Food Chemistry: Water

Basic Food Chemistry

• Foods consist of six basic nutrient groups: water, carbohydrates, lipids, protein, vitamins, and minerals
• These nutrients underpin all principles in food and nutrition
• All living things contain carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (CHNOPS)

Water

• The simplest, yet most important nutrient is water
• Water is essential at all stages of growth and development
• The functions of assimilating, digesting, absorbing, transporting, metabolizing, and excreting nutrients and by-products depend on water
• The human body is 60% to 70% water
• Losing as little as 10% of body fluids can be fatal
• Water balance is maintained by drinking liquids and eating foods, with a small amount obtained via metabolic processes
• Water in foods can be free or bound
• Free water is abundant and easily separated, while bound water is within the chemical structure of carbohydrates, fats, and proteins
• Water is a small molecule comprising one oxygen and two hydrogen atoms (H₂O)
• Specific heat is a measure against which all other substances are compared
• A calorie of heat will raise 1 gram of water by 1°C
• Water differs from other compounds in the amount of energy it takes to reach its specific freezing, melting, and boiling points
• 80 calories (0.08 kcal) of heat is lost per gram, turning water to ice when its freezing point is reached
• Unlike other substances, water expands and becomes less dense once frozen
• Pure water freezes at 32°F (0°C), but extra ingredients can alter the freezing point
• Ice heats to its melting point using at least 80 calories (0.08 kcal) of heat per gram
• A heated liquid reaches its boiling point (changing it to a gas)
• Bubbles begin breaking the surface of water at its boiling point of 212°F (100°C) at sea level
• Increasing elevation lowers the boiling point of water: at sea level, water boils at 212°F (100°C), dropping 1°F per 500-foot altitude increase
• Vaporization heat is the energy needed to convert a liquid to a gas
• The minerals in water determine its hardness
• Hard water has more calcium and magnesium compounds, while soft water has a higher sodium concentration
• Freezing, melting, and boiling points remain irrespective of water hardness
• Water is the most versatile substance and acts as a heat transfer medium and universal solvent
• Water is needed for chemical reactions and impacts food perishability/preservation

Water in Food Preparation

• Water transfers heat during these moist-heat methods: boiling, simmering, steaming, stewing, and braising
• Dry-heat methods include baking, grilling, broiling, and frying
• Water is fundamental as the earth's universal solvent
• The fluid surrounding cells contains many dissolved solutes

Chemical Reactions with Water

• These include ionization, pH changes, salt formation, hydrolysis, and carbon dioxide release
• Ionic solutions occur when solute molecules ionize into electrically charged ions or electrolytes
• Sodium chloride (NaCl) ionizes in water into individual ions of sodium (Na⁺) and chloride (Cl⁻), in the expression NaCl → Na⁺ + Cl⁻

Acids & Bases

• Acids are substances donating hydrogen (H⁺) ions; bases provide hydroxyl (OH⁻) ions
• Acids are proton donors and bases are proton receptors
• In a liquid, pH represents hydrogen (H⁺) ion concentration
• A pH below 7 is acidic, while above 7 is alkaline or basic
• A pH of 7 is neutral, with equal hydrogen (H⁺) and hydroxyl (OH⁻) ion concentrations
• A tenfold change in acidity occurs with each number on the pH scale

Salt Formation

• This occurs with combining a positive and negative ion when excluding hydrogen (H⁺) or hydroxyl (OH⁻) ions
• Sodium chloride (Na⁺Cl⁻) forms from sodium (Na⁺) combining with chloride (Cl⁻)
• Salts form by uniting an acid and base or a metal and nonmetal
• Metal salts include potassium fluoride (K⁺F⁻) and lithium bromide (Li⁺Br⁻)

Hydrolysis

• It is the basis of countless chemical reactions

Carbon Dioxide Release

• Many baked goods need to rise before baking
• Baking powder contains baking soda and acid, used when making this possible
• Carbon dioxide gas is released when baking powder mixes with water, allowing baked products to rise

Food Preservation

• Water is important for the life of microorganisms like bacteria, molds, and yeasts
• Deterioration/decay is a result of microorganism activity
• Microorganisms need water, thus limiting water inhibits their growth
• Conversely, keeping fruit/vegetables cool with water preserves freshness by preventing dehydration
• Rinsing fruits/vegetables in water (or detergent) removes microorganisms
• Detergents used as cleansing agents act on tension to remove microorganisms

