Principle of Food Science and Processing 2024 Lect. 6 PDF

Sugars and Fats 7 lecture Dr. Mohamed Elsaadany  Outline Sugars sources and roles in food products Nonenzymatic browning Types of Sugars and Sugar Syrups Properties of Sugars Sugar substitutes Baked Products Common ingredients in...

Sugars and Fats 7 lecture Dr. Mohamed Elsaadany  Outline Sugars sources and roles in food products Nonenzymatic browning Types of Sugars and Sugar Syrups Properties of Sugars Sugar substitutes Baked Products Common ingredients in baking Fats Properties of Fats and Oils Rancidity Dr. Mohamed Elsaadany 2 1 Sugars Dr. Mohamed Elsaadany 3  Sugars Sources of Sugar: Table sugar comes from two sources: Sugar beet Sugar cane Roles of Sugar in Food Systems: Sweetness, Tenderness, and Browning Acts as a separating agent to prevent lump formation in starch- thickened Sauces Reduces starch gelatinization Stabilizes egg white foams Raises the coagulation temperature of protein mixtures Adds bulk and body to foods such as yogurt Helps aerate batters and dough Reduces gluten structure by competing with gliadin and glutenin for water, thus, increasing tenderness Acts as the substrate that ferments to yield CO2 and alcohol Adds moisture retention properties to baked products Slows/prevents crystallization in candies if invert sugar is used 4 Dr. Mohamed Elsaadany 4 4  Roles of Sugar in Food Sweetness beverages Tenderness A batter/dough formula with sugar is more tender than one without sugar, because sugar binds with each of the two proteins gliadin and glutenin and absorbs water so they do not form gluten Browning Browning in some varieties of fruits and vegetables is due to enzymatic, or oxidative browning Two types of nonenzymatic browning including (1) The low-temperature Maillard browning reaction and (2) High-temperature caramelization 5 Dr. Mohamed Elsaadany 5 5  Nonenzymatic browning Maillard browning Involves the reaction of the carbonyl group of a reducing sugar with the amine group of an amino acid and occurs with: Low-temperature heat, a Maillard browning is responsible for the color changes that occur in many baked breads, cakes, and pie crusts, canned milks, meats, as well as candies Caramelization: Occurs in sugars heated to high temperatures (above its melting point [338 F (170 C), and the sugar ring (either pyranose or furanose) opens and loses The sugar becomes brown, more concentrated, and develops a caramel Caramel 6 Dr. Mohamed Elsaadany 6 6  Types of Sugars and Sugar Syrups Brown sugar. Brown sugar has a molasses film on the sugar crystals, it contains approximately 2 % moisture Confectioners’ sugar(confectionery sugar) is also known as powdered sugar and is derived from either sugar cane or sugar beet Confectioners’ sugar typically contains 3 Invert sugar. Invert sugar is created when sucrose is treated by acid or enzyme to form an It is more soluble and sweeter than sucrose and is commonly used in confections, Raw sugar. It is not approved by the FDA for sale in the United States since impurities and 7 Dr. Mohamed Elsaadany 7 7  Syrups (Liquids) The conversion of starch yields dextrose (glucose) and measured as 36–55 Corn syrup: Corn syrup is a mixture of carbohydrates (glucose, maltose, and other oligosaccharides) formed from the hydrolysis of cornstarch by using Corn syrup, due to its high glucose content, more readily participates in High-fructose corn syrup (HFCS): HFCS is a specialty syrup and contains approximately 42 % fructose, used in many beverages Honey: Honey is made from the nectar of various flowers and therefore, It contains approximately 20 % water and a mixture that is glucose and fructose (predominantly the latter), with no more than 8%sucrose 8 Dr. Mohamed Elsaadany 8 8  Syrups (Liquids) Maple syrup: The sap is boiled and evaporated, and the final product contains no more than 35 % water Molasses: Molasses is the syrup (plant juice) separated from raw sugar beet or sugar cane during its processing into sucrose, and it is a by- 9 Dr. Mohamed Elsaadany 9 9  Properties of Sugars Solubility Sucrose is more soluble than glucose and less soluble than fructose At room temperature, water is capable of dissolving sucrose in a ratio of 2:1 (67 % sucrose and 33 Elevation of Boiling Point The boiling point of sugar elevates with increasing concentrations of sucrose in Hygroscopicity However, other sugars that are high in fructose, such