Roselle flower contains various active compounds including organic acid, hydroxycitric acid, hibiscus acid, anthocyanin, flavonoids and polysaccharides The anthocyanin compounds in rosella flowers are the most important pigment of vascular plants, harmless and that make it interesting is a soluble pigment in water media Anthocyanin extract is one of the most successful natural sensitizers for solar cells, because this organic dye produces a high yield of photons to current conversion and is easy to obtain and cheap. Anthocyanins can be potential as sensitizers, because they range in the light spectrum from red to blue. The purpose of this study was to obtain anthocyanin pigments at the optimum extraction conditions from roselle flowers. The optimization of the method was carried out by analyzing the effect of ultrasonic wave frequency, process temperature, extraction time, and mass ratio of roselle flowers to the volume of distilled water on the anthocyanin concentration. The qualitative and quantitative compositions of the anthocyanin extract of rosella flowers were analyzed by UV-Vis spectrophotometer. The results showed that the optimal operating conditions for the extraction process were known at a temperature of 40 °C, a frequency of 24 kHz, a time of 5 minutes, and a ratio of 1: 25.

Fucoxanthin, an algal carotenoid with bioactivity that benefits human health, is gaining popularity as a functional food. Therefore, in this study, the effect of drying methods and conditions on the production of fucoxanthin isomers in three closely related Sargassum species with slightly different morphological lamina were investigated. The recovery of fucoxanthin after oven‐drying was 1.1–1.3‐fold higher than that after sun‐drying and varied 1.6‐fold among the S. species used, indicating that each algal species has a different heat susceptibility even among closely related species, and should be optimized for each species and drying method. In Padina australis with homogeneous morphology, the optimal temperature to maintain all‐trans form was 60°C with only a 5.3% loss, while other cis‐isomer transformations were maintained at 80°C. The apparent activation energy estimated by Arrhenius plots differed for the all‐trans form and cis‐isomer transformations, indicating the presence of different reactions between them. Practical applications Drying treatment is an efficient and cost‐effective technique for reducing the moisture content of post‐harvest seaweed to prevent decomposition, increase shelf life, and easily extract the targeted compounds. Owing to the difference in heat susceptibility, even in closely related species, the results indicated that it should be necessary not only to select appropriate algal species and drying methods but also to optimize the thermal conditions for each target substance of the selected material. This study provided qualitative information, particularly on seaweed drying procedures, and contributed to the production of marine products in the fields of food and bioactive substances, such as fucoxanthin isomers.

Hybrid materials are composed of materials that have broad spectra absorption and can be added to other materials that improve their spectrum absorption. The characteristics of hybrid materials are the same characteristics as their constituent materials. When hybrid materials were added to organic compounds which combined with semiconductors, they can be used as photovoltaic applications. One of the most widely hybrid material research developments is its use as the solar cell. This research focused on TiO2/ZnO hybrid materials synthesis combined with anthocyanin as a pigment to determine the characteristics of the hybrid material obtained. In this research is to find the extent to which method applied that determines the success of the targeted hybrid materials formation. In the synthesis process for various ratios, TiO2 and ZnO have been formed a composite material which shown by diffractogram of characteristic peaks of TiO2 and ZnO and vibrations of Zn-O-Ti detected in FTIR spectra. Testing hybrid materials by using FTIR showed a C=O vibration of anthocyanin in material hybrid TiO2/ZnO-anthocyanin, than quality testing of hybrid materials was carried out using the DR UV-Vis instrument and was proved by enhancement of band gap energy between 3.2 to 3.3 eV

One of the synthesis methods currently being carried out is green synthesis. One of the efforts to implement the green method is to use plant extracts that can be renewed. Hibiscus sabdariffa is one type of plant that is able to produce anthocyanin pigments. In this study, the synthesis of ZnO composites with gold nanoparticles will be carried out using Hibiscus sabdariffa flower extract. The composites of gold nanoparticles and ZnO were determined using XRD instrumentation where there were characteristic peaks of ZnO and gold nanoparticles.