Assessment Of Biological Functional Properties Of Dietary Fibre And Research On The Influences Of Cellulose With Molecular Weight On Gut Microbiota

Dietary fiber（DF）,as the seventh most important nutrient,is an essential nutrient for maintaining human health.With the improvement of people’s living standards,the intake of DF has significantly decreased in our modern diet,which lead to the occurrence of many chronic diseases.Therefore,the development and utilization of DF have became a research hotspot at home and abroad.Celery,a rich source of DF,is one of the most widely consumed vegetables in the world.The DF compounds are changed in different layer of celery.Thus,these chemical composition may change at different stages of development.The detailed chemical characterization of celery DF is important for the understanding of it nutritional value.Meanwhile,it is of highly significant if celery DF levels can be customized for different consumers.In order to rapidly and accurately provide the required DF,it is urgent to realize the rapid non-destructive determination and visualisation of celery DF.Cellulose,as a major kinds of insoluble DF,can alter microbiota composition.Additionally,gut microbiota produce fermentation end products（e.g.,short-chain fatty acids,SCFAs）when metabolizing DF.However,the correlation of cellulose with different molecular weight（Mw）and intestinal microbiota has not been established whether it is beneficial to health or not.Therefore,more information is needed to identify the“ideal”diet for a healthy gut microbiome.In order to further realize the improvement of intestinal microecology,DF hydrogels was used as an effective delivery system to provide for the targeted delivery of SCFAs.In this paper,it is of great significance to realize the rapid non-destructive determination of DF and to the development and application of different Mm cellulose functional foods.The mian results were as follows:1.Reseach on DF content and physicochemical/functional properties in celery of different maturity.In the work,chemical composition of stalk changed significantly in celery of different maturity.The total dietary fibre（TDF）content was higher at the 1rd stage,mostly due to higher content of insoluble dietary fibre（IDF）.The soluble dietary fibre（SDF）and IDF content were the highest at the 7rd stage and the 1rd stage,respectively.SDF values decreased while IDF values were increasing as the growth period increased.Higher SDF values of celery at 7rd stage bring higher functional properties such as water holding capacity（WHC）,Swelling capacity（SC）,oil holding capacity（OHC）and cholesterol binding capacities（CBC）.The monosaccharides component of SDF was different in specific maturity of celery.2.Non-destructive determination and visualisation of insoluble and soluble dietary fibre contents in celeries during storage periods using hyperspectral imaging technique.The feasibility of using hyperspectral imaging technique to non-destructively determine IDF and SDF contents in fresh-cut celeries and visualise their spatial distribution during storage periods was investigated.Genetic synergy interval partial least square（GA-Si-PLS）algorithm was developed to establish calibration model,which,superior to the PLS and Si-PLS developed models,achieved the prediction performance with Rp of 0.9638 and 0.9756,and RMSEP of 1.180 g/100g and 0.336 g/100g,respectively.The developed GA-Si-PLS models were then applied pixel-wise to visualise the spatial distribution of IDF and SDF contents during storage.3.Preparation and functional properties of cellulose with controlled molecular weight via ultrasonic treatment.In the present work,effect of ultrasonic treatment was evaluated to develop a preparation method of cellulose with controllable molecular weight（Mw）and preferable functional properties.Ultrasonication prominently（P<0.05）reduce the Mw of cellulose from an initial Mw of about 68.07 kDa to the final equilibrium Mw of 6.82 kDa.Interestingly,ultrasonic-treated cellulose exhibited better physicochemical properties than untreated cellulose with significant difference（P<0.05）.The cholesterol binding capacities of ultrasonic-treated cellulose at pH 7.0 and pH 2.0were increased as 2.42 fold and 1.96 fold,respectively,for the cellulose treated with ultrasonic for 30 h.The cellulose treated by ultrasonic processing method could have great potential applications in biomedical and food technology.4.Effect of H-Mw/L-Mw cellulose on gut microbiota and SCFAs in weaned mice.Here we show that mice fed different Mw cellulose exhibited altered gut bacterial composition by 16S rRNA gene sequencing.The Shannon diversity exhibited significant variability in species diversity across the H-Mw cellulose treatments,and the composition of the gut microbiota differed between three groups.In addition,the composition of the gut microbiota was partial similarity in control and L-Mw cellulose group.H-Mw cellulose reduced the relative abundance of Bacteroidetes and increased that of Firmicutes.The phyla Bacteroidetes exhibited the highest relative abundance in control group,followed low Mw cellulose group.Among the fimaly and geuns,the L-Mw cellulose supplementation increased some beneficial microbiota compared to H-Mw cellulose supplementation.Lastly,acetate,propionic acid and total SCFAs level of L-Mw cellulose group were higher than that of H-Mw cellulose groups in the fecal and the serum.Our findings demonstrated that the L-Mw cellulose intake may be beneficial to colon health in weaned mice.This study enriched the theory on the effect of different structural cellulose on gut microecology of weaned mice from the perspective of and laid a foundation for the optimizing the composition of gut microbiota5.Celery cellulose hydrogel as carriers for controlled release of short-chain fatty acid by ultrasound.In this paper,the feasibility of using celery cellulose hydrogels as carriers was explored for controlled release of short-chain fatty acids（SCFAs）triggered by ultrasound.The cellulose hydrogels were prepared with phase inversion method and characterized using FT-IR,SEM and XRD.At the optimal cellulose concentration（8.33 mg/mL and 6.25 mg/mL）,the cellulose hydrogels（F₄ and F₅）exhibited the swelling ratio of 185%.The cellulose hydrogel was loaded with SCFAs basing on its hydrophilicity and swelling properties,and the maximum encapsulation efficiency of the hydrogel was nearly 80%.In SCFAs release study,the ultrasound triggered the release of SCFAs from cellulose hydrogel（F₄ and F₅）,and the SCFAs release showed a quick release pattern.In addition,the results of mechanical properties suggested that F₄ could be a better delivery.The results indicate that celery cellulose hydrogel can be used for delivery of SCFAs,and ultrasound could have great potential in controlling the release of SCFAs.