Study On The Green Preparation Process Of Polyphenol-rich Peanut Oil

Natural plant polyphenols are a general term for a group of organic compounds with polyphenolic hydroxyl groups,which have a variety of activities such as antibacterial,antiinflammatory,antioxidant,anti-radiation,and hypotensive.Dietary intake of plant polyphenols and other beneficial ingredients is a new demand in nutritional health food.Enriching beneficial components through edible fats and oils is an important trend in the development of the fats and oils industry.The development of edible oils rich in plant polyphenols can provide a new way for our residents to consume polyphenols.Peanut oil with unique flavor and rich nutritional value,is an important edible oil category in China.However,the content of plant polyphenols in existing peanut oil is low and cannot meet the demand for ingested plant polyphenols.The existing solvent extraction method for extraction enrichment of plant polyphenols is complex,with high production costs and high food safety risks.In this paper,we innovatively prepared polyphenol-rich peanut oil by directly extracting peanut oil to enrich the plant polyphenols in peanut skin or peanut root.This preparation process does not involve organic solvents,which is green,non-polluting and low-cost.Based on this process,we combined the aqueous enzymatic preparation of peanut oil and peanut oil extraction of plant polyphenols to successfully achieve the preparation of polyphenol-rich peanut oil by the aqueous enzymatic method.The research in this paper provides a new idea for the efficient and green preparation of polyphenol-rich peanut oil.Firstly,plant polyphenols in peanut skin were extracted by peanut oil as an extractant to prepare polyphenol-rich peanut oil.It was found that pretreatment of peanut skin could significantly improve the polyphenol extraction rate,and ultrasonic cell crushing(ultrasonic treatment after mixing peanut skin and water)was the most effective pretreatment method.The optimal conditions were obtained by single-factor and response surface optimization tests:ultrasonic time of 5.5 min,ultrasonic power of 225 w,peanut skin-water mass ratio of 1:10,peanut skin-oil mass ratio of 1:8,extraction temperature of 80°C,and extraction time of 1.4 h.Under these optimized conditions,the extraction rate of peanut skin polyphenols was 3.41%,and the polyphenol content in peanut oil reached 418.20 mg GAE/kg.The study showed that the polyphenol extraction process does not affect the crystallization characteristics of peanut oil and is also applicable to high oleic peanut oil,indicating that the method has good universality of application.The resulting polyphenol-rich peanut oil met the quality standard for edible peanut oil,and its antioxidant capacity was significantly enhanced.Next,polyphenol-rich peanut oil was prepared by extracting plant polyphenols from peanut roots with peanut oil as the extractant.The extraction rate of peanut root polyphenols was significantly increased by using ultrasonic cell crushing pretreatment(peanut root and water mixture followed by ultrasonic treatment)of peanut root.The optimal conditions were obtained by single-factor and response surface optimization tests: ultrasonic time 13 min,ultrasonic power 325 w,peanut root-water mass ratio 1:8,peanut root-oil mass ratio 1:6,extraction temperature 80°C,and extraction time 1.3 h.Under these optimal conditions,the extraction rate of peanut root plant polyphenols was 16.41%,and the polyphenol content in peanut oil reached 596.03 mg GAE/kg.The study showed that the polyphenol extraction process does not affect the crystallization characteristics of peanut oil and is also applicable to high oleic peanut oil,indicating that the method has good universality of application.The resulting polyphenol-rich peanut oil met the quality standards of edible peanut oil,and its antioxidant capacity was significantly enhanced.Finally,the polyphenol-rich peanut oil was prepared by an aqueous enzymatic oil production process coupled with a polyphenol extraction process by mixing the peanut skin and peeled peanut kernel after ultrasonic pretreatment.The free oil yield and peanut oil polyphenol content were higher when the Alcalase 2.4 L protease enzyme was used for digestion.Under these conditions,the free oil yield and polyphenol content of peanut oil were83.28% and 327.52 mg GAE/kg,respectively,which were significantly higher than those of conventional aqueous enzymatic oil production content.Therefore,the simultaneous extraction of plant polyphenols in peanut skin by aqueous enzymatic method could improve the plant polyphenol content in peanut oil and the free oil yield by aqueous enzymatic method to a certain extent.