PHOSPHATES Phosphates can have a large number of

different functions in food products. Salts of phosphoric acid may be either acidic

or basic and therefore make excellent buffers. Solutions of poyphosphates have a high pH. Phosphates and polyphosphates have

negative charges (may have multiple negative charges) in solution and interact with cations and other positively charged species (proteins, gums, etc).

PHOSPHATES (multiple forms)

HO

P

O

OH

OHHO

P

O

O-

OH

HO

P

O

O-

O--O

P

O

O-

O-

PHOSPHATES (dehydration)

HO

P

O

OH

OH

+HO

P

O

OH

OH

- water

HO

P

O

O

OH

P

O

OH

OH

Phosphates have multiple pKas

pKa1~ 2.4 pKa2~6.7 Pka3 ~8.4 In milk at pH 6.6

Monophosphate/phosphoric acid – 43000/1

Diphosphate/monophospaate – 0.8/1 Triphosphate/disphosphate – 1/600000

Phosphate Nomenclature

1.Orthophosphate - Salts Of Phosphoric Acid Monobasic, Dibasic, Tribasic

2.Polyphosphates - Dehydration Products A. Pyrophosphate - 2 P Atoms B. Tripolyphosphate - 3 P Atoms C. Sodiumhexametaphosphate - Mixtures

P>4

Phosphates (GRAS, nutrient)

182.5210 Calcium glycerophosphate182.5212 Calcium phosphate182.52213 Calcium pyrophosphate182.5301 Ferric phosphate182.5304 Ferric pyrophosphate182.5306 Ferric sodium pyrophosphate182.5434 Magnesium phosphate182.5455 Magnesium glycerophosphate182.5628 Potassium glycerophosphate182.8217 Calcium phosphate182.8223 Calcium pyrophosphate182.8458 Magnesium hypophosphite

182.8778 Sodium phosphate

Phosphates (GRAS)182.6085 Sodium acid phosphate

182.6203 Calcium hexametaphosphate

182.6215 Monobasic calcium phosphate

182.6285 Dipotassium phosphate

182.6290 Disodium phosphate

182.6760 Sodium hexametaphosphate

182.6769 Sodium metaphosphate

182.6778 Sodium phosphate

182.6787 Sodium pyrophosphate

182.6789 Tetrasodium pyrophosphate

182.6810 Sodium pyrophosphate

Phosphates (GRAS)182.1073 Phosphoric Acid

182.1087 Sodium acid pyrophosphate

182.1217 Calcium phosphate (mono, di or tri basic)

182.1778 Sodium phosphate (mono, di or tri basic)

182.1781 Sodium aluminum phosphate

182.1810 Sodium tripolyphosphate

Orthophosphates (monomer

Phosphate pH (!% soln) Solubility(g/100

Monosodium 4.4 48

Disodium 8.8 11

Trisodium 11.8 13

Dicalcium 7.5 Insol

Tricalcium 7.2 Insol

Na Al –acidic 2.4-2.5 Slight

Na Al –basic 9.2-9.4 slight

Di potassium 8.8 63

Orthophosphates Help to stabilize pH in foods Mono sodium phosphate (MSP)–

used as an acidulate Di (DSP) and tri sodium (TSP)

phosphate – used to increase pH MSP and DSP combinations

generally used in buffering systems

Pyrophosphates (Dimer)Phosphate pH (1% soln) Solubility (g/100)

Pyrophosphoric acid

v. Acid Soluble

Calcium pyrophosphate

6.0 insoluble

Tetrasodium pyrophosphate

10.2 61

Sodium iron pyrophosphate

70-7.2 insoluble

TrimersPhosphate pH (1% solution) Solubility

Potassium tripolyphosphate

9.8 65

Sodium tripolyphosphate

9.8 13

Potassium metaphosphates

4-8 (n=>400) insoluble

Sodium tetraphosphate

7-8 (n =4-10 high

Tripoly phosphates Potassium tripolyphosphate

Only potassium polyphosphate is used in food

High cost Only used when others phosphates are

too astringent Sodium tripoly phosphate

Only fully neutralized salt is used Used in limited amounts in foods

Polymers of NaPO3 (>3)

