Inactivation mechanisms on pectin methylesterase by high pressure processing combined with its recombinant inhibitor

High pressure processing (HPP) juice often experiences cloud loss during storage, caused by the activity of pectin methylesterase (PME). The combination of HPP with natural pectin methylesterase inhibitor (PMEI) could improve juice stability. However, extracting natural PMEI is challenging. Gene recombination technology offers a solution by efficiently expressing recombinant PMEI from Escherichia coli and Pichia pastoris. Experimental and molecular dynamics simulation were conducted to investigate changes in activity, structure, and interaction of PME and recombinant PMEI during HPP. The results showed PME retained high residual activity, while PMEI demonstrated superior pressure resistance. Under HPP, PMEI's structure remained stable, while the N-terminus of PME's α-helix became unstable. Additionally, the helix at the junction with the PME/PMEI complex changed, thereby affecting its binding. Furthermore, PMEI competed with pectin for active sites on PME, elucidating. The potential mechanism of PME inactivation through the synergistic effects of HPP and PMEI.

Effect of compositions and physical properties on 3D printability of gels from selected commercial edible insects: Role of protein and chitin

Compositions and rheological properties of alternative protein sources, including honey bee pupa, grasshopper, cricket, earthworm, and scorpion, and their relationships with 3D printing behaviors were investigated. Protein was found to be the major composition in all insects, while chitin exhibited the most variation. At optimal moisture contents, honey bee pupa and earthworm gels displayed sufficient fluidity but resulted in unstable printed structures, as observed visually and microstructurally. Grasshopper and scorpion gels possessed weak fluidity but produced more stable printed structures. Cricket gel exhibited the most balanced flow behavior and self-supportability. Protein-to-chitin mass ratio proved to be a main factor affecting the 3D printing behavior of the gels. Possible mechanisms on how compositions and properties affected the printing behavior of the gels were proposed. Suggestions for improving the 3D printability of insect and invertebrate resembling insect gels were provided based on these proposed mechanisms.

Antioxidant Activities of Konjac Glucomannan Hydrolysates of Different Molecular Weights at Different Values of pH

Konjac glucomannan (KGM) is a high-molecular-weight polysaccharide that was originally extracted from the corms (underground storage organs) of Amorphophallus konjac. KGM and its oligomers have been reported as dietary fibers that exhibit an array of health benefits. The depolymerization of KGM via enzymatic hydrolysis at different conditions gives products of low viscosity and can be used for coating materials in microencapsulation. In the present study, konjac glucomannan hydrolysates (KGMHs) were produced by enzymatic hydrolysis using commercial mannanase at pH 4.5 at 70 °C for 5-120 min, then KGMHs' molecular weight (Mw), Degree of Polymerization (DP) and their bioactivities were determined. A longer hydrolysis time resulted in KGMH of a lower DP. Oligoglucomannans (Mw < 10,000) could be obtained after hydrolysis for 20 min. The DP of KGMH rapidly decreased during an early stage of the hydrolysis (first 40 min); DP reached around 7 at the end of the hydrolysis. Antioxidant activities were determined by the DPPH radical scavenging and FRAP assays of KGMHs prepared at pH 4.5 and evaluated at pH 2.0-8.0 depending on pH. KGMH having lower Mw exhibited higher antioxidant activities. KGMHs having the smallest molecular weight (Mw = 419) exhibited the highest DPPH radical scavenging activity. Mw and pH have a greater impact on KGMHs' bioactivities which can be useful information for KGMHs as functional ingredients.

Protocols for extraction and purification of rutin from leafy by-products of asparagus (Asparagus officinalis) and characterization of the purified product

Valorization of asparagus leafy by-products as a potential source of rutin through selected extraction and purification protocols was investigated. Protocol resulting in the highest extraction yield was first selected. Crude extract was subject to purification via multiple liquid-liquid back extraction using ethanol, methanol or water as a solvent; selection of the most appropriate purification solvent was made based on rutin solubility. The proposed purification protocol yielded yellow-color crystals, which were characterized by fluorescence microscopy, Fourier-transform infrared spectroscopy and liquid chromatography-mass spectrometry to confirm them as rutin. Purity of rutin was confirmed by ultra-performance liquid chromatography at 97.6%; yield of the purified rutin was determined to be 78.2%. The remaining rutin (21.8%) was found in the liquids collected at various stages of purification; such liquids could be recycled using the same purification process. The proposed protocols are simple, yet effective for rutin extraction and purification from asparagus leafy by-products.

