ANTIOXIDANT PROPERTIES AND STORAGE STABILITY OF SPRAY-DRIED MELASTOMA MALABATHRICUM L. FRUIT EXTRACT FOR NATURAL COLORANT

• Main Author: ZAHARI, NURUL SYAZWANI
• Format: Thesis
• Language: English; English; English
• Published: 2024
• Subjects: TP368-456 Food processing and manufacture
• Online Access: http://eprints.uthm.edu.my/12639/

Melastoma malabathricum L. is an underutilized plant that is rich with anthocyanin. Although this plant pigment is a valuable source of natural colorant, the anthocyanin is typically low in stability. Therefore, encapsulation technique was used to improve its stability. This study aimed to characterize the physicochemical properties of the encapsulated fruit extracts, to determine the antioxidant activities before and after encapsulation, and to assess the storage stability of the encapsulated fruit extract in different conditions. The encapsulation was using spray dryer techniques and maltodextrin as a wall material. The ratio of the crude extract with maltodextrin was 1:1, 1:2 and, 1:3 and pH differential methods have been used to determine the Total Anthocyanin Content (TAC) of the samples. Besides that, the encapsulated extract was characterized according to their physicochemical properties. The stability of the sample was evaluated under different conditions including at -20 °C, 4 °C and 25 °C in the absence of light, and 25 °C in the presence of light for 90 days. The antioxidant activity of the samples was tested by using three different methods including DPPH, ABTS, and FRAP assays and was expressed as IC50 values. The result showed ratio 1:3 exhibited the lowest moisture content (5.77%) and solubility time (3s), while ratio 1:1 demonstrated the lowest bulk and tapped density which were 0.36 g/mL and 0.5 g/mL respectively. The pH values for all ratios were in an acidic state and the encapsulated extract for all ratios displayed spherical particles with irregular, concave, and wrinkled surfaces, showing no significant differences in size. After encapsulation, the ratio 1:1 showed no significant difference (p>0.05) with sample before encapsulation and showed the lowest IC50 value of 28.50 μg/mL for DPPH assay, 49.03 μg/mL for ABTS assay and 39.97 μg/mL for FRAP assay. The most stable condition was at 4 °C in the dark condition, while the best ratio was at ratio 1:2. Future studies could employ multifactorial experimental design to comprehensively evaluate and determine the optimal ratio for future applications.