| Although the fish floss is nutritious and convenient,there are some problems,such as fragile texture,short shelf life,single nutritional structure,lack of functionality.The nanoemulsion edible film technology will be a novel solution to these problems.Dietary fiber polysaccharides are recognized as functional foods in the scientific community and are also one of the three matrix materials that make up the nanoemulsion edible film.As a medium,the nanoemulsion edible film can not only combine the functional polysaccharide with the fish floss to give it good functionality,but also coat the antioxidant active molecules to make the sustained release to prolong the shelf life and meet the increasingly stringent requirements of consumers.However,there are few correlation studies at present,and there is an urgent need for innovation in related processing technology and equipment.In this paper,soluble dietary fiber(SDF)and insoluble dietary fiber(IDF)were extracted from wheat bran and mung bean skin.The composition and structure of DF were characterized and identified and the functional properties were verified by in vitro antioxidant and adsorption experiments.The formula and process of fish floss were studied.The effect of dietary fiber(DF)on the lipid digestion of fish floss was analyzed by rapid evaporation ionization mass spectrometry(REIMS).The feasibility of combining DF with fish pine was discussed.The coated nanoemulsion edible film containing DF polysaccharide was prepared.The effects of nanoemulsion edible film on the morphology,water activity and flavor of the fish floss were determined.The accelerated test was used to establish a kinetic model to predict the shelf life of the coated and uncoated fish floss.The main results were as follows:1.SDF and IDF were extracted from wheat bran and mung bean skin by enzymatic hydrolysis.The total dietary fiber(TDF)content of wheat bran was 49.39%,containing 40.87%IDF and 8.52%SDF,The TDF content of mung bean skin was 70.03%,containing 59.20%IDF and 10.83%SDF.IDF was mainly composed of cellulose,lignin and insoluble hemicellulose.SDF contained pectin and soluble hemicellulose,which indicated that SDF and IDF were successfully separated and extracted.The content of IDF and SDF in mung bean skin was higher than that of wheat bran.Scanning electron microscopy,X-ray diffraction and Fourier transform infrared spectroscopy proved that the extracted SDF and IDF were standard fiber polysaccharides from the aspects of microstructure,crystallinity and characteristic functional groups.The adsorption capacities of wheat bran IDF on oil,cholesterol and sodium cholate were higher than that of mung bean skin IDF due to the loose porous surface structure,the scavenging capacities for DPPH free radical and ABTS free radicals of mung bean skin SDF were higher than that of wheat bran SDF due to antioxidants such as pectin and polyphenols.According to comprehensive analysis,mung bean skin was a better source of DF than wheat bran,so its SDF and IDF were used for subsequent experiments.2.Analysis of raw fish components showed that grass carp with high protein content and low fat content was suitable for processing fish floss.The pea powder was chosen as the fish floss excipient due to the highest sensory score and the largest b*value of the fish floss with pea powder.Univariate experiments showed that the best seasoning formula:8%pea powder,2%salt,3%sugar,and better process conditions:cooking time 30 min,initial frying time 15 min,fried crisp time 25 min.REIMS revealed the inhibitory effect of mung bean skin SDF and IDF on multistage digestion of fish floss phospholipids,The simulated in vitro digestion made the phospholipids content of fish floss without fiber decreased from 2.3%to 0.3%,the number of phospholipids decreased from 26 to 6 species,and the phospholipids concent of the fish floss fortified with mung bean skin SDF was 1.0%after digestion,which retained the diversity of phospholipids,and the phospholipids concent of the fish floss fortified with mung bean skin IDF was 0.6%after digestion,and the number of phospholipids was reduced by 8 species,indicating that the addition of fiber,especially SDF,can reduce the digestibility of phospholipids.Appropriate introduction of SDF can improve fish floss product quality and reduce lipid absorption to reduce postprandial dyslipidemia.3.The coated nanoemulsion formulation optimized by coating rate and particle size was 0.06%SDF,0.06%chitosan,0.07%sodium alginate,and 0.1%calcium chloride.The coated fish floss with 0.15 g/g nanoemulsion film-forming liquid possessed a lower water activity and the higher sensory score.The surface structure of the edible film incorporated into the nanoemulsion was rougher than that of the ordinary film,and its water vapor transmission rate was lower than that of the ordinary film,and it has good sustained release property in the simulated fat food and gastrointestinal environment release experiments.The nanoemulsion film had a positive effect on improving the morphology of the fish floss.In the high humidity environment,the Aw of the uncoated fish floss rised rapidly,while the filmed fish floss can maintain a low Aw,although the filming process will reduce the relative percentage of fish floss flavor substance,but due to the impact of the threshold,the overall impact was not large,while the film coating process can increase the types of ketones,phenols,pyrazines and positively regulate the overall flavor of the fish floss.4.The changing trends of the peroxide value(POV),thiobarbituric acid value(TBA),total number of colonies and sensory scores of fish floss coated with nanoemulsion flim,fish floss coated with common film and uncoated fish floss during storage at room temperature of 25 ℃ were studied to get the pearson correlation between POV,TBA and total number of colonies with sensory scores.POV was the key factor in the shelf life of the fish floss.Accelerated experiments were conducted to study the changes of POV during storage at 37 ℃,47 ℃ and 57 ℃ and establish the first-order kinetic model based POV.The first-order kinetic model of uncoated fish floss was A=A0exp(507.552e-25387.05/RTt),the kinetic model of fish floss coated with common flim was A=A0exp(519.465e-26093.4/RTt),the first-order kinetic model of fish floss coated with nanoemulsion flim was A=A0exp(473.76e-26592/RTt),the final prediction showed that the shelf life of uncoated fish floss,fish floss with ordinary film and fish floss coated with nanoemulsion were about 299 days,398 days and 535 days at 4 ℃.The shelf life of uncoated fish floss,fish floss with ordinary film and fish floss coated with nanoemulsion were about 138 days,179 days and 240 days at 25 ℃.At 37 ℃,the shelf life of the uncoated fish floss was about 92 days,the shelf life of the fish floss with ordinary film was about 119 days,and the shelf life of the fish floss coated with nanoemulsion was about 158 days.The shelf life gradually decreased with the increase of storage temperature.The film treatment can significantly improve the shelf life of fish floss.The treatment by nanoemulsion edible film had the best effect,which can be attributed to multi-factor barrier combination effects such as the water resistance,gas barrier properties and antioxidant function. |
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