The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial cultivat...The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial cultivation.Optimizing fertilization management can effectively increase SGs productivity,but knowledge on the relationship between potassium(K)fertilization and SGs production is still lacking.In this study,pot experiments were conducted in order to investigate the effect of K deficiency on SGs synthesis in stevia leaves,as well as the underlying mechanisms.Our results showed that when compared with standard K fertilization,K deficiency treatment has no significant effect on the biomass of stevia plant grown in a given soil with high K contents.However,K deficiency critically decreased leaf SGs contents as well as the expression of SGs synthesis-related genes.The contents of different sugar components decreased and the activities of sugar metabolism-related enzymes were inhibited under the K deficiency condition.Moreover,spraying sucrose on the leaves of stevia seedlings diminished the inhibitory effect caused by K deficiency.Our results also revealed the significant positive correlations between sucrose,glucose and SGs contents.Overall,our results suggest that K deficiency would suppress the synthesis of SGs in stevia leaves,and this effect may be mediated by the leaf sugar metabolism.Our findings provide new insights into the improvement of SGs production potential.展开更多
In order to expand the production of Stevia rebaudiana( Bertoni) Hemsl.,the main points of high-yield cultivation techniques of a two-year-old stevia cultivar Shoutian No. 3 in Gannan area of Jiangxi Province were sum...In order to expand the production of Stevia rebaudiana( Bertoni) Hemsl.,the main points of high-yield cultivation techniques of a two-year-old stevia cultivar Shoutian No. 3 in Gannan area of Jiangxi Province were summarized: cutting and transplanting in early spring; fine management,applying more basic and additional fertilizers and retaining stubbles two times in summer,retaining roots for seeding in late autumn,and mulching membrane for safe overwintering in winter. This study will provide practical guidance for the planting of S. rebaudiana in Ganzhou,Jiangxi Province.展开更多
The leaf powders from two varieties of Stevia rebaudiana (Bertoni) cultivated in Yucatan, Mexico were analyzed for their proximate composition, dietary fiber composition and functional properties. The leaf powders wer...The leaf powders from two varieties of Stevia rebaudiana (Bertoni) cultivated in Yucatan, Mexico were analyzed for their proximate composition, dietary fiber composition and functional properties. The leaf powders were a good source of carbohydrates (64.06%-67.98%), protein (12.11%-15.05%), and crudefiber (5.92%-9.52%). Total dietary fiber content in the S. rebaudiana leaf powders were 28.61 (Morita II) and 29.12 (Criolla) g/100g sample, with most of this content represented by insoluble dietary fiber 87.79% (Morita II) and 70.02% (Criolla). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in Criolla (19.29%, 17.77%, 8.98%) than Morita II variety (18.11%, 14.16%, 2.28%). Hemicellulose and cellulose were higher in Morita II (3.96%, 11.78%) than criolla variety (1.51%, 8.79%). Functional properties of leaf powder from Morita II and Criolla were, water-holding capacity (2.87-4.07 g/g sample), oil-holding capacity (6.49-6.79 g/g sample), water-absorption capacity (3.41-3.44 g/g sample), water-adsorption capacity (0.25-0.28 g/g sample), and organic molecule absorption capacity (1.13-1.81 g/g sample). These suggest that S. rebaudiana (Bertoni) leaf powders may be used as dietary supplement or as food additive.展开更多
Rumen fermentation parameters and microbiota were evaluated in 3 in vitro rumen fermentation experiments after addition of chestnut tannins(CWT)or an extract from Stevia rebaudiana Bertoni(SB)to substrates.A control(C...Rumen fermentation parameters and microbiota were evaluated in 3 in vitro rumen fermentation experiments after addition of chestnut tannins(CWT)or an extract from Stevia rebaudiana Bertoni(SB)to substrates.A control(CTR)substrate was fermented alone or added with 1.5%of CWT or SB extracts in a batch culture system(Exp.1,fermentation in 500 mL for 24 h)and in a subsequent continuous culture system(Exp.2,fermentation in 2 L bottles for 9 d).Experiment 3 used the fermentation system of Exp.1 and tested 7 doses of each extract added to CTR(additions of 0.2%,0.4%,0.6%,0.8%,1.0%,1.2%and 1.4%for48 h).The addition of CWT lowered(P<0.01)the in vitro rumen ammonia concentration in all experiments and reduced the protozoa counts in Exp.1(P<0.05).In contrast,the SB extract did not modify the ammonia concentrations,but significantly lowered the protozoa counts in all 3 experiments(reduction of 47%and 20%in Exp.1 and 2,P<0.05;and a quadratic reduction in Exp.3,R^2=0.63,P<0.01).Neither extract affected the fermentation in terms of gas production(Exp.1 and 3)nor volatile fatty acids(VFA)yield(Exp.1 