Study On The Preparation Of Deer Bone Peptide-chelated Calcium And Its Effect On Promoting Calcium Absorption

Calcium is a mineral element that is necessary for the human body,accounting for about 1~2% of adult body weight[1].However,the diet structure of many countries cannot guarantee the need of daily calcium intake.Chronic calcium deficiency can affect bone health and cause a variety of diseases.At present,calcium intake is often supplemented by calcium nutritional enhancers.The commonly used calcium nutrition fortifier,including calcium carbonate and calcium gluconate,still has many problems,such as low calcium absorption rate and many factors can affect the absorption of these calcium nutrition fortifiers in the human body.Therefore,the development of a new calcium nutrition fortifier with high bioavailability is the key to meet the daily calcium demand of the people.This paper takes the deer leg as the research object,after high pressure cooking and degreasing pretreatment,the deer bone leg was crushed into powder,and we studied the optimization of enzyme preparation of deer bone peptide solution,determined the optimization process of deer bone peptide and calcium chloride chelate preparation of deer bone polypeptide-chelated calcium,and studied the stability analysis of deer bone polypeptide-chelated calcium.The stability characteristics,physicochemical characteristics and absorption characteristics of deer bone polypeptide chelated calcium were analyzed.The main results are as follows:(1)Study on enzymatic hydrolysis of deer boneThe effect of enzymatic hydrolysis of 8 proteases on deer bone powder was compared with the activity of calcium binding and the degree of hydrolysis.Determine the use of compound protease to hydrolyze deer bone powder.The best technological conditions are as follows: The enzyme was 8034 U/g,the temperature was 54?,the value of p H was 6.7,and the concentration of the substrate was 10.2%.Under the optimal conditions,the hydrolysis degree of the deer bone powder was 23.84±0.28% with the hydrolysis of the compound protease.(2)Preparation of deer bone polypeptide chelated calciumThe calcium chelating reaction was optimized with the calcium binding rate of the deer bone polypeptide and the chelating rate of calcium ions as the index.The optimal conditions for the chelating reaction were as follows: The concentration of polypeptide in deer bone was 1.535mg/m L,the concentration of calcium chloride was 7.5mmol/L,in the reaction system,the p H value was 7,and the chelating reaction was continue for 15 min at 40?.The optimal process for preparation of deer bone polypeptide-chelate calcium is as follows: The chelating reaction was carried out under the optimal conditions.The reaction products were freeze-dried,washed with ethanol for three times,centrifuged at 3000 rpm for 15 min,collected and precipitated,freeze-dried,and the deer bone polypeptide-chelated calcium powder were got.(3)Stability of deer bone polypeptide chelated calciumIn the range of p H4.0~p H8.0,35~85?,the retention of calcium in deer bone polypeptide can reach more than 90%,which proves that the acid-base stability and the thermal stability are good.The deer bone polypeptide-chelated calcium showed the stability of simulated gastric and intestinal fluid,after simulated digestion,the calcium retention rate was more than 90%.(4)Physicochemical properties of deer bone polypeptide chelated calciumThe analysis of basal composition and amino acid content showed that the phosphate group in the deer bone polypeptide may be the main part of peptide calcium binding,and there may exist phosphosine serine structure cluster similar to casein.The carboxyl group of negatively charged amino acids(Glu and Asp),the residues of positively charged amino acids(Lys,Arg and His)and hydrophobic amino acid residues play an important role in the binding process of peptide chelated calcium.The UV spectra,fluorescence spectra and FT-IR transform infrared spectra showed that calcium ions were mainly combined in the carboxyl oxygen atoms and amino nitrogen atom reaction sites of the deer bone polypeptide.The particle size distribution and molecular weight distribution showed that the particle size and molecular weight of deer bone polypeptide-chelated calcium were larger than those of deer bone polypeptide.The chelating reaction has both intramolecular interaction and intermolecular interaction,and calcium ions may be combined with two peptide segments at the same time.In SEM and TEM images,the microstructure changed obviously after chelation.It was confirmed that the deer bone polypeptide reacted with calcium ions to form a new deer bone polypeptide chelated calcium.(5)Absorption characteristics of deer bone polypeptide chelated calciumDeer bone polypeptide chelated calcium can affect the survival of Caco-2 cells.When the concentration of deer bone polypeptide chelated calcium is higher than 0.5mg/m L,the survival rate of Caco-2 cells decreases significantly.The absorbability of deer bone polypeptide chelated calcium in Caco-2 cells was similar to that of casein calcium,which was superior to calcium gluconate and calcium chloride.The absorption of deer bone polypeptide chelated calcium was influenced by the phytic acid components in food,but not affected by phosphorus components and vitamin D.