Comparison of continuous and batch processes for pectin extraction from sunflower heads

Sunflower heads are a promising commercial source of low-methoxyl pectin. A lthough previously reported research was based on a batch extraction proces s, examples of continuous, countercurrent processes are found with other co mmodities (beet sugar, vegetable oil). The two types of processes were comp ared using ground, washed, and dried sunflower heads with 0.75% sodium hexa metaphosphate (SHMP) extractant. Under the conditions of pH 2-3.5 at liquid -to-solid (L/S) ratio 32, and L/S ratio 30-45 at pH 3.23, the maximum pecti n recovery was similar for the two processes. However, the continuous proce ss maintained maximal recovery over a wide range of pH and L/S ratio. Pecti n productivity, which is the rate of pectin extraction per working volume, was much higher in the continuous process than the batch process. At pH 2.5 and L/S ratio 32, it was more than 100% higher. Consequently, the continuo us process achieved adequate pectin recovery with less solvent and can be c onducted with smaller-size equipment than the batch. (C) 1999 Elsevier Scie nce B.V. All rights reserved.