and 2),if we exclude a reduction at the highest CWT concentration in Exp.3.Changes in VFA profile were induced by CWT and were limited to reductions in the iso-valerate(P<0.01,in Exp.2)and iso-butyrate levels(P<0.01,Exp.2).The CWT increased the abundance of Prevotella ruminicola and Selenomonas ruminantium and decreased that of Ruminobacter amylophilus(P<0.01,P<0.05 and P<0.05,respectively).The SB extract increased the relative abundance of Treponema saccarophylum(P<0.05).Both of the studied substances had an impact on rumen metabolism,with SB reducing protozoa counts and CWT lowering the rumen ammonia concentration.The effects of both extracts on the rumen were appreciable at low dietary doses,and the negative impacts on fermentation were limited to the reduction in protein degradation with the addition of CWT.展开更多
To preserve its favorable health and nutritional qualities under processing conditions and oral ingestion,Stevia rebaudiana Bertoni leaf aqueous extract was encapsulated in composite microspheres based on calcium algi...To preserve its favorable health and nutritional qualities under processing conditions and oral ingestion,Stevia rebaudiana Bertoni leaf aqueous extract was encapsulated in composite microspheres based on calcium alginate.The addition of other biopolymers to alginate(ALG)(xanthan gum(XG),casein(CA))influenced molecular interactions(mainly hydrogen bonding and electrostatic interactions)between microsphere constituents causing the change in microsphere structure and thus physicochemical properties(encapsulation effectiveness and capacity,surface morphology,swelling,stability)as well as the release of total polyphenols(TPC)in distilled water,NaCl solutions and in simulated gastrointestinal fluids.The extent of crosslinking of calcium alginate was altered by blending with XG,CA,or XG+CA,but this did not affect the control mechanism of TPC release detected as diffusion.Results revealed the unsuitability of calcium alginate microspheres for implementation in food products with high water content,while composite microspheres showed desired reduction in TPC release.The best performance(the slowest release and the amount released)for implementation in functional food products containing NaCl exhibited composite microspheres with ALG+XG+CA.The desired prevention of microsphere degradation in simulated gastro fluids was achieved with ALG+XG+CA microspheres,while in simulated intestinal fluids all microspheres were decomposed and completely released TPC.展开更多
基金supported by the Natural Science Foundation of Jiangsu Province,China(BK20180312)the Jiangsu Key Laboratory for the Research and Utilization of Plant Resources,China(JSPKLB201810)the Natural Science Foundation of Shanxi Province,China(201901D111230)。
文摘The steviol glycosides(SGs)in stevia(Stevia rebaudiana Bertoni)leaves are becoming increasingly valuable due to its high sweetness but low calorific value,which is driving the development of stevia commercial cultivation.Optimizing fertilization management can effectively increase SGs productivity,but knowledge on the relationship between potassium(K)fertilization and SGs production is still lacking.In this study,pot experiments were conducted in order to investigate the effect of K deficiency on SGs synthesis in stevia leaves,as well as the underlying mechanisms.Our results showed that when compared with standard K fertilization,K deficiency treatment has no significant effect on the biomass of stevia plant grown in a given soil with high K contents.However,K deficiency critically decreased leaf SGs contents as well as the expression of SGs synthesis-related genes.The contents of different sugar components decreased and the activities of sugar metabolism-related enzymes were inhibited under the K deficiency condition.Moreover,spraying sucrose on the leaves of stevia seedlings diminished the inhibitory effect caused by K deficiency.Our results also revealed the significant positive correlations between sucrose,glucose and SGs contents.Overall,our results suggest that K deficiency would suppress the synthesis of SGs in stevia leaves,and this effect may be mediated by the leaf sugar metabolism.Our findings provide new insights into the improvement of SGs production potential.
基金Supported by Science and Technology Project of Education Department of Jiangxi Province(GJJ161243)"11531" Project of Nanchang Normal University
文摘In order to expand the production of Stevia rebaudiana( Bertoni) Hemsl.,the main points of high-yield cultivation techniques of a two-year-old stevia cultivar Shoutian No. 3 in Gannan area of Jiangxi Province were summarized: cutting and transplanting in early spring; fine management,applying more basic and additional fertilizers and retaining stubbles two times in summer,retaining roots for seeding in late autumn,and mulching membrane for safe overwintering in winter. This study will provide practical guidance for the planting of S. rebaudiana in Ganzhou,Jiangxi Province.
