Fretzdorff B, Weipert D
Z Lebensm Unters Forsch. 1986 Apr;182(4):287-93. doi: 10.1007/BF01027626.
Phytic acid in food is considered to be responsible for a reduced bioavailability of essential dietary minerals; its detrimental effects can be diminished by hydrolysis with phytase during processing. The average phytic acid content was 8.18 mg/g and 3.44 mg/g and average phytase activity was 3.7 U/g and 2.6 U/g in rye kernels and in flour (Type 997, 1.09 ash content), respectively. Phytate and Phytase were about equally distributed between the two kernel halves (cross sections). During the early stages of germination (3 days) phytase activity did not change, and phytic acid content was reduced to 67%. After milling most of the phytic acid and phytase activity were found in the bran fractions. It is concluded that substrate and enzyme are present in the same kernel structures but separate within the cells. Cooking of ground rye caused a phytate hydrolysis which was the more effective 1.) the smaller the particle sizes were, 2.) the more water was added, and 3.) the longer phytase worked at optimum temperature. Extrusion cooking of the rye whole flour at up to 100 degrees C did not influence the phytic acid level but caused a 23% reduction at 170 degrees C. Phytase activity was reduced by 80% by extrusion cooking at 80 degrees C.
食物中的植酸被认为是导致必需膳食矿物质生物利用率降低的原因；在加工过程中通过植酸酶水解可减少其有害影响。黑麦粒和面粉（997型，灰分含量1.09）中的平均植酸含量分别为8.18毫克/克和3.44毫克/克，平均植酸酶活性分别为3.7酶活力单位/克和2.6酶活力单位/克。植酸盐和植酸酶在麦粒的两半（横截面）中分布大致相等。在发芽早期（3天），植酸酶活性没有变化，植酸含量降至67%。研磨后，大部分植酸和植酸酶活性存在于麸皮部分。得出的结论是，底物和酶存在于同一麦粒结构中，但在细胞内是分开的。研磨后的黑麦烹饪会导致植酸盐水解，1.）颗粒尺寸越小，2.）添加的水越多，3.）植酸酶在最佳温度下作用的时间越长，水解效果就越明显。黑麦全粉在高达100摄氏度的挤压烹饪过程中不会影响植酸水平，但在170摄氏度时会导致植酸水平降低23%。在80摄氏度的挤压烹饪过程中，植酸酶活性降低了80%。
