Highly efficient production and simultaneous purification of D-tagatose through one-pot extraction-assisted isomerization of D-galactose

A one-pot extraction-assisted D-galactose-to-D-tagatose isomerization strategy was proposed based on the selective extraction of D-tagatose by phenylborate anions. 4-Vinylphenylboronic acid was selected with high extraction efficiency and selectivity towards D-tagatose. The extracted sugars could be desorbed through a twostaged stripping process with the purity of D-tagatose significantly increased. In-situ extraction-assisted Dgalactose-to-D-tagatose isomerization was implemented for the first time ever reported, and the effect of boronto-sugar ratio (boron: sugar) was investigated. The conversion yield of D-tagatose at 60 degrees C increased from - 39 % (boron: sugar = 0.5) to - 56 % (boron: sugar = 1) but then decreased to - 44 % (boron: sugar = 1.5). With temperature increased to 70 degrees C, the conversion yield of D-tagatose was further improved to - 61 % (boron: sugar = 1.5), with the minimized formation of byproducts. Moreover, high purity (-83 %) and concentrated D-tagatose solution (-40 g/L) was obtained after sequential desorption. The proposed extraction-assisted isomerization strategy achieved improving the yield and purity of D-tagatose, proving its feasibility in industrial applications.