Preparation and characterization of nanoparticles from field pea starch by batch versus continuous nanoprecipitation techniques

Starch nanoparticles (SNPs) were produced by batch nanoprecipitation (BNP) and continuous techniques such as flash nanoprecipitation (FNP) and microfluidic nanoprecipitation (MNP). Water and absolute ethanol were used as solvent (S) and antisolvent (AS), respectively, while they can be mixed either dropwise or direct mixing at once. The effects of processing parameters on SNPs properties were investigated including antisolvent/solvent (AS/S) ratio, starch concentration, mixing technique and flow rate. Field emission scanning electronic microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrophotometry were used to characterize the nature of molecular interactions and structure within SNP. The results indicated that BNP can be successfully achieved in a shorter time with a smaller particle size and narrower particle size distribution, even at AS/S ratio as low as 1:1, using direct mixing at once method than the dropwise technique. Increasing the starch concentration at a fixed AS/S ratio of 1:1, initially decreased the average particle size from 135 (2.5 mg/mL) to 123 nm (10 mg/mL), and then increased to ~430 nm (50 mg/mL). Based on the optimized conditions for BNP, continuous methods (FNP and MNP), were investigated in the commercial prospective for potential scale up processing. Under the same conditions, FNP involving confined impinging jet mixer (CIJM) at an overall flow rate of 60 mL/min, had a uniform spherical shape with particle size of ~100 nm, which was superior to all other techniques investigated. Regardless of the techniques used, all SNPs had an amorphous structure with short-range molecular order.