Stability of Plant Pigments In Tradescantia Zebrina and Ixora Coccinea Linn as Potential Food Colorant with Antioxidant Activity

To, Shu Kei (2020) Stability of Plant Pigments In Tradescantia Zebrina and Ixora Coccinea Linn as Potential Food Colorant with Antioxidant Activity. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Natural food colorants from plant pigments such as anthocyanin, betacyanins, carotenoids and chlorophylls are becoming a commercial trends due to health awareness of consumers on the negative effects of consumption synthetic food colorant. In this study, the pigments of Tradescantia Zebrina and Ixora Coccinea Linn have been studied for their potential as natural food colorants. Both plant samples were extracted in 70 % ethanol and stability tests on pH and thermal were studied. The pH stability of plant pigment is determined by placing the samples in different pH buffer for a total of 30 days, and heat stability test by heating the samples for continuous 6 hours. The samples were further analyzed for the antioxidant properties. For Tradescantia Zebrina showed the highest percentage stability after 30 days (77.59 ± 1.54 %) at pH 7. While, Ixora Coccinea Linn showed the highest percentage stability after 30 days (77.74 ± 0.91 %) at pH 7. Besides, the color stability test on heat, Tradescantia Zebrina (48.04 ± 32.53 % at 50 °C; 48.52 ± 11.28% at 80 °C) showed a greater percentage of stability than Ixora Coccinea Linn (21.03 ± 12.60% at 50 °C; 6.20 ± 1.11 % at 80 °C) after 6 hours of heating. In comparison, the antioxidant analysis showed that Tradescantia Zebrina stem possessed the higher antioxidant content (Total phenolic content: 694.86 ± 54.46 mg GAE/g ; Total flavonoid content: 496.22 ± 16.56 mg CAT/g; free radical scavenging activity: 26.19 ±1.37 %), as compared to the leaf of Tradescantia Zebrina (Total phenolic content: 510.70 ± 31.45 mg GAE/g ; Total flavonoid content: 410.27 ± 8.34 mg CAT/g; free radical scavenging activity: 18.78 ± 0.00 %). In contrast, the flower of Ixora Coccinea Linn showed lower (Total phenolic content: 209.34 ± 37.71 mg GAE/g; Total flavonoid content:147.03 ± 10.91 mg CAT/g; free radical scavenging activity: 5.83 ± 0.55 %) as compared to both stem and leaf of Tradescantia Zebrina. In short, the color stability of Tradescantia Zebrina and Ixora Coccinea Linn were showed unstable due to the effectiveness of heat and acidic pH. Tradescantia Zebrina and Ixora Coccinea Linn extracts have lower viability to be used as a food colorant. Keywords: DPPH, total phenolic content, total flavonoids content, oxidative, anthocyanin, chlorophyll, food colorant, pH, heat.