Influence of Bleaching on Flavor of Fluid Whey and Whey Protein Concentrate and Benzoic Acid Concentration in Dried Whey Proteins.

LISTIYANI, MARIA ANGELICA DIANA. Influence of Bleaching on Flavor of Fluid Whey and Whey Protein Concentrate and Benzoic Acid Concentration in Dried Whey Proteins. (Under the direction of Dr. MaryAnne Drake.) Increasing use of whey protein ingredients in foods and beverages increases the demand for colorless and mild tasting whey protein. Colored fluid whey is frequently bleached to remove residual annatto colorant at different temperatures and bleach concentrations. Bleaching effects on WPC34 have not been established in previous studies. Benzoyl peroxide (BP), a bleaching agent for whey, degrades to benzoic acid (BA) and water and may elevate BA concentrations in dried whey products, which give rise to international concerns. Two studies were designed to look at different bleaching parameters and BA residue in dried whey products. The objectives of the first study were to compare the effects of hot and cold bleaching, point of bleaching (before and after fat separation), and bleaching agent on bleaching efficacy and volatile components of liquid Cheddar whey. Liquid colored Cheddar whey was manufactured in triplicate and pasteurized. Part of the whey was collected (no separation, NSE) and the rest was subjected to fat separation (FSE). NSE and FSE whey were then subdivided and bleaching treatments (BP 50 or 100 mg/kg, hydrogen peroxide (HP) 250 or 500 mg/kg, and no bleach) at 68°C for 30 min or 4°C for 16 h were applied. Norbixin was extracted to compare bleaching efficacy and volatile compounds were evaluated by gas chromatography-mass spectrometry (GC-MS). BP bleached wheys had lower norbixin content compared to HP bleached wheys (p<0.05). HP bleaching efficacy was decreased at 4°C compared to 68°C (p<0.05), but not for BP (p>0.05). Liquid whey subjected to hot bleaching at both concentrations of HP or 100 mg/kg BP had higher lipid oxidation products (aldehydes) compared to unbleached, 50 mg/kg BP hot bleached, or cold bleached wheys. Fat separation had no impact on the relative abundance of volatile lipid oxidation products (p>0.05). The objectives of the second study were to determine the impact of HP or BP bleaching on bleaching efficacy and flavor of WPC34 and to evaluate residual BA in commercial and experimental WPC manufactured with and without BP bleaching. Cheddar cheese whey was manufactured in duplicate. Pasteurized fat-separated whey was subjected to hot bleaching with either HP at 500 mg/kg, BP at 50 or 100 mg/kg, or no bleach. Bleached and unbleached whey was ultrafiltered and spray dried into WPC34. Color (L*a*b*) measurements and norbixin extractions were conducted to compare bleaching efficacy. Descriptive sensory and instrumental analyses were used to evaluate bleaching effects on flavor. Benzoic acid was extracted from experimental and commercial WPC34 and WPC80 and quantified by high performance liquid chromatography (HPLC). The b* value and norbixin concentration of BP bleached WPC34 were lower than unbleached and HP bleached WPC34. Descriptive sensory analysis demonstrated that HP bleached WPC34 had higher cardboard flavor and relative abundances of volatile lipid oxidation products than BP bleached or unbleached WPC34. BP bleached WPC34 and WPC80 had higher BA concentrations than unbleached and HP bleached samples, in which WPC80 had smaller differences than those observed in WPC34. Benzoic acid extraction from permeate demonstrated that WPC80 permeate contained more BA than WPC34 permeate (p<0.05). These studies suggest that fat separation had no measurable impact on bleaching efficacy or initial lipid oxidation and hot bleaching may result in increased lipid oxidation in fluid whey. In addition, BP is a more effective bleaching agent compared to HP both in color removal and flavor side effects and BA concentration is decreased by ultrafiltration and diafiltration.