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

Abstract

Sunflower heads are a promising commercial source of low-methoxyl pectin. Although previously reported research was based on a batch extraction process, examples of continuous, countercurrent processes are found with other commodities (beet sugar, vegetable oil). The two types of processes were compared using ground, washed, and dried sunflower heads with 0.75% sodium hexametaphosphate (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 pectin recovery was similar for the two processes. However, the continuous process maintained maximal recovery over a wide range of pH and L/S ratio. Pectin 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 continuous process achieved adequate pectin recovery with less solvent and can be conducted with smaller-size equipment than the batch.