不同浓度食用酒精对鲜切山药褐变及质构品质的影响

Effects of Different Concentration Edible Alcohol on Browning and Texture Quality of Fresh-Cut Yams During Storage

鲜切加工时山药易发生褐变、软化和营养损失等问题。为探究食用酒精(Edible alcohol,EA)对鲜切山药褐变及质构品质的影响,研究设定3个浓度处理(10%、20%和40%),以水处理为对照,处理后4℃贮藏7 d,测定失重率、质构、总酚含量、多酚氧化酶(Polyphenol oxidase,PPO)活性以及过氧化氢酶(Catalase,CAT)活性和1,1-二苯基-2-三硝基苯肼(1,1-Diphenyl-2-picrylhydrazyl,DPPH)自由基清除率等品质和生理指标。结果表明:第7天,3种处理均明显延缓果肉褐变,同时降低失重率,其中10%和20%EA处理抑制褐变效果更显著。7 d内,3种处理均不同程度延缓总酚的积累(P<0.05),并抑制PPO活性升高。第4天,10%EA处理总酚含量低于40%EA处理,而40%EA处理PPO活性低于另外2个处理。第7天,10%和40%EA处理的PPO活性均低于对照(P<0.05)。3种处理CAT活性始终高于对照,其中10%EA处理的活性最高,7 d时20%EA处理CAT活性也高于40%EA处理(P<0.05)。另外7 d时,3种处理的DPPH自由基清除率亦高于对照(P<0.05)。3种处理均可延缓硬度、脆性、回复性的上升及黏附性的下降(P<0.05)。此外不同处理的硬度和脆性均与黏附性(紧实度)呈负相关,而它们与胶着性、咀嚼性和回复性正相关。综上所述,3种浓度EA(尤其是低浓度10%和20%)处理通过延缓山药总酚积累及PPO酶活性升高,同时升高抗氧化酶系统CAT活性及DPPH自由基清除率,最终降低山药失重率并延缓黏附性下降以及硬度和脆性的上升,抑制果肉褐变,保持山药质构和外观品质。

Quality deterioration,such as browning,softening and nutrition loss,was prone to occur in processed yams.The effect of edible alcohol(EA) on the browning and texture quality of fresh-cut yams were investigated.Yams treated with water(as control) and three concentrations of EA(10%,20%and 40%) respectively,then were stored at low temperature(4 ℃) for 7 days.Quality and physiological indicators such as weight loss rate,texture,total phenolic content,polyphenol oxidase(PPO) activity,antioxidant enzyme catalase(CAT) activity and 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical clearance rate were measured.The results showed that the three EA treatments delayed the browning of freshcut yams and reduced the weight loss rate at the 7th day,especially the browning inhibitory effects were more pronounced in 10% and 20% EA treated yams.The increases in total phenolic content and PPO activity were all reduced in the three EA treatments at different degrees(P<0.05).At the 4th day,the 10% EA treatment lowered content of phenolic in comparison with 40% EA treatment,however,lower PPO activity was found in the 40% EA treatment.At the 7th day,the PPO activity in the treatments of 10% and 40% EA were lower than that in the control(P<0.05).Within 7 days,the three EA treatments all enhanced CAT activity,and it was the highest in the 10% EA treatment(P<0.05).Furthermore,the 20% EA treatment showed higher CAT activity than the 40% EA treatment at the 7th day.In addition,the three EA treatments also increased DPPH clearance rates at the 7th day(P<0.05).The three EA treatments delayed the increases in hardness,fracturability,and resilience,as well as the decreases in adhesiveness(P<0.05).In addition,the hardness and fracturability of the EA treatments were negatively correlated with adhesiveness,while they were positively correlated with gumminess,chewiness,and resilience.Therefore,the above three EA treatments(especially for low concentrations of 10% and 20%EA treatments) could improve the antioxidant capacity of fresh-cut yams by delaying the increases in total phenolics and the PPO activity,and enhancing the CAT activity and DPPH clearance rate.Ultimately,they reduce the weight loss rate,retard the decline of adhesiveness and increases in hardness and fracturability,inhibit the browning of flesh,and maintain the texture and appearance quality of yam.