as invert sugar, HFCS, honey, Fermentable Occurs by biological process in which bacteria, mold, yeast, and enzymes anaerobically convert complex organic substances, such as sucrose, glucose, 10 10 Dr. Mohamed Elsaadany 10  Properties of Sugars Body and Mouth feel Sugars contribute body and “mouthfeel” words, the addition of sugar makes a food more viscous or gives If sugar is replaced by a non-nutritive or high intensity sweetener such as aspartame or saccharin, the consistency of 11 11 Dr. Mohamed Elsaadany 11  Sugar Substitutes Sugar substitutes include two categories: Artificial (or high-intensity) Sweeteners (noncaloric, nonnutritive) Sugar substitutes are “generally recognized as safe”(GRAS) Artificial sweeteners Acesulfame K. It is 200 times sweeter than sucrose and its not metabolized in the body; Its heat stable, used for baking and cooking purposes The acceptable daily intake of acesulfame potassium is listed as 15 mg/kg/day Aspartame. Aspartame is a nutritive sweetener that contains the same number of calories per gram as sugar (4 cal The upper limit of safety for aspartame = 40-50mg/Kg Note: Phenylalanine. Not advise for those with the genetic disease phenylketonuria (PKU) because the phenylalanine 12 12 Dr. Mohamed Elsaadany 12  Sugar Substitutes Saccharin. 300–700 The ruling required that foods containing saccharin must be labeled to read as follows: Use of this product may be hazardous to your health Saccharin is often used in baked goods, jams, jelly, chewing gum, canned fruit, candy, dessert toppings, and salad Cyclamate. it is still used as a sweetener, but does not approve by FDA Sugar alcohols (caloric, nutritive). Sorbitol( Mannitol ( Xylitol ( Novel Sweeteners (Stevia) It is a white powder composed of one or more intensely sweet glycosides derived from the leaves of a stevia (Stevia rebaudiana) and used as noncaloric sweetener 13 13 Dr. Mohamed Elsaadany 13 2 Baked Products Dr. Mohamed Elsaadany 14  Baked Products: Batters and Dough Type of Bread 1. Quick bread: This type of bread use baking powder or backing soda as 2. Yeast bread Common ingredients in all baking: Flour and Liquid in addition to substances, such as: Starch, Fats or oil Sugar, Sweeteners Leavening agent to produce CO2, liquid, Flavoring agents, and perhaps eggs. 15 15 Dr. Mohamed Elsaadany 15  Gluten development Gluten is - a substance made up of proteins present in wheat flour that gives structure and strength to baked Gluten development is required for dough expand and without gluten the expansion does nor occur when CO2 is generated from yeast, and the dough does not reach its Extracted gluten is used to fortify protein content of some breakfast cereal, for binding breading on meat, poultry or fish, and as an extender for fish and meat products 16 16 Dr. Mohamed Elsaadany 16  Function of Various Ingredients in Batters and Dough Flour Function Types of flour... Bread flour (Hard wheat flour): highest gluten content; creamy white color Cake flour: very low gluten content; pure white color Pastry flour: very low gluten content; creamy white color; slightly less delicate than cake flour All purpose flour: medium gluten content; medium white color; good for general production work Gluten-free flour: People who have a gluten sensitivity or Celiac Disease cannot tolerate certain levels of gluten 17 17 Dr. Mohamed Elsaadany 17  Liquids Function Liquids Function Liquids are crucial in hydrating the proteins required for gluten formation and the liquids are the solvent for dissolving many recipe ingredients such as the leavening Types of liquids Milk and cream Eggs, honey, molasses and even butter 18 18 Dr. Mohamed Elsaadany 18  Leavening Agents Function Leavening Agents Function leavening agents raise dough or “ ” Include air, carbon dioxide (CO2), and steam The amount of air depends on: - Mixing method, - Sifting flour prior to addition, beating, creaming, and so forth Carbon dioxide (CO2) Produced chemically by: Baking Soda – Alkali & Acid combine to form carbon dioxide which expands when Baking Powder – combination of baking soda & dry acid 19 19 Dr. Mohamed Elsaadany 19  Leavening Agents Function Yeast – Microscopic plant that reproduces quickly Needs food: sugar and flour Needs moisture Needs warmth Gives off carbon dioxide as it grows Create bubbles in dough Give baked products a special flavor and smell Steam: is the works of combination When