Stable retorted whey protein beverages with 5% protein concentration were
prepared. The effect of protein concentration, fat concentration and homogenization
pressure on the heat stability and the stability of emulsions of sterilized whey protein
beverages was determined. Beverages containing >1% protein formed aggregates during
the heat treatment. Food grade additives were added to the beverages with >1% protein
to determine if the heat stability could be improved. Lecithins and polyphosphates
improved the heat stability while hydrocolloids decreased the heat stability. Lecithins
improved the heat stability of emulsions better than polyphosphates but polyphosphates
were more effective in beverages without fat. Lecithins modified by acetylation or
hydrolysis provided more protection against heat denaturation of proteins than regular
lecithin. Acetylated lecithin created the emulsions most stable against creaming.
Improvement in the emulsion stability by the use of phospholipids was associated with a
more negative charge at the interface of the fat droplets. The effect of polyphosphates
on the heat stability was related to the chain length of the polyphosphates. Short chain
polyphosphates (dp~4) were more effective than other polyphosphates. Polyphosphates
probably improved the heat stability of the systems by changing the structure of water
and this prevented aggregation of whey proteins. Hydrocolloids decreased heat stability
most probably through thermodynamic incompatibility that locally increased the
concentration of proteins and promoted aggregation during the heat treatment.The effect of homogenization pressure, concentration of acetylated lecithin, and
the concentration of short chain polyphosphate on the storage stability of retorted whey
protein beverages containing 5% protein and 3% fat was determined. The creaming
index and particle size index changed over 28 d of storage and indicated creaming of the
emulsions. The use of homogenization pressures of 55 and 90 MPa compared to 20 MPa
reduced the magnitude of the change of the particle size index and creaming index
during storage. Inclusion of polyphosphates reduced the storage stability of the
emulsions.
Optimization of parameters showed that emulsions formulated with 5% protein,
3% fat and 0.3% lecithin without polyphosphates and homogenized at 90 MPa had the
best stability after 28 d of storage.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/2344 |
| Date | 29 August 2005 |
| Creators | Perez Hernandez, Gabriela |
| Contributors | Richter, Ronald |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 979727 bytes, electronic, application/pdf, born digital |
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