文摘The leaf powders from two varieties of Stevia rebaudiana (Bertoni) cultivated in Yucatan, Mexico were analyzed for their proximate composition, dietary fiber composition and functional properties. The leaf powders were a good source of carbohydrates (64.06%-67.98%), protein (12.11%-15.05%), and crudefiber (5.92%-9.52%). Total dietary fiber content in the S. rebaudiana leaf powders were 28.61 (Morita II) and 29.12 (Criolla) g/100g sample, with most of this content represented by insoluble dietary fiber 87.79% (Morita II) and 70.02% (Criolla). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in Criolla (19.29%, 17.77%, 8.98%) than Morita II variety (18.11%, 14.16%, 2.28%). Hemicellulose and cellulose were higher in Morita II (3.96%, 11.78%) than criolla variety (1.51%, 8.79%). Functional properties of leaf powder from Morita II and Criolla were, water-holding capacity (2.87-4.07 g/g sample), oil-holding capacity (6.49-6.79 g/g sample), water-absorption capacity (3.41-3.44 g/g sample), water-adsorption capacity (0.25-0.28 g/g sample), and organic molecule absorption capacity (1.13-1.81 g/g sample). These suggest that S. rebaudiana (Bertoni) leaf powders may be used as dietary supplement or as food additive.
文摘Rumen fermentation parameters and microbiota were evaluated in 3 in vitro rumen fermentation experiments after addition of chestnut tannins(CWT)or an extract from Stevia rebaudiana Bertoni(SB)to substrates.A control(CTR)substrate was fermented alone or added with 1.5%of CWT or SB extracts in a batch culture system(Exp.1,fermentation in 500 mL for 24 h)and in a subsequent continuous culture system(Exp.2,fermentation in 2 L bottles for 9 d).Experiment 3 used the fermentation system of Exp.1 and tested 7 doses of each extract added to CTR(additions of 0.2%,0.4%,0.6%,0.8%,1.0%,1.2%and 1.4%for48 h).The addition of CWT lowered(P<0.01)the in vitro rumen ammonia concentration in all experiments and reduced the protozoa counts in Exp.1(P<0.05).In contrast,the SB extract did not modify the ammonia concentrations,but significantly lowered the protozoa counts in all 3 experiments(reduction of 47%and 20%in Exp.1 and 2,P<0.05;and a quadratic reduction in Exp.3,R^2=0.63,P<0.01).Neither extract affected the fermentation in terms of gas production(Exp.1 and 3)nor volatile fatty acids(VFA)yield(Exp.1 and 2),if we exclude a reduction at the highest CWT concentration in Exp.3.Changes in VFA profile were induced by CWT and were limited to reductions in the iso-valerate(P<0.01,in Exp.2)and iso-butyrate levels(P<0.01,Exp.2).The CWT increased the abundance of Prevotella ruminicola and Selenomonas ruminantium and decreased that of Ruminobacter amylophilus(P<0.01,P<0.05 and P<0.05,respectively).The SB extract increased the relative abundance of Treponema saccarophylum(P<0.05).Both of the studied substances had an impact on rumen metabolism,with SB reducing protozoa counts and CWT lowering the rumen ammonia concentration.The effects of both extracts on the rumen were appreciable at low dietary doses,and the negative impacts on fermentation were limited to the reduction in protein degradation with the addition of CWT.
基金supported by the Croatian Science Foundation[Project:UIP-2014-09-6462].
文摘To preserve its favorable health and nutritional qualities under processing conditions and oral ingestion,Stevia rebaudiana Bertoni leaf aqueous extract was encapsulated in composite microspheres based on calcium alginate.The addition of other biopolymers to alginate(ALG)(xanthan gum(XG),casein(CA))influenced molecular interactions(mainly hydrogen bonding and electrostatic interactions)between microsphere constituents causing the change in microsphere structure and thus physicochemical properties(encapsulation effectiveness and capacity,surface morphology,swelling,stability)as well as the release of total polyphenols(TPC)in distilled water,NaCl solutions and in simulated gastrointestinal fluids.The extent of crosslinking of calcium alginate was altered by blending with XG,CA,or XG+CA,but this did not affect the control mechanism of TPC release detected as diffusion.Results revealed the unsuitability of calcium alginate microspheres for implementation in food products with high water content,while composite microspheres showed desired reduction in TPC release.The best performance(the slowest release and the amount released)for implementation in functional food products containing NaCl exhibited composite microspheres with ALG+XG+CA.The desired prevention of microsphere degradation in simulated gastro fluids was achieved with ALG+XG+CA microspheres,while in simulated intestinal fluids all microspheres were decomposed and completely released TPC.