Production and characterization of nanofibrillated cellulose gels simultaneously exhibiting thermally stable green color and oil-in-water emulsion stabilizing capability from Centella asiatica

Nanofibrillated cellulose (NFC) gels simultaneously exhibiting Pickering stabilizing capability and thermally stable green color were developed for use as food additive in thermally processed food emulsion requiring the expression of color. Chopped Centella asiatica plant was mixed with zinc amino acid chelate solution and subject to autoclaving at 130°C for 2 h to form zinc-chlorophylls complex and to remove noncellulosic components. Autoclaved sample was high-shear homogenized at 26,000 rpm for 15 min and microfluidized at either 80, 120, or 160 MPa for 5 passes. An increase in microfluidization pressure resulted in a decrease in NFC diameters; microfluidization at 160 MPa did not nevertheless yield any further reduction in the diameters when compared with that at 120 MPa. From energy consumption point of view, microfluidization at 120 MPa for 5 passes was then noted as optimal condition for preparation of NFC coloring gel; NFC with diameters of 8-42 nm and crystallinity index of 35% was obtained. Freshly prepared gel exhibited gel-like behavior and dark green color. Heating at 121°C for 1 h did not affect diameters, viscoelasticity, and color of the gel. Addition of the gel at 0.9% or 1.2% (w/w) into soybean oil-in-water emulsion, in combination with high-shear homogenization at 18,000 rpm for 5 min, resulted in adequate emulsion stability. The emulsion exhibited stable dark green color and no phase separation after heating at 121°C for 1 h and during storage for 8 weeks. PRACTICAL APPLICATIONS: Information presented here can serve as a guideline for further development of a multifunctional food ingredient exhibiting thermally stable green color and oil-in-water emulsion stabilizing capability. In other words, one simple ingredient can serve at the same time as both natural food colorant and emulsion stabilizer.

Effect of the Structure of Highly Porous Silica Extracted from Sugarcane Bagasse Fly Ash on Aflatoxin B1 Adsorption

Sugarcane bagasse fly ash is industrial waste produced by incinerating biomass to generate power and steam. The fly ash contains SiO₂ and Al₂O₃, which can be used to prepare aluminosilicate. This latter material exhibits high potential as an adsorbent in various applications, including the livestock industry where issues related to contamination of aflatoxins in animal feeds need to be addressed; addition of adsorbents can help decrease the concentration of aflatoxins during feed digestion. In this study, the effect of the structure of silica prepared from sugarcane bagasse fly ash on physicochemical properties and aflatoxin B1 (AFB1) adsorption capability compared with that of bentonite was investigated. BPS-5, Xerogel-5, MCM-41, and SBA-15 mesoporous silica supports were synthesized using sodium silicate hydrate (Na₂SiO₃) from sugarcane bagasse fly ash as a silica source. BPS-5, Xerogel-5, MCM-41, and SBA-15 exhibited amorphous structures, while sodium silicate possessed a crystalline structure. BPS-5 possessed larger pore size, pore volume, and pore size distribution with a bimodal mesoporous structure, while Xerogel-5 exhibited lower pore size and pore size distribution with a unimodal mesoporous structure. BPS-5 with a negatively charged surface exhibited the highest AFB1 adsorption capability compared with other porous silica. However, the AFB1 adsorption capability of bentonite was superior to those of all porous silica. Sufficient pore diameter with high total pore volume as well as high intensity of acid sites and negative charge on the surface of the adsorbent is required to increase AFB1 adsorption in the in vitro gastrointestinal tract of animals.

