Optimization of subcritical water extraction of phenolic compounds from Ziziphus jujuba using response surface methodology: evaluation of thermal stability and antioxidant activity

Abstract

Background The jujube is mainly grown in the subtropical and tropical regions of Asia. Due to owning bioactive compounds such as polyphenols, it was considered as medicinal and nutritional plant in traditional medicine. This study aimed to extract phenolic compounds from Ziziphus jujuba using subcritical water (SCW) process. The possible combinations of temperature, time, and fruit-to-solvent ratio were investigated using response surface methodology. Results The total phenolic compounds (TPC) and radical scavenging capacity (RSC) of 975.94 mg/g and 53.98%, respectively, were recovered at optimum extraction conditions (170 °C, 74.49 min, and fruit-to-solvent ratio of 1:5.29). The extract obtained in SCW optimum conditions was put under thermal treatments including low temperature long time, high temperature short time, cooking, baking, and sterilization. The results showed after baking, the amount of TPC, RSC, and absorbance at 420 nm increased. The quantity of gallic acid, chlorogenic acid, p-coumaric acid, ferulic acid, and rutin increased significantly. The efficiency of SCW extract in retarding lipid oxidation in bulk oil and O/W emulsion model was investigated at 50 °C for 10 days. After 10 days, the peroxide value of bulk oil (1.1 meq O2/kg) containing SCW extract was lower than O/W emulsion model (2.2 meq O2/kg). Conclusion The subcritical extracted phenolic compounds seem to have good antioxidant activity as well as thermal stability for using in food or drug industries.

Extraction of Procyanidin B2 From Apple Peel Using Subcritical Water

“…The predominant peak in the UV-Vis spectra of all the water-soluble products was observed at approximately 280 nm. We hypothesized that the intramolecular hydrogen bonds of the phenolic groups of the lignin component of the apple peel were destroyed during subcritical water treatment [23][24][25]. Ersan et al [23] extracted the components of Pistacia vera L. hull, including phenolic compounds, using subcritical water in the temperature range of 110-190 °C.…”

“…Lachos-Perez et al [24] also used subcritical water to extract phenolic compounds from defatted orange peel in the temperature range of 110-150 °C. Furthermore, Niazmand et al [25] optimized the extraction of phenolic substances from Ziziphus jujuba using the subcritical water technique. Using a response surface method, they evaluated the effect of temperature on the extraction process and confirmed that the extraction yield of phenolic substances increased significantly upon increasing the temperature from 110 to 170 °C.…”

“…Therefore, the solubility of less polar compounds in liquid water under these conditions is improved. In addition, the efficiency of subcritical water extraction can be enhanced by increasing temperature because rapid thermal desorption is favored and the vapor pressure of the target compounds is higher at high temperatures [1,2,25].…”

“…In addition to the extraction temperature, the extraction time significantly affects the subcritical water extraction process [24,25,28]. Herein, the extraction time was the time the liquid water came in contact with the apple peel under the predetermined experimental conditions.…”

Advanced extraction techniques for Berberis species phytochemicals: A review

“…Subcritical water extraction (SWE) is an alternative green method for eliminating the use of toxic organic solvents for the extraction of bioactive compounds. In SEW, subcritical water is maintained at high temperature and pressure to retain the liquidity of subcritical water (critical temperature of water = 374 °C, critical pressure of water = 22.1 mPa) (Niazmand et al ., 2021). At high temperatures, water has a lower dielectric constant, which reduces the strength of the hydrogen bonds and reduces its polarity reaching a polarity level similar to that of methanol and ethanol, thus making it capable of extracting a wider range of phenolic compounds (Ko et al ., 2020).…”