| Cyperus esculentus is a high-quality,high-yield herbaceous plant that contains nutrients such as starch,oil,and cellulose,and has high comprehensive utilization value.Among them,Cyperus esculentus oil,like olive oil and camellia oil,is characterized by a relatively high proportion of oleic acid in the fatty acid composition and has certain health benefits.In addition,Cyperus esculentus has the advantages of short growth period,less diseases and insect pests,and lower requirements for growth conditions,so it can be sown in different soil of various provinces in China.China is a large edible oil consumer,and the domestically produced edible oil is relatively small,which is far behind the market demand.At the same time,it is accompanied by the low utilization rate of edible resources.Therefore,this paper takes Cyperus esculentus as the research object,uses aqueous enzymatic method to extract Cyperus esculentus oil,optimizes the aqueous enzymatic extraction process through single factor analysis,response surface analysis and mixture experiment,and explores the physical and chemical properties of Cyperus esculentus oil,so as to provide a new way for the efficient extraction of Cyperus esculentus oil.At the same time,in order to improve the comprehensive utilization rate of Cyperus esculentus,starch extraction and bean-dregs product development were carried out on the residue after oil extraction.The main research contents and conclusions are as follows:(1)The effects of cellulase,alkaline protease,?-amylase,and pectinase on the oil extraction rate of Cyperus edulis were compared and analyzed.The results showed that alkaline protease had the best oil extraction effect.Through single-factor experiments,the effects of the addition of alkaline protease,enzymolysis time,temperature,p H,and materialto-liquid ratio on the oil extraction rate of Cyperus esculentus were studied.Then the BoxBehnken response surface method was used to optimize the experiment.The experimental results showed that when the ratio(g/m L)of material to liquid was 1:5,the addition amount of alkaline protease was 1.70%,the p H of enzymatic hydrolysis was 8.6,the enzymatic hydrolysis temperature was 55?,and the enzymatic hydrolysis time was 4.6 h,the highest oil extraction rate was 80.43%.At the same time,the changes in the cell structure of Cyperus esculentus before and after enzymolysis were compared and analyzed,and it was found that the cell structure of Cyperus esculentus was damaged greatly after alkaline protease treatment,indicating that the alkaline protease could be used to extract Cyperus esculentus oil.(2)On the basis of single enzymatic extraction of oil from Cyperus esculentus,the effect of multi-step enzymatic hydrolysis on the extraction rate of oil from Cyperus esculentus was studied,and the optimal oil preparation process was obtained: firstly,it was pretreated with a complex enzyme composed of cellulase,pectinase,and ?-amylase,and then hydrolyzed with alkaline protease.The best ratio of the complex enzyme was cellulase: pectinase: ?-Amylase= 0.59:0.24:0.17.According to this ratio,the extraction rate of Cyperus esculentus oil was85.61%,which was significantly higher than that of single enzyme hydrolysis.(3)Comparing the quality of Cyperus esculentus oil extracted by single enzymatic hydrolysis method,compound enzyme multi-step hydrolysis method,pressing method,and leaching method,it was found that the four methods of extracting Cyperus esculentus oil met the requirements of the national standard “GB2716” for crude oil(AV ? 4 mg KOH/g,POV? 0.25 g/100g);there was no significant difference between the acid value of oil extracted by single enzymatic hydrolysis and the acid value of oil extracted by multi-step enzymatic hydrolysis,which were less than those by pressing method and solvent method;The peroxide value of the oil extracted by compound enzyme step-by-step enzymatic hydrolysis was higher than that extracted by single enzyme hydrolysis.The iodine value of the oil extracted by single enzymatic hydrolysis method was higher than that of the oil extracted by compound enzyme step-by-step enzymatic hydrolysis method.The iodine value of the oil extracted by solvent extraction method was the highest.The content of water and volatiles in the oil extracted by the two methods was the highest;there were differences among other physical indexes,but the differences were not significant.In addition,the sterol and tocopherol contents of single enzymatic hydrolysis were 158.07 mg/100 g and 41.46 mg/100 g,respectively,which were significantly higher than those of multi-step enzymatic hydrolysis(158.02 mg/100 g and 38.83mg/100g).The fatty acid composition of Cyperus esculentus oil obtained by four extraction processes was analyzed.The results showed that oleic acid was the main component of Cyperus esculentus oil,and the content of fatty acid composition would be affected by the extraction process,but the type of fatty acid would not change with the different extraction process.It was found that the oxidation induction time of oil extracted at 110? or 120? was the longest,and the oxidation induction time of oil extracted by multi-step enzymatic hydrolysis was the shortest.Through infrared spectrum analysis,it was considered that the extraction process would not change the basic composition of oil.(4)The starch was extracted from the centrifuged precipitates of oil extracted by two kinds of water enzyme methods.The basic physical and chemical properties of the starch were determined,and the effects of complex enzymes on the starch were explored.The starch was compared with potato starch and corn starch commonly used in food industry.The results showed that the amylose content of Cyperus esculentus starch was lower than that of potato starch and corn starch.The amylose content of compound enzymatic hydrolysis of starch(CEHS)was higher than that of single enzymatic hydrolysis of starch(SEHS),There was no significant difference in amylose content between the two groups;The freeze-thaw stability of CEHS was lower than that of SEHS,but higher than that of potato starch and lower than that of corn starch;In terms of solubility and swelling degree,potato starch was significantly higher than that of SEHS,CEHS and corn starch,but there was no significant difference between SEHS and CEHS.There was no significant difference in transparency between SEHS and CEHS,which were lower than potato starch and corn starch.The thermodynamic analysis of starch showed that the gelatinization temperature ranges of SEHS,CEHS,corn starch and potato starch were: 67.3?80.6?,66.9?0.6?,52.2?71.3?,62.6?76.6?,respectively.The gelatinization temperature of Cyperus esculentus starch was higher,which indicated that Cyperus esculentus starch could be expanded and gelatinized during higher gelatinization process.SEM results showed that the starch was small granule starch,mainly spherical and oval.Compared with SEHS,CEHS had pits of different sizes on the surface,and some starch was broken into pieces.(5)According to the characteristics of high fiber content of Cyperus esculentus dregs obtained after the oil and starch were extracted by the compound enzyme multi-step hydrolysis method,a kind of biscuit made from the dregs was developed.When the dregs was added at15%,the dietary fiber content of the biscuit was higher than that of the control group,the hardness,sensory evaluation,and color were all within the acceptable range,and the taste was crispy and the fragrance was pleasant. |
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