large amounts of water and high heat are present Water turns to steam, and product rises The steam leaves a cavity in product (great for fillings) 20 20 Dr. Mohamed Elsaadany 20  Eggs Function Act as binders, holding ingredients together. The whole eggs and yolks contain emulsifiers that distribute fat in the dough (a greater percentage of egg is necessary in a high-fat formulation compared to a low-fat or high-liquid Egg leavens Provide coagulated structure Nutritive value, color, and flavor improved flavor and color of cookies Eggs contribute elasticity 21 21 Dr. Mohamed Elsaadany 21  Fat Function Fat Function Fats and oils tenderize baked products by coating flour proteins in the batter or Shorten by controlling gluten strand length Create the flakes or dough layers Fats and oils help prevent the staling process of baked products Promote greater volume of the developed protein matrix, allowing it to stretch more easily without breaking Fats containing water in the mix are less effective in their shortening ability than 100 % fats 22 22 Dr. Mohamed Elsaadany 22  salts and Sugars Salt Function To controls the growth of yeast with its CO2 production, The absence of salt in yeast bread dough allows rapid yeast Sugar Function Contributing flavor Sugar makes a product tender Elevates the temperature at which the protein coagulates, and starch gelatinizes, thus extending the time for CO2 to expand the baking dough A substrate for producing CO2, acids, alcohols, and a 23 23 Dr. Mohamed Elsaadany 23 3 Fats Dr. Mohamed Elsaadany 24  Fats Fats belong to a larger group of compounds called lipids, which include both fats and oils and cholesterol etc Fat formed by the reaction between fatty acids and Glycerol forming Ester called triglycerides If 3 Fatty acids are chemical chains that contain carbon, hydrogen, and oxygen atoms Fatty acids that have as many hydrogen atoms as they can hold are called saturated fatty acids Fatty acids that have fewer hydrogen atoms than they can hold are called unsaturated fatty acids 25 Dr. Mohamed Elsaadany 25  Properties of Fats and Oils Solubility However, in the presence of a suitable substance known as an emulsifying agent, it’s possible to form a stable mixture of fat and water The Emulsion may be a Fat – in – Or a Water – in – Fats and oils are soluble in organic solvents such as petrol and carbon Plasticity Some of the fatty acids forming the triglyceride will stay solid for longer than – Has a wide range of plasticity and will spread whereas most 26 26 Dr. Mohamed Elsaadany 26  Properties of Fats and Oils Effect of Heat Melting Point Most fats melt at temperatures of 30°/40°C Melting point for oil is below normal air temperature – The more double bonds, the lower Smoke Point When a fat or oil is heated to a certain temperature it starts to decompose, producing a Most fats and oils start to smoke at 200°C Smoke Point for lard = 185°C Corn Oil = 232°C Smoke is useful to measure when assessing the suitability of a fat or oil for frying 27 27 Dr. Mohamed Elsaadany 27 Properties of Fats and Oils 28 28 Dr. Mohamed Elsaadany 28  Properties of Fats and Oils Saponification Hydrogenation Hydrogenation is used to add hydrogen to the oil to break the Hydrogenated fat makes TRANS fats which increases likelihood of cancer and CIS 2 Trans 29 29 Dr. Mohamed Elsaadany 29  Rancidity Oxidative Rancidity Oxygen molecules join across the double bond of the triglyceride molecule Aldehydes and Ketones – gives Hydrolytic Rancidity Enzymes known as lipase hydrolyse fats, breaking them down into glycerol and Fat + Water Glycerol + Fatty Acids Short Chains = More rancid 30 30 Dr. Mohamed Elsaadany 30  How to prevent Rancidity Do not store oil in iron containers use glass Anti- 31 31 Dr. Mohamed Elsaadany 31  Uses in Food Preparation Frying Fast cooking method – bad for health as it increases fat content, but Frying occurs at 180°C Shortening It’s an effect that fat has on a product – increases the crumbly texture of Creaming and Aerating Adding air bubbles Lighter colour Increases volume – 32 32 Dr. Mohamed Elsaadany 32  Fat sources Vegetable Oils 70% of all oils in the world are vegetable oils Margarine The vegetable fat being used is first hydrogenated to give it some hardness (plasticity), and is then Butter Churning of pasteurised cream, this causes the cream to become more viscous forming a solid 33 33 Dr. Mohamed Elsaadany 33