Use of ingredients and processing to control the stability of high whey protein concentration retort sterilized beverages

摘要

Stable retorted whey protein beverages with 5% protein concentration wereprepared. The effect of protein concentration, fat concentration and homogenizationpressure on the heat stability and the stability of emulsions of sterilized whey proteinbeverages was determined. Beverages containing >1% protein formed aggregates duringthe heat treatment. Food grade additives were added to the beverages with >1% proteinto determine if the heat stability could be improved. Lecithins and polyphosphatesimproved the heat stability while hydrocolloids decreased the heat stability. Lecithinsimproved the heat stability of emulsions better than polyphosphates but polyphosphateswere more effective in beverages without fat. Lecithins modified by acetylation orhydrolysis provided more protection against heat denaturation of proteins than regularlecithin. Acetylated lecithin created the emulsions most stable against creaming.Improvement in the emulsion stability by the use of phospholipids was associated with amore negative charge at the interface of the fat droplets. The effect of polyphosphateson the heat stability was related to the chain length of the polyphosphates. Short chainpolyphosphates (dp~4) were more effective than other polyphosphates. Polyphosphatesprobably improved the heat stability of the systems by changing the structure of waterand this prevented aggregation of whey proteins. Hydrocolloids decreased heat stabilitymost probably through thermodynamic incompatibility that locally increased theconcentration of proteins and promoted aggregation during the heat treatment.The effect of homogenization pressure, concentration of acetylated lecithin, andthe concentration of short chain polyphosphate on the storage stability of retorted wheyprotein beverages containing 5% protein and 3% fat was determined. The creamingindex and particle size index changed over 28 d of storage and indicated creaming of theemulsions. The use of homogenization pressures of 55 and 90 MPa compared to 20 MPareduced the magnitude of the change of the particle size index and creaming indexduring storage. Inclusion of polyphosphates reduced the storage stability of theemulsions.Optimization of parameters showed that emulsions formulated with 5% protein,3% fat and 0.3% lecithin without polyphosphates and homogenized at 90 MPa had thebest stability after 28 d of storage.