Encapsulation of bioactive compounds extracted from haritaki pulp (Terminalia chebula Retzius): characterization of physical, thermal, and morphological properties

Abstract

The bioactive compounds of haritaki (Terminalia chebula Retzius) were microencapsulated using zein and starch as the encapsulating agents, utilizing both conventional (encapsulator) and advanced (freeze drying) techniques. It has been found that freeze-drying is a highly effective method for producing bioactive compounds with high encapsulation efficiency and yield. The bioactive compounds were extracted using supercritical fluid extraction. The optimized conditions for the supercritical fluid extractor were flow rate 3.34 ml min⁻¹, pressure 166.94 bar, temperature 51.97 °C, time 67.47 min and CO₂ mass flow rate of 5 kg h⁻¹, kept constant for all the experiments. Comparing the different drying techniques, fresh haritaki produced the highest recovery of phenolic chemicals. Different combinations of starch : zein were tested for encapsulating the bioactive compounds, and based on the yield, encapsulation efficiency, and powder density, 100% starch presented the best yield (65.45 ± 2.58), encapsulation efficiency (75.95 ± 0.88), powder bulk density (0.61 ± 0.01) and tapped density (0.72 ± 0.01). Encapsulates were found to have an uneven and rough shape based on the SEM analysis. The combination of 70 : 30 (starch : zein) showed the largest mass loss (68.12%) using TGA, whereas 100% zein (58.63%) showed the lowest mass loss. From the DSC curves, it was noticed that the maximum onset point (88.40) and peak point (120.40) came from using 50 : 50 (starch : zein) encapsulates, while the minimum onset point (77.70) and peak point (107.00) from 70 : 30 (starch : zein) encapsulates. The endpoint was seen in 100% zein (142.70) and 100% starch encapsulates (142.50) whereas 70 : 30 (starch : zein) encapsulates (122.30) showed a minimum value. The bond stretching and vibrations of 100% zein encapsulates were the greatest, while those made from 100% starch encapsulates had very little stretching and low bond intensities, according to the FTIR spectra. The XRD patterns showed that the only encapsulate with a strong peak were the 50 : 50 (starch : zein). According to this study, freeze-drying the bioactive chemicals of haritaki extract can successfully encapsulate them, and the encapsulates can then be used to manufacture functional foods.