Optimization of narirutin extraction during washing step of the pectin production from citrus peels

Citrus peels can be a valuable source of pectin and narirutin. Narirutin can be extracted during the washing step of citrus peels in the pectin production process. In this study narirutin extraction conditions were optimized to maximize the narirutin extraction yield while minimized pectin loss. Washing temperature, time, and HCl concentration of the washing solution were chosen as independent variables of the central composite design. The results showed a good fit with the second-order polynomial equation, which was statistically acceptable at P<0.05 level. Pectin loss was directly correlated with the increases in temperature, time, and HCl concentration during washing procedure. Consequently, the higher the temperature and longer the time, the yield of narirutin extracted was greater, although higher HCl concentration had a negative effect on narirutin extraction yield. The present study indicated that the combination of washing temperature (62 °C), time (30 min), and the absence of HCl in the washing solution was found to be optimum conditions, yielding 0.6% of narirutin with a pectin loss of only 1.5% based on the dry citrus peels. The characterization of narirutin extracted from citrus peels was performed using HPLC and NMR.