chapter 2 water, fbt

• Water is essential for life, and lack of water reduces survival to only a few days
• All foods contain water with different amounts
• Water in the human body is essential for nutrition, as it is involved in nutrient transport, digestion, absorption, and excretion
• 20% of water consumed is from foods and does not provide energy
• Water's chemical properties:

  • Two hydrogen atoms covalently bound to an oxygen (H2O)bonds
  • Each water molecule can hydrogen bond to 4 other water molecules (which means that one molecule of water has 4 hydrogen bond)
  • Water is a universal solvent
• Water's physical properties:

  • Found in all three states: liquid, solid, steam
• Water in acid, base, and chemical reactions:

  • Proton (H+) hopping in water is called ionization of water
  • Water acts as a weak base in the presence of strong acids
  • Water acts as a weak acid in the presence of strong bases
  • Hydrolysis involves breaking a bond in a molecule using water
  • Condensation produces water in a chemical reaction
• Water hardness:

  • Water hardness prevents the lathering of soap and depends on mineral content
  • Only water containing soluble Ca2+ and Mg2+ or other dissolved metals cause hardness
  • Classification: Soft, Medium, Hard, Very Hard
  • Temporary hard water: contains insoluble calcium/magnesium bicarbonate and can be removed by boiling in an open container
  • Permanent hard water: usually contains calcium and magnesium sulfate and/or chlorides, forming insoluble salts with soap and decrease its cleaning capacity. It cannot be removed by boiling
• Hard water at high temperature:

  • Forms insoluble salts with soap and decreases its cleaning capacity
  • Cannot be removed by boiling because it does not precipitate on boiling or distillation
• How to remove hard water:

  • Ion exchange column, where calcium and magnesium ions are exchanged with sodium ions in the column
  • Addition of washing soda (Na2CO3) in water to react with calcium sulfate (CaSO4) present in hard water, forming CaCO3 precipitate and Na2SO4
• Effects of hard water mineral salts (calcium) on food preparation:

  • Hard water affects the rehydration and softening of dried beans and peas during soaking and cooking
  • Alkalinity of hard water may affect the color in cooked vegetables and promote cloudiness in iced tea
• Water as a solvent and dispersion:

  • Food molecules can form hydrogen bonds with water (dissolve)(solvation action)
  • Food molecules interact with water through hydrophobic interactions (disperse)(dispersing action)
  • Water solvates and disperses minerals, salts, vitamins, sugars, complex carbohydrates, amino acids, and proteins
• Water hydration of biomolecules:

  • Water dissolves ions and biomolecules by hydrating them
  • Hydration is the process where water molecules surround and interact with solutes by acting as a solvent
  • Water acts as a carrier of hydrophilic (polar) substances and a diluent of food ingredients
• Water as a good solvent:

  • Water dissolves ions through electrostatic interactions
  • Water dissolves molecules with polar side groups (OH, NH2, COOH, SH) and can undergo hydrogen bonding
  • Water is an excellent solvent for charged compounds and can dissolve charged molecules easily
• Water in food:

  • Water activity is the ratio of water vapor pressure of the amount of water in food to the water vapor pressure of pure water at the same temperature
  • Free water retains the properties of pure water and can act as a solvent or dispersing agent to other molecules
• Water form in foods:

  • Bound water remains unfrozen at temperatures below 0°C and is tightly chemically bonded to carbohydrates, fats, and proteins
  • Adsorbed water associates in layers through intermolecular hydrogen bonds around hydrophilic food molecules by electrochemical forces
• Water activity and moisture:

  • Bound water is inversely related to water activity
  • Water activity measures the amount of available (free) water in food range 0 to 1.0 (pure water) and affects microbial growth, moisture migration, chemical and biochemical stability, physical properties, and shelf-life of products
• Component of emulsion:

  • Water is a component of emulsions, which are colloidal dispersions of immiscible fluids
  • containing two phases that normally does not mix which are dispersed phase and continuous phase
  • Emulsions can be Oil-in-Water (O/W) or Water-in-Oil (W/O) emulsions
• Heat transfer:

  • Water acts as a medium of heat transfer due to its high specific heat
  • Water conducts thermal energy to food molecules and possesses kinetic energy proportional to the temperature increase
• Component of food ingredient:

  • Water is a component of processed food and acts as a solvent, freeze-thaw agent, and fat replacer in food products
• Plasticizer:

  • Water is a primary plasticizer in food systems, determining the product's texture performance
  • Plasticizer softens food systems by increasing food polymer molecular volume and mobility, especially in low-moisture and frozen foods
  • plasticity- the ability to be molded or shaped, in plastic fats, both solid crystal and liquid are present,
• Physicochemical states of water in food:

  • Most foods are multiphasic with amorphous, rubbery, glassy, and water states
  • Water contributes to the plasticity and texture of food products, affecting the glass-to-rubber transition temperature (Tg)
• Physicochemical states of food:

  • Most foods are multiphasic (amorphous + rubbery + glassy + water)
  • Crystalline state has the lowest mobility (e.g: ice)
  • Glassy state has low polymer mobility (e.g: crisp toast)
  • Rubbery state has high polymer mobility (e.g: soggy bread)
  • Liquid state has the highest mobility (e.g: liquid water)
• Functional properties of water:

  • Water acts as a plasticizer in food systems
  • Plasticization by water affects the glass-to-rubber transition temperatures (Tg’) of many synthetic and natural amorphous polymers, particularly at low moisture contents
• • Capable of removing up to 99%+ of dissolved salts, particles, colloids, organics, bacteria, and pyrogens from the feed water
  • Pros include improving digestion and hydration, while cons include tooth decay and flare up of IBS symptoms
• Types of water as beverages:

  GROUP 1: Mineral Water

  • Contains a large quantity of dissolved minerals or gases
  • Commonly high in calcium carbonate, potassium, magnesium sulfate, and sodium sulfate
  • Advantages include lowering blood pressure, strengthening bones, and containing high quantities of minerals like magnesium, calcium, and sodium
  • Disadvantages include damaging teeth enamel and being harmful for people on a sodium diet

  GROUP 2: Reverse Osmosis Water

  • Process to purify water by pushing it under pressure through a semi-permeable reverse osmosis membrane
• Carbonated Water:

  • Water that has dissolved carbon dioxide gas
  • Also known as sparkling water, seltzer water, and soda water
• Infused Water:

  • Benefits include dehydration prevention, weight loss, and cancer treatment support
  • Contains vital salts and electrolytes like sodium, potassium, and magnesium
  • Side effects may include diarrhea, vomiting, fever, heat injury, seizures, and more
  • Helps reduce sugar/carb intake and contributes to feelings of fullness
• Alcoholic Drinks:

  • Contain ethanol produced by fermentation of grains, fruits, or other sources of sugar
  • Undistilled drinks have comparatively high alcoholic concentration, while distilled drinks have low alcoholic concentration
  • Examples include vodka, beer, whiskey, and wine
  • Side effects of long-term drinking can include dehydration of the skin, facial flushing, immune cell impact, nerve damage, and more
• Caffeinated Drinks:

  • Types include coffee, tea, soft drinks, energy drinks, energy shots, pre-workout supplements, and iced tea
  • Beverages containing caffeine, a natural stimulant found in coffee beans, tea leaves, and other plants
  • Known for stimulating effects on the central nervous system, increasing alertness, and reducing fatigue
• Sparkling Drinks:

  • Contains carbon dioxide gas added during production for a bubbly taste and texture
  • Common examples include carbonated water, soda, sparkling juice, and sparkling wine (champagne)
  • Excessive consumption can lead to obesity, diabetes, heart disease, and tooth decay
• Recap Questions:

  1. Identify three ways in which water is held within a food substance.

  2. Water [disperse / dissolve] fats in food products.

  3. Give an example of cooking that used water as a medium of heat transfer.

  4. Water that comes from underground water is [mineral water / reverse osmosis / deionized water]
• structure of the water molecule showing intramolecular bond angle and charge separation. The arrangement is nonlinear, having an H-O-H bond angle of 104.5 degrees.
• The bent shape of a water molecule means that the electrons aren't spread equally, and so the molecule is said to be polar.
• Non-covalent bonds (electrostatic, van der Waal's, hydrogen, hydrophobic interactions)

  • are not as strong as covalent bonds, but it is important in the stabilization of molecules.
  • do not share electrons
  • critical in maintaining the three-dimensional structure of large molecules, such as proteins and nucleic acids.
• electrostatic interactions are formed between positive and negative ions that form ionic bonds.
• van der Waals forces (London forces) are very weak forces between temporary dipoles. These forces may be attractive or repulsive. Also non-directional.
• Hydrogen bond results when a hydrogen atom that is covalently bound to an electronegative atom (O, N, S)
• Hydrophobic interactions result when non-polar molecules are in a polar solvent.
• Non-covalent boin in water molecules: Hydrogen bonds

  • Hydrogen bonds are constantly being broken and reformed
  • Each hydrogen bond= 20 kJ/mol
  • Individual hydrogen bonds are relatively weak. However, the large number of hydrogen bonds that exist in water which pull molecules together give water its special density and phase transition properties.
  • Hydrogen bonding gives water a high boiling point, high specific heat capacity, and high heat of vaporization.