Effect of Non-Thermal Ultrasound on Inulin from Jerusalem Artichoke and Its Application in Dairy Industry

Abstract

Jerusalem artichoke (JA) is a rich source of dietary fiber. The major dietary fiber inside of JA is inulin which is a heterogeneous collections of fructose polymers with many health benefits for humans. To investigate the effect of ultrasound on the inulin from JA, JA powder, Purified JA inulin (PJAI) was treated with 20KHz ultrasound compared with chicory inulin (CI). Ultrasound treatment time had a positive linear relationship with reducing sugar content of these samples. After ultrasound treatment, reducing sugar content in JA powder increased from 6.101g/100g up to 12.273g/100g. In PJAI, reducing sugar content increased from 10.378g/100g up to 12.274g/100g. Reducing sugar content in CI increased from 1.126g/100g up to 2.183g/100g. Also, determined by HPLC and GPC, for PJAI, there was a negative linear relationship between high degree of polymerization (DP) inulin with ultrasound treatment time (R 2 =0.9169), and a positive linear relationship between low DP inulin with ultrasound treatment time (R 2 =0.9738), which was not observed for inulin from chicory. Furthermore, JA powder was added into whey and milk and treated with 20KHz ultrasound to investigate the structure change. Ultrasound changed the microstructure of milk resulting in a flatter surface for milk and whey. Ultrasound combined particles of milk and whey This kind of phenomenon was much more obvious only for milk when mixed with JA powder. III