Chemical Structure of Food

Chemical Structure of FoodHRM 408

FOOD

FOODIs a mixture of Chemicals in well-ordered system of cellular structures.

Any food item can be separated into chemically identifiable substances.

Chemical Structures in FoodCarbohydratesFatsProteinsVitaminsMineralsWater6 categories

WATER

WATERWater is present in all food itemsThe most aboundant of all elements in its natural stateWater is a biological solventBoiling poin 100C

Properties Of WaterH2O

2 Hydrogen atoms + 1 oxygen atom

Atoms are aranged in non linear, three-dimentional structure

Water ActivityWater activityor (aw) is the partial vapor pressure ofwaterin a substance divided by the standard state partial vapor pressure ofwater.

aw= water activityP= partial pressure water in the foodP0=partial pressure of water at the same temperature

Carbohydrates

Carbohydrates(CH2O)nHydrates of CarbonEnergy source

CarbohydratesSubdivided into: Sugars (simple sugars)Polysaccharides (complex)

Sugar

Classified as:MonosaccharidesDisaccharidesTrisaccharidesMost common sugarsGlucose(grape sugar)Fuctose(fruit sugar)Sucrose(sugar cane)

OligosaccharidesMeans several units of sugarTrisaccharides like raffinose is usualy classified as Oligosaccharides

PolysaccharidesA long chain of glucose molecules forms an important polysaccharide starchStarch has many uses in cookery contriutes significantly to the supply of calories in diets

PolysaccharidesStarch is chief food reserve of plants and is converted into sugar(by plant) Cellulose chief structural carbohydrates of plants Pectin another complex carbohydrate present in fruitsFiber term applied to polysaccharides that cannot be digested in human digestive tract

Classification of Polysaccharides and Food SourcesPolysaccharidesA. Digestible1.Starch2.Dextrins3.Glycogen(animal starch)B. Partially Digestible1.Galactogens2.Inulin3.MannosansC. Indigestible1.Cellulose(vegtable stalks)2.Hemicellulose (a. agar-agar, b. pectin)3Lignin

Food Sources

Cereal(grain,rice,corn),unripe fruits and vegtablesToasted bread and intermidiate

Pectins,Snail,agar-agarMushroom,onion,garlicLegumes

Skins of fruits and seed coveringSlightly unripe fruits,seeweedsWoody parts of plant

FATS

FatsCharacterize by their appearance and greesy feels and inability to mix with water.

Natural OilsAnimal Fat Marine FatVegtable Fat (most aboundant food fat)Classified accourding to origin:

Proteins and Amino Acids

ProteinsAre Organic SubstancesThe building units of Proteins are amino acids1 protein contains 500 or more units of amino acids

ProteinsDenaturation is a term applied to any alteration to original properties of protein but not in amino acid sequenceDenaturation of meat usually occurs 57 75C

Classification of Protein and Food SourcesProtein I. Simple proteinsAlbuminsGlobulinsGlutelinsProlaminesII.Conjugated ProteinsNucleoproteins MucoproteinsChromoproteinsPhosphoproteinsMetalloproteins

Sources

Legumes in peas,albumin in eggwhitesSerum globulin,myosin in mucle, edestin in wheat Glutenin in wheat, oryzenin in riceProtein of nails,bones connective tissues as collagen

Ribonucleuprotein in cell cytoplasmOvomucoid in egg white, osseomucoid in bonesHemoglobin, FlavoproteinCasein in milk and ovovitellin in eggyolkHemoglobin and hemocuprein

Classification of Protein and Food Sources

III. Derived ProteinsProtein, metaproteins and coagulated proteins

Proteoses, peptones and peptides

Cooked protein foods as in fried eggs,cooked meats,fish and legumes chees and custard

Intermediate products of protein digestion or hydrolysis

Enzymes- protein molecules syntesized by living organism for specific action as biological catalysts.

Useful application of enzymes in food:Meat tenderizer bromelin from pineapple and papain and effective tenderizers of mussle meat.Invertase sucrose inversion is facilitated by adding enzyme invertasefor certain confections like the soft of chocolate centers of candiesAnylases The splitting of starch in flour during bread making by the presence pf amylases yields fermentable sugars to be acted upon by yeast

Useful application of enzymes in food:4. Pectinases Ripening of fruits5. Microbial enzymes bring about fermentation and proteolysis as in patis and bagoong, vinegar and wine making, and cheese ripening.

Vitamins

VitaminsComplex organic compounds that are required in the diet in very small amount but are vital for maintenance of healthAbsence of these compounds cause defieciency diseases

The fat-solabel vitamins are: Retinol: (vitaminA), Cholecalciferol(vitamin D), Tocopherol (vitamin E), and Phyloquine (vitamine K)The water-soluble vitamins are: Ascorbic asid(vitamin C), Thiamin(vitamin B1), Riboflavin(vitamin B2), Pyridoxide(vitamine B6),Niacin Pantothenic acid, Cobalamines(vitamin B12), Folic acid,Biotin, Choline, Inositol.

Minerals and Trace Elements

Minerals and Trace elementsAre inorganic substances that may be or may not be in combination with organic constituentsClassified into two categories:Those that need more than 0.005 percent of body weight and those who dontThe latter are called Traced elements