Dept. of Food, Bioprocessing and Nutrition Sciences, Southeast Dairy Foods Research Center, North Carolina State Univ., Raleigh, NC 27695, U.S.A.
Dept. of Mathematical Science, Clemson Univ., Clemson, SC 29634, U.S.A.
J Food Sci. 2013 Oct;78(10):C1535-C1542. doi: 10.1111/1750-3841.12251. Epub 2013 Sep 16.
Fluid whey or retentate are often bleached to remove residual annatto Cheddar cheese colorant, and this process causes off-flavors in dried whey proteins. This study determined the impact of temperature and bleaching agent on bleaching efficacy and volatile components in fluid whey and fluid whey retentate. Freshly manufactured liquid whey (6.7% solids) or concentrated whey protein (retentate) (12% solids, 80% protein) were bleached using benzoyl peroxide (BP) at 100 mg/kg (w/w) or hydrogen peroxide (HP) at 250 mg/kg (w/w) at 5 °C for 16 h or 50 °CC for 1 h. Unbleached controls were subjected to a similar temperature profile. The experiment was replicated three times. Annatto destruction (bleaching efficacy) among treatments was compared, and volatile compounds were extracted and separated using solid phase microextraction gas chromatography mass spectrometry (SPME GC-MS). Bleaching efficacy of BP was higher than HP (P < 0.05) for fluid whey at both 5 and 50 °C. HP bleaching efficacy was increased in retentate compared to liquid whey (P < 0.05). In whey retentate, there was no difference between bleaching with HP or BP at 50 or 5 °C (P > 0.05). Retentate bleached with HP at either temperature had higher relative abundances of pentanal, hexanal, heptanal, and octanal than BP bleached retentate (P < 0.05). Liquid wheys generally had lower concentrations of selected volatiles compared to retentates. These results suggest that the highest bleaching efficacy (within the parameters evaluated) in liquid whey is achieved using BP at 5 or 50 °C and at 50 °C with HP or BP in whey protein retentate.
乳清液或浓缩物通常会经过漂白以去除辣木籽黄橙色素奶酪着色剂的残留颜色，而这一过程会导致乳清蛋白粉产生异味。本研究旨在确定温度和漂白剂对乳清液和乳清浓缩物（浓缩物）漂白效果和挥发性成分的影响。采用过氧苯甲酰（BP）100 mg/kg（w/w）或过氧化氢（HP）250 mg/kg（w/w），于 5 °C 下处理新鲜乳清（6.7%固形物）或浓缩乳清蛋白（浓缩物）（12%固形物，80%蛋白质）16 小时或于 50 °C 下处理 1 小时进行漂白。未漂白的对照样品则经历了类似的温度处理过程。该实验重复了三次。比较了不同处理方法对辣木籽的破坏效果（漂白效果），并采用固相微萃取气相色谱-质谱联用（SPME-GC-MS）提取和分离挥发性化合物。在 5 和 50 °C 下，BP 的漂白效果均高于 HP（P < 0.05）。与乳清液相比，HP 可增加浓缩物的漂白效果（P < 0.05）。在浓缩物中，50 和 5 °C 下，用 HP 或 BP 漂白均无差异（P > 0.05）。在任何温度下，用 HP 漂白的浓缩物中戊醛、己醛、庚醛和辛醛的相对丰度均高于 BP 漂白的浓缩物（P < 0.05）。与浓缩物相比，乳清液中某些挥发性物质的浓度通常较低。这些结果表明，在 5 或 50 °C 下使用 BP 或在 50 °C 下使用 HP 或 BP 可以实现乳清液的最高漂白效果（在所评估的参数范围内）。