Production of salad dressings via the use of economically prepared cellulose nanofiber from lime residue as a functional ingredient

Production of cellulose nanofiber (CNF) via the use of a more economical and less energy-intensive means is desirable. Once formed, it is necessary to determine whether or not the prepared CNF would be capable of forming a Pickering emulsion as in the case of traditionally prepared nanofiber. In the present study, oil-in-water emulsions, namely, salad dressings, with CNF as a functional ingredient, were prepared. Lime residue powder as the source of dietary fiber was subject to high-shear homogenization to form CNF suspension, which was then mixed with other ingredients. Different contents of fat (20%-40%), egg yolk (0%-4%), and lime residue powder (0%-4%) were tested. The formed CNF successfully acted as a Pickering emulsifier and allowed the production of salad dressings with desirable characteristics at 30%-40% fat, 2% egg yolk, and 2% lime residue powder. The dressings exhibited adequate physicochemical properties and remained stable throughout the storage period of 28 days. PRACTICAL APPLICATION: The presently proposed means would allow the industry to produce cellulose nanofiber (CNF) in a more economical and less energy-intensive manner. The so-produced CNF exhibits comparable properties as traditionally prepared nanofiber and can be used as a stabilizer in food emulsions.

Rapid smartphone-based assays for pesticides inspection in foods: current status, limitations, and future directions

Smartphone-based assays to inspect pesticides in foods have attracted much attention as such assays can transform tedious laboratory-based assays into real-time, on-site, or even home-based assay and hence overcoming the limitations of conventional assays. Although an array of smartphone-based assays is available, information on the use of these assays for pesticides inspection is scattered. The purposes of this review are therefore to compile, summarize and discuss state-of-the-art as well as advantages and limitations of the relevant technologies. Suggestions are provided for further development of smartphone-based assays for rapid inspection of pesticides in foods. Smartphone-based assays relying on enzyme inhibitions are noted to be nonselective qualitative, capable of reporting results in a quantitative manner only when a sample contains an individual pesticide. Smartphone-based assays relying on chemical reactions also target only individual pesticides. Smartphone-based visible spectroscopy can, on the other hand, inspect individual and multiple pesticides with the aid of appropriate colorimetry-, luminescence-, or fluorescence-based assay. Smartphone-based visible-near infrared and Raman spectroscopies are suitable for simultaneous multiple pesticides inspection. Raman spectroscopy is of particular interest as it can detect pesticides even at lower concentrations. This spectroscopic technique can also serve as a real-time assay with the aid of cloud network computations.

Improvement of Moist Heat Resistance of Ascorbic Acid through Encapsulation in Egg Yolk–Chitosan Composite: Application for Production of Highly Nutritious Shrimp Feed Pellets

Simple Summary

Egg yolk (EY) is an excellent supplement for aquatic animals and has good food functionality. According to the high lipid content in EY, it was, for the first time, used in combination with chitosan (CS) to encapsulate the ascorbic acid (AA) to minimize the loss of AA during exposure to feed processing and seawater. The microcapsules’ production yield, EE, and moist heat resistance were evaluated. One selected encapsulated AA was fortified in shrimp feed. The AA retention in feed processing and seawater was evaluated. Both EE and production yields of the microcapsules were relatively high compared to other reports. Moist heat resistance capability of the encapsulated AA was up to 82%. EY was essential in moist heat protection, while CS significantly improved the microcapsules’ production yield, EE, and morphology. The loss of AA in feed processing and seawater was remarkably improved by 16 folds compared to the unencapsulated AA. The microcapsules showed high potential application for foods and aquatic feed to protect heat-labile and hydro-soluble substances.

