Stabilization of Black Rice (Oryza Sativa, L. Indica) Anthocyanins Using Plant Extracts for Copigmentation and Maltodextrin for Encapsulation

Abstract

Black rice (Oryza sativa L. indica) is one of the cereal commodities considered to be a source of anthocyanin. One of the obstacles of using anthocyanins as natural food colorants is their low stability. The objective of this study was to determine the effect of natural plants extracts on anthocyanin copigmentation and to study the stability of the encapsulated copigmented anthocyanin during storage under different temperatures and light exposure. Dried bilimbi leaves (BL) and sow thistle leaves (STL) were extracted using ethanol to obtain the crude flavonoid extract that was subsequently purified using solid phase extraction. Both crude (CBL, CSTL) and purified (PBL, PSTL) extract were used as copigment agents with the molar ratio of 1:0.1 to 1:10 at pH 1 and pH 3. The copigmentation effect was evaluated by measuring the wavelength and absorbance shifts at wavelengths of 500 to 600 nm. The stability of the dried anthocyanin powder was evaluated under different temperatures and light exposure for up to 4 weeks. Anthocyanin was successfully copigmented with BL and STL extracts showing a wavelength shift and absorbance increase at pH 1 and pH 3. Purification of BL enhanced the hyperchromic effect more than that of the crude form, in contrast to the STL. Meanwhile, the retention of absorbance (%) for encapsulated copigmented anthocyanin samples was within 74% to 83% at the end of the storage period. Practical Application Natural food pigment such as anthocyanin obtained from plant extract usually shows very limited stability under various processing conditions. This study shows that color stability of anthocyanin extracted from black rice can be improved by copigmentation with flavonoids extracted from particular plants. Encapsulation of the copigmented anthocyanin could further enhance its color stability. The availability of encapsulated and copigmented anthocyanins with improved color stability is expected to provide more alternatives for especially the beverage industry to choose suitable natural colorant for their products.

Preparation and characterization of gamma oryzanol loaded zein nanoparticles and its improved stability

“…Encapsulation has been proposed as an effective technique for maintaining the quality and stability of active food ingredients (Padua & Wang, 2009) against oxidation and provide better solubility (Raharjo et al., 2019). The small particle size could help the delivery of the bioactive compounds within the body.…”

Combination of copigmentation and encapsulation strategies for the synergistic stabilization of anthocyanins

“…By this means, the red color of spray‐dried microparticles is significantly intensified, as well as the degradation of anthocyanin is retarded even with exposure to heat at 80°C for 2 hr and natural light for 12 days. In another study, the copigments, including rutin, ferulic, and flavonoid extracts, are added in the spray‐dried maltodextrin microparticles (Raharjo et al., 2019; Weber et al., 2017). The results have shown that within the range of the molar ratio of copigment to anthocyanin from 1:1 to 10:1, all the microparticles have deeper red color and higher chemical stability than those without copigments.…”

“…Examples of delivery systems that can be used to encapsulate copigmented anthocyanins efficiency, and stability of anthocyanins (Raharjo et al, 2019;Tan et al, 2019;Xue et al, 2019). These features are of critical importance in sustainable food engineering that aims at satisfying the consumer demand for both perception and health benefits.…”

“…Integrating copigmentation and encapsulation may overcome the limitation of usage of a single technique. It has been demonstrated that the combinatorial use of appropriate copigments and encapsulation agents enables the simultaneous achievement of color intensification, higher encapsulation efficiency, and stability of anthocyanins (Raharjo et al., 2019; Tan et al., 2019; Xue et al., 2019). These features are of critical importance in sustainable food engineering that aims at satisfying the consumer demand for both perception and health benefits.…”

Addition of Chelators Increased the Stability of Black Rice Anthocyanins against the Metallic Ions in Tap Water and Improved the Coloration of Steamed Cold Noodles

“…Black rice has a high anthocyanins content in the pericarp layer, and the black rice extract (BRA) has been reported able to effectively reduce cholesterol level, suppress tumor growth, delay aging, and prevent cardiovascular diseases [ 14 ]; meanwhile, the extract has excellent antioxidant strength that is twice that of blueberries [ 15 ]. The application of BRA as a food colorant has been a hot topic in recent years [ 16 ].…”