The effect of high humidity hot air impingement blanching on the changes in molecular and rheological characteristics of pectin fractions extracted from okra pods

The aim of study was to evaluate the changes in molecular and rheological characteristics of pectin fractions extracted from okra pods subjected to high-humidity hot air impingement blanching (HHAIB). HHAIB had pronounced impact on the pectin solubility of okra pods, their structure and rheology. For example, short HHAIB, i.e. 15 and 30 s, resulted in some microcracks on the surface of okra pods, while the longer ones, i.e. 60, 90 and 120 s, resulted in higher stress and teared the outer skin of okra pods. HHAIB for 15 and 30 s prevented extractability of pectins from okra pods and resulted in a decrease in yield. HHAIB for 60 s facilitated pectin extraction providing higher yields, while HHAIB for 90 and 120 s led to the extraction of non-pectin cell wall components as well. Molecules of pectins of okra pods have been characterized by different molecular size, shape, and branching that depended on both solvent used for extraction and the time of HHAIB treatment. Degradation, aggregation and transformation of molecules to more easy soluble fractions was observed during blanching treatment. A pick of consistency index and viscosity was observed for pectins extracted from okra pods subjected to HHAIB treatment for 30–60 s. HHAIB was found to be one of the heat treatment methods that may be suitable support for improving pectin extraction and useful in tailoring pectin properties for further applications.