Extraction And Preliminary Purification Of Procyanidins And Chlorogenic Acid From Almond

Almond skin is reddish brown seed coat of almond, blongs to the Rosaceae Prunus, is a byproduct in the process of almond industrial processing. And almond skin often used as livestock feed resources lead not to be fully utilized. In this thesis, almond skin as the research object, a new method for extracting proanthocyanidins and chlorogenic acid was established. Extraction parameter was optimized by response surface method. Subsequently, the crude extracts of almond skin were purified by macroporous adsorption resin. Then, obtained higher purification of proanthocyanidins and chlorogenic acid and achieved a waste recycling.There are three parts in this thesis:Part one:reviewFirst, an overview of almond skin, which introduced the active ingredients and research status of almond skin. Then, introduced proanthocyanidins and chlorogenic acid, respectively, including their properties, structure, method of extraction and purification, as well as other aspects of biological activities.Part two:the extraction of proanthocyanidins and chlorogenic acid of almond skinsThe evaluation index was yields of proanthocyanidins and chlorogenic acid, which were determined by vanilline-hydrochloric acid and complex chromogrnic method, respectively. This article chose surfactant polyethylene glycol (PEG) as a new extraction solvent, next measured the interference of PEG for extraction. The result showed that the interference of PEG was so little that can be neglected.Different concentrations of methanol, ethanol, acetone and PEG with different molecular weight coupled with ultrasound-assisted method to extract proanthocyanidins and chlorogenixc acid were compared. The results showed that the highest extraction yields of proanthocyanidins and chlorogenic acid from almond skin were obtained by PEG200solution combined with ultrasound-assisted method. On the basis of solvent selection and single factor experiment result, response surface method was applied to optimize the extraction conditions, the result is shown below: concentration of PEG was50%, liquid-solid ratio was20:1ml/g, ultrasonic power was120W. The actual average extraction yields of proanthocyanidins and chlorogenic acid were32.68±0.22mg/g and16.01±0.19mg/g, respectively. Finally, compared with PEG based ultrasound-assisted extraction, PEG based room temperature extraction and PEG based hot water bath extraction, the proposed method improved the yield of extraction while reduced the time if extraction.Part three:purification of proanthocyanidins and chlorogenic acid from almond skinsThree polarity of macroporous resin including X-5, D101, AB-8, LX-28and LX-38were used to purify the proanthocyanidins and chlorogenic acid from almond skins, the experiment of static adsorption capacity manifested that AB-8resin at pH4.0is better than others. The static adsorption isotherm result showed that the adsorption of proanthocyanidins and chlorogenic acid complied with Langmuir isothermal adsorption equation, belonged to monolayer adsorption. Then the static adsorption kinetic experiment revealed that the static adsorption balance time was7h. At last, dynamic adsorption and dynamic desorption experiments to studyed the effection of sample valume, desorption concentration, dynamic desorption flow rate and desorption agent for proanthocyanidins and chlorogenic acid. Then under the optimum process conditions, the purifications of proanthocyanidins and chlorogenic acid were60.90%and28.27%, respectively.This study not only has scientific value but also brings economic benefits, and provides a theoretical basis for proanthocyanidins and chlorogenic acid of almond skin in industrial production.