the West Indies, a German visitor to the English court named Paul Hentzner described Queen Elizabeth I as she appeared in 1598: attributed to Aristotle, the question is asked, "Why do figs, which are soft and sweet, destroy the teeth?" Nearly 2,000 years later, as sugar cane was being established in the West Indies, a German visitor to the English court named Paul Hentzner described Queen Elizabeth I as she appeared in 1598: Next came the Queen, in the Sixty-fifth Year of her Age, as we were told, very majestic; her Face oblong, fair, but wrinkled; her Eyes small, yet black and pleasant; her Nose a little hooked; her Lips narrow, and her Teeth black; (a defect the English seem subject to, from their too great use of Sugar)...

We now know that certain kinds of Streptococcus Streptococcus bacteria colonize the mouth and cling to undisturbed surfaces, where they live on food residues, converting sugars into sticky "plaque" carbohydrates that anchor and protect them, and into defensive acids that eat away at tooth enamel and so cause decay. Clearly, the more food there is for the bacteria, the more active they will be, and hard sugar candies that slowly dissolve in the mouth provide a feast for them. But pure sugar is not the only culprit in tooth decay. Starchy foods like bread, cereals, pasta, and potato chips are also harmful because they stick to the teeth and then are broken down into sugars by enzymes in the saliva. A few other foods, notably chocolate, cocoa, and licorice extract among candy ingredients, as well as coffee, tea, beer, and some cheeses, actually inhibit decay-causing bacteria. There's evidence that phenolic compounds interfere with the adhesion of bacteria to the teeth. The sugar alcohols in low-calorie candies (p. 662) are generally not metabolized by bacteria in the mouth and don't contribute to tooth decay. bacteria colonize the mouth and cling to undisturbed surfaces, where they live on food residues, converting sugars into sticky "plaque" carbohydrates that anchor and protect them, and into defensive acids that eat away at tooth enamel and so cause decay. Clearly, the more food there is for the bacteria, the more active they will be, and hard sugar candies that slowly dissolve in the mouth provide a feast for them. But pure sugar is not the only culprit in tooth decay. Starchy foods like bread, cereals, pasta, and potato chips are also harmful because they stick to the teeth and then are broken down into sugars by enzymes in the saliva. A few other foods, notably chocolate, cocoa, and licorice extract among candy ingredients, as well as coffee, tea, beer, and some cheeses, actually inhibit decay-causing bacteria. There's evidence that phenolic compounds interfere with the adhesion of bacteria to the teeth. The sugar alcohols in low-calorie candies (p. 662) are generally not metabolized by bacteria in the mouth and don't contribute to tooth decay.

Caramel Food ColoringsCooks have been confecting caramel candies and syrups for many centuries, and have been making "burnt" sugar for its brown color since ancient times. The commercial production of caramel syrups as food colorings began in Europe and the United States in the middle of the 19th century. They're now the most common food coloring, and provide the deep brown of colas, root beers and other soft drinks, spirits, candies, and many prepared foods. In addition to color, the pigment molecules also have some antioxidant activity that helps preserve flavor. Caramel colors were originally produced by heating sugar syrup in an open pan. With time, closed vacuum pans were introduced to control color development more finely, and manufacturers began to add various chemicals to obtain pigments with good dispersing or emulsifying properties.

