The structural characterization, physicochemical properties, and stability of gardenia yellow pigment microcapsules

Gardenia yellow pigment (GYP) is a natural food coloring agent with a variety of pharmacological activities. However, the applications of GYP are limited due to its poor stability. The aim of this study was to prepare GYP microcapsules using different combinations of maltodextrin (MD), gum arabic (GA), soy protein isolate (SPI), and whey protein (WP) as wall materials to improve the stability of GYP, and evaluated its structural, physicochemical properties, and stability. Scanning electron microscopy (SEM), fourier transformed infrared spectrometer (FTIR), and X-ray diffraction (XRD) results confirmed inclusion of GYP within microcapsules. Thermogravimetric (TG) experiment indicated that GYP microcapsules had good thermal stability below 220 °C. Furthermore, the encapsulation efficiency (EE) and loading amount (LA) of GYP microcapsules were between 58.73 and 83.16% and 1.63–3.32 g/100 g, respectively. WP-MD microcapsule showed significantly higher EE and LA than other microcapsules. A significant lower hygroscopicity was observed in spray-dried double emulsion microcapsules (WP–O and WP-MD-O). The results of the stability studies revealed that the five kinds of microcapsules could significantly improve the thermal stability, light stability, and pH stability of GYP, and there was no significant difference. Overall, these results may guide the potential application of GYP microcapsules in nutraceutical and functional foods.