| Adlay?Coix lachryma-jobi L.?,an annual or perennial grass group,has long been used as a food source as well as an herbal medicine due to its high nutritional and medicinal values.Although China is a major adlay cultivation and consumption country,the processing of adlay in China is still on the initial stage.Most enterprises are restricted to adlay raw materials sale and simple nutritional powder production,and further processing and application development on adlay have not yet been done.Furthermore,adlay seeds are rich in protein,starch and lipid,and have a strong tendency to develop the textural hard-to-cook defect which result in long cooking times and reduced sensory properties.Germination process has been used to improve the nutritional and physicochemical properties of brown rice,oat and buckwheat.However,there is little information available regarding adlay germination.In this research,the changes of nutritional,physicochemical,and biological properties of adlay during a 60-h germination were characterized.This could provide a theoretical basis for adlay deep processing and improve its economic and social benefits.Firstly,three commonly consumed adlay cultivars?GX,GD and PC?in their brown and polished forms were assessed for their chemical compositions and antioxidant activities.The results showed that adlay was rich in nutrition and has high antioxidant activity.Adlay contained 11.93%-15.61%of protein and 9.00%-9.85%of lipid.K was the richest macro mineral elements in adlay?2.43-2.62 g/kg?,while Fe was the richest trace mineral elements?21.29-27.84 mg/100g?.Adlay was rich in mono-and poly-unsaturated fatty acids,and it contained high contents of oleic acid?47.36%-48.38%?and linoleic acid?34.74%-35.18%?.Seven triacylglycerol compounds were detected in adlay.GD contained the highest amount of triolein,and the contents of it in the brown and polished GD were 9.66 and 8.97 mg/g DW,respectively.The content of?-oryzanol in the brown adlay?341.44-375.35?g/g DW?was higher than in the polished adlay?176.52-193.25?g/g DW?,but there was no significant difference among the different cultivars.?-Tocopherol was the predominant tocopherol within adlay,and the content ranged from 22.41?polished GX?to 37.03?g/g DW?brown GD?.The phenolic and flavonoid in adlay were mainly presented in free form,and brown GX had the highest contents of free phenolic?134.53 mg GAE/100g DW?and flavonoid?22.25 mg RE/100g DW?.Moreover,the antioxidant activities of free phenolic extracts were higher than the bound phenolic extracts,and the free phenolic extract of brown GX showed the highest antioxidant activities among the tested samples.Then,the variations of compositional and physicochemical properties of adlay during soaking at various temperatures and times were determined.The results indicated that soaking had insignificant effects on the lipid content,the fatty acid profile and X-ray diffraction pattern?XRD?of adlay.However,it significantly increased the relative crystallinity?RC?of adlay flour,and the RC increased from 32.03%to 38.22%after soaking at 55?C for 12 h.Soaking led to the degradation and leakage of the sodium dodecyl sulfate?SDS?soluble proteins as well as the SDS insoluble proteins,and the extent of degradation and leakage increased as the soaking time and temperature increased.Further,soaking treatment destroyed the protein network and the compact structure of adlay flour,and reduced the adlay flour particle size and the starch surface proteins.Moreover,soaking increased the values of peak,trough,breakdown,final and setback viscosities of adlay flour.Secondly,the dynamic changes of the nutritional and physicochemical properties of adlay seed during germination were investigated.The results showed that the 60 h germination brought significant decrease of the dry matter,lipid,starch,and triolein contents by 22.4%,3.4%,20.8%and 13.8%?p<0.05?,respectively,whereas 2.4-fold increase in?-aminobutyric acid?GABA?and 2.6-fold increase in coixol.However,the protein content remained stable?p>0.05?during the germination process.Size exclusion high performance liquid chromatography?SE-HPLC?indicated that during germination,adlay storage proteins were significantly hydrolyzed,and some SDS insoluble proteins were depolymerized into SDS soluble high molecular proteins while the SDS soluble proteins were hydrolyzed into smaller proteins,peptides and amino acids.Fourier transform infrared spectroscopy?FTIR?indicated that the lipid was hydrolyzed,and the–C=O carbonyl bond from lipids was clearly visible at1745 cm-1 but gradually weakened during germination.Scanning electron microscope?SEM?showed that germination exerts a