# Characteristic Aroma Compound in Cinnamon Bark Extract Using Soybean Oil and/or Water
## 1 Introduction  
Cinnamomum cassia, known as Chinese Cinnamon, is a member of the Lauraceae family and is widely distributed in the Guangxi, Guangdong, and Yunnan provinces of China [1]. Cinnamaldehyde, the major constituent of cinnamon essential oil, has obvious analgesic and antibacterial effects [2, 3], and thus cinnamon has become a popular traditional Chinese medicine substance. In addition, cinnamon is one of the earliest spices used by humans, and its strong aroma makes it popular in Chinese cooking [4]. In China, cinnamon is the most important spice in stewed meat, used to enhance the flavor intensity of meat products and remove the peculiar odor of meat products [5]. The amount of cinnamon added to stewed meat products is approximately 1% of the meat weight [6], and China produces approximately 50 million tons of stewed meat products each year. As a result, approximately 10,000 tons of cinnamon are consumed annually by China's meat processing industry. At the end of stewing, the cinnamon is discarded, although it always has a cinnamon aroma. [PERSON] et al. [7] reported that 50% of cinnamon essential oil was still present in cinnamon even after 5 h of stewing. In the aroma research on Chinese stewed meat, the water extract of cinnamon is used for evaluating volatile compounds [4, 6, 7]. In addition, studies on the effect of spices on the flavor of stewed meat products and the identification of the major volatile compounds were performed [7, 8], and these studies only focused on the effect of spices on the flavor of meat products and ignored the fact that spices in the stewing system should be extracted into the aqueous phase beforebeing transferred to the meat. Therefore, it is an essential step to reveal the aroma formation of stewed meat by studying the dissolving rule of volatile compounds from spices to the aqueous phase during the long-term heating process, but there is not yet any research. Steam extraction is a common water extraction method for cinnamon bark, and the main purpose of this method is to obtain essential oils [1; 2]. In addition, hot-water extraction of spices is also used to obtain the essential oils via evaporation [9]. The main fields of study of essential oil components in cinnamon include (1) effects of extraction methods on essential oil components [9]; (2) aroma differences in origin, type, and parts of cinnamon [10]; (3) antioxidant properties of cinnamon essential oils [11]; and (4) antibacterial effect of essential oils [12]. Essential oils, in particular, have been widely reported as functional components of edible film in terms of shelf-life extension, increased water retention, or the inhibition of discoloration of meat products [2; 11; 12]. In addition, there are still few studies on the aroma profile of water extracts of spices. Moreover, the oil/water extraction of spices is a necessary process for the production of braised meat products. The main odorants in spices are hydrophobic, and these substances are easily soluble in oil but hardly soluble in water. For example, cinnamaldehyde, the highest percentage of cinnamon essential oil [1], has a hydrophobicity value of 1.9. As a result, the distribution of characteristic aroma compounds in the cinnamon extract between the oil phase and the aqueous phase is of particular importance in terms of the extraction efficiency of aroma substance; however, it is unknown. This experiment investigated in detail the dissolving process of aroma compounds from spices into the aqueous phase during the stewing process. Furthermore, in order to simulate the extraction process of spices in the authentic system of Chinese stew meat, cinnamon bark extract using soybean oil and/or water was designed. Soybean oil was chosen because it is a low-cost, odorless matrix with the largest market share.