SOC Annotated PPT Chpt 13

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Chapter 13: Sweets – Two most common sources of Chocolate & Candies sucrose – cane and beet

Fig. 13-1

Sugar dissolves Sugars dissolve readily in water

Sprinkling powered sugar onto a baked dessert can be a nice finishing touch. But on a humid or rainy day, the powdered sugar will often seem to disappear or melt into the cake. What is happening to the sugar, and Sugar crystals what is the chemical explanation for why? The hydrogen bonding capacity of sugars allows them to retain moisture in baked goods. It is this “wet sugar” that forms the sticky matrix that holds granola bars together, and gives glazes a glossy appearance

Mixture or impure solutions Pure sugar forms crystals do not form crystals

There is less water, so now some sugar molecules are hydrogen bonding to each other to form a crystal

https://www.youtube.com/watch?v=qLaEdDNHGqc

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Mixtures of sugars Lots of sugar… don’t crystallize but no crystals easily

Add a small amount of acid (e.g. lemon Other molecules (like fat, etc) can juice) to 1 cup of sucrose dissolved in prevent sugar crystallization by water will break some of the sucrose glucose and fructose interfering with large crystal formation Agitating, stirring apart into glucose and fructose – isomers or beating the sugar solution essentially creating invert sugar syrup also interferes on the spot. with crystal Cold beverages are formation often sweetened with fructose containing syrups to prevent sugar crystals

This trick of adding lemon juice to sucrose is a Fructose is very soluble, and the strategy for preventing crystallization of sucrose as in more fructose there is, the harder it the making of caramel candies. is for anything to crystallize.

The composition and relative sweetness of Sugars are sweet different sugars and syrups Sucrose (table sugar) has been Alternative assigned the arbitrary value of 100 – Relative Sugar Composition of mono- and disaccharides name so all the sweetness measurements sweetness Fructose Levulose Pure fructose are simply a comparison to sucrose 120 Glucose Dextrose Pure glucose 70 Sucrose Table sugar Dimer of glucose and fructose 100 Lactose Milk sugar Dimer of galactose and glucose 40 Maltose Dimer of glucose 45 Mixture of glucose and maltose, and longer glucose Corn syrup 30-50 A “simple syrup” ischains sucrose dissolved in waterMixture (1:1) of fructose and maltose, and longer glucose High fructose corn syrup 80-90 chains. Higher fructose concentration. Invert sugar syrup Mixture of fructose, glucose and sucrose 95 Mixture of fructose (38%), glucose (31%), sucrose Honey ~97 Because we perceive simple sugars (like glucose and fructose) and (1.5%), other disaccharides, acids and minerals (~7%) dimers like sucrose and lactose as sweet – all of these Mixture of sucrose (62%), glucose and fructose (3%) Maple syrup ~100 monosaccharides and disaccharides are commonly called sugar. with trace amino acids, minerals and malic acid

Corn syrup is made from The composition and relative sweetness of different sugars and syrups breaking down corn starch Why is HFCS sweeter?

Polymers like starch How are corn syrup and are tasteless to HFCS different? humans Relative Sugar Composition of mono- and disaccharides To make corn syrup, sweetness Mixture of glucose and maltose, and longer glucose manufacturers break down Corn syrup 30-50 corn starch using acid. chains Mixture of fructose and maltose, and longer glucose High fructose corn syrup 80-90 chains. Higher fructose concentration. Invert sugar syrup Mixture of fructose, glucose and sucrose 95 Mixture of fructose (38%), glucose (31%), sucrose Honey ~97 Invert sugar(1.5%), syrup other is made disaccharides, by treating acids and minerals (~7%) Viscosity = dextrins a simple syrupMixture (sucrose of sucrose and(62%), water) glucose and fructose (3%) Sweetness = sugars Maple syrup ~100 with thewith enzyme trace amino invertase acids, minerals. and malic acid

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High fructose corn syrup is Fructose and human health made from corn syrup Fructose metabolism occurs primarily in the liver Fructose is enriched in soft drinks and processed foods (i.e. high fructose corn syrup). Some studies suggest it is the fructose content in added sugars, which may account for why sugary soft drinks are so Fructose is sweeter than strongly linked with the development of obesity, fatty liver and sucrose and prevents insulin resistance. crystallization…which is Fructose intake Every country that has adopted the Western diet — one helpful when sweetening causes your body to dominated by low-cost, highly processed food — has cold beverages make glycogen and witnessed rising rates of obesity and related diseases. store fat (Nutrition There are now 30% more people who are obese than and Metabolism, who are undernourished. (Nature, 2012) 2013 In rat studies, excessive glucose, sucrose or fructose consumption (even on a diet, that is – restricted calories) causes fatty liver, insulin resistance (pre-diabetes) and diabetes. (Nature Comm. 2013)

Fructose and human health The Fructose controversy “The toxic truth about sugar” Wait! Isn’t fructose the problem…and all those processed foods. Isn’t it ok to eat natural sweeteners and avoid HFCS?

Sucrose (i.e. table sugar) is half fructose.

Honey contains fructose (% depends on what the bees ate), agave nectar is 50- 90% fructose, maple syrup contains sucrose, glucose and fructose.

Your body can convert glucose into fructose in the liver. I spend an entire lecture on this in Advanced Biochemistry…trust me.

Starches are polymers of glucose, and are easily broken down by your body into glucose. Sugar is natural. In fact, fructose is naturally Sugar is the problem. Any form. found in many foods. But, consuming all your calories from sugar/carbohydrates? That is a really bad plan. 16

Caramel begins with Caramelization browned sugar During caramelization, the sugar appears to "melt" when it is actually undergoing a variety of complex chemical reactions

The caramelans are large brown colored molecules. These large molecules give the mixture its brown color and semisolid texture

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Caramelization - aroma Caramelization

ketone In crème brûlée (literally, “burned cream”), a baked custard of egg yolks and cream (usually flavored with vanilla) is topped with a hard, thin layer of caramel. The caramel is made by spreading sugar on the surface of the chilled custard and then heating it with a propane torch. The caramel should shatter when tapped with the back of your spoon.

Why is the use of the torch (or a very hot broiler) ketone Ester necessary to form the caramel?

Chapter 13: Sweets – Chocolate Chocolate & Candies

The cover of a famous book Traités nouveaux & curieux du café du thé et du chocolate. Dufour first described the beneficial pharmacological effects of chocolate including counteracting drunkenness, upset stomach, and menstrual disorders.

Chapter 13: Sweets – Ethanolic Fermentation Chocolate & Candies

In the absence of oxygen, yeast will metabolize glucose to pyruvate and ultimately produce ethanol to replace NAD for continued metabolism.

Fig. 13-9

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