In this study, weld plant dyes were extracted by ultrasonic waves assisted extraction (UAE) method and then, transformed to the concentrated extracts and powder. The efficiency of the extraction process was optimized with employment of a central composite design (CCD), and the optimum conditions of the influential variables, including temperature, time, power of ultrasound, and the bath pH were investigated with response surface methodology (RSM). In this way, an amount of 0. 1 g of weld plant powder was extracted in 100 ml of distilled water as the solvent. The optimized amount of variables was found to be of 30 ° C, 40 min, 73% of ultrasonic power and pH= 11 of the dyeing bath, where the extraction efficiency was of 87. 14%. Then, the extract was analyzed by GC-MS analytical method and 3, 7-dioxo-6, 6, 10-trimethyl-8, 10-undecadien-4-yl was identified as the coloring agent of the plant. Also, comparison of using methanol, as the solvent, in conventional extraction method and in UAE method revealed that the use of ultrasound significantly increases the extraction efficiency. Moreover, this technology needs for shorter time in comparison to that of the conventional method. J. Color Sci. Tech. 12(2018), 115-124© . Institute for Color Science and Technology.

Introduction: Dried rhizomes of turmeric have been traditionally used as a medicinal herb, dietary spice, food source, food preservative, and natural coloring agent in many Asian countries. This study aimed to develop the ultrasonic-assisted extraction (UAE) method for the extraction of curcumin from turmeric powder, evaluate the extraction efficiency, curcumin concentration, and biological activities. Methods: The UAE effects were examined based on several parameters of extraction efficiencies. The curcumin content was also determined using high-performance liquid chromatography (HPLC), and the total phenolic content (TPC) was estimated by Folin-Ciocalteu colorimetric method. The antibacterial activity of the extracted was evaluated against the test pathogenic bacteria by the disc diffusion method. The correlation between extraction yield and curcumin content was performed by principal components analysis (PCA). Results: The optimal UAE conditions were: ethanol, a solid-liquid ratio of 1: 10 (w/v), an extraction time of 40 min, and only one extraction step. Under the optimal conditions, the yield of curcumin was 160. 3 ± 1. 17 (mg/g extract) and the TPC was 185. 5 ± 3. 07 (mg gallic acid equivalent /g extract). PCA presented the positive correlation between curcumin and the TPC of the studied extracts. Comparison of antibacterial activity between UAE and maceration method against the tested bacteria showed no significant difference at P > 0. 05. Conclusion: UAE was a viable alternative as a rapid, efficient, and simple means of extraction of curcumin from turmeric. The extracts had great potential as a source of antioxidant agents with high amounts of curcuminoids, phenolic compounds and exhibited activity against pathogenic bacteria.

In this study, natural colorants of hawthorn fruit, Crataegus elbursensis were extracted using ultrasonic energy. The effect of extraction variables such as solvent type, time, temperature, pH, and crude dye concentration was optimized through one-factor at a time method. Optimum extraction conditions of dye concentration 10 g/L, ethanol/water ratio of 4.1 V/V, temperature 50oC, time 30 minutes, and pH 4 were obtained. Moreover, comparison of extraction data obtained by two conventional and ultrasonic extraction methods demonstrated that using ultrasound, extraction time and temperature were reduced and the amount of natural dye extracted was enhanced.

Ultrasound-assisted extraction (UAE) was evaluated as a simpler and more effective alternative to conventional extraction methods for the isolation of curcuminoids from turmeric plant rhizomes. The turmeric samples were extracted under indirect sonication in an ultrasonic bath, and compared with the conventional methods. It was found that the yield of ultrasound-assisted extraction was approximately three times higher than the traditional method. Taguchi experimental design was employed to study the effect of pH, solvent composition and extraction time on the yield of extracted curcuminoids from turmeric. The optimum combination was determined as a solvent composition ethanol/water 70:30 (V: V), pH of 3 and an ultrasoundassisted extraction time of 15 min. The extracts were analyzed using high performance liquid chromatography (HPLC).