Water Activity

• Water activity (a sub w) or availability regulates food's perishability
• Bacteria need water to proliferate, and growth is not supported under 0.85 a sub w (pure water's a sub w is 1.00)
• Foods high in water, such as milk, meat, vegetables, and fruits, spoil more easily than grains, nuts, or dried foods
• Ways to lower water activity below 1.00 is by introducing salt, sugar, glycerol, propylene glycol, or modified corn syrup
• Measure water activity by dividing the vapor pressure exerted by water in food solution, by the vapor pressure of pure water, or P sub w (equal to 1.00)

Osmosis

• Process causes drawing of water to solutes

Carbohydrates

• These are sugars, starches, and fibers
• The primary source is plants, excluding milk (containing lactose)
• Muscles from animals feature glycogen that converts into lactic acid upon slaughter
• Storage of carbohydrates happens in seeds, roots, stems, and fruit
• Common sources include grains (rice/wheat/rye/barley/corn), legumes (beans/peas/lentils), fruits, and vegetables (carrots/potatoes/beets)
• Sugar cane and sugar beets give table sucrose, while nectar from flowers create honey

Carbohydrates Composition

• The basic elements are carbon (C), hydrogen (H), and oxygen (O)
• Carbohydrates break down into carbon (C) and hydrate (H2O)
• The carbohydrate formula is Cn(H2O)n, where n ranges from 2 to thousands
• Synthesis of carbohydrates happens in green plants
• Photosynthesis Reaction: carbon dioxide + water + sun energy yields glucose + oxygen
• The carbon, hydrogen, and oxygen atoms arrange into a saccharide

Saccharide Units

• Monosaccharides feature 1 saccharide unit
• Disaccharides have 2 monosaccharides linked
• Oligosaccharides have 3-10 monosaccharides linked with lower food prevalence
• Polysaccharides have many monosaccharides linked, like starch and fibers

Monosaccharides

• Simplest sugars are classified by the number and carbon in the saccharide unit
• Triose has 3 carbons
• Tetrose has 4 carbons
• Pentose has 5 carbons
• Hexose has 6 carbons
• "-ose" is a chemical name of sugars
• Pentose and hexose sugars are more common with ribose and arabinose being the main pentoses and glucose, fructose, and galactose being the predominant hexoses

Ribose and Arabinose

• Key for making nucleosides, part of genetic material deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and the energy-yielding adenosine triphosphate (ATP)
• Ribose forms of vitamin B2 (riboflavin)
• Arabinose forms the architecture of vegetable gums and fiber

Monosaccharides examples

• Glucose are the common hexose found in foods
• Functions as free-state in fruits, honey, corn syrup, and some vegetables
• Forms repeating units in starch and glycogen, also found in many fibers
• Used with refined glucose (dextrose, as used commercially) to yield candies, beverages, baked goods, canned fruits, and alcoholic beverages
• Fructose are the "fruit sugar" (levulose), from fruits and honey
• Is the sweetest of all sugars
• Galactose are the part of lactose, the sugar found in milk
• Derivative of galactose (galacturonic acid), make up pectin, important for fruit ripening and the gelling of jams

Disacchardies

• Combining two saccharides forms a disaccharide.
• The three most common disaccharides are sucrose, lactose, and maltose.
• Sucrose: Table sugar is a glucose molecule + 1 fructose molecule linked
• Lactose is 1 glucose molecule + 1 galactose molecule derived from animal sources
• Makes up 5% of fluid milk ("milk sugar")
• Lactose intolerant results in inability to digest
• Maltose is formed with 2 glucose molecules for malt sugar, used make beer, breakfast food and infant forms
• This forms when starch breaks, examples include when in human digestion

Oligosaccharides

• Include raffinose with 3 monosaccharides and stachyose (4 monosaccharides)
• Are hard to digest, found in dried beans, and produce intestinal bacterial activity/gas production
• There are 12 classes of food-grade oligosaccharides commercially (extracted from soybeans/synthesized by disaccharides/broken starches)
• Used for calorie reduction, confectionery production, milk beverage production, and fat replacement
• They benefit against harmful byproducts

Polysaccharides

• Starch, glycogen, and fiber are the common polysaccharides
• Contain many monosaccharides linked
• Can be digestible (starch and glycogen)or indigestible (fiber)

