Principles of Food Science Unit 2 ReviewFood Chemistry: Macro & Micronutrients

Key Concepts and Definitions

• Macronutrients provide energy and essential building blocks for growth and maintenance of the body
  • Carbohydrates, proteins, and fats are the three main macronutrients
• Micronutrients are essential nutrients required in small amounts for proper functioning of the body
  • Vitamins and minerals are the two main categories of micronutrients
• Bioavailability refers to the proportion of a nutrient that is absorbed and utilized by the body
• Chemical reactions in food involve changes in the structure and properties of food components
  • Maillard reaction, caramelization, and oxidation are examples of chemical reactions in food
• Nutrient density is the amount of nutrients per calorie of food
  • Foods with high nutrient density provide substantial amounts of vitamins, minerals, and other nutrients relative to their calorie content (leafy greens, berries)
• Recommended Dietary Allowances (RDAs) are the average daily intake levels sufficient to meet the nutrient requirements of nearly all healthy individuals
• Dietary Reference Intakes (DRIs) are a set of reference values for nutrient intake, including RDAs, Adequate Intakes (AIs), and Tolerable Upper Intake Levels (ULs)

Macronutrients: Structure and Function

• Carbohydrates are the primary source of energy for the body and are composed of carbon, hydrogen, and oxygen
  • Simple carbohydrates include monosaccharides (glucose, fructose) and disaccharides (sucrose, lactose)
  • Complex carbohydrates are polysaccharides, such as starch and dietary fiber
• Proteins are essential for growth, repair, and maintenance of body tissues and are composed of amino acids
  • Essential amino acids cannot be synthesized by the body and must be obtained through diet (leucine, lysine)
  • Non-essential amino acids can be synthesized by the body
• Fats, also known as lipids, provide energy, insulation, and protection for organs
  • Saturated fats are solid at room temperature and are mainly found in animal products (butter, lard)
  • Unsaturated fats are liquid at room temperature and are found in plant-based sources (olive oil, avocados)
    • Monounsaturated fats have one double bond in their chemical structure
    • Polyunsaturated fats have two or more double bonds in their chemical structure
• Water is essential for many bodily functions, including nutrient transport, temperature regulation, and waste removal

Micronutrients: Types and Importance

• Vitamins are organic compounds required in small amounts for various metabolic processes
  • Fat-soluble vitamins (A, D, E, K) are stored in the body's fatty tissues and can accumulate to toxic levels if consumed in excess
  • Water-soluble vitamins (B-complex, C) are not stored in the body and need to be consumed regularly
• Minerals are inorganic elements that play crucial roles in many bodily functions
  • Macrominerals (calcium, phosphorus, magnesium) are required in larger amounts
  • Microminerals or trace elements (iron, zinc, iodine) are needed in smaller quantities
• Antioxidants are compounds that protect cells from damage caused by free radicals
  • Vitamins C and E, beta-carotene, and polyphenols are examples of antioxidants
• Phytochemicals are bioactive compounds found in plants that have potential health benefits (flavonoids, carotenoids)
• Deficiencies in micronutrients can lead to various health problems
  • Iron deficiency can cause anemia, characterized by fatigue and weakness
  • Vitamin D deficiency can lead to rickets in children and osteomalacia in adults

Chemical Reactions in Food

• Maillard reaction occurs between amino acids and reducing sugars, resulting in browning and flavor development (seared steak, toasted bread)
  • The reaction produces melanoidins, which contribute to the color and flavor of foods
• Caramelization is the browning of sugars when exposed to heat, resulting in the formation of complex flavors and aromas (caramel, dulce de leche)
• Oxidation of lipids leads to rancidity and off-flavors in foods
  • Antioxidants can help prevent or delay lipid oxidation (vitamin E, rosemary extract)
• Enzymatic reactions can cause both desirable and undesirable changes in food
  • Ripening of fruits involves enzymatic reactions that break down cell walls and change texture
  • Enzymatic browning occurs when cut fruits and vegetables are exposed to air (sliced apples, potatoes)
• Fermentation is a process in which microorganisms convert sugars into alcohol or acids, resulting in unique flavors and textures (yogurt, sauerkraut, beer)

