The Changes Of Physiological And Physicochemical Properties Of Cabbage During Fresh-cut And Dry Processing

Cabbage is one of the main vegetables consumed in China.It is a cruciferous plant and contains a variety of glucosinolates.The isothiocyanate have high anti-cancer effect.Preservation and drying are two important processing methods of cabbage.It is of significance to explore the physiological,biochemical and quality changes of cabbage during freshing cutting and drying.In this thesis,cabbage was used as an experimental material.The effects of ozone combined with phytic acid treatment on the physiological and biochemical of fresh-cut fruit cabbage were first studied.Meanwhile,the effects of blanching and ultrasonic intensification of hot air drying on cabbage property were studied.The changes of glucosinolates and their degradation products in cabbage under different processing methods were further studied.The results are shown as follows:1.The effect of ozone on the germicidal efficacy and quality of fresh-cut cabbage were studied.The fresh-cut cabbage was treated by ozone with different concentrations(10,30,50 ppm).It was found that the the number of Escherichia coli decreased by 3.97 LogCFU/g after 50 ppm ozone treatment for 15 min,and the number of Pseudomonas fluorescens decreased by 0.82 LogCFU/g.Ozone at 10,30 and 50 ppm was used to treat fresh-cut cabbage for 15 min.After treatment,they were stored in polyethylene fresh-keeping bag and stored at 4?.It was found that the total number of colonies,mycophillas and Escherichia coli in cabbages treated by 30 ppm ozone decreased by 1.50,0.24 and 1.46 respectively.At the same time,30 ppm ozone treatment inhibited the degradation of soluble sugar,soluble protein,ascorbic acid and total glucosinolates,increased the content of total phenol and isothiocyanate,inhibited the activity of POD and CAT,and increased the activity of SOD and PAL.In summary,30 ppm ozone treatment effectively inhibited the growth of microorganisms,extended the self-life of fresh-cut cabbage,and improved the quality of fresh-cut cabbage.2.The effect of ozone combined with phytic acid treatment on fresh-cut fruit cabbage during storage was studied.Ozone treatment(30 ppm,10min)along,phytic acid immersion(0.5 mmol/L,15min),and combined ozone and phytic acid treatment(phytic acid immersion at 0.5 mmol for 15 min followed by ozone treatmen at 30 ppm for 10 min)were used for the preservation of fresh-cut fruit cabbage.The fresh-cut fruit cabbage without any treatment was regarded as control group.The results revealed that the contents of soluble sugar,soluble protein and ascorbic acid in samples treated by combined ozone and phytic acid were 21%,28%and 12%higher than that in control samples on the 8tri day of storage.Meanwhile,combined ozone and ascorbic acid treatment led to a higher retention of glucosinolate and isothiocyanate in fresh-cut fruit cabbages.Furthermore,ozone and phytic acid treatment enhanced the content of total phenolics and the activities of superoxide dismutase and phenylalanineammonialyase,as well as inhibited the activities of peroxidaseand and catalase.Besides,the aerobic plate count in the samples treated by combined ozone and phytic acid was 2.10 log cfu/g lower than that in control samples.In summary,the combination of ozone and phytic acid could improve the quality of fresh-cut fruit cabbage,thus extending the shelf life.3.The effects of blanching pretreatment and ultrasonic enhanced hot air drying on the quality of cabbage were studied.Meanwhile,the glucosinolates and their degradation products during the drying of cabbage were analyzed.In this experiment,cabbages were pretreated by blanching(30 s,100?)and then dried by hot air(60?)and contacting ultrasound(492 W/m2,1131 W/m2).The results showed that the drying time of the sample was decreased by 71.42%after blaching pretreatment followed by hot air drying enhanced by ultrasound at 1131.06 W/m2.Meanwhile,the drying rate increased by 98.27%.Furthermore,blanching pretreatment and sonication at 1131.06 W/m2 significantly(kp<0.05)improved the color and water rehydration of the products and reduced the loss of ascorbic acid and total phenol.In the drying process,the degradation of glucosinolates was inhibited(p<0.05)and the formation of the harmful product 3-indolonitrile was reduced.Therefore,the combination of blanching pretreatment and sonication at 1131 W/m2 can effectively shorten drying time,shorten drying time and improve cabbage quality.4.The air humidities during storage of cabbage powders were screening,and the changes of the glucosinolates and quality of cabbage powder during storage were studied.Cabbage powders were stored in different humidity environments(11%,33%,55%)for 90 d.The results showed that cabbage powderd under 11%humidity condition had better flow properties.The rest angle and the sliding angle were smaller than that of other samples,while the bulk density and tapped density were larger.No caking problem emerged.Meanwhile,cabbage powders had lower moisture content,higher WHC and solubility,and better color.The loss of ascorbic acid in cabbage powder decreased by 80.22%,and the loss of glucobrassicin decreased by 21.51%compared with cabbage powders stored under 55%conditions.Therefore,cabbage powders had the best quality when they were stored in a humidity of 11%.