Faraji Habibollah, Lindsay Robert C
Department of Food Science, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
J Agric Food Chem. 2004 Nov 17;52(23):7164-71. doi: 10.1021/jf035291k.
Polyols have been incorporated into fish oil emulsions as a means for the inhibition of lipid oxidation and suppression of fishy flavor. However, the role of sugars and polyhydric alcohols as antioxidants has not been clearly established. Selected polyols were evaluated for their performance as antioxidants and modifiers of oxidation pathways in a model system. Oil/water (O/W) emulsions were prepared with freshly steam-deodorized menhaden oil. A layer of emulsion in aluminum pans held at 5 degrees C was exposed to 2550 lx fluorescent lights for 24 h before peroxide values and volatile flavor compounds were analyzed by GC headspace entrainment procedure. Antioxidant activity was confirmed for fructose, sucrose, raffinose, sorbitol, or mannitol when incorporated at 16% of the aqueous phase into model fish oil-in-water emulsions. Peroxide values were suppressed 10-18% in treated samples compared to control samples. Viscosity data did not exclude possible contributions from a restricted oxygen diffusion mechanism in the antioxidant activity, but revealed that emulsion viscosity did not govern fish oil oxidation rates. Combining polyols with phenolic antioxidants (alpha-tocopherol, BHT, or TBHQ) frequently diminished the antioxidant activity compared to that for individual phenolic antioxidants, which was interpreted as indicating that the H-donating activity of phenolic antioxidants was hindered by the H-bonding activity of polyols. A viscosity-based inhibition of the retroaldol conversion of (E,Z)-2,6-nonadienal to (Z)-4-heptenal with a high fructose concentration (67%) was attributed to a restriction of molecular mobility of reactants, but the conversion was only slightly inhibited by the concentration of fructose (16%) used in experimental emulsions. The data supported a hypothesis that either or both free radical scavenging and transition state metal chelation activities were provided by polyols in fish oil emulsions. Also, polyols retarded the water-requiring retroaldol decomposition of (E,Z)-2,6-nonadienal to (Z)-4-heptenal in the model systems and the reaction may be involved in some suppression of fishy flavors in emulsions.
多元醇已被添加到鱼油乳液中，作为抑制脂质氧化和抑制鱼腥味的一种手段。然而，糖和多元醇作为抗氧化剂的作用尚未明确确立。在一个模型系统中，对选定的多元醇作为抗氧化剂和氧化途径调节剂的性能进行了评估。用新鲜蒸汽脱臭的鲱鱼油制备油/水（O/W）乳液。在铝盘中的一层乳液在5摄氏度下暴露于2550勒克斯荧光灯下24小时，然后通过气相色谱顶空进样程序分析过氧化物值和挥发性风味化合物。当果糖、蔗糖、棉子糖、山梨醇或甘露醇以水相的16%掺入模型水包油型鱼油乳液中时，抗氧化活性得到证实。与对照样品相比，处理过的样品中过氧化物值降低了10 - 18%。粘度数据并未排除抗氧化活性中受限氧扩散机制的可能贡献，但表明乳液粘度并不控制鱼油的氧化速率。与单独的酚类抗氧化剂相比，将多元醇与酚类抗氧化剂（α-生育酚、丁基羟基甲苯或叔丁基对苯二酚）结合使用时，抗氧化活性常常降低，这被解释为表明酚类抗氧化剂的氢供体活性受到多元醇氢键活性的阻碍。高果糖浓度（67%）基于粘度对（E,Z）-2,6-壬二烯醛向（Z）-4-庚烯醛的逆羟醛转化的抑制作用归因于反应物分子流动性的限制，但实验乳液中使用的果糖浓度（16%）对该转化的抑制作用较小。数据支持了这样一个假设，即多元醇在鱼油乳液中提供了自由基清除和过渡态金属螯合活性中的一种或两种。此外，多元醇在模型系统中延缓了（E,Z）-2,6-壬二烯醛向（Z）-4-庚烯醛的需水逆羟醛分解反应，该反应可能与乳液中鱼腥味的部分抑制有关。