Abstract

Egg yolk (EY) is an excellent supplement for aquatic animals and has good technofunctionality. Ascorbic acid (AA) is a potent bioactive substance and is essentially added to shrimp feed; however, it is drastically lost in both feed processing and in rearing environments. In this study, AA was microencapsulated in an EY–chitosan (CS) composite. The encapsulated vitamin was then mixed into a shrimp feed mixture to form pelleted feed via twin-screw extrusion. The effects of the EY/AA ratio and the amount of CS on moist heat resistance, production yield, encapsulation efficiency (EE), and morphology of microcapsules were investigated. The molecular interaction of the microcapsule components was analyzed by FTIR. The size and size distribution of the microcapsules were determined using a laser diffraction analyzer. The microstructure was evaluated by SEM. The physical properties of the microcapsule-fortified pelleted feed were determined. The AA retention at each step of feed processing and during exposure to seawater was evaluated. The results showed that the microcapsules had a spherical shape with an average diameter of ~6.0 μm. Decreasing the EY/AA ratio significantly improved the production yield, EE, and morphology of the microcapsules. EY proved to be the key component for moist heat resistance, while CS majorly improved the production yield, EE, and morphology of the microcapsules. The microcapsules showed no adverse impact on feed properties. The loss of AA in food processing and seawater was remarkably improved. The final content of the encapsulated AA remaining in shrimp feed was 16-fold higher than that of the unencapsulated AA.

Increased plasma trimethylamine-N-oxide levels are associated with mild cognitive impairment in high cardiovascular risk elderly population

Trimethylamine-N-oxide (TMAO) has been shown to be associated with cardiovascular (CV) disease and cognitive impairment. The association between early stages of cognitive impairment and TMAO in a high CV risk population has not been previously investigated. This study aimed to investigate the association between the plasma TMAO level and cognitive function in a population with a high risk of CV disease. Participants at a high risk of CV were included. The cognition was evaluated using the Montreal Cognitive Assessment. A score lower than 25 out of 30 was used to indicate mild cognitive impairment (MCI). Blood samples of all participants (n = 233) were collected to measure the plasma levels of TMAO and other metabolic parameters, including fasting blood sugar and lipid profiles. Logistic regression was used to evaluate the association between MCI and high plasma TMAO levels, adjusted for confounding factors. Of 233 patients, the mean age of patients in this study was 64 years old (SD 8.4). The median TMAO level was 4.31 μM (IQR 3.95). The high TMAO level was an independent risk factor of MCI (aOR 2.36, 95% CI 1.02 to 5.47; p 0.046), when adjusted for age, gender, health care service scheme, smoking history, metabolic syndrome, and history of established CV events. The high TMAO level was associated with MCI, after adjustment for potential confounding factors. These findings demonstrate that plasma TMAO levels can serve for target prediction as an independent risk factor for MCI in this population.

Defects in 3D/4D food printing and their possible solutions: A comprehensive review

3D food printing has recently attracted significant attention, both from academic and industrial researchers, due to its ability to manufacture customized products in such terms as size, shape, texture, color, and nutrition to meet demands of individual consumers. 4D printing, which is a technique that allows evolution of various characteristics/properties of 3D printed objects over time through external stimulation, has also been gaining more attention. In order to produce defect-free printed objects via both 3D and 4D printing, it is necessary to first identify the causes of defects and then their mitigation strategies. Comprehensive review on these important issues is nevertheless missing. The purpose of this review is to investigate causes and characteristics of defects occurring during and/or after 3D food printing, with a focus on how different factors affect the printing accuracy. Various techniques that can potentially minimize or eliminate printing defects and produce high-quality 3D/4D printed food products without the need for time-consuming trial and error printing experiments are critically discussed. Guidelines to avoid defects to improve the efficiency of future 3D/4D printed food production are given.

Spray drying of non-chemically prepared nanofibrillated cellulose: Improving water redispersibility of the dried product

