Utilization Of Starch And Cellulose In Residue Of Dioscorea Zingiberensis C.H.Wright Tubers

The tubers of Dioscorea zingiberensis C.H.Wright.is also known as yellow ginger,which is an important plant source of diosgenin,and diosgenin is the starting material for synthesis of various hormone drugs,which is in great demand in the market.In industrial production,diosgenin is often obtained by physical separation and acid hydrolysis with low cost.However,the residue after physical separation of diosgenin contains a large amount of starch,cellulose and a small amount of diosgenin components.Direct disposal of diosgenin results in a great waste of plant resources.In this research,the residue of D.zingiberensis tuber after physical separation of diosgenin was studied,the starch,cellulose and a few remaining components of diosgenin were analyzed and the resource utilization was studied.The p H-sensitive intelligent indicator film of D.zingiberensis starch（DZS）and fluorescent carbon quantum dots of D.zingiberensis cellulose were developed,aiming at making full use of the biomass resources in D.zingiberensis residue and reducing the waste of resources.It provides a new method and research idea for the comprehensive utilization of D.zingiberensis resources.The specific content includes the following three parts:（1）The cellulose and starch were separated by cold immersion and physical separation technology.After purification,the composition,morphological characteristics,particle size,total starch content,amylose content and gelatinization temperature were characterized.In order to release the remaining diosgenin components in the residue after physical separation and improve the yield of diosgenin,four kinds of bacteria were selected to perform acid hydrolysis on the residue after pre-biotransformation,and HPLC method was established to determine the content of diosgenin in the hydrolyzed product.The results showed that turmeric starch production rate was 18.20%,78.58±0.03%purity,which amylose content was 63.20%,T_onset,T_peak,T_end andΔH were 66.6℃,70.2℃,73.6℃and 2.307 J/g,turmeric starch granules assumes the circular or elliptic.The average particle size is 27.2μm.Turmeric cellulose production rate was 13.90%,68.37%after purification.HPLC analysis results showed that there was a good linear relationship between the peak area（Y）and the concentration（X）of diosgenin in the concentration range of 0.002 mg/m L～1.024 mg/m L（R²=0.9993）,and the fitting linear regression equation was Y=12339X+78.523.Among the four strains,the highest yield of diosgenin was 1.27%in group H.in.According to the scanning electron microscope（SEM）images before and after the biotransformation of D.zingiberensis residue（DZR）,the biotransformation of DZR destroyed the outer wall of DZR,promoted the release of diosgenin components originally wrapped inside,and finally achieved the purpose of increasing the yield of diosgenin.（2）The DZS film was prepared with DZS as raw material.The appearance and physical properties of the films with different starch concentrations（2%,3%,4%,w/v）were investigated,and the film forming property and mechanical strength of the films were integrated.The DZS film was prepared with 3%starch concentration,and the butterfly pea flower extract-DZS intelligent indicator film was further prepared.Polyphenols were extracted from butterfly pea flower（BPE）by cold immersion and continuous organic solvent extraction at low temperature,and were added into DZS film to prepare the intelligent indicator film of BPE-DZS.The results showed that the addition of BPE had certain effects on the color,light transmittance,mechanical strength and physical parameters of the starch film.The starch film loaded with BPE had a certain antioxidant activity,especially the scavenging ability of ABTS⁺free radicals was significantly stronger than that of the film without BPE.The prepared films have good color rendering ability and p H sensitivity,and have the potential to be developed into intelligent indicator films.BPE-DZS smart film is sensitive to environmental p H,especially when placed in alkaline environment for 5 mins,the color changes significantly.The results of chicken freshness monitoring showed that when the film was stored at 25℃for 24hrs,the color of the film changed from blue-purple to blue-green,and the p H value of the chicken at this time changed significantly>7,TVB-N value>20 mg/100g,total number of colonies>6 log FCU/m L indicates that meat has deteriorated,indicating that the DZS intelligent indicator membrane can indicate the freshness of chicken through color changes.（3）Using D.zingiberensis cellulose as C source and urea as N source,nitrogen doped carbon quantum dots（NC-CDs）were prepared by hydrothermal method under high temperature and high pressure,and their morphology,optical properties,structure,element composition,metal ion detection ability and other physical properties were characterized.The yield of NC-CDs was 3.31%and the fluorescence quantum yield was 19.3%.The morphology is spherical with an average particle size of 3.91 nm.NC-CDs can emit bright blue fluorescence under ultraviolet light,and the fluorescence intensity is the highest when the excitation wavelength is 360 nm.The results of XPS and FT-IR analysis show that the surface of the prepared NC-CDs contains hydroxyl,amino,carbonyl groups and other functional groups.These functional groups determine the properties of NC-CDs,making it have good fluorescence characteristics and water solubility.The selectivity of NC-CDs for metal cations showed that NC-CDs could detect Fe³⁺sensitively,the fluorescence intensity decreased with the increase of Fe³⁺concentration,and the linear fitting results showed a linear correlation（R²=0.9928）.The results showed that NC-CDs was stable at p H 6～8,and its fluorescence intensity remained stable within 12 hrs.