Browning of chitooligomers and their optimum preservation

Chitooligomers have attracted much interest due to their unique biological activities. However, chitooligomers easily turn brown during shelf life. The factors influencing the browning of chitooligomers were investigated. The results indicated that the browning was attributed to the structure change of chitooligomers. The water-solubility, thermal stability and moisture–adsorption of chitooligomers decreased with the increase of browning. The time, temperature, pH, moisture, oxygen and reductant all had effect on the browning of chitooligomers. The optimal preservation condition for chitooligomers should be at low temperature and humidity, at pH below 4 or above 10, and in absence of oxygen.