Food AdditivesFood Chemistry IIIlyana A. Causing

Food AdditivesI. Stabilizers and Thickeners

II. Fat ReplacersIII. Masticatory SubstancesIV. Firming TexturizersV. Appearance Control and Clarifying AgentsVI. Flour Bleaching Agents and Bread ImproversVII. Anticaking Agents

Stabilizers and Thickeners

Stabilizers and Thickeners• Hydrocolloid materials • Used for their unique textural, structural and functional characterictics• They provide stabilization for

1. Emulsions2. Suspensions and Foams3. General Thickening Properties

• Derived from natural sources but some are chemically modified

Stabilizers and Thickeners• Most stabilizers and thickeners are polysaccharides

- Guar Arabic- Guar Gum- Carboxymethycellulose- Carrageenan- Agar- Starch- Pectin

• Gelatin – non-carbohydrate stabilizers used

Stabilizers and Thickeners• Effective stabilizers and thickeners • Are hydrophilic• Dispersed in solutions as colloids

• Which leads to hydrocolloid

• General Properties of Hydrocolloids1. Significant Solubility in water2. Capability to increase Viscosity3. Ability to form Gels (in some cases)

Stabilizers and Thickeners• Specific Functions of Hydrocolloids• Improvement and stabilization of texture• Inhibition of crystallization • Stabilization of emulsions and foams• Improvement of Icings in baked goods – reduced stickiness• Encapsulation of flavors

Stabilizers and Thickeners• Hydrocolloids are generally used at a concentration of about

2 % or less• Because many exhibit dispersibility • Desired functionality is provided at these levels

• Efficacy of Hydrocolloids is directly dependent on their ability to increase viscosity• Example: Hydrocolloid – stabilize oil-in-water emulsions

• But they can’t function as true emulsifiers • They lack combination of strong hydrophilic and lipophilic properties

Fat Replacers

Fat ReplacersQuick! Introduction• Fat is an essential dietary component

• But too much fat in the diet has been linked with higher risk of coronary heart disease and cancer

• Consumers are advised to eat lean meats, low-fat dairy products and restrict consumption of fried foods, high-fat baked goods, sauces and dressings• However consumers want reduced-calorie

foods that posses sensory properties of traditional high-fat foods

Fat Replacers• When fat is either partially or completely omitted – properties of foods are

altered and so it’s necessary to replace it • Hence the term “Fat Replacers”

• Fat Substitutes – provide identical physical and sensory properties but without the calories

• Both convey fat-like sensory properties in foods and perform physically (frying foods)

Fat Replacers• “Fat Mimetics” – other ingredients that do not posses full

functional equivalency to fats. They can be made to mimic the effects of fats

1. Carbohydrate Fat Mimetics2. Protein Fat Mimetics3. Reduced-Calorie Synthetic Triacyglycerol Fat Substitutes4. Synthetic Fat Replacers

a. Polydextroseb. Sucrose

Fat ReplacersCarbohydrate Fat Mimetics• Modestly processed starches, gums, hemicelluloses and celluloses• Provide fat functionality in reduced fat foods• Some provide no calories (gums and cellulose), others provide up to 16.7 kJ (modified starches)

• Traditional Fats – 37.6 kJ

• They mimic the smoothness and creaminess of fats • By moisture retention and bulkiness of their solids

• Example are moistness in baked goods and textural bite of ice cream• Tradenames: Avicel, Oatrim, Kelcogel, Stellar and Slendid

Fat ReplacersProtein Fat Mimetics• These proteins as fat mimetics is limited

• Because they do not perform like fats at highly elevated temperatures (frying)

• They are valuable in replacing fats in foods in oil-in-water emulsions• Proteins provide thickening, lubricity and mouth-coating effects

• Example: Gelatin - provides thermally reversible gelation during margarine production and provides thickness

• Particulate proteins are obtained by inducing • Hydrophobic interactions• Isoelectric precipitation• Heat denaturation and/or coagulation• Protein-protein complex formation• Protein-polysaccharide complex formation

• Tradenames: Simplesse, Trailblazer and Lita

Fat ReplacersReduced-Calorie Synthetic Triacylglycerol Fat Substitutes• Triacylglycerol – unique structural features and don’t yield full caloric value when consumed• Triglycerides – synthesized utilizing hydrogenation and directed esterification or interesterification

• Medium-chain Triglycerides (MCTs) – used in the treatment of certain lipid metabolism disorders• They provide about 34.7 kJ compared to triglycerides containing 37.6 kJ

• Incorporation of saturated short-chain fatty acids along with long-chain saturated fatty acids in a triglyceride molecule• Greatly reduces the caloric value

Fat ReplacersReduced-Calorie Synthetic Triacylglycerol Fat Substitutes• Tradenames1. Salatrim

