Jong-Yea Kim

Production of starch nanoparticles using normal maize starch via heat-moisture treatment under mildly acidic conditions and homogenization

Normal maize starch was subjected to heat-moisture treatment (HMT) under mildly acidic conditions (0.000, 0.050, or 0.075M H2SO4) for various treatment times (3, 5, or 8h) followed by homogenization up to 60min to prepare nanoparticles. The combination of HMT (0.075M, for 8h) and homogenization (60min) produced nanoparticles with diameters of less than 50nm at a yield higher than 80%. X-ray diffractometry and size-exclusion chromatography revealed that HMT under mildly acidic conditions selectively hydrolyzed the starch chains (especially amylose and/or long chains of amylopectin) in the amorphous region of the granules without significant damage to the crystalline structure, however, modification of the molecular structure in the amorphous region increased fragility of the granules during homogenization. Homogenization for 60min caused obvious damage in the long-range crystalline structure of the HMT starch (0.15N, for 8h), while the short-range chain associations (FT-IR) remained intact.

Radical scavenging-linked anti-adipogenic activity of Alnus firma extracts

The purpose of the present study was to investigate the antioxidant activity and anti-adipogenic effect of extracts from Alnus firma (A. firma), which is an edible plant that grows in mountainous areas. The total phenolic, flavonoid and anthocyanin content as well as the antioxidant activity of a 70% ethanolic extract of A. firma (AFE) was assessed. Furthermore, the effects of AFE on lipid accumulation and reactive oxygen species (ROS) production during adipogenesis of 3T3-L1 cells were investigated. The results revealed that the total phenolic, flavonoid and pro-anthocyanidin content of AFE as 436.26±3.30 mg gallic acid equivalents/g, 73.82±0.54 mg quercetin equivalents/g and 149.25±6.06 mg catechin equivalents/g, respectively. In addition, AFE exerted significant antioxidant effects in terms of 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity, 2,2′-azino-bis(3-ethylbenzothia-zoline-6-sulfonic acid) radical scavenging activity, reducing power, oxygen radical absorbance capacity and nitric oxide radical scavenging activity. As for its anti-adipogenic activity, AFE significantly inhibited ROS production and lipid accumulation during adipogenesis of 3T3-L1 cells compared with those in control cells. In addition, AFE regulated adipogenic transcription factors including peroxisome proliferator-activated receptor-γ, CCAAT/enhance-binding protein α and adipocyte protein 2. These results indicated that A. firma is a potential candidate for a functional food supplement.

Starch nanoparticles resulting from combination of dry heating under mildly acidic conditions and homogenization

To modify starch granular structure, normal maize starch was subjected to dry heating with various amounts of 1.0M HCl (1.2, 1.4 or 1.6mL) and different treatment times (2, 4 or 8h). For all reaction conditions, at least 80% of the starch substance was recovered, and amylose and amylopectin B1 chains were preferentially cleaved. As acidic condition and/or treatment time increased, the treated granules were readily fragmented by homogenization. The treatment appeared to alter short-range crystalline structure (FT-IR), but long-range crystalline structure (XRD) remained intact. Homogenization for 60min fragmented the treated starch granules (subjected to reaction condition of 1.4mL/4h, 1.6mL/2h, and 1.6mL/4h) into nanoparticles consisting of individual platelet-like and spherical particles with diameters less than 100nm. However, the fragmentation caused obvious damage in the long-range crystalline structure of starch nanoparticles, while the short-range chain associations remained relatively intact.