_of gums in food systems genome discovery在食品系统功能基因组发现牙龈课件

FOOD FOOD CHEMISTRYCHEMISTRY GumsGums BY DR BOOMINATHAN Ph.D. M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGSWI, Israel), Ph.D (NUS, SINGAPORE), PDF (USA) PONDICHERRY UNIVERSITY Sixth lecture 17/August/2012 Source: Collected from different sources on the internet and modified by Dr Boominathan Ph.D Ref. Food chemistry by Fennema . GoalsGoals lStructural arrangements of different Gums: lMeska lXanthan lComposition lPhysico-chemical properties of Meska 2. L-arabinose, 24%; 3. D-glucuronic acid,14.5% ; 4. L-rhamnose, 13%; 5. 4-O-methyl-D-glucuronic acid, 1.5%. 1 2 3 4 5 Meska They contain main chains of (1 3)-linked b-D-galactopyranosyl units having two- to four-unit side chains consisting of (1 3)-b-D- galactopyranosyl units joined to it by (1 6)-linkages. Both the main chain and the numerous side chains have attached -L- arabinofuranosyl, -L-rhamnopyranosyl, -D-glucuronopyranosyl, and 4-O-methyl-b-D-glucuronopyranosyl units. The two uronic acid units occur most often as ends of chains. Plant exudate : Different Gums Gum karaya Gum ghatti Gum Tragacanth Gum arabic Gums: Gums: Applications of MeskaApplications of Meska Gum candy and pastilles (A medicated lozenge used to soothe the throat) lRetards sugar crystallization lFunctions as a Coating agent and a binder lIts functions in confections are to prevent sucrose crystallization and to emulsify and distribute fatty components. Ice cream and sherbets (A frozen dessert made primarily of fruit juice and sugar, but also containing milk, egg-white or gelatin) linduces and maintains small ice crystals Beverages lfoam and emulsion stabilizer lused in beverage powders (e.g. citrus drink mixes) to maintain and stabilize flavor (encapsulates flavors) Bakery and snack products lLubricant and binder lThe soft drink industry consumes about 30% of the gum supply as an emulsifier and stabilizer 14 * It is an important ingredient in soft drink syrups, “hard“ gummy candies such as gumdrops, marshmallows, chocolate candies and edible glitter, a very popular, modern cake-decorating staple. * For artists, it is the traditional binder used in watercolor paint, in photography for gum printing, & Branchingdecreases gelation lHydration: Increased hydration increases viscosityincreases stabilizing effect lDecreased hydration decreases viscosity decreases stabilizing effect lpH: Decreased pH (acidic)- increases aggregation-increases precipitation lIncreased pH (basic)- decreases aggregation increases solubility QuestionsQuestions lThe viscosity of carrageen is quite stable over a wide range of pH values lUses of aliginate in food industry. lUses of pectin in food industry. lThe most important seaweed polysaccharide used in food industry is ? ? Functions of Functions of GumsGums in in Food SystemsFood Systems Water bindingViscosity building GelationSuspension Emulsions stabilizationFoam stabilization EncapsulationBinder Fat Replacement Functions of gums in foods are related Functions of gums in foods are related to interactions with other food to interactions with other food componentscomponents Gums interact with: lComponent Affects lWater All properties lProteins Emulsions, foams,gels lLipids Emulsions lIons Gels lParticle surfacesStabilization Hydration of GumsHydration of Gums lAll functions of gums require that the gums be hydrated. lFailure to hydrate gums properly is the leading cause of problems in foods containing gums. lCompetition for water with other water loving components affects properties Hydration of GumsHydration of Gums lLinear, uncharged polysaccharide molecules are held tightly together by hydrogen bonds. Substantial inputs of energy are required in order to make these function properly. lAmylose crystalline structure requires substantial input of heat before gelatinization occurs. (No branches) lCarbogum (has some branches) requires heating to fully develop viscosity lGuar Gum ( 2x as many branches) swells in cold water lIntroduction of branches and/or charges into the chain limit the amount of hydrogen bonding that can take place between polysaccharide molecules and thus increase the interaction with water and make gums more easy to hydrate. * Increased no. of Branches increases the interaction with water. Structure and FunctionStructure and Function lCarageenan - charge of sulfates lXanthan - Charge on carboxyl + branches lGuar Gum- increased branches Interaction of Gums with ProteinsInteraction of Gums with Proteins Gums May affect protein stability by: lElectrostatic interaction - negatively charged hydrocolloids may interact with positively charged groups on proteins. lInteractions depend on: lpH lpK of ionizable group lIonic strength lRatio of protein to gum lInterference with calcium binding - -Protect calcium sensitive proteins e.g carageenan lCompeting for water - hydrocolloids may cause proteins to precipitate by limiting the water available to hydrate the protein. Gums and LipidsGums and Lipids lOnly a few gums show affinity for lipid. lGum Arabic, hydroxypropyl cellulose, and propylene glycol alginate have a little affinity for lipid. lStabilization of emulsions, foams, etc. is dependent upon: linteractions with the protein on the surface and l increases in viscosity of the continuous phase. lGums which are complexed with other food components may not be able to exert their primary functions. Viscosity of GumsViscosity of Gums lAll are highly viscous except Gum Arabic lViscosity is dependent upon hydration of the polysaccharide. lLarger polymers generally give higher viscosity. Interactions with other polymers may dramatically affect viscosity. Stability of GumsStability of Gums lMost gums are resistant to microbial degradation lPectin is a notable exception lCommercial stabilizers almost always are”standardized“ with sugar and thus are readily fermented. lDepolymerization upon heating is common. Classification of gums used in Classification of gums used in food products:food products: Non-ionic seed polysaccharides Guar, Carobgum Anionic (negatively charged) exudate polysaccharides Gum Arabic/Meska Classification of gums used in Classification of gums used in food productsfood products: : lAnionic seaweed polysaccharides Agar, Algin, Carrageenan lMicrobial gums - Xanth