• Short and long acyltriglyceride molecule• Mixture of triglycerides (mainly stearic acid and portion of acetic, propionic and butyric acid)• 19.6 – 21.3 kJ• Fatty acid composition can be controlled – to provide desired physical properties (melting points)

2. Caprenin • Synthesized, reduced-calorie triglyceride (20.9 kJ)• Contains caprylic and capric acid along with behenic acid• Used in candy bars

Fat ReplacersSynthetic Fat Replacers• Provide either fat mimetic or fat substitute properties• Contain triacylglycerol-like structural and functional groups

• Example: Trialkoxycarballates – ester groups reversed compared to conventional fats• Resistant to enzymic hydrolysis and undigested in the gut

1. Polydextrose• Used as a reduced-calorie, carbohydrate bulking ingredient• Yields only 4.18 kJ• Reduces calorie from carbohydrates and fats• Tradename: Litesse

Fat ReplacersSynthetic Fat Replacers1. Polydextrose

• Used as a reduced-calorie, carbohydrate bulking ingredient• Yields only 4.18 kJ• Reduces calorie from carbohydrates and fats• Tradename: Litesse• Manufactured by polymerizing glucose (min. 90 %), sorbitol (max. 2 %) and citric acid• Molecular Weight below 22,000 – maintain suitable water solubility

2. Sucrose Polyester• Tradename: Olestra• Lipophilic, nondigestible, nonabsorbable fat-like molecule• Manufactured by various means of esterification of sucrose with long-chain fatty acids from vegetable fats• For fat substitute – high degree of esterification• For emulsifier – lower degree of esterification

Masticatory Substances

Masticatory Substances• To provide long-lasting, pliable properties of chewing gum• Synthetic masticatory substances

• Prepared by the Fischer-Tropsch process

• Chemically modified masticatory substances• Prepared by partially hydrogenating wood rosin then esterifying the products with pentearythritol or glycerol

• Derived directly from plant gums• The gums are purified by extensive treatments (heating, centrifuging, filtering)

• Chicle – Sapotaceae (Sapodilla) family• Gums – Gutta Katiau from Palaquium sp.• Latex solids (natural rubber) – Henea brasiliensis

Firming Texturizers

Firming Texturizers• Thermal processing or freezing of plant tissues – causes softening because the cellular structure is

modified• Stability and Integrity of tissues

• Dependent of maintenance of intact cells and firm molecular bonding between constituents of cell walls

• Pectic substances – involved in structure stabilization • Calcium salts (0.1-0.25 % calcium) – increases firmness

• Enhanced cross-linking – increase amounts of insoluble calcium pectinate and pectate• Stabilized structures supports tissue mass and integrity is maintained even through heat

processing

Firming Texturizers• Adding one or more calcium salts prior to canning or freezing – firms fruits, tomatoes, berries and

apple slices• Most commonly used salts

1. Calcium chloride2. Calcium citrate3. Calcium sulfate4. Calcium lactate5. Monocalcium phosphate

• Most calcium salts are sparingly soluble and contribute a bitter flavor at higher concentration

Firming Texturizers• Salts are added to fermented, salt-brined pickles to make cucumber products crispier and firmer• Example of salts

1. Acidic alum salts2. Sodium aluminum sulfate3. Potassium aluminum sulfate4. Ammonium aluminum sulfate5. Aluminum sulfate

• Trivalent aluminum ions – involved in the crisping process • Through formation of complexes with pectin substances

• Aluminum sulfate – softening effect on fresh-packed or pasteurized pickles• Adjusting the pH to near 3.8 with acetic or lactic acid

Firming Texturizers• Firmness and texture of some vegetables and fruits

• Can be manipulated during processing without use of direct additives• Example: Pectin methylesterase

• Activated during low-temperature blanching • Degree of firmness produced can be controlled by holding time prior to retorting • Hydrolyzes methanol from carboxyl groups on pectin to yield pectinic and pectic acids

• Pectin • Water soluble • Free to migrate from the cell wall• Few free carboxyl groups

• Pectinic Acid and Pectic Acid• Insoluble• Remain in the cell walls during processing and produce firm textures• Large numbers of free carboxyl groups

Firming Texturizers• Activation of Pectin methylesterase – firming effect

• Snap beans, potatoes, cauliflower and sour cherries• Addition of Calcium ion with enzyme activation

• Leads to additional firming effects

Appearance Control and Clarifying Agents

Appearance Control and Clarifying Agents• Long-standing problems in beer, wine and fruit juices

• Formation of hazes or sediments• Oxidative deterioration

• Natural phenolic substances are involved• Proteins and pectic substances participate with polyphenols – formation of haze-forming colloids• Enzymes – utilized to partially hydrolyze high-molecular-weight proteins

