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Semester 1: Advanced Food Science
Food Science: Definition, food colloids, sols, gels, emulsions and foams
Food Science
Definition of Food Science
Food science is an interdisciplinary field that combines various sciences such as chemistry, microbiology, engineering, and nutrition to study the physical, biological, and chemical makeup of food, as well as the principles of food processing and preservation.
Food Colloids
Food colloids are mixtures in which small particles are dispersed within a continuous phase. These particles can be solid, liquid, or gas. Common examples in food include milk, mayonnaise, and ice cream. Colloids play a crucial role in determining the texture, flavor, and stability of food products.
Sols
Sols are colloidal systems where solid particles are dispersed in a liquid medium. They can exhibit either a fluid or semi-fluid consistency. Examples include fruit juices and soups. The stability of sols is affected by factors such as particle size and concentration.
Gels
Gels are colloidal systems that exhibit a semi-solid state, formed when a liquid is entrapped in a network of solid particles. Examples include gelatin desserts and certain pates. The formation of gels is significant in food textural properties and formulations.
Emulsions
Emulsions are mixtures of two immiscible liquids where one liquid is dispersed in the other in the form of droplets. Mayonnaise, salad dressings, and creams are common emulsions. Emulsifiers such as lecithin are often used to stabilize these mixtures.
Foams
Foams are created when gas bubbles are dispersed in a liquid or solid matrix. Examples include whipped cream and meringue. The stability of foams depends on the presence of surfactants or stabilizing agents that help retain the structure of the foam.
Cereals: Structure, composition, nutritive value, cereal cookery, protein gluten formation, starch gelatinisation, retrogradation, effects of heat
Cereals
Structure of Cereals
Cereals consist of three primary parts: the husk, the bran, and the endosperm. The husk is the outer protective layer, while the bran is rich in fiber and nutrition. The endosperm constitutes the bulk of the grain and mainly contains starch, serving as the energy reservoir for the germ.
Composition of Cereals
Cereals are composed primarily of carbohydrates, proteins, fats, vitamins, and minerals. The carbohydrates are mainly in the form of starch. Proteins in cereals include glutenin and gliadin, which are important for gluten formation. Essential vitamins such as B-complex and minerals like iron and magnesium are also present.
Nutritive Value of Cereals
Cereals serve as a significant source of energy due to their high carbohydrate content. They also provide dietary fiber, which aids in digestion. The protein content varies by cereal type, influencing overall protein intake. Whole grains are more nutrient-dense compared to refined grains.
Cereal Cookery
Cereal cookery involves methods such as boiling, baking, and steaming. Different cooking techniques affect the texture and digestibility of the cereal. Precooking methods like soaking can enhance the cooking process. Proper cooking is essential to retain nutrients and ensure palatability.
Protein Gluten Formation
Gluten is formed when water is added to flour, activating glutenin and gliadin proteins, which develop a network that provides structure to baked products. The degree of gluten formation is crucial for the texture of bread and other baked goods.
Starch Gelatinisation
Gelatinisation is the process where heat and moisture cause starch granules to swell and absorb water, resulting in a thickening effect. This is critical in cooking cereals, as it affects the mouthfeel and digestibility.
Retrogradation
Retrogradation occurs when gelatinized starch molecules reassociate upon cooling, leading to changes in texture and potentially affecting the shelf life of products. This process can cause staling in baked goods.
Effects of Heat on Cereals
Heat affects cereals in various ways, including changing the texture, flavor, and digestibility. Different cooking methods can lead to variations in nutrient availability and sensory properties. Overheating can lead to nutrient loss and undesirable flavors.
Pulses: Composition, nutritive value, digestibility, toxic constituents, cooking quality
Pulses: Composition, Nutritive Value, Digestibility, Toxic Constituents, Cooking Quality
Composition of Pulses
Pulses are legumes that consist mainly of protein, carbohydrates, and dietary fiber. They are low in fat and contain essential vitamins and minerals. The primary proteins in pulses are globulins and albumins, while carbohydrates mainly consist of starches and non-starch polysaccharides.
Nutritive Value of Pulses
Pulses are rich sources of plant-based proteins, providing a significant portion of the daily protein requirement, particularly in vegetarian diets. They are also high in dietary fiber, which aids in digestion and helps maintain healthy cholesterol levels. Pulses are rich in micronutrients such as iron, magnesium, potassium, and folate.
