## 1 Introduction  
The genus _Curcuma_ belongs to the _Zingiberaceae_ family, and it has more than seventy species of rhizome herbs worldwide. Those species were classified into _Curcuma longa_, _Curcuma amada_, _Curcuma amoratica_, and _Curcuma zedoria_[1]. Asian countries have a wide distribution of turmeric species, particular for tropics and subtropics countries. Curcumionoids are a mixture of three different components in turmeric (_Curcuma longa_). They are the main compounds responsible for the biological activity of turmeric. Curcumin (CUR) is a yellow-colored crystalline polyphenol in purified form. Besides curcumin, curcuminoids contain two other vital derivatives, i.e., demethoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC) [2]. In turmeric rhizome, curcuminoids occupy around 30-150 mg/g depending on geographical origin [3]. Curcumionoids are non-polar compounds; hence, curcuminoid solubility in an organic solvent is significantly higher than in the aqueous solutions. Establishing a selective extraction procedure for curcuminoids is the main goal in some research activities. According to [PERSON], et al. [4], the conventional protocols generally use solvents and solid-liquidextraction techniques such as steam distillation, maceration, and Soxhlet extraction. For the conventional methods, the techniques generally involve high temperature (usually higher than 60 \({}^{\circ}\)C), long extraction time (up to 72 h for maceration), organic solvents, and less selective extraction [5]. Furthermore, these methods use a high amount of solvent and energy input, which leads to low practical application possibilities. In curcuminoids extraction, conventional extraction methods usually lead to degeneration by light and high temperature during the long exposure. In the literature, a wide range of extraction techniques for curcuminoids extraction has been presented. With conventional extraction, heating or steaming could be used, but it has a low extraction yield [6; 7]. Organic solvents are widely applied, such as ethanol, acetone, and hexane [8]. Furthermore, non-conventional techniques were applied for curcuminoids extraction, such as supercritical carbon dioxide [9], microwave-assisted extraction [9; 10], ultrasound-assisted extraction [11]. Thermal pretreatment (TP) was considered conventional, fast, and low operational costs [12]. The starch content in turmeric reaches 35% \(w/w\) of dry basis [13], changing the hydrophilic phase's viscosity and affecting total curcuminoids recovery. Relevant studies used TP as a pretreatment method for further extraction [14] or reference treatment compared to non-conventional extraction techniques [15]. According to [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [1], high temperature during extraction enhances curcumin extraction yields because temperature changed different physical characteristics, including viscosity, diffusivity, solubility, and surface tension. In this research, the effect of TP is compared to non-conventional pretreatments such as ultrasound pretreatment (UP), enzyme pretreatment (EP), pulsed electric field pretreatment (PEF). Ultrasound pretreatment (UP) belongs to non-conventional methods, and it was used to enhance the extraction of polyphenols in various materials. Ultrasound is considered an efficient technique with intensive impact [16]. [PERSON], et al. [17] concluded that ultrasound could be considered promising and practical for bioactive compounds extraction, with higher yields and short processing time. For curcuminoids extraction, UP is highly recommended due to the increased extraction yield of curcuminoids [9; 18; 19]. When applying ultrasound during the extraction, the mass transfer can be significantly improved by rupture of plant cells and particle size decrease and improved penetration of the solvent into the plant material [1]. However, the effect of UP on cell disruption in the absence of an effective solvent has been little researched.