• Reduces tendency toward haze formation

• Excess enzymic activity – adversely affect other desirable properties (foam formation in beer)

Appearance Control and Clarifying Agents

Appearance Control and Clarifying Agents• Clarifying (“fining”) agents and adsorbent

• Important means of manipulating polyphenolic composition • To control both desirable and undesirable effects

• Preformed haze – least partially removed by filter aids • Diatomaceous earth

• Many clarifying agents are nonselective• They affect the polyphenolic content more or less incidentally

Appearance Control and Clarifying Agents• Bentonite- Montmorillonite clay

• Minerals employed as clarifying agents• Montmorillonite - complex hydrated aluminum silicate with exchangeable cations• Selective adsorbent for proteins - attraction between the positive charges of the proteins

and negative charges of the silicate• Used as a clarifying or fining agent for wines to preclude protein precipitation• Forms a heavy compact sediment and final filtration removes precipitated colloids

Appearance Control and Clarifying Agents• Important clarifying agents – selective affinity for tannins, proanthocyanidins and other

polyphenols (proteins and certain synthetic resins)• Polyamides and Polyvinylpyrrolidone (PVP)

• Gelatin and Isinglass – proteins most commonly used as clarifying agents• Addition of 40-170 g per 380 L to apple juice

• Causes aggregation and precipitation of a gelatin-tannin complex• Settling enmeshes and removes other suspended solids

• Juices containing low levels of polyphenols• Supplemented with added tannin or tannic acid (0.005-0.01 %) to facilitate flocculation of the

gelatin

Appearance Control and Clarifying Agents• Gelatin and other soluble clarifying agents

• Low concentration can act as protective colloids• High concentrations can cause precipitation • Higher concentration can again fail to cause precipitation

• Molecules of the clarifying agents and polyphenol can combine in different proportions to either neutralize or enhance the hydration and solubility of a given colloidal particle

• Most complete precipitation – nearly complete disruption of H bonding between water and either protein or the polyphenol• Expected when the amount of dissolved clarifying agent roughly

equals the weight of the tannin removed being

Appearance Control and Clarifying Agents• Synthetic resins – used to prevent browning in white wines and remove haze for beers

• Polyamides and Polyvinlypyrrolidone (PVP)• Available in both soluble and insoluble forms• Use of high-molecular-weight cross-linked forms (insoluble) - when little or no residual polymer in

beverage is required• Useful in the beverage industry

• Reversible refrigeration-induced haze (chill haze)• Permanent haze – development of oxidized flavors

• Hazes – caused by formation of complexes between native proteins and proanthocyanidins from malted barley

• Excessive removal of proteins – lead to defective foam character• Selective removal of polyphenols – extends stability of beer

Appearance Control and Clarifying Agents• Treatment with 1.4-2.3 % kg of insoluble PVP per 100 barrels beer

• Provides control of chill haze and improves storage stability• PVP is added after fermentation and prior filtration – rapidly adsorbs polyphenols

• Bentonite – removes some tannins along with preferentially adsorbed proteins• Selective tannin adsorbents – remove some proteins along with the phenolics• Activated charcoal – quite reactive and adsorbs amounts smaller molecules (flavors, pigments)

along with larger compound that contribute to haze formation• Tannic acid (tannin) – used to precipitate proteins and can lead to undesirable effects• These have selective adsorptive capacities for polyphenols

• Proteins with low solubility – keratin, casein and zein• Soluble proteins – sodium caseinate, egg albumin and serum albumin

Flour Bleaching Agents and Bread Improvers

Flour Bleaching Agents and Bread Improvers• Freshly milled wheat flour – pale yellow tint and yields a sticky dough and does not handle or

bake well• Flour is stored – slowly becomes white and undergoes aging or maturing process• In Practice

• Chemical treatments employed to accelerate natural processes• Use other additives to enhance yeast leavening activity and retard onset of staling

Flour Bleaching Agents and Bread Improvers• Flour bleaching

• Primarily oxidation of carotenoid pigments• Disruption of the conjugated double bond system of carotenoids to a less conjugated

colorless system• Dough-improving action of oxidizing agents

• Involve the oxidation of sulfhydryl groups in gluten proteins• Oxidation agents employed may participate in:

1. Bleaching only2. Both bleaching and dough improvement3. Dough improvement only

Flour Bleaching Agents and Bread Improvers• Benzoyl peroxide• Commonly used flour bleaching agent• A bleaching or decolorizing action• But does not influence baking properties• Free radical initiator• Added to flour (0.25-0.075 %) at the mill• Usually added along with diluting or stabilizing agents (calcium sulfate,

magnesium carbonate, dicalcium phosphate, calcium carbonate and sodium aluminum phosphate)• Requires several hours after addition to decompose to free radicals for

initiation of carotenoid oxidation

Flour Bleaching Agents and Bread Improvers• Bleaching and Improving agents

• Chlorine gas• Chlorine dioxide• Nitrosyl chloride• Oxides of nitrogen• Nitrogen textroxide

