The increasing popularity of Morinda citrifolia, commonly known as noni fruit, which is known for its rich bioactive compounds like saponins, polyphenols, flavonoids, and vitamin C, has led to its introduction into the market in the form of noni powder. Numerous methods are employed to dry noni fruit, with this study focusing on microwave drying. The primary objective was to investigate the impact of microwave drying conditions on the physicochemical properties of noni powder, while also exploring its preservation through moisture sorption isotherm and Q10 experiments.
The microwave drying process for noni fruit slices involved three different power settings, namely 1.29 W/g, 1.71 W/g, and 2.29 W/g. The results revealed that the most suitable microwave power setting for drying noni fruit was 1.71 W/g, when combined with a material loading of 4 kg/m2. Under these conditions, the content of bioactive compounds, including saponins, polyphenols, flavonoids, and ascorbic acid, was maximized, with values of 48.0 mg AE/g db, 12.9 mg GAE/g db, 8.3 mg QE/g db, and 0.3 mg AA/g db, respectively. In the context of storage, the sorption curve of noni powder at 30°C was modeled using the BET model, with an Mo value of approximately 4%. Furthermore, the Q10 value for noni powder indicated that total polyphenols, saponins, flavonoids, and vitamin C can maintain 70% of their initial content over a span of 2 months at 5°C or 1 month at 10°C when stored under conditions devoid of oxygen and light.