Food Sugars and Blood Sugar: The Problem of Diabetes Some foods rich in sugars can contribute to the disruption of the body's system for controlling its own sugar levels. Glucose is the body's primary form of chemical energy, so it's distributed to all cells via the blood. On the other hand, glucose is a reactive molecule, and excess quant.i.ties can damage the circulatory system, eyes, kidneys, and nervous system. So the body tightly regulates blood glucose levels, and does so with the hormone insulin. Diabetes is a disease in which the insulin system is unable to control blood glucose adequately. And a high intake of some food sugars overloads the blood with glucose and puts stress on the insulin system. This is dangerous for people who suffer from diabetes. The foods that raise blood glucose levels the most are foods rich in glucose itself, including such starchy foods as potatoes and rice that our enzymes digest into glucose. Table sugar, a combination of glucose and fructose, has a somewhat smaller effect, and fructose itself has a much smaller effect, since it must be metabolized in the liver before the body can use it for energy. One valuable property of many sugar subst.i.tutes is that they do not raise blood sugar levels. Some foods rich in sugars can contribute to the disruption of the body's system for controlling its own sugar levels. Glucose is the body's primary form of chemical energy, so it's distributed to all cells via the blood. On the other hand, glucose is a reactive molecule, and excess quant.i.ties can damage the circulatory system, eyes, kidneys, and nervous system. So the body tightly regulates blood glucose levels, and does so with the hormone insulin. Diabetes is a disease in which the insulin system is unable to control blood glucose adequately. And a high intake of some food sugars overloads the blood with glucose and puts stress on the insulin system. This is dangerous for people who suffer from diabetes. The foods that raise blood glucose levels the most are foods rich in glucose itself, including such starchy foods as potatoes and rice that our enzymes digest into glucose. Table sugar, a combination of glucose and fructose, has a somewhat smaller effect, and fructose itself has a much smaller effect, since it must be metabolized in the liver before the body can use it for energy. One valuable property of many sugar subst.i.tutes is that they do not raise blood sugar levels.

Sugar Subst.i.tutes Sugars combine several useful qualities in one ingredient: energy, sweetness, substance, moisture binding, and the ability to caramelize. The problem with this versatility is that each quality comes with the others. And sometimes we want just one or two alone: the pleasure of sweetness without the calories or stress on the body's system for regulating blood sugar levels, for example, or the substance without the sweetness, or substance and sweetness without the tendency to brown when cooked. Manufacturers have therefore developed ingredients that offer some but not all of the properties of sugars. Many of these ingredients were originally discovered in plants; a few are entirely artificial. Inventive cooks are now experimenting with some to make candy-like savory foods and other novelties.

There are two main kinds of sugar subst.i.tutes. The first includes various carbohydrates that provide bulk without being as digestible as the sugars. They therefore don't raise blood sugar levels as quickly, and supply fewer calories. The second is high-intensity sweeteners: molecules that provide the sensation of sweetness without supplying many calories, usually because they are hundreds or thousands of times sweeter than sugar, and are used in tiny quant.i.ties. Low-and no-calorie sweets are made by combining these two kinds of ingredients, whose qualities are summarized in the chart on pp. 660661.

The Glycemic Index of Various Sugars and FoodsThe "glycemic index" is a measure of how much a given food raises blood glucose levels. The glycemic index of glucose itself is set at 100.

Sugar

Glycemic Index Glycemic Index

Maltose

110 110.

Glucose

100 100.

Potatoes

95 95.

White rice

95 95.

Honey

90 90.

Table sugar

90 90.

Banana

60 60.

Fruit preserves

55 55.

Fructose

20 20.

Some Sugar Subst.i.tutes and Their Qualities Some Sugar Subst.i.tutes and Their QualitiesIn this table, the sweetness of table sugar is represented as 100. A sweetness of 50 means that the substance is half as sweet as table sugar; a sweetness of 500 means that it is 5 times sweeter. The sugar alcohols and corn syrups with sweetnesses less than 1 are mainly useful for providing bulk and viscosity with reduced calories and effects on blood sugar. The intensive sweeteners, with sweetnesses greater than 100, provide taste with reduced calories and effects on blood sugar. Even those sugar subst.i.tutes that were originally found in nature are now manufactured by chemical modification of a natural or synthetic starting material.

Ingredient

Polydextrose (Litesse) Polydextrose (Litesse)

Relative Sweetness

0 0.

Original Source

Glucose (modified) Glucose (modified)

Date of Commercialization

1980s 1980s

Notable Qualities

Produces high viscosities Produces high viscosities

Ingredient

Corn syrup Corn syrup

Relative Sweetness

40 40.

Original Source

Starch Starch