| The anchovy has a high fat content.When it is processed into fish meal,a large number of by-products,crude fish oil,are produced.The content of high unsaturated fatty acids in anchovy crude oil is high,and the content of EPA and DHA is more than 20%.However,crude anchovy oil contains more free fatty acids,impurities and oxidation products,so it needs to be refined in processing and utilization.This study focused on the following four links:(1)optimization of the degumming and deacidification process of anchovy oil by response surface methodology;(2)orthogonal optimization of the compound decolorization process of anchovy oil,and the effects of five common decolorants and composite decolorizers on the physicochemical properties,sensory evaluation and fatty acids of anchovy oil in the decolorization process;(3)in the deodorization process,the deodorization temperature and time were explored.The change of quality of anchovy oil in the process of odor;(4)Finally,the release kinetics,oxidation stability and shelf life prediction of anchovy oil microcapsules during storage were explored.The main conclusions of this study are as follows:(1)Citric acid and acetic acid were selected as basic decolorizers from phosphoric acid,sulphuric acid,citric acid and acetic acid degumming agents by using anchovy crude oil as experimental raw material and degumming rate as index sieve.Single factor tests were carried out on the proportion of degumming agents,degumming temperature,degumming time and degumming agent dosage,and the process parameters were optimized by response surface methodology.The optimized results are as follows: citric acid: acetic acid is 1.3:1(v/v),degumming temperature is 70?,dosage is 1.80% of oil weight,and time is 29.90 min.Under the optimum conditions,three experiments were carried out to verify that the degumming rate was 4.11%,the transparency of degummed anchovy oil was better and the fishy smell was lighter.(2)Using anchovy degumming oil as raw material,the deacidification process was optimized by using the amount of alkali added in the theory of haploid.On the basis of single factor experimental results,Box-Behken response surface methodology was designed with four factors: deacidification time,deacidification temperature,alkali concentration and super-alkali content.The deacidification process of anchovy oil was optimized with acid value as response value.Finally,the optimum conditions for deacidification of anchovy oil were obtained as follows: acid temperature 68.76?,holding time 30.14 min,alkali liquid 30.14 min.Concentration is 25.88%,super alkali content is 24.15%,acid value is 0.47744 mg KOH/g.After deacidification,anchovy oil has better transparency,less fishy smell and better oil quality.(3)In this study,the decolorization process of anchovy oil was optimized by orthogonal design based on zeolite,diatomite,activated clay,activated carbon and bentonite.The decolorization rate and the color of the decolorized oil were taken as the criteria,and the decolorizing agent was selected as the basic decolorizing agent.The optimum decolorizing process was obtained as follows: decolorizing agent added 10% of oil weight,holding time 30 min.The decolorization temperature was 90? and the ratio of composite decolorizer was 2:1(activated carbon: activated clay).The decolorization rate of the decolorized anchovy oil was 97.57%.(4)The effects of six decolorizers,zeolite,diatomite,activated clay,activated carbon,bentonite and compound decolorizer,on the physicochemical properties,sensory evaluation and fatty acid composition of anchovy oil during decolorization were investigated.The results showed that after decolorization,the acid value of anchovy oil decreased slightly,and the effect of active clay and compound decolorizer was the most obvious.Active clay is the best,while diatomite is the best for iodine value and saponification value.The uncolored anchovy oil has strong fishy odor and rancidity.After decolorization experiment,the fishy odor and rancidity of decolorized anchovy oil have been reduced to varying degrees,which shows that decolorization process has an impact on the removal of oil odor.Among them,zeolite has the strongest ability to remove odor,but the decolorization ability of zeolite is poor.At the same time,decolorization process has a significant impact on the fatty acid changes of oil.Among the six decolorants,the compound decolorizer has a more favorable effect on the fatty acid of anchovy oil.(5)The acid value and peroxide value of deodorized anchovy oil were determined at different deodorization temperature and time to study the effect of different deodorization temperature and time on the quality of the oil.The results showed that the acid value of anchovy oil decreased with the increase of deodorization time and temperature.However,with the increase of time,the influence on acid value and peroxide value of anchovy oil gradually weakened,and the peroxide value of anchovy oil decreased with the increase of deodorization time at different deodorization temperatures.When the deodorization time is too long,and then the deodorization time is increased,the peroxide value of anchovy oil decreases slowly,and the effect on the peroxide value of anchovy oil decreases.(6)Fatty acid composition and trans-fatty acid composition of deodorized anchovy oil were determined at different deodorization temperature and time to study the effect of different deodorization temperature and time on the quality of deodorized anchovy oil.The results show that the content of saturated fatty acids decreases gradually with the increase of deodorization temperature,while the content of trans fatty acids increases with the increase of deodorization temperature.For deodorization temperature,the content of saturated fatty acids decreases gradually with the increase of deodorization temperature,the content of monounsaturated fatty acids and polyunsaturated fatty acids increases gradually,and the content of trans fatty acids increases with the increase of deodorization temperature.However,the amount increased with the increase of deodorization temperature.(7)By HS-SPME-GC-MS,it was found that the content of hydrocarbons and aldehydes in the decolorized oil of anchovy oil was high,which made the oil have strong odor,earthy odor and unpleasant fatty odor.The main hydrocarbons and aldehydes were pentadecane,octadecane,octane,(E)2-octene aldehyde and(E)2-nonolenic aldehyde.Keywords:anchovy oil,Refining process optimization,Microcapsule;quality;Fatty acid composition,Volatile components,Release kinetics,oxidation kinetics,Shelf life(8)Release kinetics of anchovy oil microcapsules were studied under storage conditions of 25%,35%,and 45%,respectively.The results showed that the release reaction of anchovy oil microcapsules under three different storage conditions was between diffusion kinetics and first-order release kinetics.According to the release reaction equation,the release rate of microcapsules increased with storage temperature.The degree of microencapsulation increases gradually,so the storage conditions of microencapsulation should be placed at a lower storage temperature for storage.(9)The anchovy oil microcapsules were stored at 25~45?for 63 days,and the refined anchovy oil was stored at 25? for 63 days.According to the zero-order reaction oxidation kinetics formula and the first-order reaction oxidation kinetics formula,the oxidation kinetics of the anchovy oil microcapsules was linearly fitted,and the first-order reaction kinetics was determined to be the first-order reaction kinetics.At the same time,it is predicted that the shelf life of the three kinds of microcapsules are 201 days and 97 days for the anchovy oil microcapsules stored at 25? and refined anchovy oil,and 51 days for the anchovy oil microcapsules stored at 45?. |
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