Deacidification Of Adlay Bran Oil With High Acid Value And Its Characteristics

Adlay（Coix lacryma-jobi L）,also named coix,coix seed,medicinal corn and so on,provides medical benefits as well as traditional nurients.China has the largest planting area of adlay in the world and it also is the largest adly processing country in the world,which is abundant of adlay rice bran resource.Meanwhile,A large amount of adlay bran is used to make animal feed bringing relatively low economic value.Adlay bran oil is the ideal oil which is rich in physiological activator and unsaturated fatty acids and has the functions of anti-inflammation,anti-allergy and immunity regulation.Acid value and yield are the significant influence factors of adlay bran oil production and processing.Adlay bran crude oil commonly has a high acid value between 40 and 60 mgKOH/g.Furthermore,it contains a lot of impurities.Traditional alkali deacidification and physical deacidification make neutral oil and physiological activator loss,produced a lot of waste and pollute the environment.So far,there is no refining process of adlay bran oil used to produce edible adlay bran oil.Therefore,it is necessary to compare the refining processes of high acid value adlay bran oil to find the optimum conditions of refining process.Basing on the theory of above,the key issues of refining adlaya bran oil have been the focus of the study.Before optimizing and defining he optimum technology parameters of adlay bran oil with high acid value,the optimum deacidification process of simulated vegetable oil with high acid value has to be researched first.Then studying on changes of its quality and composition of fatty acid and triglycerides of adlay bran oil.The analyzed of refining adlay bran oil（RABO）during simulated digestion and intestinal flora fermentation in vitro were analyzed.These studies may provide some theoretical basises and references to the actual production and sale of adlay bran oil.Meanwhile,this research may be helpful for evaluating the nutrient value of edible adlay bran oil.The main results were as follows.1.Deacidification of high acid value adlay bran oilThree deacidification methods,including twice alkali refining（TAR）,three times ethanol solvent extraction（TESE）and molecular distillation-alkali refining（MDR）,were compared and then applied to deacidify the rapeseed oil with smulated high acid value under the maximum deacidification degree and the optimal deacidification conditions.The obtained results revealed that the maximum deacidification degree of alkali refining deacidification was 60 mgKOH/g.The TAR can deacidify the acid value to 0.111 mgKOH/g,while the TESE and MDR can deacidify its acid value to 3.158 mgKOH/g and 0.280 mgKOH/g.Meanwhile,the total yields for TAR,TESE and MDR were 34.82%,47.77%and 57.45%,respectively.A maximal yield was obtained by optimized refining conditions（evaporator temperature 165℃,internal condenser temperature30℃,and 365 r/min wiper speed）using MDR.The optimal alkali refining conditions were determined as the follows:deacidification temperature 0℃,NaOH solution concentration 60 g/L,and NaCl eluent concentration 100 g/L.The yield（57.05%）and deacidification acid value（from63.41to 0.441 mgKOH/g）of adlay bran oil with high acid value（63.41 mgKOH/g）under these conditions corresponded fairly well to the rapeseed oil with smulated high acid value and achieve national standard of grade Ⅲ rice bran oil.Overall,the result confirmed that the MDR developed in the present study was adequate for deacidifing the rapeseed oil with smulated high acid value.2.physicochemical properties of adlay bran oilChanges of quality and composition of fatty acid and triglycerides of adlay bran oil were studied.The obtained results revealed that the RABO was tan,clear,transparent and no foreign bodies with the inherent odour of adlay bran oil.The acid value and peroxide value of RABO was0.441 mg KOH/g（achieving national standard of grade Ⅲ rice bran oil）and 4.393 mmol/kg（achieving national standard of grade I rice bran oil）.RABO is rich in Vitamin E（43.254μg/g）,oryzanol（2.619 mg/g）,stigmasterol（51.125 mg/g）,β-sitosterol（18.631 mg/g）and squalene（62.822μg/g）.The oxidative stability index（OSI）of RABO was 9.03 h at 120℃.The Q₁₀0 were applied to estimate shelf-life（514.29 d）of RABO.In addition,RABO was mainly composed of oleic acid,linoleic acid,palmitic acid,stearic acid andα-linolenic acid which was rich in unsaturated fatty acids（81.431%）.The main types of triglycerides in RABO wereβ-OOL,β-OLL,β-OHL,β-OOO,β-OLO,β-POO,β-OHO,β-PLO,β-OPL,β-OO_CL,β-LOL,β-POL,β-LLL,β-PLL,β-PHO,β-OPO,β-OO_CO,β-LHL,β-PHL,β-PPO,accounting for 73.76%of the total triglyceride content.3.changes of adlay bran oil during simulated digestion and intestinal flora fermentation in vitroTwo experiments,including simulated digestion in vitro（SD）and intestinal flora fermentation（IFF）,were applied to research the changes of RABO during the experimentation.The results were as follows.（1）The digestion rate of RABO was fast firstly and then slow.The release of FFA increased rapidly at first,then slowly,and eventually tended to be flat.In the process of gastric digestion,the emulsion particles were gradually hydrolyzed into small particles（100 nm）and large particles（420 nm）.In the process of intestinal digestion,the two particles further hydrolysis into particulates（230 nm）,then made polymerization and adsorption,eventually settled around 320nm.Zeta potential of the system was delayed over the first 30 min during the gastric digestion and increased gradually after that.Zeta potential increased first,then decreased and finally increased during the intestinal digestion.In addition,with the digestion process proceeding,the content of monoglyceride in the system gradually increased,while the content of diacylglycerol and triglyceride gradually decreased.（2）The changes of physicochemical parameters of fermentation broth were consistent with the changes of intestinal flora composition in IFF in vitro.The species similarity between high-level adlay bran oil group（EH）and high-level soybean oil group（CH）was higher,and the species difference between other groups was greater.Compared with the low-level adlay bran oil group（EL）and the low-level soybean oil group（CL）,the abundance of Bacteroides increased significantly in the high-level adlay bran oil group and the high-level soybean oil group,and the Bacteroides was negatively correlated with ammonia nitrogen content.In addtion,the abundance of Ruminococcaeae,Lachnospiraceae,Bacteroidaceae and Coriobacteriaceae increased significantly,and the abundance of Lachnospiraceae and Coriobacteriaceae was positively correlated with SCFAs,while the abundance of Shewallaceae and Enterobacteriaceae decreased significantly.Moreover,it promoted the pantothenate and CoA biosynthesis,glycosyltransferase and other metabolic pathways,and inhibited lipopolysaccharide biosynthesis.In conclusion,high-level adlay bran oil group and high-level soybean oil group can effectively promoted the growth of beneficial bacteria and inhibited the growth of harmful bacteria.They could also reduced the pH and the content of ammonia nitrogen of fermentation broth,increased the content of SCFAs of fermentation broth.Especially the high-level adlay bran oil group had better inhibition effect on harmful bacteria.Conclusion:The optium deacidification of adlay bran oil is molecular distillation-alkali refining.The refined adlay bran oil is of good quality and rich in nutrients,unsaturated fatty acids and various triglycerides.It also can be digested and hydrolyzed by human body.Moreover,high-level adlay bran oil can effectively promote the growth of beneficial bacteria and inhibit the growth of harmful bacteria in intestinal flora in vitro.