Structural and functional properties of hydrolyzed/glycosylated ovalbumin under spray drying and microwave freeze drying

Ovalbumin(OVA),the main protein in egg white,affects most of the functional properties of egg white protein in food processing.The aim of this study was to investigate the effects of spray drying(SD)and microwave freeze drying(MFD)on the preparation of hydrolyzed/glycosylated ovalbumin(HGOVA)and provide useful information on the applications of egg protein powders in the food industry.Results demonstrated that the structure of HGOVA was considerably changed,and its functional properties were improved compared with those of native OVA.SD and MFD processing did not lead to dissociation of HGOVA subunits.SD-HGOVA exhibited higher protein solubility,emulsifying activity,foaming capacities,and gel hardness than MFD-HGOVA.However,MFD-HGOVA was better than the SD-HGOVA in terms of color,emulsion stability,foam stability,water/oil absorption capacity,and thermal stability.Selection of an appropriate drying method could enhance the potential applications of HGOVA in the food industry.

Research on Freeze Drying and High-temperature Molding in Medium-temperature Fluorocarbon Board

A research and test system for the carbon anode plate preparation technology was established to optimize the physical and chemical indicators of carbon anode plates,such as bulk density,resistivity,and compressive strength,and improve the operating cycle.In this study,a carbon plate was prepared via a combination of high-temperature molding and freeze drying using a formulation with asphalt content much lower than the industry standard.The experimental results show that the density of the carbon plate is increased by 0.02-0.04 g/cm^(3) by improving the drying method.The carbon plate prepared in the laboratory has a bulk density of 1.814 g/cm^(3),resistivity of 29.8μΩ·m,and compressive strength of 89.27 MPa.The bulk density,room-temperature resistivity,compressive strength,graphitization,and other key indices of the carbon plates made in the laboratory and those procured from a factory in Shanxi,Datong,were tested.Additionally,the specimens were analyzed using thermogravimetry-differential scanning calorimetry,scanning electron microscopy,and X-ray fluorescence.The laboratory-made carbon plates were superior to the factory specimens in terms of all the indicators tested.The process in this study improves the performance of the carbon anode plate and is used to provide technical support for electrolytic fluorine production in enterprises.The carbon plates prepared in the laboratory fully meet the process requirements of a medium-temperature electrolytic fluorine production line,which indicates the possibility of its use in the stable production of fluorine gas.

Atmospheric freeze drying of garlic slices based on freezing point depression

Garlic is difficult to dry due to browning reaction and degradation of heat-sensitive component.Freeze drying(FD)can keep good shape,color and nutrition of dried garlic,but it consumes long drying time and high energy.To shorten drying time and obtain high quality products,atmospheric freeze drying(AFD)was developed for drying garlic slices.The effects of different inlet air temperature programs on product quality and drying process were studied during AFD process.It was found that freeze point depression could lead to part of ice thawing resulting in product quality deterioration when the air temperature was not low enough.Based on this,a step-down-up temperature program was developed to reduce the drying time and provide good product quality.

Boosted activity of Cu/SiO_(2) catalyst for furfural hydrogenation by freeze drying

The biomass valorization is of great importance as an alternative for the production of transport fuels and fine chemicals.Furfural hydrogenation to furfuryl alcohol is a prevailing industrial route for the utilization of hemicellulose component of biomass.The toxicity of the chromium species in commercial copper chromite catalyst for furfuryl alcohol production motivates the development of efficient chromium-free catalyst.Thus,a highly efficient silica supported copper catalyst is developed in this study.The catalyst is prepared by freeze drying of a gel precursor that is synthesized by ammonia evaporation,followed by calcination and H_(2)reduction.The catalyst exhibits higher furfural hydrogenation activity than oven dried catalyst,commercial copper chromite catalyst and a plant supplied commercial silica supported copper catalyst.The catalyst also shows good stability.The superior performance of the freeze dried catalyst has resulted from its developed pore structure and higher amount of Cu^(0)as well as Cu^(+)active sites.