significant effect on the structure of adlay flour.During germination,the continuous and compact matrix structure of adlay flour was destroyed,and starch granules became rough and eroded.After 60 h of germination,the starch granules in the adlay flour were seriously damaged,almost no intact one could be found.Moreover,differential scanning calorimetry?DSC?indicated that germination increased the onset,peak and conclusion temperatures,while rapid visco analyser?RVA?indicated that germination decreased the peak,through,breakdown,final and setback viscosities of adlay.Thirdly,after extracting the free and bound polyphenols,the changes of phenolic content and antioxidant activities of adlay during germination were investigated.Meanwhile,the hypolipidemic and antioxidative effects of germinated adlay in hyperlipidemic mice were evaluated.The results indicated that the free phenolic and flavonoid contents increased by 112.5%and 168.3%after 60 h of germination,respectively,whereas both of the bound phenolic and flavonoid contents significantly decreased.p-Coumaric,ferulic and isoferulic acids were the main phenolic acids found in the bound phenolic extracts,and the content of ferulic acid slightly decreased after germination.However,p-coumaric,protocatechuic,hydroxybenzoic,vanillic and caffeic acids in the free phenolic extracts showed a significant increase after germination.Further,germination process significantly enhanced the antioxidant activities of adlay,and the total oxygen radical absorbance capacity?ORAC?,ABTS radical cation scavenging activity and ferric reducing antioxidant power?FRAP?increased by 294.5%,21.6%and 192.2%after 60 h of germination.High correlations were found among ORAC,ABTS and FRAP values?p<0.01?during the correlation analysis.Meanwhile,the antioxidant activities of adlay positively correlated with the total phenolic and flavonoid contents?p<0.01?.The results of animal experiment showed that germinated adlay has better performance on preventing and combating hyperlipidemic than ungerminated adlay.Dietary germinated adlay could significantly reduce serum TG and LDL-C levels,while increase HDL-C level.Further,dietary germinated adlay could improve the oxidative stress status of mice.It improved the activities of SOD,GSH-Px and CAT?p<0.05?,enhanced T-AOC?p<0.05?,and reduced the production of MDA?p<0.05?in the liver and serum of mice.Moreover,germinated adlay could protect against the hepatic injury induced by hyperlipidemic,and it significantly reduced the activities of serum ALT and AST?p<0.05?.After that,the effects of citric and lactic acids soaking on the selected nutritional and physicochemical properties of germinated adlay were evaluated.Compared to that soaked with water,soaked with acid resulted in significant decrease of the degradation of both adlay storage protein and starch during germination.After germination,the amount of total free amino acids increased from 488.0 to 1451.4 mg/kg DW.Citric acid soaking resulted a further increase of the amount to 2089.5 mg/kg DW,whereas it decreased to 900.1 mg/kg DW after lactic soaking.Soaking with citric acid significantly increased the phenolic,flavonoid contents and ORAC values by 18.3%?17.0%and 39.1%compared with the water soaking,whereas lactic acid soaking significantly decreased these parameters by 14.9%?9.0%and 16.8%.Furthermore,acid soaking increased the pasting viscosities of germinated adlay,especially the lactic soaking.SEM showed that acid soaking reduced the extent of change in the morphological properties during germination,and starch granules have more surface proteins in acid-soaked germinated adlay flours than in the water-soaked.Finally,impacts of germination on the chemical components and biological properties of adlay water extract were studied.The glucose and maltose contents of the water extract increased by 157.1%and 327.6%,respectively,after germination,whereas the fructose content decreased by 42.4%.The contents of vitamins C and B1 showed 1.61-and 2.68-fold increase,respectively,after 60 h of germination,while the total phenolic content and FRAP increased by64.36%and 61.08%,respectively.After germination,the level of total free amino acids rose from 54.09 to 128.22?g/m L,and the percentage of essential amino acids was elevated from21.63%to 42.13%.The amounts of peptides in the water extract,especially those with a molecular weight under 3000 Da,were also significantly increased.Moreover,the inhibitory activities of the water extract on ACE,xanthine oxidase and tyrosinase increased from 46.44%,10.09%and 21.96%to 70.71%,63.36%and 38.68%,respectively. |
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