ChanLei

• Food


  Natural products, fresh or processed, which are consumed by human beings for their nourishment
• Food Science


  A discipline in which biology, physical sciences, and engineering are used to study the nature of foods, the causes of their deterioration, and the principles underlying food processing
• Food Chemistry


  One of the major disciplines of food science which is mainly focusing on changes in the composition and chemical, physical, and functional properties of foods and food products during various stages from farm to fork
• Importance of Food Chemistry

  • Understanding of the composition of foods, and the desirable and undesirable reactions in raw and end products
  • Maximize the production and preservation of health-promoting compounds while minimizing the formation of harmful substances

  
• Approaches to the Study of Food Chemistry

  • Determining those properties that are important characteristics of safe, high-quality foods
  • Determining those chemical and biochemical reactions that have important influences on loss of quality and/or wholesomeness of foods
  • Integrating the first two points so that one understands how the key chemical and biochemical reactions influence quality and safety
  • Application to various situations encountered during formulation, processing, and storage of food

  
• Why Should Food Chemists Become Involved in Societal Issues?

  • They have received high level of formal scientific education
  • Their activities influence the general welfare of the public
  • They are qualified to speak on techno-societal issues
• Food Issues


  • The use of chemicals to modify foods
  • The issue of "Chemophobia" – fear of chemicals
  • Food additives to represent hazards inconsistent with fact
  • Credibility of information about food: Use of the World Wide Web Credibility of the author, Appropriateness of literature citations, Credibility of the publisher

  
• Societal Obligations


  • Good job performance
  • Good citizenship
  • Guarding the ethics of the scientific community
  • Help in the interpretation of scientific knowledge used by the society
  • Participate in pertinent professional societies
  • Serve on governmental advisory committees, when invited
  • Undertake personal initiatives of a public service nature
• History of food chemistry

  • The origins are obscure and have not been rigorously studied and recorded
  • Acquire a clear identity until the 20th century
  • Entangled with that of agricultural chemistry
  • Available information is sufficient to indicate when, where, and why certain key events occurred
  • Related to changes in the wholesomeness of the food supply since the early 1800s
• Carl Wilhelm Scheele


  Swedish pharmacist who discovered chlorine, glycerol, and oxygen, isolated and studied the properties of lactose, prepared mucic acid by oxidation of lactic acid, devised a means of preserving vinegar by the application of heat

  
• SCHEELE'S METHOD


  1. Boil the vinegar in a tin kettle for a quarter of a minute and then immediately pour it into bottles

  2. Vinegar treated this way could be stored for several years

  3. The degradation of vinegar was caused by microbes, and s heat treatment sterilized it

  4. The first report of what would later be known as pasteurization
• Antoine Laurent Lavoisier


  French Chemist who formulated the principles of modern chemistry, established the fundamental principles of combustion organic analysis, first to show that the process of fermentation could be expressed as a balanced equation, determined the elemental composition of alcohol, wrote first papers on organic acids of various fruits
• (Nicolas) Théodore de Saussure

  French Chemist who formalized and clarified the principles of agricultural and food chemistry provided by Lavoisier, studied carbon dioxide and oxygen gas changes during plant respiration, studied mineral contents of plants by ashing and made the first accurate elemental analysis of alcohol
• Joseph Louis Gay-Lussac & Louis-Jacques Thenard


  Devised the first method to determine percentages of carbon, hydrogen, and nitrogen in dry vegetable substances
• Sir Humphry Davy


  English chemist who isolated the elements K, Na, Ba, Sr, Ca, and Mg, wrote a book on Agricultural Chemistry stating that plants are usually composed of only 7 or 8 elements, and that "the most essential vegetable substances consist of H, C, and O in different proportion, generally alone, but in some few cases combined with azote (N)"
• Jons Jacob Berzelius & Thomas Thomson

  Their works resulted in the beginnings of organic formulas, "without which organic analysis would be a trackless desert and food analysis an endless task"
• Jons Jacob Berzelius


  Swedish Chemist who determined the elemental components of about 2000 compounds, thereby verifying the law of definite proportions, and devised a means of accurately determining the water content of organic substances
• Thomas Thomson


  Scottish Chemist who showed that laws governing the composition of inorganic substances apply equally well to organic substances
• Michel Eugene Chevreul


  French Chemist who listed the elements known to exist at that time in organic substances, was a pioneer in the analysis of organic substances, led to the discovery and naming of stearic and oleic acids, cited the processes for organic analysis
• Dr. William Beaumont