Effects of different pretreatments on the pore structure of Chinese yam during microwave freeze drying

In order to explore the effects of different pretreatments on the pore structure of Chinese yam during Microwave Freeze Drying(MFD),the samples were treated by typical drying pretreatments including osmosis,blanching and ultrasound,and compared with the untreated samples.The results showed that the pretreatment had significant impacts on the porosity of MFD Chinese yam.Ultrasonic pretreatment could obtain the highest open porosity,and the internal pore network structure of the material showed a uniform sponge shape.The shape of pores obtained by blanching pretreatment was the most irregular.The pore network structure obtained by different pretreatments could result in various product texture and rehydration,which implied that pretreatment methods should be carefully selected according to actual requirements.All these pretreatments could improve the open porosity of MFD Chinese yam,which result in a better rehydration capability.Among them,ultrasonic treatment is worth further investigating.

Optimization of Freeze-drying Protective Agents for Lactobacillus plantarum KLDS1.0391 by Response Surface Methodology

In this study, the Single Factor Test（SFT） was used to optimize the pre-freezing conditions of L. plantarum KLDS1.0391（KLDS1.0391）. Further, the Freeze-Drying Protective Agents（FDPA） of KLDS1.0391 was optimized by Response Surface Methodology（RSM）. The optimum pretreatment conditions were as the follows： initial concentration of KLDS1.0391 was 1011 CFU · m L-1 and KLDS1.0391 was pre-freezed at –80℃ for 8 h to achieve the survival rate of 46.21%. The main components of FDPA were skim milk, sucrose, sodium glutamate and Tween-80. And the influence of four factors on the survival rate of KLDS1.0391 in freeze-drying was in order as the follows： skim milk〉sucrose〉Tween-80〉sodium glutamate. The optimal FDPA composition was skim milk 11.3%, sucrose 9.8%, sodium glutamate 5.1% and Tween-80 0.2%. Under the above conditions, the survival rate of the cells was 82.98%. Comparing the predicted values, the relative error was 0.37% and the difference was not significant, which indicated that the established model could effectively reflect the actual protection of FDPA to KLDS1.0391.

Physico-chemical properties and nutrition quality of potato flour: chuño vs modern processing technology

Chuño production is a kind of ancient method of potato preservation that has been used to the present day.In this study,physicochemical property and nutrition quality of white chuño(WC),black chuño,and dehydrated potato flour prepared by hot air drying(AD)and freezing drying were analyzed and compared.The results revealed that the average particle size of the starch in WC is almost 10 times of the dehydrated potato flour by AD treatment according to the laser particle size meter.During the dehydration of WC,water-soluble minerals(K+,Mg2+),proteins,ascorbic acid,etc.were partly lost while Ca2+content increased dramatically.In addition,WC showed the lowest antioxidant capacity among the four different kinds of dehydrated potato products.The polyphenol oxidase activity of WC,black chuño and AD were between 0.62–12.2 U/g fresh weight,which indicated that the color will be stable when chuño was used as staple food ingredient in the subsequent process.Therefore,as a potato processed food,chuño displayed great potential for promotion in the cold and poor rural areas of the northern China.

Progress involving new techniques for liposome preparation

The article presents a review of new techniques being used for the preparation of liposomes.A total of 28 publications were examined.In addition to the theories,characteristics and problems associated with traditional methods,the advantages and drawbacks of the latest techniques were reviewed.In the light of developments in many relevant areas,a variety of new techniques are being used for liposome preparation and each of these new technique has particular advantages over conventional preparation methods.However,there are still some problems associated with these new techniques that could hinder their applications and further improvements are needed.Generally speaking,due to the introduction of these latest techniques,liposome preparation is now an improved procedure.These applications promote not only advances in liposome research but also the methods for their production on an industrial scale.

Effects of freeze-drying and spray drying processes on functional properties of phosphorylation of egg white protein

Egg white protein(EWP)was phosphorylated with Sodium Tripolyphosphate(STP)at pH 4.5.Freeze drying and spray drying were used for drying purpose and the effects of these drying methods on the functional properties were investigated.The functional properties of native and modified proteins were also determined.The results demonstrated that phosphorylation of EWP markedly improved its functional properties,and that it was more effective for the food industry.The freeze-dried STP-EWP powders were superior in terms of solubility,emulsion stability,water holding capacity,oil and water absorption capacity and heat gel strength than spray-dried STP-EWP powders.The results in viscosity showed no significant differences between freeze-dried and spray dried.The spray-dried powders were better in terms of foaming ability and foam stability than freeze-dried powders.However,the spray drying required the longest time to produce.Freeze drying was found to be the best method in terms of production of modified EWP powders with superior functional properties.

