Extraction Of Polyphenols From Spent Coffee Grounds And Its Application In Cosmetics

In recent years,with the improvement of people’s living standards,the penetration rate of coffee beverages in China has gradually increased.But at the same time,a large amount of spent coffee grounds has been produced.Most of them are discarded as wet garbage,it will cause ecotoxicological impact on the environment and waste of resources if not properly treated.Nevertheless,an important content of bioactive compounds can be found in spent coffee grounds,such as polyphenols,polysaccharides and oils,which present antioxidant,anti-inflammatory and antibacterial properties and have considerable recyclable value.In this study,spent coffee grounds were used as raw materials to extract polyphenols by ultrasound-assisted extraction.And the purification,components analysis,activity and application of polyphenols from spent coffee grounds were also studied.The main results are as follows:1.Taking the extraction rate of total polyphenols from spent coffee grounds as index,the extraction time,liquid-to-solid ratio,ethanol concentration,extraction temperature and ultrasonic power were selected as the investigating factors.Based on the results of the single-factor experiment,response surface optimization experiment was designed.The optimum process conditions for the ultrasound-assisted extraction were obtained as follows:the extraction time was 25 min,liquid-to-solid ratio was 47:1,ethanol concentration was 47%,extraction temperature was 70℃and ultrasonic power was 600 W.The extraction rate of total polyphenols from spent coffee grounds was3.263%under these conditions.2.The purification effects of six domestic macroporous resins with different polarities on the crude polyphenols extract were investigated.The result showed that the content of polyphenols was improved from 178.11 mg GAE/g to 315.95 mg GAE/g after purification with DM301 macroporous resin.The best purification conditions of polyphenols were concentration on 0.4 mg/m L,the sample flow rate of 1.0 m L/min,ethanol concentration of 70%as eluent and elution flow rate of 1.0 m L/min.HPLC/MS-MS was used to identify the components of purified polyphenols from spent coffee grounds(P-SCP).A total of 4 compounds were identified,including quinine,caffeine,3-O-caffeoyl-γ-quinide and quercetin.Through the tests of DPPH·scavenging experiment,ABTS~+·scavenging experiment and ferric ion reduction,the antioxidant capacities of polyphenols before and after purification were investigated.The results showed that P-SCP had strong in vitro antioxidant activities.3.Based on the design principles of facial cream,the raw materials were determined and a stable formulation was designed.The formulation was optimized by single-factor examination and orthogonal experiment,and the optimal contents of cetearyl alcohol(2%),mineral oil(3%),dimethicone(3%),2-ethylhexyl palmitate(3%),xanthan gum(0.02%)were obtained from the examined factors.P-SCP was added to the optimal formulation as the only functional component.The result showed that the sensory and physical and chemical properties of the cream met the industry standards.Finally,the self-made facial cream containing 0.2%P-SCP had a good antioxidant performance compared with the two commercial creams which contained various plant extracts.Therefore,P-SCP can be used as a natural antioxidant in cosmetics,providing the foundation for the reuse of spent coffee grounds and the application of polyphenols from it in cosmetics.