Study On The Effects Of Processing Units On Secondary Metabolites And Their Functional Properties In Carrot Processing

Plant secondary metabolites is a category of minor molecule compounds that is not necessary compounds in plant growth and development.Plant secondary metabolites have not only significative on plant ecology and physiology,but also have important biological activity to human being.Therefore,the systemic study on alteration of secondary metabolites in growth and processing is very significative.Food of plant origin is not only food resource to acquire nutrition,but also a approach of intake in plant secondary metabolites,however,in past years,Food of plant origin was emphasized on carbohydrate,fat,protein,solid content and acidification,few focused on secondary metabolites and functional properties in Food of plant origin,such as pigment,polyphenol and essential oil and so on.Therefore,there is very significative that the systemic study on alteration of the major secondary metabolites and functional properties.The main objective of the present study was to investigate the effects of processing units on carotene,polyphenol and essential oil during production of carrot juice,and evaluate their functional properties.The main results as follows.1.Effects of processing units on caroteneThe harvest of 12 weeks was best,because contents ofα-carotene,β-carotene and lutein were most high,based on HPLC analysis results.To peel method of carrot,peeling with compound phosphate was optimal to peel off carrot skins, compared to other methods,because carotene content determined in carrot juice was higher,which was peeled by compound phosphate.The optimal condition was 1.0%Na₃PO₄,4.0%Na₂HPO₄, 3.0%Na₄P₂O₇.In blanch treatment,blanching temperature and time strongly influenced carotene content in carrot juice,the optimal condition of blanching was 86℃,10minutes.Enzymatic treatment strongly influenced carotene content in carrot juice,in particular use sequence and mixture ratio of cellulase and pectase.The maximum carotene content was showed in enzymatic treatment by pectase using prior to cellulase and higher ratio pectase in mixture enzymes, based on determine of carotene content SEM observes.Carotene degradation fitted a first-order reaction model during storage,the degradation rates of carotene increased with increasing sterilization temperature during heating,but sterilization with high temperature contributed to the stability of carotene within carrot juice during storage.During carrot juice processing,there were stereoisomer phenomena inα-carotene,β-carotene and lutein,carotene stereoisomers were not observed in carrot juice with enzymatic treatment.However, carotene stereisomers were determined in carrot juice by blanching and sterilization treatment.2.Effects of processing units on carrot essential oilBy GC-MS analysis,37 chemical compositions were identified in essential oil from carrot juice. Ascanbeseen,carotol(20.20%),sabinene(12.80%),caryophyllene(8.04%) andα-pinene(6.05%) were main components of essential oil.Blanching and sterilization treatment had significantly influence on chemical compositions of essential oil from carrot juice,there were decreasing in chemical compositions of essential oil and loss in minor molecular weight terpene compositions.However,essential oil of carrot juice with enzymatic treatment was not significantly observed on decreasing of chemical compositions, compared to control.In antimicrobial activity determining,carrot juice essential oil had a wide range of antimicrobial activities against all 8 microorganisms,and possessed much higher against Gram-negative bacteria than Gram-positive bacteria,moreover,there were mild antimicrobial activities against yeast and mould.In general,essential oil of carrot juice was much more effective antimicrobial activities by enzymatic treatment than was by blanching and sterilization treatment,but essential oil by enzymatic treatment showed weaker effective against Salmonella bacteria than the control.SEM observations showed the physical damage and considerable morphological alteration to all 8 tested bacteria treated with essential oil from carrot juice,moreover,the modes of damage of bacteria treated with essential oil depended on the type of microorganisms.3.Effects of processing units on carrot polyphenolBased on identification results by LC-MS,phenolic compounds extracted from carrot juice were chromatographic separated 6 components,and 5 components were identified as 5-O-trans-caffeoylquinic acid,5-O-cis-caffeoylquinic acid,dicaffeoylquinic acid,O-p-coumaroylquinic acid, the predominant component was 5-O-trans-caffeoylquinic(chlorogenic acid).Enzymatic treatment and blanching contributed to enhance polyphenol content of carrot juice during carrot juice processing,and decreasing in polyphenol content was found on carrot juices with sterilization treatment.Difference in phenolic compounds extracted from carrot juice depended on different unit processing,which was ascribed as degradation and stereoisomers functions.The polyphenol extracts from carrot juice showed higher antioxidant activity in scavenging DPPH free radical and Fe²⁺ chelating capacity than in lipid peroxidation protection,and varying degrees of efficacy in each assay in a dose-dependent manner.Therefore,carrot juice polyphenol can serve as a potential food antioxidant.Degradation of carrot juice polyphenol compounds fitted a first-order reaction model during storage,the degradation rates of polyphenol compounds increased with increasing pH value,but sterilization temperature had no significantly influence on stability of polyphenol compounds during storage.