ARS | Publication request: Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey products

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2011
Publication Date: August 1, 2011
Citation: Listiyani, M.A., Campbell, R.E., Miracle, R.E., Dean, L.L., Drake, M.A. 2011. Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey products. Journal of Dairy Science. Volume 94, Issue 9, pgs 4347-4359.

Interpretive Summary: Whey is the liquid portion of milk that remains when solids are removed for cheese making. It can be concentrated by removing water and has other uses a food ingredient depending on the concentration. As it becomes more concentrated, the amount of protein present increases. These products are called whey protein concentrates (WPC) and are labeled according to their protein content. For instance, WPC70 is the designation for a whey protein concentrate product with a protein concentration of 70%. It is common in the dairy industry to remove color from dairy products by chemical bleaching agents such as hydrogen peroxide (HP) and benzoyl peroxide (BP). Although there are not legal limits in the US for residual amounts of these chemical in dairy products, there are global concerns that might impact the export of US dairy products that have been chemically bleached. The research presented here showed that the higher the protein content of the whey concentrate, the higher the bleaching agent breakdown products remained after processing. These residues could be removed by filtration.

Technical Abstract: Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations in dried whey products. No legal limit exists in the United States for BP use in whey, but international concerns exist. The objectives of this study were to determine the effect of hydrogen peroxide (HP) or BP bleaching on the flavor of 34% WPC (WPC34) and to evaluate residual BA in commercial and experimental WPC bleached with and without BP. Cheddar whey was manufactured in duplicate. Pasteurized fat-seperated whey was subjected to hot bleaching with either HP at 500 mg/kg, or no bleach. Whey was ultrafiltered and spray dried to WPC34. Color [L*(lightness), a* (red-green), and b* (yellow-blue)] measurements and norbixin extractions were conducted to compare bleaching efficacy. Descriptive sensory and instrumental volatile analyses were used to evaluate bleaching effects on flavor. Benzoic acid was extracted from experimental and commercial WPC34 and 80% WWPC (WPC80) and quantified by HPLC. The b* value and norbixin concentration of BP-bleached WPC34 were lower than HP-bleached and control WPC34. Hydrogen peroxide-bleached WPC34 had higher BA concentrations than unbleached and HP-bleached WPC34 and BA concentrations were also higher in BP-bleached WPC80 compared with unbleached and HP-bleached WPC80, with smaller differences than those observed in WPC34. Benzoic acid extraction from permeate showed that WPC80 permeate contained more BA than did WPC34 permeate. Benzoyl peroxide is more effective in color removal of whey and results in fewer flavor side effects compared with HP and residual BA is decreased by ultrafiltration and diafiltration.