Evolution of pore structure during microwave freeze-drying of Chinese yam

In order to reduce the energy consumption of freeze drying(FD),microwave freeze drying(MFD)can be used to dry Chinese yam.Porosity is a critical factor influencing transport mechanism,and can be considered as an important index to reflect the changes of structure of MFD foods.In this study,the changes of pore structure during the process of MFD Chinese yam were investigated by SEM and mercury porosimetry.The results showed that some closed pores could transform to open pores in drying process,and the open porosity showed a rising trend throughout the drying process.The pore size distribution range was about 10 nm to 10^(6) nm throughout the drying process.In the early stage of drying,the pore size was mainly in the range of 10-10^(4) nm,and then the pore size and the number of pores reduced.In the middle and late drying stages,the size of large pores increased again.

Preparation of Ceramic Foams Suitable for Aircraft Arresting by the Airport Runway Based on a Protein Foaming Agent

Crushable ceramic foams are more suitable to be used as an arrestor material applied in engineered materials arresting system （EMAS） for airport runway for their properties of widely controllable strength, negligible crushing-rebounding behavior, durability, and chemically-inert composition, comparing with traditional concrete foams. The synthesis of ceramic foams adopted direct-foaming method and used an animal protein as foaming agent. Kaolin, talc powder and alumina were the main raw materials. Effects of the ratios of raw materials, calcination temperatures, heating rates, holding time, viscosities of potyvinyl alcohol （PVA） solution as well as the amounts of protein foaming agent and water on microscopic structure, densities, compressive strength and open porosities of ceramic foams were investigated systematically. The results indicate that ceramic foams with typical pore sizes 100-300 μm, open porosities from 73.1% to 91.5%, densities from 0.25 to 0.62 g.cm-3, compressive strength from 0.19 to 4.89 MPa, are obtained by properly adjusting the parameters mentioned above. And the mechanical strength meets the requirement for the EMAS for airport runway. In addition, good correlations are observed among compressive strength, open porosity, microscopic structure, and crystal phase. Furthermore, the possibility of producing the general dimensions of such aircraft arresting components with the proposed method was also discussed.

Freeze and microwave vacuum combination drying technique for sea cucumber

To improve the quality and efficiency of sea cucumber drying,an orthogonal experiment of freeze and microwave vacuum combination drying technique was carried out.Factors and levels were FD time of conversion point(8 h,16 h and 24 h),initial microwave power density(1.7 W/g,2.0 W/g and 2.3 W/g)and microwave intermittent ratio(12s-on/18s-off,14s-on/16s-off and 20s-on/10s-off).Results showed that the optimal parameters of FD-MVD were 8 h FD conversion point,1.7 W/g initial microwave power density,12 s-on/18 s-off microwave intermittent ratio,and the maximum rehydration rate of 280.71%,the lowest shrinkage rate of 14.48%,the least drying time of 9.25 h and energy consumption of 77316 kJ could be obtained.

Comparative study on the effects and efficiencies of three sublimation drying methods for mushrooms

Freeze drying(FD)yields the best quality of dried mushrooms but needs long drying time and higher cost.Air drying(AD)gives relatively poor product quality.In order to achieve faster drying along with high product quality,microwave freeze drying(MFD)and atmospheric freeze drying(AFD)were developed to dry mushrooms.By comparison of three sublimation drying processes,it was concluded that FD could lead to the best product quality,but cost the highest energy consumption.AFD mushrooms had the worst quality and longest drying time,but the lowest energy consumption.Compared with FD and AFD,MFD could get relatively acceptable quality and drying efficiency.As a result,MFD can be used to replace traditional FD,and AFD also should be popularized because of its low energy consumption.

Use of Thermogravimetric Analysis for Moisture Determination in Difficult Lyophilized Biological Samples

Residual moisture is a key quality control parameter for lyophilized biologicals, as high moisture can correlate with poor stability. Coulometric Karl Fischer titration is the most widely used technology to determine residual water content;some chemicals are known to cause problems with Karl Fischer titration, but these chemicals do not usually occur in biologics. Three biological samples, of fibrinogen, heparin and Haemophilus influenza b polysaccharide, have caused particular issue in our hands by routine Karl Fischer analysis, illustrating different limitations with this method. The use of thermogravimetric analysis, with evolved gas mass spectrometric monitoring, is described here as a successful alternative for moisture analysis in these materials.

