Emulsifying and lipid adsorptive properties of starch nanocrystals from Solanum lycocarpum fruits

Abstract

The emulsifying properties of a nitric acid-hydrolyzed starch nanocrystal (SNC) from Solanum lycocarpum were examined. The scanning electron microscopy of SNC revealed globular particles measuring 89.4 nm (± 20) in average. The values of the water absorption index (1.066 g g−1) and oil absorption capacity (1.013 g g−1) revealed the amphiphilic character of the SNC. The emulsifying properties using ultrasound and Ultra-Turrax, were, respectively, emulsifying activity: 77.81% (± 0.92) and 74.95% (± 1.09); emulsion stability: 99.43% (± 1.32) and 97.30% (± 2.78). The characteristics observed for the droplet obtained using ultrasound and Ultra-Turrax were PDI: 0.04 to 0.35, size: 1.514 μm and 3.579 μm, zeta potential: −21.35 (±1.06) and −26.80 (±1.27), respectively. The starch nanocrystals/cholesterol resisted simulated gastric/intestinal digestion (retention 94.8%) and anionic detergent (retention 97%). The inclusion of 1.0 or 2.0% (w/v) of SNC resulted in ice creams with 127.9 (± 21.1) and 156.6 N (± 19.2) firmness and 142.9 (± 17.4) and 171.3 kgf·mm (± 34.3) consistency, respectively. Similarly, using 1.0 or 2.0% (w/v) of SNC, the amount of extractable lipids from ice creams decreased by 34 and 56% and free cholesterol by 29.5 and 46.5%, respectively. Sensory analysis of the ice cream produced with 2.0% (w/v) SNC revealed 96.1% overall acceptability and average scores above 8 for texture, aroma, flavor, and appearance.