Studies On Nutritional Quality And Selenospecies In Se-enriched Pleurotus Eryngii

Selenium(Se)is an essential trace element in human body.Compared to inorganic Se,organic Se mainly in the form of selenium protein and seleno-amino acids,is easier for human to absorb.Among the plant foods,edible mushroom have a high content of protein and have stronger capacity to enrich Selenium.Pleurotus eryngii,a special kind of mushroom,has a good taste and high affluent nutritional content,and.multi-bioactive properties,such asanti-fatigue,anti-virus,reducing cholesterol levelsand preventing arteriosclerosis.With the popularization and development of P.eryngii cultivation techniques in food industry,its production increased rapidly.In this paper,Se-enriched P.eryngii grown on the substrate supplemented with selenium salt(Na2SeO3)was studied.Growth indexes of P.eryngii,the content and speciation of Se and nutritional quality were studied.Se contents were determined using ICP-MS and Se speciation was analyzed using HPLC-ICP-MS.Moreover,an in vitro gastrointestinal digestion was employed to evaluate the potential elemental bio-accessibility of Se-enriched P.eryngii bodies.The edibility and safety of Se-enriched P.eryngii was evaluated based on the above result.The main results are as follows:1.P.eryngii mycelium were cultured in plate and liquid culture,which substrates supplemented with different Se contents.The values of growth rates,biomass,Se levels,bio-concentration factors(BCF)and organic Se contents of P.eryngii mycelium were used to analyze the capacity of Se-resisting and Se-enriched.Results showed that the addition of selenium salt to the substrates led to a significant increase of Se contents in P.eryngii mycelium.The addition of selenium salt led an insignificant effect on the growth of P.eryngii mycelium.There was a significant inhibition on the growth of P.eryngii mycelium when the Se content of substrates was more than 60 mg/L.While the content of Se in substrates was in the range of 0-60 mg/L,there was a significant linear correlation between the Se contents of P.eryngii mycelium and that of the substrates.When the content of Se in substrates was in the range of 20-40mg/L,the content of Se in P.eryngii mycelium was among 630-1200 mg/kg,BCF and organic Se contents of P.eryngii mycelium reached the highest.Therefore,the optimal Se content in the substrates of P.eryngii mycelium was in the range of 20-40 mg/L.2.P.eryngii were cultured on substrates supplemented with different Se contents.The values of Se content,BCF,the organic Se content,bio-accessibility of P.eryngii bodies,Se speciation and Se distribution were used to estimate Se-enriched characters.Results showed that the addition of selenium salt(0-60 mg/kg)to the substrates led to a significant increase of Se content in P.eryngii bodies.There was insignificant difference between the Se levels of the stipes and caps of P.eryngii.When the content of Se in substrates was in the range of 40-50 mg/kg,BCF and organic Se contents of P.eryngii bodies were higher.The majority of Se in P.eryngii bodies was organic Se and nearly 66.55%of the total Se was metabolized into extracted proteins,albumin-Se,globulin-Se,glutelin-Se and prolamin-Se.Comparing the Se contents of the different protein fractions,it was found that the albumin-Se and glutelin-Se contained the high amount of Se,34.4%and 25.42%of the total Se in P.eryngii bodies,respectively.3.In vitro gastrointestinal digestion was used to evaluate the bio-accessibility of Se-enriched P.eryngii.The high molecular weight Se-containing compounds of P.eryngii bodies can be digested to low molecular weight peptides(<5kDa)and SeMet(60.10%).The extraction efficiency of Selenospecies was 86.04%using enzyme and ultrasonic wave extraction methods.P.eryngii bodies digestion solutions by HPLC-ICP-MS detection.The chromatograms obtained revealed that the major Selenospecies found in P.eryngii bodies was SeMet(59.32%).The minority selenospecies were SeCys2 and SeIV.4.The soluble protein,total sugar,As,Pb,Hg,Cd and MDA contents,the activity of GSH-Px,SOD and CAT were used to estimate Se-enriched P.eryngii nutritional quality and antioxidant enzyme activity.Compared to the control group,the soluble protein and total sugar content as well as the activity of GSH-Px,SOD and CAT were significantly increased.The composition of amino acids in Se-enriched P.eryngii was similar to that of non-supplemented P.eryngii.But the contents of 7 essential amino acids in Se-enriched P.eryngii were higher than the control.While the Se content of substrates increased,the content of Cu,Hg,Pb and Cd in P.eryngii bodies significantly decreased,indicating the possible metabolic antagonism between Se and heavy metals Cu,Hg,Pb and Cd.The proper Se content of substrates can significantly increased the bio-activities of GSH-Px,SOD and CAT and decreased the content of MDA,which increased the antioxidant properties of P.eryngii bodies.In conclusion,Se-enriched P.eryngii bodies can be regards as a reliable Se source in daily diet.