Southeast Dairy Foods Research Center, Department of Food, Bioprocessing & Nutrition Science, North Carolina State University, Raleigh, NC 27695, USA.
J Dairy Sci. 2011 Sep;94(9):4347-59. doi: 10.3168/jds.2011-4341.
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-separated whey was subjected to hot bleaching with either HP at 500 mg/kg, BP at 50 or 100 mg/kg, or no bleach. Whey was ultrafiltered and spray dried into 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% WPC (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 displayed higher cardboard flavor and had higher volatile lipid oxidation products than BP-bleached or control WPC34. Benzoyl 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.
先前的研究表明，漂白会对 70%乳清蛋白浓缩物（WPC70）的风味产生负面影响，但对低蛋白产品的漂白效果尚未确定。过氧化苯甲酰（BP）是一种乳清漂白剂，会降解为苯甲酸（BA），并可能提高干乳清产品中的 BA 浓度。在美国，BP 在乳清中的使用没有法律限制，但国际上对此存在担忧。本研究的目的是确定过氧化氢（HP）或 BP 漂白对 34%乳清蛋白（WPC34）风味的影响，并评估商业和实验用 WPC 经 BP 和无 BP 漂白后的残留 BA。重复生产切达干酪乳清。巴氏杀菌的脱脂乳经 HP （500mg/kg）、BP（50 或 100mg/kg）或无漂白剂进行热漂白。乳清经超滤和喷雾干燥制成 WPC34。进行颜色[L*（亮度）、a*（红-绿）和 b*（黄-蓝）]测量和诺贝希因提取，以比较漂白效果。采用描述性感官和仪器挥发性分析评估漂白对风味的影响。从实验和商业 WPC34 和 80%乳清蛋白（WPC80）中提取 BA，并通过 HPLC 定量。BP 漂白的 WPC34 的 b*值和诺贝希因浓度低于 HP 漂白和对照 WPC34。过氧化氢漂白的 WPC34 具有更高的纸板味，且挥发性脂质氧化产物高于 BP 漂白或对照 WPC34。BP 漂白的 WPC34 的 BA 浓度高于未漂白和 HP 漂白的 WPC34，BP 漂白的 WPC80 的 BA 浓度也高于未漂白和 HP 漂白的 WPC80，与 WPC34 相比，差异较小。从渗透物中提取的 BA 表明，WPC80 渗透物中的 BA 含量高于 WPC34 渗透物。与 HP 相比，BP 更有效地去除乳清的颜色，且产生的风味副作用更少，超滤和渗滤可降低残留的 BA。
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