非肝素类天然抗凝血多糖的研究进展

血液凝固和血小板凝集是局部缺血性疾病发病的最重要的原因,诱发心血管和脑血管甚至全身各处的相关疾病。肝素类物质已被广泛应用于相关疾病的治疗,作用效果显著但副作用较大。本文介绍了非肝素类具有抗凝血功能的天然多糖类物质,其单糖组成主要是葡萄糖(醛酸)、半乳糖(醛酸)、阿拉伯糖、甘露糖、木糖、鼠李糖等,其中源于海洋的多糖均含有硫酸根,与多糖形成多糖硫酸酯类物质;而源于陆地的,一般不含硫酸根,含己糖醛酸或尿酸等酸性成分。不同来源的多糖其分子组成和结构差异较大,抗凝作用机理也不尽相同。本文着重阐述了海藻类、海洋无脊椎动物、植物及其果实、可食用菌等来源的抗凝血多糖结构特点、抗凝作用机理,希望能为高抗凝活性、低毒副作用的天然多糖类药物的进一步研究提供一定的参考。

Challenges in the microbiological food safety of fresh produce:Limitations of post-harvest washing and the need for alternative interventions

Fresh produce(processed fruit and vegetables)continues to be the main source of foodborne illness outbreaks implicating pathogens such as Escherichia coli O157:H7,Salmonella,Listeria monocytogenes and human parasites(e.g.hepatitis A,Cyclospora).Previously,outbreaks were primarily limited to leafy greens,tomatoes,and cantaloupes,but more recently there has been a trend of more diverse produce types(e.g.cucumbers and papayas)being implicated.Although on-farm good agriculture practices(GAP)contribute to preventing pathogens entering the fresh produce chain,it cannot be relied upon completely due to the open nature of farming.As a consequence,there is an identified need for interventions that can remove field-acquired contamination,especially given fresh produce is eaten raw.In the following review,an overview of foodborne illness outbreaks linked to contaminated fresh produce will be described along with potential sources of contamination.Post-harvest washing that was once considered decontamination is now viewed as a high-risk cross-contamination point.The challenges in monitoring the post-harvest wash process will be discussed along with processing factors that need to be considered.A range of alternative,or supplemental,non-aqueous interventions will be described including irradiation,ultraviolet light,high hydrostatic pressure,gas phase(ozone and chlorine dioxide),and hydroxyl radicals generated through advanced oxidative process or gas plasma.All have been proved to be effective at pathogen control on the laboratory scale and are poised to enter commercial application.The current status of these alternative interventions along with challenges of integrating into commercial practice will be described.

Identification and characterization of soybean dreg soluble dietary fibre by combination of extrusion pre-treatment and enzymatic modification

OBJECTIVES:Soybean dreg is a by-product of soy milk processing,which contains high levels of soluble dietary fibre(SDF).In this study,we aimed to provide comprehensive processes of pre-treated extrusion for the improving structure and properties of soybean dreg soluble dietary fibre(SDSDF),which would be a valuable approach to enhance physiological activity.METHODS:Here,we characteristic the functional role of SDSDF employing to extrusion pretreatment.Soybean dregs were pre-treated using the twin screw extrusion method followed by enzymatic modification using neutral protease,α-amylase,glucoamylase,and cellulose to produce SDSDF.The physical properties and antioxidant activity of SDSDF were investigated.RESULTS:The morphology and crystal structure of SDSDF were observed that,through extrusion processing and enzymatic modification,the SDSDF yield increased by 106.28%.Moreover,the surface structure showed block-shaped or reticular formations in the extruded SDSDF,and the size of block-shaped cells was about 10μm.Infrared spectroscopic analysis showed that a characteristic absorption peak of polysaccharide appeared at 1631 cm−1 during extrusion processing.However,after extrusion processing,decreased absorption peaks were observed for the extruded SDSDF.Furthermore,XRD analysis showed that the 2θdiffraction peak changed at 24.16°for the extruded SDSDF.CONCLUSIONS:The overall findings suggest that the water holding capacity(WHC),oil holding capacity(OHC),expansibility,and the water solubility were significantly decreased in extruded SDSDF.In addition,the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl(DPPH),-OH,O_(2)^(-),and the total reducing power were significantly improved,indicating that beneficial changes had taken place in the crystal structure of cellulose or hemicellulose to improve the physiological activity in extruded SDSDF.

Quantification of browning in apples using colour and textural features by image analysis

This study analyses the effect of browning through image analysis based on colour and textural features in fresh-cut apple slices.A computer vision system(CVS)was developed for image acquisition,which consisted of a digital camera and a florescent lamp source for illumination with a contrasting background.The CVS was calibrated using standard colour values and a model was developed by artificial neural network technique.Three varieties of apples such as Honey crisp,Granny Smith,and Golden Delicious were used for the analysis.The apples were freshly cut and subjected to image acquisition.Normalized colour features(L*,browning index,hue,and colour change)and textural features(entropy,contrast,and homogeneity)were analysed from the acquired images.The varieties Honey Crisp and Granny Smith did undergo browning within 120 min,whereas Golden delicious did not brown significantly.The study concluded that colour and textural features were important decision features for detecting browning in apples through image analysis.

Treatment of spent wash water derived from shredded lettuce processing using a combination of electrocoagulation and germicidal ultraviolet light

Objective:Water recycling is a significant part of an overall water management system.The current study evaluated electrocoagulation,used in combination with ultraviolet light(at 254 nm),to reduce the organic content and enhance the microbiological quality,of wash water derived from shredded lettuce processing.Method:The composition of spent wash water derived from a commercial lettuce processing operation was used to prepare a simulated solution to be applied to validate the water recycling system.The simulated spent wash water was subjected to an electrocoagulation process followed by filtration and a tertiary ultraviolet(254 nm)treatment.The efficacy of the recycling treatment to decrease turbidity(nephelometric turbidity units,biological oxygen demand(BOD),chemical oxygen demand(COD)and decrease in introduced bacterial numbers.Results:Spent wash water sampled from a commercial processing line was found to be colloidal in nature(78±26 NTU)with low total solids content(544±87 mg/L),BOD(230±53 mg/L)and COD(309±53 mg/L).An electrocogaultion process performed for 10 min using 3.48 A/m2 current density at pH 6.5 and conductivity of>100μS/cm supported an 87%removal of turbidity,38%reduction in BOD along with 49%decrease in COD.The electrocoagulation process was also found to reduce the levels of Escherichia coli,Salmonella and Listeria monocytogenes by 1-2 log cfu.The tertiary UV treatment of water derived from the electro coagulation process,supported further reduction in model pathogens,although it was noted that the D values for inactivation were in the order of 1.01-1.60 mJ/cm^(2),which compares to 0.22-0.31 mJ/cm^(2) in saline.The apparent increase in bacterial resistance to ultraviolet was likely due to the UV absorbing low molecular weight constituents within wash water that provided protection against inactivation.Conclusion:In conclusion,the study demonstrated the feasibility of applying electrocoagulation and UV to rapidly treat spent lettuce wash water to facilitate in-process recycling within shredded lettuce processing operations.