| Mulberry leaf(Morus alba L.)resource is rich in China.At present,mulberry leaves are used only for sericulture or fodder processing,which cause huge waste of the resource.Existing reports show that mulberry leaves contain a lot of calcium(up to 2699 mg/100g),but there is no report about its function in enhancing bone density.KGM has functions of promoting intestinal SCFA secretion,reducing intestinal pH,increasing intestinal microbial complexity and diversity.Intestinal health is closely related to the absorption of calcium.It is hoped that the combination of mulberry leaf powder and KGM can produce the synergistic effect of enhancing bone mineral density(BMD).In this study,the contents of basic components,total calcium and different forms of calcium in mulberry leaf powder were measured and analyzed.In vitro gastrointestinal digestion experiment was used to compare the bioavailability of calicium in mulberry leaf powder,calcium carbonate and calcium gluconate.According to the Health Food Inspection and Evaluation Standard(Version 2003),animal experiments was designed to evaluate the mixture's function in enhancing BMD.The microstructure and pathological changes of femur was observed by Micro-CT and HE staining,respectively.Three point bending test was applied to measure the biomechanical properties of femur.The prebiotic function of mulberry leaf powder/KGM mixture was evaluated by determining the pH value,short chain fatty acid concentration,number of microbes etc in cecal contents.This research aimed to seek for new breakthroughs of mulberry leaf powder in functional food and dietary supplement.The main conclusions of this stduy were as follows:(1)Study on the content of calcium and the amino acid composition in mulberry leaf powder and its bioavailability in vitro.The results showed that the calcium content in mulberry leaf powder is abundant,reaching 1614.85 mg/100 g.Its water-soluble calcium,pectic calcium and calcium carbonate ratio of 60% of the total calcium content,which is conducive to the absorption of human body.Mulberry leaf powder is rich in amino acids and the proportion was suitable.Calculation results showed that the ratio of EAA to TAA was 40.36% and the ratio of EAA to NEAA was 67.67%,which were close to the standard mode of FAO/WHO.This indicated that mulberry leaf powder is a kind of high quality protein resource.The results of simulated gastrointestinal digestion in vitro showed that mulberry leaf powder can slowly release Ca2+ through theacidification of gastric acid,and compared with the quick release of calcium carbonate and calcium gluconate,it can alleviate the stimulation to stomach.In the simulatedintestinal tract,the permeation rate of calcium was higher than that of calcium carbonate and calcium gluconate.Therefore,mulberry leaf powder has good in vitro bioavailability(2)Study on the effect of mulberry leaf powder/KGM mixture on enhancing BMD.The results showed that the mixture of mulberry leaf powder and KGM increased the length of femur and bone density,but there was no significant difference(p>0.05).The diameter,dry weight,index and bone calcium content of femur was increased significantly(p<0.05).Which indicate that the mixture of mulberry leaf powder and KGM can promote the bone growth of mice.Calcium metabolism experimental results showed that the apparent absorptivity of calcium of mice in mulberry leaf powder and KGM group was not lower than calcium carbonate group,which possessing the same calcium level.At the same time,the mixture of mulberry leaf powder and KGM has a positive effect on improving the bone mass of cancellous bone and restoring trabecular structure,and it is helpful to improve the biomechanical properties of the femur.Based on the judgment methods of enhancing bone density function in Health Food Inspection and Evaluation Standard(Version 2003),it can be concluded that mulberry leaf powder/KGM mixture has the function of enhancing BMD.(3)Study on the prebiotic function of mulberry leaf powder/KGM mixture.The results showed that the mixture of mulberry leaf powder and /KGM could significantly increase the surface area,the content of water and short chain fatty acids in the cecal content of the mice(p<0.05),while the pH value and free ammonia was significantly reduced(p<0.05).Mulberry leaf powder/KGM mixture can effectively inhibit the reproduction of Escherichia coli and significantly promote the growth of beneficial bacterium,such as bifidobacterium,lactic acid bacteria(p<0.05).The above results show that the mixture of mulberry leaf powder and /KGM can improve the intestinal environment and regulate the role of intestinal flora,and promote the absorption of calcium,which is conducive to the enhancement of bone mineral density functions. |
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