Storage stability of freeze-dried colostral whey powders with different additives

Effects of different additives(sucrose and maltodextrin)on storage stability of colostral whey(CW)powders packaged in aluminium-laminated polyethylene pouches were investigated under different storage conditions(4℃and 40%-70%relative humidity(RH),25℃and 50%RH,and 50℃and 20%-60%RH).All the samples stored under 50℃and 20%-60%RH showed the highest levels of lipid oxidation,Maillard reaction,proteolysis,and color difference,and the lowest immunoglobulin G(IgG)retention.Moisture contents showed an increase trend with increasing RH.Addition of sucrose into CW powders increased water adsorption capacity and Maillard reaction,whereas addition of maltodextrin showed the opposite effects.Maltodextrin as drying aids was suitable for keeping quality during storage.Sucrose did not clearly play any roles in protecting denaturation of IgG during 90-day storage.The low storage temperature and RH were helpful for keeping storage stability of CW powders with different additives.

Freeze–dried synthesized bifunctional biopolymer nanocomposite for efficient fluoride removal and antibacterial activity

Local fluoride contamination and bacterial infections in potable water have dangerous effects on the human body and are today a global concern.In this study,we have synthesized a pH-responsive bifunctional biopolymer nanocomposite(HAZ)of humic acid with incorporating aluminum zirconium bimetallic oxide by deep freeze–drying method.Fast nucleation and interconnection of nanoparticles form a highly porous network because of sublimation of frozen HAZ.This duo nanocomposite has efficiently worked for fluoride removal and showed potent antibacterial activity against the Escherichia coli Gram-negative and Staphylococcus aureus Gram-positive bacteria.The X-ray photoelectron spectroscopy(XPS)analysis demonstrates that the hydroxyl groups act as a pivot in the ion exchange process of adsorption,each element of bimetallic oxide primarily takes part in the adsorption mechanism.The maximum adsorption capacity of the adsorbent was 180.62 mg/g at pH seven.Thermodynamic parameters like Gibbs free energy change(△G0),entropy(△S0),and enthalpy(△H0)indicate that the process was endothermic,feasible,and taken place by a chemisorption mechanism.This is the first novel freeze–dried bifunctional biopolymer nanocomposite composed of humic acid natural polymer incorporated with Al–Zr metal oxide,and it exhibited three times higher adsorption efficacy with excellent antibacterial action at a concentration of 5μg/mL of the nanocomposite.

In vitro assessment of the effect of microencapsulation techniques on the stability,bioaccessibility and bioavailability of mulberry leaf bioactive compounds

Mulberry(Morus alba L.)leaf extract is well-known for its health-promoting features.However,food processing conditions affect its bioactive profile,which could be limited by encapsulation.Nevertheless,assessing the impact of encapsulating techniques on the digestibility of embedded biocompounds requires further knowledge.Hence,the aimed of this study was to assess the effects of carrier materials and drying techniques on(i)bioaccessibility and bioavailability indexes,(ii)stability of nutraceuticals,and(iii)changes in antioxidant activities of mulberry leaf extract powder by using an in vitro oral-gastrointestinal digestion.Digestion was performed out at 37°C in darkness by shaking encapsulated extract with human saliva during 2 min,followed by 2 h of incubation with a pepsin-HCl mixture,then mixed for 2 h with bile salts and pancreatin.After digestion the samples were acidified and HPLC assayed.A significant(p<0.05)decrease in nutraceuticals content was noted during the intestinal phase with more reduction in gamma-aminobutyric acid(34.91–51.14%)compared to that of flavonols(16.58–28.90%),1-deoxynojirimycin(17.56–20.42%)and phenolic acids(0.53–0.67%)in the gastric digesta.Although encapsulation was observed to enhance the bioaccessibility,negative effects were found in terms of the bioefficiency and bioavailability.Furthermore,encapsulation techniques mostly affected the ion reducing capacity than the radical scavenging capacity.The outcomes suggested that carriers had a major effect on the digestibility and antioxidative activity,whilst the drying techniques mostly affect the bioaccessibility and bioavailability of the flavonols.