Anthocyanin-loaded double Pickering emulsion stabilized by octenylsuccinate quinoa starch: Preparation, stability and in vitro gastrointestinal digestion.

In this study, anthocyanin-loaded water1-in-oil-in-water2 (W1/O/W2) double Pickering emulsions stabilized by octenylsuccinate quinoa starch (OSQS) were optimized, and their storage stability and in vitro gastrointestinal digestion were evaluated. Novel starch-based double emulsions as anthocyanin cargos were achieved at 2% (w/v of oil) of polyglycerol polyricinoleate concentration, the W1/O volume proportion of 3:7, 6% (w/v of total volume) of OSQS concentration, and the volume proportion of (W1/O): W2 = 6:4 and 5:5. CLSM results evidenced the formation of double Pickering emulsions, and the significant decreases in the encapsulation stability of anthocyanins were closely related to the increases in the droplet size induced by osmotic pressure. Less than 15% of anthocyanins in the double Pickering emulsions was released after incubated for 60 min under simulated stomach conditions; controlled-release of anthocyanins was observed during the 120 min of simulated intestinal digestion, consistent with starch hydrolysis data. These findings will be useful for designing starch-based double Pickering emulsion with intestinal-targeted delivery as a novel carrier of sensitive hydrophilic bioactive compounds.

Effects of alpha-amylase reaction mechanisms on analysis of resistant-starch contents.

This study aimed to understand differences in the resistant starch (RS) contents of native and modified starches obtained using two standard methods of RS content analysis: AOAC Method 991.43 and 2002.02. The largest differences were observed in native potato starch, cross-linked wheat distarch phosphate, and high-amylose corn starch stearic-acid complex (RS5) between using AOAC Method 991.43 with Bacillus licheniformis α-amylase (BL) and AOAC Method 2002.02 with porcine pancreatic α-amylase (PPA). To determine possible reasons for these differences, we hydrolyzed raw-starch granules with BL and PPA with equal activity at pH 6.9 and 37°C for up to 84 h and observed the starch granules displayed distinct morphological differences after the hydrolysis. Starches hydrolyzed by BL showed erosion on the surface of the granules; those hydrolyzed by PPA showed pitting on granule surfaces. These results suggested that enzyme reaction mechanisms, including the sizes of the binding sites and the reaction patterns of the two enzymes, contributed to the differences in the RS contents obtained using different methods of RS analysis.

Effects of heat treatment and moisture contents on interactions between lauric acid and starch granules.

This study aimed to understand the effects of the moisture content of granular normal cornstarch (NC), heat treatment at 80 °C, and order of adding lauric acid (LA) to starch before or after the heat treatment on the physicochemical properties and digestibility of the starch. LA was added to NC priority heated with different moisture contents (10, 20, 30, 40, and 50%) or added to dried NC and then heated with different moisture contents. The hydrothermal/LA treatments increased the pasting temperature but decreased the peak viscosity of the NC. Light and scanning electron microscopy revealed that the addition of LA retarded gelatinization. The hydrothermal/LA treatments changed the X-ray pattern of the NC to a mixture of A- and V-type patterns. The thermal property and digestibility analysis showed that 40% was the optimum moisture content for the formation of the amylose-LA complex and adding LA prior to heating the NC favored the formation of slowly digestible starch.

Preparation and characterization of modified starch granules with high hydrophobicity and flowability.

Normal cornstarch (NC) was chemically modified by octenylsuccinic anhydride (OSA) and Al2(SO4)3. The effects of the concentration of NaOH, OSA, and Al2(SO4)3 on the properties of modified starch(OS-starch-Al) were investigated. The OS-starch-Al was characterized by repose angle, activation index, inductively coupled plasma-atomic emission spectrometry (ICP-OES), light microscopy, SEM, FT-IR, and (27)Al NMR. The results showed that pH 4 was the optimum condition for Al(3+) cross-linking with OS-starch and for obtaining high flowability and hydrophobicity. When the concentration of OSA and Al2(SO4)3 was 2%, the OS-starch-Al was characterized by high flowability. A concentration of 4% OSA and Al2(SO4)3 yielded the highest activation index. The moisture content affected the flowability of native NC, but had a minor effect on OS-starch-Al. SEM and polarized microscopy revealed that the modification had slight effects on the crystalline structure and morphology of NC. During the preparation, some dust particles functioning as flow additives were produced on the surface of starch granules. The results of FT-IR, ICP-OES, and (27)Al NMR confirmed the formation of ester group and the cross-link with Al(3+).