Digestible Polysaccharide

• Plants store solar energy and photosynthesis-derived glucose as starch
• This provides plant energy
• Microscopic starch granules feature in rice, tapioca, wheat, and potato
• Amylose and amylopectin are found in these granules
• Alpha-1,4 glycosidic linkages between both kinds of starch is digest by human enzymes
• Amylose features straight/repeating glucose units, and amylopectin features alpha-1, 6 bonds every 15 to 30 glucose molecules
• 75% Amylopectin and 25% amylose can be found in their natural starchy form
• People can break starches with digestion and absorption
• In food, heat, enzymes, and acid break such smaller, sweeter segments into dextrin chains
• Ex: Toasted bread has a sweeter taste due to dextrins

Digestible Animal Polysaccharide

• Glycogen (animal starch) is a rare carbohydrate found in animals (liver and muscles)
• Animal bodies store long chains of glucose molecules as glycogen
• This forms by branched alignment of energy source reserve
• Animals use enzymes to hydrolyze glycogen quickly to let glucose maintain blood glucose levels
• Glycogen in meat changes to lactic acid during slaughter
• Shellfish have trace glycogen, producing that sweet taste

Fiber vs Indigestible Polysaccharide

• Fiber is roughage/bulk from a group of indigestible polysaccharides
• Human digestive enzymes can't break sugars' links
• Fiber won't transfer energy (passes through the human body without caloric means)
• All from plants (especially certain grains, vegetables, and fruits)
• Plant cells use fiber between cell walls to form strength

Common Plant Fibre Types

• Includes cellulose, hemicellulose, and pectic stuff
• Other fiber types are veggie gums, inulin, beta-glucan, oligosaccharides, fructans, some resistant starches, and lignin (rare fiber with non-carbohydrate form)

Hemicellulose

• Hemicellulose includes monosaccharides
• Key chain parts use xylose, mannose, and galactose and common sides use arabinose, glucuronic aci,d; and galactose chains
• Baking soda helps veggies maintain color (but reduces hemicellulose and causes mushiness)

Cellulose

• One of earth's biggest compounds
• Every cell wall of plants partly features repeating glucose that look like starch, but starch branches less, bonds glucose more and cannot allow digestive enzymes into it
• As a result, the fiber won't be absorbed; gives no calories but goes along the tract itself with its energy.
• Plant eating animals use grasses and plant life to help harvest cellulose with enzymes.

Pectic Substances

• Polysaccharides seen in cell walls of fruits and veggies (protopectin, pectin/pectic acid)

Food Industry

• A cementing agent used in thickening jams/jellies/preserves/to keep salad dressing intact and control texture in food. product

Vegetable Gums

• Polysaccharides called hydrocolloids

Food Industry

• Made to help with thickening/viscosity/gelling/stabilize/emulsify processed foods and add body, flavor and mouth feel to food to keep ingredients mixed Also bonds as much as 10x the water and produces desirable appearance with long lasting flavor.

• Gums come from planet matter OR bacterium sold with the powder texture and produce dressings, foods and freezer meals

• Agar yields quick icing used in reducing glazed donuts and cracks

Carbohydrates and Food

• Sugars influence color, sweet, crystallization, fermentation, preservation, solubility and texture, moisture absorption
• Starches help edit the thickening agents, edible films and sweetener form

Lipids

• Fats, oils or things called fats
• Distinctions lie in state: Fats are solid
• Animal derived vs plant derived

Foods High in Lipids

• Animals yield dairy, poultry, animals
• Avocados, seeds and coconut from plant-based sources
• Many food groups don't yield them
• Marbling = Invisible fats
• Vegetable Oils, etc = Visible

Lipids

• Carbon/hydrogen/oxygen mix in unequal formats
• Dissolvant in solvent without any edible means

Major Groups of Lipids

• Edible lipid, triglyceride, phospholipid, and sterol
• 95 % triglyceride
• "Tri", fatty acids meet the glycerol mix
• Two or one fatty acid create diglyceride with monoglyceride.
• Fatty acids may be simple OR mixed

Acids

• Differ from one another on two measures
• Length of carbons
• Bonds on it
• Three different structures
• Saturation influences rate of temperature of acid/molecules

Acids in Foods

• Foods have acid and saturation, yet those are predominated
• Animals yield 50% saturate and polyunsaturated, plants yield 85%

Acids Nomenclature

• 40 acids can yield in the world
• Those common are those in butter: linoleic and linolenic
• Acids configuration by the bounds

Acids

• Those in configuration are defined by double bond

Phospholipids

• As a triglyceride, those form chains and glycerol yet phosphorus replaces fatty acid

• Forms solubility of water AND helps acid solubles.

• Assist and influence a vitamin hormone with food such egg, etc.

Uses

• A emulsifier yields egg yolk/lecithin to help the mixing or compounds together, also to apply emulsions used in food of candy.