Nutrient Interactions and Bioavailability

• Nutrient interactions can affect the absorption and utilization of nutrients in the body
  • Vitamin C enhances the absorption of non-heme iron from plant-based sources
  • Calcium can interfere with the absorption of iron and zinc when consumed in large amounts
• Bioavailability of nutrients is influenced by various factors, including the food matrix, processing, and individual differences
  • Heme iron from animal sources has higher bioavailability compared to non-heme iron from plant sources
  • Fat-soluble vitamins require the presence of dietary fat for optimal absorption
• Antinutrients are compounds that can interfere with the absorption and utilization of nutrients
  • Phytates in whole grains and legumes can reduce the absorption of minerals like iron and zinc
  • Oxalates in spinach and other leafy greens can bind to calcium and reduce its absorption
• Nutrient synergy occurs when the combined effect of nutrients is greater than the sum of their individual effects
  • Vitamin D and calcium work together to promote bone health
  • Vitamin C and vitamin E have a synergistic effect in protecting cells from oxidative damage

Food Processing and Nutrient Changes

• Thermal processing, such as cooking and pasteurization, can affect the nutrient content of foods
  • Heat can destroy heat-sensitive vitamins like vitamin C and thiamin
  • Cooking can improve the digestibility and bioavailability of some nutrients (lycopene in tomatoes, beta-carotene in carrots)
• Mechanical processing, such as milling and refining, can remove nutrient-rich parts of foods
  • Refining whole grains into white flour removes the bran and germ, which contain fiber, vitamins, and minerals
• Fortification is the addition of nutrients to foods to prevent deficiencies or restore nutrients lost during processing
  • Iodized salt helps prevent iodine deficiency disorders
  • Vitamin D is often added to milk to promote calcium absorption and bone health
• Fermentation can enhance the nutritional value of foods by increasing the bioavailability of nutrients and producing beneficial compounds
  • Fermented dairy products, such as yogurt and kefir, contain probiotics that support digestive health
  • Fermentation of soybeans into tempeh and miso increases the bioavailability of isoflavones and other beneficial compounds

Health Implications and Dietary Recommendations

• Balanced nutrition is essential for maintaining optimal health and preventing chronic diseases
  • Consuming a variety of nutrient-dense foods from all food groups helps ensure adequate intake of essential nutrients
• Dietary Guidelines for Americans provide evidence-based recommendations for healthy eating patterns
  • Emphasize the consumption of fruits, vegetables, whole grains, lean proteins, and healthy fats
  • Limit the intake of added sugars, saturated fats, and sodium
• Chronic diseases, such as obesity, type 2 diabetes, and cardiovascular disease, are often associated with poor dietary habits
  • High intake of added sugars and saturated fats can contribute to the development of these diseases
  • Adequate intake of fiber, vitamins, and minerals can help reduce the risk of chronic diseases
• Nutrient deficiencies can lead to specific health problems
  • Vitamin A deficiency can cause night blindness and impaired immune function
  • Folate deficiency during pregnancy can increase the risk of neural tube defects in the developing fetus

Practical Applications in Food Science

• Food product development involves the creation of new food products with desired nutritional profiles
  • Formulating products with reduced sugar, fat, or sodium content while maintaining taste and texture
  • Incorporating functional ingredients, such as prebiotics and probiotics, to promote health benefits
• Nutrient analysis is the process of determining the nutrient content of foods
  • Analytical techniques, such as chromatography and spectroscopy, are used to quantify nutrients
  • Nutrient databases, such as the USDA FoodData Central, provide information on the nutrient composition of various foods
• Food labeling regulations require the disclosure of nutrient information to consumers
  • Nutrition Facts panels on packaged foods display the amount of calories, macronutrients, and selected micronutrients per serving
  • Health claims on food labels must be supported by scientific evidence and approved by regulatory agencies
• Sensory evaluation is used to assess the acceptability and quality of food products
  • Trained panelists evaluate the appearance, aroma, taste, and texture of foods
  • Consumer testing helps determine the preferences and attitudes of target populations towards food products
• Food safety practices aim to prevent foodborne illnesses and ensure the quality of food products
  • Implementing Hazard Analysis and Critical Control Points (HACCP) systems to identify and control potential hazards
  • Monitoring and controlling factors such as temperature, pH, and water activity to prevent microbial growth and spoilage