Digestibility of Pulses
The digestibility of pulses can vary based on the type of pulse, cooking method, and individual digestive health. Pulses contain anti-nutritional factors such as phytic acid and tannins that can hinder nutrient absorption. Cooking methods such as boiling or pressure cooking help break down these anti-nutritional factors, enhancing digestibility.
Toxic Constituents in Pulses
Some pulses contain toxic constituents such as lectins, protease inhibitors, and certain alkaloids. These compounds can cause digestive discomfort or adverse effects if not adequately controlled through cooking processes. Proper soaking and cooking are essential to reduce the levels of these toxic substances.
Cooking Quality of Pulses
Cooking quality refers to the texture, taste, and overall acceptability of cooked pulses. Factors affecting cooking quality include soaking time, cooking time, and the type of cooking method used. Pulses ideally should be soaked before cooking to reduce cooking time and improve texture.
Milk and milk products: Composition, nutritive value, physical and chemical properties, types of milk
Composition of Milk
Milk is a complex liquid consisting primarily of water, fats, proteins, lactose, and minerals. The composition can vary depending on the source (cow, goat, sheep, etc.). Typically, whole milk contains about 87% water, 3.5% protein, 4.5% lactose, 3.5% fat, and various vitamins and minerals.
Nutritive Value of Milk
Milk is a nutrient-rich food that provides a good source of calcium, protein, and vitamins such as A, D, and B12. It supports bone health, muscle growth, and overall dietary needs. For many, it is an essential component of a balanced diet.
Physical Properties of Milk
Milk has unique physical properties, including its white color, opacity, and viscosity. It has a pH of approximately 6.5 to 6.7. The fat globules in milk give it its creamy texture, and milk can form emulsions when mixed with other substances.
Chemical Properties of Milk
The chemical properties of milk include its ability to undergo fermentation and spoilage due to the action of bacteria. The lactose in milk can be broken down into glucose and galactose, and proteins in milk can denature when exposed to heat.
Types of Milk
Various types of milk are available, including whole milk, skim milk, low-fat milk, evaporated milk, and powdered milk. Other milk alternatives include plant-based options such as almond milk, soy milk, and oat milk, which cater to different dietary preferences.
Meat, fish, poultry, and eggs: Classification, composition, nutritive values, cooking principles
Meat, fish, poultry, and eggs: Classification, composition, nutritive values, cooking principles
Classification
Meat is classified into red meat (beef, lamb) and white meat (poultry, pork). Fish is categorized as fatty or lean. Eggs are classified by size and processing methods.
Composition
Meat consists mainly of water, proteins, fats, vitamins, and minerals. Fish is rich in omega-3 fatty acids. Poultry contains protein and lower fat levels compared to red meat. Eggs are composed of proteins, fats, vitamins, and minerals.
Nutritive Values
Meat is a good source of high-quality protein, iron, and B vitamins. Fish provides essential fatty acids and contributes to heart health. Poultry is lower in calories and saturated fat. Eggs offer complete proteins and essential nutrients.
Cooking Principles
Cooking methods include roasting, grilling, boiling, and frying. Proper cooking ensures safety and enhances flavors. Techniques differ based on the type of protein and desired outcome. Thawing and marination can improve tenderness.
Vegetables and Fruits: Classification, composition, nutritive value, pigments, enzymes, cooking changes, browning
Vegetables and Fruits: Classification, Composition, Nutritive Value, Pigments, Enzymes, Cooking Changes, Browning
Vegetables and fruits can be classified based on various criteria such as botanical classification, culinary uses, and nutrient composition.
Botanically, vegetables are derived from various parts of plants while fruits are the mature ovary containing seeds.
Culinary practices often categorize fruits based on sweetness and cooking methods, with some fruits treated as vegetables in cooking.
Nutritionally, vegetables and fruits vary in content of carbohydrates, vitamins, minerals, and fibers.
Vegetables and fruits have high water content, ranging from 70% to 95%.
They are major sources of carbohydrates, with fruits generally containing more sugars.
Rich in vitamins A, C, K, and various B vitamins, along with essential minerals such as potassium and magnesium.
Regular consumption is linked to reduced risk of chronic diseases.
High fiber content aids digestion and promotes satiety.
Contain various phytochemicals that provide health benefits and combat oxidative stress.
Natural pigments in vegetables and fruits include chlorophylls, carotenoids, and anthocyanins.
