Effect of Feed Liquid Temperature on the Structural Morphologies of d‐Limonene Microencapsulated Powder and Its Preservation

Abstract

The influence of the feed liquid temperature of the spray drying was investigated on the particle morphology (vacuole size and shell thickness of hollow particle) and the stability of encapsulated d-limonene. The feed liquid was the mixture of d-limonene emulsified in a wall material of blending gum arabic (GA) and maltodextrin (MD) at the mass ratio of 1 : 2, and the liquid temperature was varied from 40 to 80 degrees C. The percentage of the hollow particle in the spray-dried powder was over 40% and slightly increased with the rising of the feed temperature. Hollow particles have shells of different thickness, which was estimated from the image with a confocal laser scanning microscope (CLSM). The shell thickness increased with the increase in the feed temperature. This finding was qualitatively supported by scanning electron microscopy (SEM) images of the fractured particles. In addition, release and oxidation stability of encapsulated d-limonene were measured at constant temperature and humidity. The powder at high temperature of feed has higher stability for release and oxidation of d-limonene than that at a lower feed temperature. The result may partly be attributed to the increase of the shell thickness of the particle at a higher feed temperature. The thicker shell wall possibly served as the barrier of the flavor release and the diffusion of oxygen and moisture from the surrounding environment.

Effect of oil droplet size on the oxidative stability of spray-dried flaxseed oil powders

“…The detailed configuration of the spray dryer is described elsewhere. 18) The feed rate was 30 mL/min, the atomizer speed was 30,000 rpm, and the airflow rate was set at 110 kg/h. The inlet air temperature was 180°C and the outlet air temperature was in the range of 80-90°C.…”

Microencapsulation of grape seed oil by spray drying

“…The wall materials used were gum Arabic (GA) and maltodextrin combined with gum Arabic (GA/MD, 50:50). The total solids concentration (wall material + oil) in the emulsion and oil concentration in relation to the total solids were 30% (Paramita et al, 2010) and 10% (Garcia et al, 2012;Frascareli et al, 2012) respectively. The wall material was dissolved in distilled water at 40°C and cooled to room temperature.…”

Determination of microcapsule physicochemical, structural, and mechanical properties

“…It is, however, worth remembering that the resolution is lower than that of TEM; this emphasizes that CLSM should be considered if interactions with the embedding medium cause shell degradation. There are reports of the use of CLSM in various microcapsule studies, in which the shell thickness was determined by examining the intensities across the mid-points of the resulting cross-sectional profiles (Lebedeva, Kim, & Vinogradova, 2004;Pan et al, 2013;Paramita, Iida, Yoshii, & Furuta, 2010;Tavera, Kadali, Bagaria, Liu, & Wong, 2009). …”