Preparation And Application Of Bergamot Pectin Oligosaccharides

Bergamot pomace is a by-product of the production process of bergamot products.Every year,a large amount of bergamot pomace is produced,which causes waste of resources without comprehensive utilization.Because bergamot pomace contains flavonoids,polysaccharides,pectin and other organic substances,it has a wide range of uses in the food industry,pharmaceutical industry and cosmetics industry.In this thesis,the bergamot pomace was used as the research object.The pectin oligosaccharide and low molecular pectin were prepared by enzymatic method.The extraction,isolation,purification,physical-chemical properties,structural elucidation of oligosaccharides.Examined the bacteriostatic activity,antioxidant activity and fruit preservation ability.The results of the four parts as follows:(1)In this paper,the single factor and orthogonal experiments were carried out on the ultrasonic assisted extraction of bergamot pectin from bergamot residue.and the best combination of process conditions is obtained:the ratio of material to liquid is 1:50,and the pH is 1.0.The temperature is 90?and the ultrasonic time is 90 min.Under this optimal process condition,the extraction rate of bergamot pectin reached18.42%.(2)The enzymatic hydrolysis of bergamot pectin oligosaccharides(BPO)was studied by using laboratory-made pectinase A and commercially available pectinase B.By analyzing the single factor and orthogonal test conditions of pectinase B enzymatic hydrolysis conditions,the best preparation process combination was obtained with the yield of bergamot pectin oligosaccharide:enzymatic hydrolysis temperature 45?,enzymatic hydrolysis pH 4.5,the pectinase added amount is 0.30mg/mL,and the enzymatic hydrolysis time was 2 h.Under the optimal conditions,the yield of bergamot pectin oligosaccharides was 64.5%,and the yield of bergamot pectin oligosaccharides increased by 3.4%.(3)Carried out separation and purification and structural characterization of bergamot pectin oligosaccharide.Separation and purification of bergamot pectin oligosaccharide to obtain single component BPO-1,the average molecular weight is2.15×10~3Da.The results showed that bergamot pectin oligosaccharide BPO-1 mainly consists by mannose,galacturonic acid and very small amounts of galactose and arabinose.The polysaccharide subunit of BPO-1 was analyzed by infrared spectroscopy and nuclear magnetic resonance,indicated that the possible backbone was?4)-?-D-GalpA-(1?.(4)Used different polymerization bergamot pectin oligosaccharide to do bacteriostatic experiment with Bacillus subtilis,Staphylococcus aureus and Escherichia coli.The antibacterial activity of bergamot pectin oligosaccharide on Escherichia coli was lower than Bacillus subtilis and Staphylococcus aureus.The minimum inhibitory concentration of bergamot pectin oligosaccharide on Bacillus subtilis and Staphylococcus aureus is 6.0 mg/mL on average,and the bergamot pectin oligosaccharide was combined with sodium benzoate,sorbus potassium and nisin had good antibacterial activity.The free radical scavenging of bergamot pectin oligosaccharides,when the concentration of bergamot oligosaccharide was 25.0 mg/mL,the superoxide radical scavenging rate was 23.12%,and the DPPH free radical scavenging rate was 58.67%.The experiment showed that bergamot pectin Oligosaccharides have good antioxidant activity.For the first time,fresh strawberry was preserved by bergamot pectin oligosaccharide.The strawberry was delayed by 2 days compared with strawberry immersion in sterile water,which proved that bergamot pectin oligosaccharide had better berry fruit.Antiseptic and fresh-keeping effect.This paper realizes the reuse of the resources of bergamot pomace,and re-uses the resources of pomace and provides a theoretical basis for the production of high value-added products.For the first time,the bacteriostatic test of bergamot pectin oligosaccharides separated into different molecular weight fractions was carried out,and it was proved that the antibacterial effect of bergamot pectin oligosaccharides on E.coli,B.subtilis and S.aureus was related to its molecular weight.