[THESIS] EXTRACTION OF CASHEW CATECHINS

Hello teachers, I'm a senior at HCMUT in Vietnam. In this semester, I'm doing my thesis in English. It's really hard to do that, so please check some passages in this for me <3 Thank you so muchhh.

The desire for having better living conditions, in modern life, is increasing day by day. People strongly care about antioxidants, especially natural products which can use as nutraceuticals. They are natural antioxidants which have positive effects on people’s health and their immune systems. Nutraceuticals currently are being used worldwide, and have an important role to play in human life. These natural compounds could be easily found in plant-based parts such as fruits, seeds, leaves, etc. These days, people figure out the presence of these antioxidants in root and testa due to their pharmaceutical benefits, and the cashew testa is considerably involved in this scientific debate [1, 2].

Anacardium occidentale L. (commonly known as Cashew) is was introduced into Vietnam in the 19^th century due to the suitable soil and climatic conditions. Thesedays, the cashew tree is grown around the world especially in Vietnam, India, Nigeria, Indonesia, Benin, Guinea-Bissau, Philippines, and the Ivory Coast [3]. In the early 1980s, cashew tree was used as a forest tree, a shade tree for home gardens, and soil erosion in Vietnam. As the result, the crop gave extremely poor yields and low-quality nuts. After ten years, the Ministry of Agriculture realised the potential value of this plant, beginning to recognize the crop as an industrial crop. Since then, there was a boost in the area of production [4, 5]. The most valuable part from the cashew tree is the cashew nut which is removed from the shell and testa. On the other hand, cashew apple juice is commercialized as concentrated juice or ready-to-drink, or being used as the material to prepare beverage in Brazilian Northwest named “cajunia”, for instance [3]. Besides, the cashew tree’s applications in popular medicine is considerable, common uses include analgesic, diuretic, antiseptic for oral hygiene, asthenia treatment, respiratory problems, genital infections, and skin diseases [6].

In fact, the cashew tree is suitable with warm and moderately dry climates, between 18 – 38 , and distributed in the height of 0 – 600 meters above the sea level. The increase in distributed height can lead to the slow development of ineffectiveness. As a result, the height of 1000 meters is an upper limmit that the cashew tree can survive. It needs at least around 2,000 hours of yearly sun exposure [7]. Fruit set happens in the dry season, and it takes normally around two months from fruit set to harvest. The nut establishes first, then the peduncle grows rapidly until its ripening stage [3]. At present, the cashew is planted and raised in many Vietnamese provinces like Tayninh, Binhthuan, Daklak, Daknong, Binhphuoc, Lamdong, etc [4, 5]. According to the FAO, all the worldwide countries produced 3,713,467 tons of cashew nuts (with shell) in the year 2014 [3].

The cashew nut obviously is the most financial part, consisting: shell, kernel, and testa [6] that being illustrated in Figure 1.1. The previous studies on the coat were scarce, but the potential benefits that could be utilized from testa have not received much attention in recent years [2]. Testa is the reddish-brown-coloured and thin skin but could be able to protect the nut inside event when it only constitutes about 1 – 3% of the total weight of cashew nuts. In the food industry, however, the removal of this part usually should be done at barely high temperate (from 75 to 200 ^oC) after shelling because of its bitter or astringent. As the result, the final products could achieve a higher price on the available market [2]. With the development of technology and chemical analysis equipment, researchers figured out that cashew testa is a rich source of hydrolysable tannins [2] with (+)catechin and ()-epicatechin as major polyphenols [1]. For instance, the amounts of (+)catechin and ()-epicatechin in the cashew testa is five-folded in comparison with that of dark chocolate [8]. Also, the maximum amount of the catechin found in aqueous extract of cashew testa was up to 13.65% of plant extracts by using Shoxhlet Extractor and Freeze Dryer [9]. However, cashew is also a good source of terpene, flavonoid, terpenoid, tannin, and sterol.

These catechins have surpassing pharmacological activities and antioxidant properties that attracted more interest from the academic figures [6]. Thus, the utilization of cashew testa on the industrial scale to extract the polyphenols compounds, especially catechins, is a potential and financial way in the future. Extraction is the most important step to take the polyphenols out. Due to the previous published researches, there are several ways that can be applied in the extraction such as original extraction, microwave-assisted extraction, ultrasound-assisted extraction, or the extraction with supercritical fluids [10], typically supercritical carbon dioxide extraction.

Figure 1.1. Cross section of a cashew nut [6].

In the past years, industrial and governmental research institutes have put efforts into finding practical ways to produce highly pure catechin compounds [11] as the higher catechin purity which is an economic value of the final products obtained. The isolation and purification of pure compounds, however, is usually difficult, tedious, and expensive [9]. The application of HPLC method for the isolation and quantification of catechins in the cashew testa was established [9], but there are no report on the purification of cashew catechin on the industrial scale.