Effects of Waterborne Elastic Polyester with Different Compositions on the Properties and Compatibility of Maize Starch

Waterborne elastic polyester (WEP) with different content of hard polyester was applied in the maize starch (MS) based composites (MS/WEP) via solution casting method.The effects of WEP with different contents of hard polyester on the structure and properties of starch were studied by Fourier transform infrared,X-ray diffraction,ultraviolet-visible,tensile test,differential scanning calorimeter,thermogravimetric analysis and moisture measurement.The experimental results show that the addition of WEP does not change the crystalline type of starch,and only reduces the crystallinity of starch.And the structure and properties of MS/WEP are related to not only the content of starch but also the microstructure of WEP or the content of hard polyester in WEP.Waterborne elastic polyester with 30wt% hard polyester (WEP30) has the best modification effect on the maize starch among all the WEPs.For example,MS/WEP30 film has the optimum toughness,aging resistance and transmittance,the lowest crystallinity and glass transition temperature among all the MS/WEP films,and the lower moisture content.It is related to the compatibility between starch and WEP,resulting from the number of physical crosslinking points in WEP..

Anaerobic biodegradation,physical and structural properties of normal and high-amylose maize starch films

Biodegradable plastics have attracted considerable attention in recent years due to their biodegradability,biocompatibility and non-toxicity.In this study,normal maize starch(containing 25%amylose)and high-amylose maize starch(containing 80%amylose)were served as model materials to prepare starch/polyvinyl alcohol(PVA)blends.To comprehensively study the effects of amylose contents on the film performances,the mechanical properties,water resistance and anaerobic biodegradability of the two films were examined.Moreover,the processes of anaerobic degradation were investigated by evolutions of biogas production,pH in reactors and the changes of film structures and compositions.The results indicated that amylose content played an important role in the microstructures of starch film as well as mechanical properties and water resistance,whereas it had no significant influence on anaerobic biodegradability of the films.Nonetheless,the structure of high-amylose maize starch/PVA film was more suitable and beneficial to the anaerobic biodegradation than that of the normal maize starch/PVA film,because it could effectively avoid accumulation of volatile fatty acids,which contributed to the stable biogas production,short fermentation period and non-souring in the reactor.

Effects of hot air drying temperature and tempering time on the properties of maize starch

Yellow maize as raw materials,hot air drying was used to reduce moisture content,and the tempering was implemented after drying.This study aimed to investigate the effects of hot air drying temperature and tempering time on the properties of maize starch.The wet milling was used to extract maize starch.Starch yield,protein content,amylose and amylopectin content,transparency and coagulation,solubility index and swelling power,color,pasting properties,and gelatinization properties were researched.The results showed that when the hot air temperature increased,the properties such as starch yield,amylopectin content,transparency,solubility,swelling power,whiteness decreased,and properties such as protein content and amylose content,coagulation,gelatinization temperature increased.Compared to drying temperature,tempering time has a less remarkable effect on the maize starch properties.The maize starch with better whiteness,solubility,swelling power could be obtained by adjusting tempering time.

Effect of steam-flaking on chemical compositions,starch gelatinization,in vitro fermentability,and energetic values of maize,wheat and rice

Intact and steam-flaked grains of maize,wheat and rice（with whole hulls） were analyzed for chemical composition,starch gelatinization degree（SGD） and in vitro fermentation characteristics to investigate the influence of cereal type and steam-flaking（SF） processing on their nutritive values.The treatments were arranged in a 3×2 factorial design.Obvious differences（P〈0.001） in chemical composition and energetic values were observed among the different cereal types.SGD and gas production（GP） rate was significantly increased（P〈0.001） by SF processing.SF processing also increased（P〈0.01） the proportion of propionic acid and decreased the acetic：propionic acid ratio in vitro.Steam-flaking also increased organic matter digestibility and the energetic value of the cereal grains,especially rice.Based on these results,rice probably is more amendable to SF processing than maize and wheat.In conclusion,it is feasible to partially substitute maize grain with wheat or rice in ruminant diets,and steam-flaking can significantly improve the nutritional value of wheat and rice grains.

Determination of Protein and Starch Content in Whole Maize Kernel by Near Infrared Reflectance Spectroscopy

Using 128 bulk-kernel samples of inbred lines and hybrids, a study was conducted toinvestigate the feasibility and method of measuring protein and starch contents inintact seeds of maize by near infrared reflectance spectroscopy (NIRS). The chemometricalgorithms of partial least square (PLS) regression was used. The results indicated thatthe calibration models developed by the spectral data pretreatment of firstderivative+multivariate scattering correction within the spectral region of 10000-4000cm-1, and first derivative + straight line subtraction in 9000-4000cm-1 were thebest for protein and starch, respectively. All these models yielded coefficients ofdetermination of calibration (R2cal) above 0.97, while R2cv and R2val of cross and externalvalidation ranged from 0.92 to 0.95, respectively; however, the root of mean squareerrors of calibration, cross and external validation (RMSEE, RMSECV and RMSEP) werebelow 1(ranged 0.3-0.7),respectively. This study demonstrated that it is feasible touse NIRS as a rapid, accurate, and none-destructive technique to predict protein andstarch contents of whole kernel in the maize quality improvement program.

Transcriptome analysis of near-isogenic lines provides molecular insights into starch biosynthesis in maize kernel

Starch is the major component in maize kernels,providing a stable carbohydrate source for humans and livestock as well as raw material for the biofuel industry.Increasing maize kernel starch content will help meet industry demands and has the potential to increase overall yields.We developed a pair of maize near-isogenic lines（NILs） with different alleles for a starch quantitative trait locus on chromosome 3（q HS3）, resulting in different kernel starch content. To investigate the candidate genes for q HS3 and elucidate their effects on starch metabolism, RNA-Seq was performed for the developing kernels of the NILs at 14 and 21 d after pollination（DAP）. Analysis of genomic and transcriptomic data identified 76 genes with nonsynonymous single nucleotide polymorphisms and 384 differentially expressed genes（DEGs） in the in trogressed fragment, including a hexokinase gene, Zm HXK3 a, which catalyzes the conversion of glucose to glucose-6-phosphate and may play a key role instarch metabolism. The expression pattern of all DEGs in starch metabolism shows that altered expression of the candidate genes for q HS3 promoted starch synthesis,with positive consequences for kernel starch content. These results expand the current understanding of starch biosynthesis and accumulation in maize kernels and provide potential candidate genes to increase starch content.