Sodium hexametaphosphate (n=5-15) PH 7.0, soluble

Sodium metaphosphate (n=50-100) pH 6.2, soluble

Poly Phosphates Polyphosphates often used to

modify protein functionality. Two common ones in use are: “Quadraphos (n= 4 to 8) Hexametaphosphate(n=10-15)

Closer control of n provides better functionality from batch to batch (11-13)(13-15)

Phosphate Functions

Sequester metal ions Buffer Increase water binding Adjust pH Anti-caking agent Form ionic "bridges" Interact with proteins, other charged

hydrocolloids

Phosphates found in many foods – most common are:

Carbonated beverages Cereal products Dairy products Egg products Fruits and vegetables Gums and gels Meat products Polyphosphates as microbial inhibitors

Phosphates in carbonated beverages Mineral supplementation in some

carbonated and non carbonated beverages Iron and calcium phosphates – most common in

non carbonated beverages Complex metal ions

Prevent loss of carbonation caused by heavy metals (25-90% less CO2 needed in untreated water

Acidification Common in cola beverages

Improve flow of powders in dry mixes Tricalcium phosphate (TCP) most common in use and

also assists in size distribution of the dry mix

Phosphates In Cereal Products

Leavening Agents Decreased Cooking Time Buffer pH in cereals during cooking Dough Conditioners (SALP, acidic CP Inhibition of enzyme activity (DSP) Antioxidant activity (MSP & DSP) Cheater Mineral Enrichment Color Improvement Improved Tortillas by steeping corn in MSP,DSP or TSP

(generally alkaline) Use of high molecular weight

Phosphates as leavening agents

Largest use is in prepared mixes because of broad choice of phosphates with different rates of CO2

Salts of phosphoric acid and its polymers used through neutralization to form acidic salts

Chemical Leavening Reaction between sodium bicarbonate

and acidic phosphate salt The phosphate will have at least two

replaceable hydrogen atoms Phosphates provide

Acidification for release of CO2 Buffering to provide optimum pH for baked

product Interaction with flour ingredients to provide

optimum viscosity and elasticity in the dough or batter

Factors affecting leavening action Proper selection of acidulation Bubble size formed during mixing Quality of the gluten in the flour Viscosity during mixing Type of emulsification of the system Dough reaction rate (DRR) which

combines CO2 release during mixing and during bench action (relaxation)

Ratio of CO2 release during baking to that during dough preparation (varies widely)

DRR for different phosphate salts

 

Evolution of CO2 (%)   2 min. 8 min. During baking Mono Ca P 60 0 40 MCaP(coated) 15 35 50 Di Ca P 0 0 100 SALP 22 9 69 SAPP (slowest 22 11 67 SAPP (med.) 30 8 60 SAPP (fast) 40 8 52

Notes on most commonly used phosphate leavening agents Mono calcium phosphate (MCP)

Most rapid release of CO2 – complete during mixing – used in combination with slower acting to retain CO2 release during baking

Anhydrous coated calcium phosphate (AMCP) – cake mixes, self rising dough

Di-calcium phosphate (DCP) Slowest release of CO2, generally all released during

baking Sodium aluminum phosphates(SALP)

Bland flavors Used in a wide range of bakery products

Sodium acid pyrophosphates (SAPP) Astringent Only leavening agent usable for refrigerated dough Commonly used for cake doughnut mixes (or with MCP)

Some combinations Cake mixes

Use of highly emulsified shortenings, gives finer structure and reduces the amount of leavening agent needed

AMCP & SALP in white and yellow cakes AMPC and SAPP or DCP in chocolate cakes, since

