Electrohydrodynamic (EHD) Drying: A Novel Approach to Producing High-Quality Instant Idli Batter Powder

Abstract

Objectives: The objectives of this study were to optimize the Electrohydrodynamic (EHD) drying process for producing instant idli batter powder and to evaluate the effect of EHD drying on the survival and viability of yeast cultures present in the batter. Additionally, the study aimed to analyze key physicochemical properties of the final powder, including color, water activity, and rehydration behavior, and to compare the nutritional quality and retention of essential nutrients in EHD-dried powder with those of conventionally dried samples. Methodology: Idli batter was EHD-dried (5cm gap) at 13kV, 17kV, and 21kV. The resulting powders were comprehensively analyzed for rheological (pasting, sweeps, flow curve), physicochemical (swelling, solubility, color), and structural/thermal (FTIR, FESEM, CLSM, DSC) properties. Crucially, biochemical quality was assessed via yeast viability, enzyme activity (amylase, protease), amylose/amylopectin content, and in vitro starch digestibility. This study aims to identify the optimal voltage for preserving the powder's functional, nutritional, and microbial quality. Result & Conclusion: EHD drying at 17kV yielded an optimal instant idli batter powder, as compared to 13kV and 21kV treatment. 21kV treatment induced significant degradation, as revealed by FESEM and DSC analyses, which revealed microstructural collapse and thermal degradation. At the same time, the 13kV treatment sample exhibited lower digestibility, solubility, and textural properties. The 17kV condition achieved optimal properties, exhibiting maximum yeast viability, superior biochemical retention, such as amylase/protease activity, and enhanced in vitro starch digestibility. Rheological (pasting, flow curve) and FTIR analyses further confirmed that the 17kV powder retained superior functional and chemical integrity, establishing it as the optimal processing voltage.