Pigments contribute to the color, flavor, and nutritional quality, and have antioxidant properties.
Enzymes influence ripening, flavor development, and can affect texture.
Enzymatic activity can lead to spoilage and is often inhibited by cooking or freezing.
Cooking can cause loss of water-soluble vitamins but can also enhance bioavailability of certain nutrients.
Cooking alters the texture, making them softer and often more palatable.
Enzymatic browning occurs due to enzymatic oxidation when fruits and vegetables are cut or bruised.
Methods to prevent browning include the use of acids like lemon juice or blanching.
Nuts and oilseeds: Classification, composition, toxins, cooking role
Nuts and oilseeds: Classification, composition, toxins, cooking role
Classification
Nuts and oilseeds can be classified based on their botanical characteristics and culinary uses. Common categories include true nuts (e.g., walnuts, hazelnuts), drupes (e.g., almonds, cashews), legumes (e.g., peanuts), and oilseeds (e.g., sesame, sunflower).
Composition
Nuts and oilseeds are rich in macronutrients such as proteins, fats, and carbohydrates. They also provide essential micronutrients including vitamins, minerals, and phytochemicals. The fat content primarily consists of healthy unsaturated fats, especially omega-3 and omega-6 fatty acids.
Toxins
Some nuts and seeds may contain naturally occurring toxins. For example, raw cashews contain urushiol, a toxic compound that can cause allergic reactions. Other nuts like bitter almonds contain cyanogenic compounds that can release cyanide when metabolized. Proper processing and cooking methods can mitigate these risks.
Cooking Role
Nuts and oilseeds play a versatile role in cooking. They can be used for flavor, texture, and nutritional enhancement in various dishes. Roasting enhances their flavors, while grinding transforms them into butters or flours. They can also be pressed to extract oils used in cooking or as dressings.
Fats and oils: Nutritional importance, functions, rancidity and prevention
Fats and oils: Nutritional importance, functions, rancidity and prevention
Nutritional Importance of Fats and Oils
Fats and oils are essential macronutrients providing energy, facilitating the absorption of fat-soluble vitamins A, D, E, and K. They support cell structure and hormone production. Essential fatty acids, such as omega-3 and omega-6, play critical roles in brain function and inflammation regulation.
Functions of Fats and Oils
Fats and oils serve various functions including energy storage, thermal insulation, and cushioning for organs. They also contribute to the flavor and texture of foods, enhance satiety, and are involved in essential metabolic processes.
Rancidity of Fats and Oils
Rancidity refers to the undesirable changes in fats and oils that result from oxidation or hydrolysis, leading to off-flavors and odors. There are two main types: oxidative rancidity, caused by exposure to oxygen, and hydrolytic rancidity, resulting from water action.
Prevention of Rancidity
To prevent rancidity, fats and oils should be stored in cool, dark places, away from light and moisture. Antioxidants can be added to inhibit oxidative rancidity. Proper packaging and minimizing exposure to oxygen can also extend shelf life.
Sugar and spices: Sources, properties, sugar crystallisation, spices classification and functions, aromatics, beverages
Sugar and spices: Sources, properties, sugar crystallisation, spices classification and functions, aromatics, beverages
Sources of Sugar
Sugar is primarily sourced from sugarcane and sugar beets. Other sources include fruits and honey. Different types of sugars include glucose, fructose, and sucrose, each with distinct properties and uses in food.
Properties of Sugar
Sugar provides sweetness, contributes to flavor development, and acts as a preservative. It can influence texture and color in cooking and baking.
Sugar Crystallisation
Crystallisation is a process where sugar forms solid crystals from a solution. Factors influencing crystallisation include temperature, concentration, and presence of impurities.
Classification of Spices
Spices can be classified based on their origin such as seeds, bark, roots, and fruits. Common categories include dry spices (like pepper and cumin) and fresh spices (like basil and cilantro).
Functions of Spices
Spices enhance flavor, color, and aroma in food. They also possess various health benefits, including antioxidant and anti-inflammatory properties.
Aromatics
Aromatics refer to a group of herbs and spices that add fragrance and flavor to dishes. Examples include garlic, onion, and ginger, often used as a base in cooking.
Beverages
Many beverages incorporate sugar and spices for flavor. Common examples include spiced teas, flavored coffees, and traditional drinks like masala chai, indicating the cultural significance of these ingredients.
