Meat emulsions - batters– Frankfurters are the best example

-produced with unique technology that is highly protein

dependent

-failures, i.e. “broken” emulsions are a dramatic mess

(fat caps where separated fat rises to upper ends of the

frankfurters as they hang on smoketrucks during

cooking, then solidifies into solid fat when chilled)

-successful, i.e. stable emulsion/batter is the result of 3

factors:

Emulsion/batter stability is determined by:

1. Meat quality

– meaning - myofibrillar protein content and functionality

– quality problems like PSE pork can result in emulsion/batter problems

– WHC and fat binding

2. Handling knowledge and technology

– meaning - appropriate use of salt, temperature, added water and chopping to properly manage soluble protein and dispersed fat

3. Additional binders to help stabilize emulsion/batters and control physical properties

Before we cover specifics --- some definitions

emulsion - stable dispersion of one immiscible liquid in another

– i.e. water-in-oil (mayonnaise, butter)

oil-in-water - frankfurters

– 30% fat is well-hidden

true emulsion

– dispersed particle size is 0.1µ or less

meat emulsion - particle size is typically 1.0 µ or more therefore often called a “batter”

What is “fat binding”?

1. Fat cell walls

– intact cells retain fat

– dried cells i.e. “salted” can be very stable due to collagen/cell wall rigidity and impermeability

2. Emulsification membranes

– myofibrillar proteins

– hydrophobic portion fat

– hydrophilic portion water

fat

protein

water

fat

Proteins rearrange somewhat and consequently lose some water binding ability (know this)

Therefore there are three necessary components for every emulsion/batter

– internal phase

i.e. fat

– external phase

i.e. water

– emulsifier

i.e. protein

“Membranes” are critical to raw emulsion/batters -- but cooking then

results in:

3. Heat-set gelation - crosslinking proteins to form a 3 dimensional matrix

– semi-rigid “trap” for fat and water

– critical to cooked stability, texture, slicing, appearance

More definitions

– Emulsion/batter capacity

– maximum amount of fat or oil stabilized by a given amount of protein

– measured by oil-in-water dispersion with clear blender jar, colored oil, protein solution

– model system comparisons

– emulsion/batter stability– amount of fat or oil retained (or separated) after stressing, usually

with heat, a formed emulsion/batter

– practical comparisons

– affected by process technology and non-meat ingredients

Factors affecting stability can be found in Stokes Law:

D = diameter of fat globules

de = density of external phase

di = density of internal phase

k = constant

vis = viscosity

V = D2(de-di) k vis

– smaller fat globules are more stable (also require more protein)

– greater viscosity (protein solubility, protein quality, temperature, non-meat ingredients, salt concentration) is more stable

Practically: V = D2

vis

Processing parameters

1. Start with lean meat plus salt

– best at 4-5% (brine strength)

plus ice/cold water– temperature control

– increased protein solubility and swelling

– can chop or mix (extract) longer

– low temperature increases viscosity

2. Chopping/mixing

– two effectsa. dissolves (1-5%) and swells (remainder) of myofibrillar

protein

b. breaks fat cells and subdivides fat into small globules

– chopping needs to be extensive enough to achieve small fat globules with solubilized protein membrane coatings

– over chopping will destroy the protein membranes and “break” the emulsion/batter

– usually chop lean, salt, water to about 40oF

Critical considerations:

– chopper speed

– sharp knives

– bowl/knife clearance

– temperature control and monitoring

– add fat meat at 40oF and chop to 55oF (pork fat), 65oF (beef fat)

3. pH is critical

– Protein “functionality” is closely related to the pH - WHC curve / relationship– therefore increasing pH increases emulsion stability

– pre-rigor meat is 50% - 100% more effective than post-rigor– phosphates are important

– pre-blends (lean meat + salt + 1/2 nitrite) are very effective (and advantageous for cured color as well)

4. Collagen

– High collagen meat sources are a potential problem– high capacity, low stability

– forms membranes but converts to gelatin when heated

– however, ground/powdered collagen appears to be effective probably depending on adequate dispersion followed by gelatin formation

5. Other emulsifier proteins

– myofibrillar proteins might be best “saved” for WHC and gelation– “pre-emulsions” --- use another protein to coat fat

globules --- then add “pre-emulsion” as fat to meat mixture

– soy and caseinate

– skin / collagen is sometimes used

6. Vacuum processing

– Chopping/mixing under vacuum can increase capacity and stability

6. Vacuum processing

– microscopic observations show air “bubbles” probably surrounded by protein thus consuming some protein functionality– air competes with fat for the emulsifier making the

emulsion/batter less stable– more critical for round globular sarcoplasmic proteins than

for filamentous, long myofibrillar proteins

6. Vacuum processing

– product density and diameter will differ with vacuum– can contribute “plumpness”

– major effects on cured color development – with about 50 ppm in going nitrite vacuum will give good

cooked color while non-vacuum will give gray cooked color

– absence of air also will decrease likelihood of rancidity development– not as much an issue in cured meats as for fresh products

(i.e. pork sausage)

7. Stuffing

– Pressure flow of product, proper casing diameter

– minimize smear/separation of fat and breaking emulsion membranes prior to heating

8. Heating / cooking

– humidity– important to yields, thus is kept high --- only risk is

high collagen content

– heating rate– critical to proper protein gelation

– protein unfolding crosslinking gel formation

Remember:

– “Bind” values listed for calculating formulations with different meat ingredients reflect water and fat binding ability

Ex. Bull meat 17.0Pork picnics 16.050 pork trim 4.1Liver 1.25Beef hearts 0.3