• These are gaseous and exert action immediately upon contact with flour• Dough Improvers

• Potassium bromate• Potassium iodate• Calcium iodate• Calcium peroxide

• Exert their action during the dough stages rather than in the flour

Flour Bleaching Agents and Bread Improvers• Gaseous agents – oxidizing flour

• Bleaching efficiencies• Effectively improve baking qualities of suitable flours

• Treatment with Chlorine dioxide• Improves flour color slightly• Yields flour with improved dough handling properties

• Chlorine gas – contain small amount of nitrosyl chloride• Used as a bleaching and improver for soft wheat cake flour• Hydrochloric acid is formed from oxidation reactions of chlorine – resulting slightly lowered pH which

leads to improved cake baking properties

• Nitrogen tetroxide and other oxides of nitrogen• Moderately effective bleaching agents• Produce good baking qualities in treated flour

Flour Bleaching Agents and Bread Improvers• Oxidizing agents – that function primarily

as dough improvers• Added to flour (10-40 ppm) at the mill• Often incorporated into a dough conditioner

mix then added at the bakery

• Potassium bromate• Oxidizing agent and Dough improver• Unreactive until yeast fermentation lowers

pH of the dough and sufficiently to activate it• Causes increased loaf volume, improved loaf

symmetry and improved crumb and texture characteristics

Flour Bleaching Agents and Bread Improvers• Improved baking qualities – from treatment with oxidizing agents• Inhibition of the proteolytic enzymes present in flour

• Excessive oxidation of flour must be avoided• Leads to inferior products• Gray crumb color, irregular grain and reduced load volume

Flour Bleaching Agents and Bread Improvers• Addition of soybean flour to wheat flour for yeast-leavened dough• Addition of soybean lipoxygenase

• Way to initiate the free radical oxidation of carotenoids• Greatly improves the rheological properties of the dough

• Inorganic salts • Ammonium chloride• Ammonium sulfate• Calcium sulfate• Ammonium phosphate• Calcium phosphate

• They are added to dough to facilitate yeast growth• Ammonium salts – provide a ready source of nitrogen for yeast growth• Phosphate salts – improve dough by buffering the pH slightly lower than normal value

Flour Bleaching Agents and Bread Improvers

• Dough improvers in the baking industry1. Calcium stearoyl-2-lactylate

• Used at low levels (up to 0.5 %)• Improve mixing qualities of dough and promote increased loaf volume

2. Hydrocolloid gums• Improve the water-holding capacity of dough • Modify other properties of dough• Carrageenan, carboxymethylcellulose, locust bean gum and methylcellulose

• Methylcellulose and carboxymethylcellulose - retard retrogradation and staling in bread

• Carrageenan (0.1 %) – softens the crumb texture of sweet dough products

• Carboxymethylcellulose (0.25 %) – incorporated into doughnut mixtures to decrease the amount of fat absorbed during frying because a effective hydrated barrier

Anticaking Agents

Anticaking Agents• Conditioning agents – used to maintain free-flowing characteristics of granular and powdered

forms of food that are hygroscopic in nature• Function to readily absorbing excess moisture

• By coating particles to impart a degree of water repellency and/or providing an insoluble particulate diluent

• Calcium silicate – used to prevent caking in baking powder (up to 5%) and table salts (up to 2%)• Finely divided can absorb liquids in amounts up to 2 ½ times its weights and remains free flowing• Effectively absorbs oils and other nonpolar organic compounds

• Useful in complex powdered mixes and certain spices that contain free essential oils

Anticaking Agents• Food-grade calcium and magnesium salts of long-chain fatty acids – derived from tallow

• Used as conditioning agents in dehydrated vegetables products, salt, onion and garlic salts

• Calcium stearate – added to powdered foods • To prevent agglomeration• Promote free flow during processing• Insure freedom from caking during the shelf life of finished product• Insoluble in water • Provides a partial water-repellent coating• Used as a release lubricant (1 %) in pressed tablet-form candy

• Commercial stearate powders – high bulk density and possess large surface areas• Make conditioners (0.5-2.5 %) reasonably economical

Anticaking Agents• Other anticaking agents in the food industry

• Sodium silicoaluminate• Tricalcium phosphate• Magnesium silicate• Magnesium carbonate

• They are essentially insoluble in water• Exhibit ability to absorb moisture

• Example: 1 % sodium silicoaluminate is used in powdered sugar• Microcrystalline cellulose powders

• Used to prevent grated or shredded cheese from clumping• Anticaking agents – either metabolized or exhibit no toxic actions