Regulation And Mechanism Of Cod Polypeptides On Browning Of Fresh-cut Potato

With the quickening pace of people's life,the demand for fresh cut fruits and vegetables is increasing,and its market potential is huge.However,cleaning,peeling and cutting during the processes of fresh-cut fruits and vegetables have broken the original physiological process of fruits and vegetables,making the series of metabolic processes quite different from the whole fruits and vegetables,and the quality deterioration is more likely to occur during the storage.As the main product of fresh-cut fruits and vegetables,the browning of fresh-cut potatoes during storage is the main metabolic deterioration affecting their appearance and nutritional quality.Although chemical anti-browning agents such as Vc and citric acid have certain anti-browning effects,it is of great significance for the fresh-cut industry to develop integrated anti-browning and antibacterial agents with functional nutritional biological activities.Based on the fresh cut potato slices as the research object,with different concentrations of cod peptides processing fresh cut potato chips,the color change of potato slices has been studied,regulation and control of enzymatic browning key enzyme POD,PAL,PPO dynamic regulation rules,enzymatic browning substrates total phenol,cell membrane integrity and the changing rule of the oxidation products such as MDA,made clear the cod peptide prevents browning control effect,and through the simulation experiment in vitro and cod random peptide composition and relative content analysis,preliminary illustrates the mechanism of action of cod polypeptides.The specific research results are as follows:(1)By 1.0%(w/w),0.1%(w/w),0.01%(w/w)three cod peptide concentration treatment group and control group(group)water treatment for fresh-cut potato slices in brown 8 days 4? storage period color variation analysis results show that 0.1%of cod peptide treatment can restrain the good fresh cut potato slices of browning in brown,its a red degree values than the control group significantly reduced,and significantly higher brightness L value,color composite indicator ? E minimum value change.However,what was more interesting was that the potato chips treated with 1%(w/w)cod polypeptide solution did not inhibit browning,but the browning degree from day 0 was significantly higher than that of the control group.It can be seen that cod polypeptide has a dual mechanism of low concentration inhibition and high concentration promotion on the regulation of browning of fresh-cut potato chips.(2)Changes in POD and PPO of polyphenol oxidase,a key enzyme regulating browning,indicated that 0.1%(w/w)cod polypeptide treatment could effectively inhibit POD and PPO activities during storage compared with other treatment groups and control groups.PAL activity analysis also showed that 0.1%(w/w)cod polypeptide treatment could effectively inhibit the polyphenol content and the key enzyme activity.In addition,by measuring MDA content of membrane lipid oxidation products and changes of membrane permeability of indicator indexes of cell membrane integrity,it was shown that cod polypeptide with 0.1%concentration played an effective regulatory role in the integrity and antioxidant activity of fresh cut potato chip film,inhibiting further oxidative damage to the tissues that suffered from mechanical injury.The 1%cod polypeptide treatment had opposite promoting effect on the above indexes and effectively activated the enzymatic browning.(3)The composition and relative content of cod polypeptide were determined by GC-MS,and the sequence composition and function of related polypeptide chain were predicted and analyzed.The cod polypeptides used in this study were randomly hydrolyzed polypeptides,consisting of more than 1,700 polypeptides,of which 31aa and 35aa peptides accounted for a large proportion.Some peptides with PPO inhibitory activity and amino acid residues were found in random polypeptides of cod.(4)In order to explore the concentration effect of cod polypeptide on potato browning and the mechanism of duality,the hypothesis that Vc in potato may cause non-enzymatic browning with cod polypeptide was put forward.High concentration of cod in vitro simulation peptide reaction with Vc,use "the function of the wavelength scanning ultraviolet spectrophotometer measured the absorption peak of simulation system,the cod and cod peptide solution polypeptide Vc+ simulation set at 230 nm and 275 nm absorption peak,the product with non-enzymatic browning of furfural two absorption peak is consistent,and add the Vc simulation system in wider near the two peaks,speculated that the enzymatic browning may exist,but its mechanism remains to be further explored.