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 d e = density of external phase d i = density of internal phase k = constant vis = viscosity V = D 2 (d e -d i ) 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 = D 2 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 effects a. 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 40 o F

Critical considerations: –chopper speed –sharp knives –bowl/knife clearance –temperature control and monitoring –add fat meat at 40 o F and chop to 55 o F (pork fat), 65 o F (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 meat17.0 Pork picnics pork trim 4.1 Liver 1.25 Beef hearts 0.3