Khanal R C, Howard L R, Brownmiller C R, Prior R L
Dept of Food Science, Univ of Arkansas, Fayetteville, AR 72703, USA.
J Food Sci. 2009 Mar;74(2):H52-8. doi: 10.1111/j.1750-3841.2009.01063.x.
Blueberry juice processing by-products are a rich source of procyanidins, which comprise a group of compounds shown to possess numerous health benefits, including protection against coronary heart disease, type II diabetes, and obesity. Most of the procyanidins present in blueberry pomace, however, are large molecular weight compounds that are poorly absorbed and show weak bioactivity compared to the smaller molecular weight monomers and dimers. The objective of our study was to identify optimal extrusion variables to enhance the contents of monomers and dimers at the expense of large molecular weight procyanidin oligomers and polymers. Extrusion variables temperature (160 and 180 degrees C) and screw speed (150 and 200 rpm) were tested using mixtures of blueberry pomace with decorticated white sorghum flour at a ratio of 30 : 70 and 45% moisture content. Extrudates were analyzed for procyanidin composition and total anthocyanin content. Extrusion of blueberry pomace increased the monomer, dimer, and trimer contents considerably at both temperature and screw speeds. The highest monomer content, obtained at 180 degrees C and 150 rpm screw speed, was 84% higher than the nonextruded control. Significantly higher levels of dimer and trimer contents were also obtained under these conditions. Increases in monomer, dimer, and trimer contents apparently were the result of reduced polymer contents, which was approximately 40% lower for samples extruded at 180 degrees C temperature and 150 rpm screw speed. Extrusion processing reduced total anthocyanin contents by 33% to 42% indicating that additional treatments are needed to retain the pigments. These results demonstrate that extrusion processing can be used to increase procyanidin monomer and dimers in blueberry pomace.
蓝莓汁加工副产品是原花青素的丰富来源，原花青素是一类已被证明具有多种健康益处的化合物，包括预防冠心病、II型糖尿病和肥胖症。然而，蓝莓果渣中存在的大多数原花青素是高分子量化合物，与较小分子量的单体和二聚体相比，它们的吸收性差且生物活性弱。我们研究的目的是确定最佳挤压变量，以增加单体和二聚体的含量，同时减少高分子量原花青素低聚物和聚合物的含量。使用蓝莓果渣与去皮白高粱粉按30:70的比例混合且水分含量为45%的混合物，测试挤压变量温度（160和180摄氏度）和螺杆转速（150和200转/分钟）。对挤出物进行原花青素组成和总花青素含量分析。蓝莓果渣的挤压在温度和螺杆转速条件下均显著增加了单体、二聚体和三聚体的含量。在180摄氏度和150转/分钟的螺杆转速下获得的最高单体含量比未挤压的对照高84%。在这些条件下，二聚体和三聚体的含量也显著更高。单体、二聚体和三聚体含量的增加显然是聚合物含量降低的结果，对于在180摄氏度温度和150转/分钟螺杆转速下挤出的样品，聚合物含量降低了约40%。挤压加工使总花青素含量降低了33%至42%，这表明需要额外的处理来保留色素。这些结果表明，挤压加工可用于增加蓝莓果渣中原花青素单体和二聚体的含量。