CALP dulls the chocolate color Self rising flours

AMCP because of stability Blends of AMCP SALP give better flavor and more

stability in conditions of high humidity Pancake mixes

Combinations of MCP+SALP or MCP+SALP+SAPP to provide stability during frozen storage. Freeze/thaw stability

Prepared Biscuit mixes Blends of 30-50% AMCP+50-70% SALP or SAPP

Phosphates In Dairy Products

Heat Stability Age Gelation Stability Emulsifying Chelation Of Fe & Cu In Butter Milk Gels (TSPP) Control Of Gum Gelation Prevents Churning Of Ice Cream Melting Of Processed Cheese Whipping Aid

Phosphates and the casein system of milk

Casein exists in milk as micelles that are stabilizes by colloidal calcium phosphate

Calcium ortho phosphate is involved in the formation and stabilization of the casein system

Many of the applications in the processing of dairy products involves interactions between phosphates and the casein or the calcium in the micelles

Heat stability “salt balance” (ratio of citrate & phosphate

to calcium and Magnesium) appears to control heat stability of evaporated milk

Addition of ortho phosphate stabilizes concentrated milk to retort sterilizations

UHT sterilization of concentrated milk gives different results with phosphates. Age gelation is actually increased by the addition of orthophosphate and inhibited by poly phosphates

Mechanisms are very complex and not fully understood.

Milk gels, Puddings & Cheesecake Dry mixes are blended with milk, blended and

refrigerated to gel Gelation is by the action of: TSPP in the presence of calcium acetate MCP as the gelation acceleration with acetylated

monoglycerides Carrageenan in the presences of TSPP, STP or

TSP with an additional calcium phosphate for puddings

Instant cheese cake also used TSPP and MCP. Milk is added, poured into a graham cracker crust and refrigerated – ready to serve in 15 minutes

Cheese applications Processed cheese requires a calcium sequestering

agent to remove calcium from the casein micelle of the cheese in order to emulsifiy the fat and turn the casein into a thermal plastic material

In addition, the citrates and/or phosphates provide a buffering capacity to stabilize the system in the pH range of 5.4-5.6

Blends of phosphates and citrates most commonly used, singly or in combination

Citrates predominate in products made with young cheese

Phosphates predominate in products with aged cheese, SALP provides less flavor than DSP

Since both young and aged cheeses used in most processed cheese and blend is used

Egg products Protect whole egg or egg yolk against

discoloration Polyphosphates stabilize eggs against the

action of proteolytic enzymes STP enhances the whipping properties of

egg whites. SMP stabilized egg whites to pasteurization,

with triacetin to prevent loss of foaming MSP reduced tendency for overbeating of

egg whites by reducing pH to 8.0

Other Dairy (non cheese) Applications

Increase solubility of nonfat dry milk Increase whipping properties of casein Stabilize frozen desserts to fat agglomeration Stabilize coffee whiteners during heat treatment

and concentration and prevent “feathering”–type depends on other ingredients (DSP and KSP commonly used – with the potassium salt giving less flavor and being more soluble; SALP used in some instances

Serve as buffers and stabilizing agents for protein films needed to make a stiff foam (DSP, DKP, TSPP)

Phosphates In Meat Products

Stabilize Color Polyphosphates (SMPH) provide pH 6.5-6.6 to retard

oxidation of natural meat pigments that accelerate at the normal ph of meat (5.2-6.0

Increased Tenderness Phosphates (SMPH, TSPP) cause dissociation of

actomyosin and improve tenderness of all meats. Action not associated with pH Pyrophosphates combine with magnesium to give

muscle relaxation and improve tenderness

Phosphates In Meat Products (cont)

Enhance binding Assist in extraction of actinomyosin and

improves binding – used for reformed meat Increases moisture retention

SMHP increases juiciness SHMP decreases cooking losses

Retard Oxidation DSP most effective STP, SHMP and SAPP +TSPP not effective