  American Army surgeon who performed classic experiments on gastric digestion, destroyed the concept existing from the time of Hippocrates that food contained a single nutritive component, experimented on Alexis St. Martin (Canadian) by introducing food directly to the stomach
• Justus von Liebig


  Showed that acetaldehyde occurs as an intermediate between alcohol and acetic acid during fermentation of vinegar, classified foods as either nitrogenous or nonnitrogenous, did quantitative analysis of organic substances, researched on the water-soluble constituents of muscle

  
• Four phases History of Food Adulteration

  • 1ST Ancient Times to about 1820: Not a serious problem, Small businesses, Involved interpersonal accountability
  • 2ND Early 1800s to about 1920: Rise of modern chemistry, Intentional food adulteration increased greatly, Increased centralization of food processing and distribution
  • 3RD 1920s: Regulatory pressures, Effective methods of detection, Situation has gradually improved
  • 4TH About 1950s: Foods containing legal chemical additives became increasingly prevalent, Highly processed food increased, Contamination of foods by Hg, Pb, and pesticides
• Adulterations cited in the Early 1800s

  • Annatto: Red lead and copper
  • Pepper, black: Gravel, leaves, stalks, and, and ground parts of plants
  • Essential oils: Oil of turpentine, other oils, and alcohol
  • Vinegar: Sulfuric acid
  • Coffee: Roasted grains
  • Tea: Redried tea leaves, and leaves of many other plants
  • Milk: Watering, chalk, starch
  • Beer: Black extract
  • Wine: Colorants, preservatives, ageing agents, etc.
  • Sugar: Sand, dust, lime, pulp, and coloring matters
  • Butter: Excessive salt and water, potato flour, and curds
  • Chocolate: Starch, brick dust, ocher, ferric oxide, and potato flour
  • Bread: Alum, and flour made from products other than wheat
  • Confectionery products: Colorants containing lead and arsenic
• Chemistry and food chemistry began to assume importance in Europe in the 1820–1850 period, with the establishment of chemical research laboratories and the founding of new journals for chemical research
• The first publicly supported agriculture experiment station was established in Weede, Germany in 1860, with Wilhelm Hanneberg as Director and Friedrich Stohmann as Chemist, who developed an important procedure for the routine determination of major constituents in food
• In 1871, Jean Baptiste Duman suggested that a diet consisting of only protein, carbohydrate, and fat was inadequate to support life
• In 1862, the Congress of the United States passed the Land-Grant College Act by Justin Smith Morrill, which helped establish colleges of agriculture in the United States
• Isaac Newton


  First Commissioner, when U.S. Department of Agriculture was established
• Harvey Washington Wiley


  Chief chemist of the U.S. Department of Agriculture, led the campaign against misbranded and adulterated food - Pure Food and Drug Act in the United States (1906)
• In 1887, agriculture experiment stations were established in the US following enactment of the Hatch Act, authored by Rep. William H. Hatch, which led to the world's largest national system of agriculture experiment stations with great impact on food research
• In the first half of the 20th century, most of the essential dietary substances were discovered and characterized (Vitamins, minerals, FA, and AA)
• In the middle 1900s, there was development and extensive use of chemicals to aid in the growth, manufacture, and marketing of foods
• Several current issues have replaced the historical ones in terms of what the food science community must address in further promoting the wholesomeness and nutritive value of foods
• Water


  Small inorganic molecule that occurs abundantly in all three physical states, essential for life as a regulator of body temperature, solvent, carrier of nutrients and waste products, reactant and reaction medium, lubricant and plasticizer, stabilizer of biopolymer conformation, and facilitator of the dynamic behavior of macromolecules
• Water Structure


  • Covalent Bonds: Water has polar covalent bonds with a bond angle of 105° (liquid), and 109° (ice)
  • Hydrogen Bonds: A weak bond between polar compounds where a H atom of one molecule is attracted to an electronegative atom of another molecule, each water molecule can form up to four hydrogen bonds with its nearest neighbors, the structure is dynamic and are continually breaking and reforming between different water molecules
• Carbohydrates


  Organic compounds containing carbon, hydrogen, and oxygen, may be simple or complex molecules
• The ratio of hydrogen to oxygen in carbohydrates is always 2:1
• Biomolecules


  Any of numerous substances that are produced by cells and living organisms
• Types of carbohydrates


  • Simple sugars
  • Starches
  • Plant and wood fibers (cellulose)
  • Dextrins
  • Hemicelluloses
  • Pectins
  • Gums
• Functions of carbohydrates in food

  • Source of energy or fiber
  • Sweeteners
  • Thickeners
  • Stabilizers
  • Gelling agents
  • Fat replacers