Study Of Antioxidant Activity And Nitrite Scavenging Capacity Of Ginger Extract

The rhizome of Zingiber offinale Roscoe,commonly known as ginger,is native to Asia.It has many physiological functions,such as antioxidation,anti-inflammatory activity and so on.The pungency of ginger is due primarily to the gingerols,which are identified as the major active components in ginger.Many researches on the bioactivities of ginger extract have mainly foucused on antioxidant activity at home and abroad.Studying the active compounds of ginger usually involves the traditional mode which is based on separation,purification and identification.It will increase the blindness of isolation and identification of active components and be detrimental to the development and utilization of ginger.In this study,we optimized the cellulase-assisted extraction conditions of gingerols and studied the antioxidant and nitrite scavenging activities of ginger extract under optimal conditions.In addition,we quickly screened and identified the antioxidant components from ginger extract.The influencing factors and main active fractions of ginger extract for nitrite scavenging were discussed,and its practical effects in food were also investigated.1.The single factor method and orthogonal array design were used to optimize the exrtaction conditions of gingerols.The optimal hydrolysis conditions were as follows:hydrolysis time,90 min;extraction temperature,50 ?;enzyme dosage,0.95%;solid/liquid ratio,1:50.Under such conditions,the extraction yield of gingerols was 1.85±0.07%.The enzyme-assisted extraction gave higer yield of gingerols than ethanol extraction.Under these conditions,the ginger extract contained 4.64±0.15%gingerols,4.94±0.03%total phenolics and 40.00±0.35%polysaccharide.2.The ability of different polarity fractions(ginger extract,dichloromethane-soluble fraction and water-soluble fraction)to scavenge DPPH and ABTS free radicals and reduce ferric ions were measured.The results indicated that the antioxidant capacity of different fractions could be ranked in the following order:dichloromethane-soluble fraction>ginger extract>water-soluble fraction.Six gingerol-related compounds from dichloromethane-soluble fraction were tentatively identified by analyzing the mass spectral data and retention times with those of reference standards and published data.The off-line HPLC-DPPH· system was used to quickly screen the antioxidants from dichloromethane-soluble fraction.The fourteen compounds separated by HPLC all presented the DPPH scavenging activity to different extents.6-shogaol had the strongest antioxidant capacity among the identified substances.However,Peak 1,4,5,12,13 which were not identified also had strong antioxidant activity.3.Based on the single factor method,orthogonal array design was used to search for the optimal reaction conditions for nitrite scavenging.The reaction of 17.5 mg/mL of ginger extract for 15 min at 100 ? gave a maximum scavenging rate of 99.32±0.22%.The nitrite scavenging ability of different polarity fractions(ginger extract,dichloromethane-soluble fraction and water-soluble fraction)were measured.The results showed that dichloromethane-soluble fraction and water-soluble fraction all presented the nitrite scavenging activity to a certain extent,in which dichloromethane-soluble fraction had the highest activity.According to the analysis,there was a significant positive correlation between the total phenolics and the nitrite scavenging ability of each fraction.The phenolics especially medium polar phenolics of ginger extract might be related to its nitrite scavenging activity.4.The effects of ginger extract amount and nitrite amount on residual nitrite in minced pork were examined.The results indicated that ginger extract can effectively reduce residual nitrite of minced pork,but its effect was influenced by nitrite amount.During the curing process,ginger extract and sodium D-isoascorbate reduced residual nitrite and increased color characteristics of the meat mixtures to different extents.The ability of sodium D-isoascorbate to reduce the residual nitrite was stronger than ginger extract.The lightness of minced pork added with ginger extract was much higher,but they had no significant effects on integrated color characteristics of minced pork.