Alkali-washing facilitates thermal-processed lignin to slow the hydrolysis of pancreatic ?-amylase in starchy foods

作者：Zhu, Jian; Liu, Hongsheng; Yu, Long^*; Zou, Wei^*

来源：Carbohydrate Polymers, 2022, 290: 119502.

DOI：10.1016/j.carbpol.2022.119502

• Alkali-washing
• Thermal processing
• Lignin
• Slow starch hydrolysis rate

Lignin, despite being able to slow starch digestion, needs to be heated at over 300 degrees C. To make the benefit achievable at a food-grade temperature, alkali-washing is studied as an additional procedure to facilitate the thermally processed lignin to slow the starch digestion in vitro. Lignin was firstly washed using Na2CO3/NaHCO3 mixture of various pH 7-10 followed by the thermal process at 150, 200, 250, and 300 degrees C respectively. The mild alkali-washing (pH 10) was found to allow the lignin heated at only 200 degrees C to achieve a significant inhibition on the hydrolysis of pancreatic alpha-amylase (alpha-AA) in starch-rich pasta. After the structural-characterization using atomic force microscopy and fluorescence spectroscopy, the mechanism hypothesis is confirmed due to a modification of insoluble-lignin surface morphology which might immobilize the alpha-AA content in solution. The findings highlight the potential of alkali-washing for facilitating thermally processed lignin in slowing the digestion of starchy foods.