Despite increasing interest in using nanofibrillated cellulose (NFC) as food thickener and emulsifier, poor water redispersibility of dried NFC, which is form suitable for practical utilization, significantly limits such applications. Studies are lacking on preparation of dried NFC with superior redispersibility. The present study therefore proposed and examined strategies to improve water redispersibility of spray dried NFC via the use of selected co-carriers, i.e., gum Arabic with/without xanthan gum, carboxymethyl cellulose or pectin. Synergistic interactions between NFC and co-carriers, as confirmed by X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra, helped prevent NFC agglomeration during spray drying. All reconstituted spray-dried NFC/co-carriers suspensions exhibited shear-thinning and gel-like behaviors, thus supporting the use of such suspensions as thickener and emulsifier. Spray-dried NFC with 80% gum Arabic and 20% xanthan gum (SD-NFC/GA20XG) resulted in suspension with highest viscosity; the suspension also performed best at recovering viscous characteristics of NFC. Water thickened by SD-NFC/GA20XG had strongest shear-thinning behavior, indicating that SD-NFC/GA20XG suspension resulted in smoothest mouth feel and easiest swallowing. Such observations were supported by XRD patterns of SD-NFC/GA20XG, which suggested that its relative crystallinity was the lowest. Its FTIR spectra also showed the highest intensity of -OH bending and carbonyl bands, which are directly related to water adsorption capability of NFC. Use of reconstituted SD-NFC/GA20XG as emulsifier also resulted in highest stability for oil-in-water (O/W) Pickering emulsion during storage for up to 30 days.

Textural properties and muscle activities during mastication of normal and ultrasonically softened sticky rice aimed for consumers with swallowing disorder: A pilot study

Ultrasonication was used to develop softer sticky rice for elder adults. Textural properties of original sticky rice (oSR) and ultrasonically modified sticky rice (mSR) were determined. In addition, jaw muscle activities during mastication of both oSR and mSR were investigated. Twenty-seven healthy elderly subjects, age 68.9 ± 7.6 years, were asked to masticate both types of sticky rice in random sequence for three times with a 5-min rest between each test. Activities of bilateral masseter and suprahyoid muscles were recorded. Root mean square (RMS) and mastication duration were analyzed. After mastication trials, subjects were asked to rate preference and softness of the samples. mSR exhibited significantly lower hardness than oSR, while cohesiveness and adhesiveness values of the two samples were not significantly different. Interestingly, all the muscle activities were not significantly different between masticating oSR and mSR, whereas the number of chewing cycles while chewing the mSR was larger. However, 92% of the subjects preferred mSR and felt that it was softer. mSR may therefore be regarded as having potential for elder people who have difficulty masticating hard solid foods based on its lower hardness and higher level of preference compared to oSR.

Microstructures of encapsulates and their relations with encapsulation efficiency and controlled release of bioactive constituents: A review

Vitamins, peptides, essential oils, and probiotics are examples of health beneficial constituents, which are nevertheless heat-sensitive and possess poor chemical stability. Various encapsulation methods have been applied to protect these constituents against thermal and chemical degradations. Encapsulates prepared by different methods and/or at different conditions exhibit different microstructures, which in turn differently influence the encapsulation efficiency as well as retention of encapsulated core materials. This review provides a summary of various microstructures resulted from the use of selected encapsulation methods or systems, namely, spray coating; co-extrusion; emulsion-, micelle-, and liposome-based; coacervation; and ionic gelation encapsulation, at different conditions. Subsequent effects of the different microstructures on encapsulation efficiency and retention of encapsulated core materials are mentioned and discussed. Encapsulates having compact microstructures resulted from the use of low-surface tension and low-viscosity encapsulants, high-stability encapsulation systems, lower loads of core materials to total solids of encapsulants and appropriate solidification conditions have proved to exhibit higher encapsulation efficiencies and better retention of encapsulated core materials. Encapsulates with hollow, dent, shrunken microstructures or thinner walls resulted from inappropriate solidification conditions and higher loads of core materials, on the other hand, possess lower encapsulation efficiencies and protection capabilities. Encapsulates having crack, blow-hole or porous microstructures resulted from the use of high-viscosity encapsulants and inappropriate solidification conditions exhibit the lowest encapsulation efficiencies and poorest protection capabilities. Compact microstructures and structures formed between ionic biopolymers could be used to regulate the release of encapsulated cores.

Effective pretreatment technologies for fresh foods aimed for use in central kitchen processing

The central kitchen concept is a new trend in the food industry, where centralized preparation and processing of fresh foods and the distribution of finished or semi-finished products to catering chains or related units take place. Fresh foods processed by a central kitchen mainly include fruit and vegetables, meat, aquatic products, and edible fungi; these foods have high water activities and thermal sensitivities and must be processed with care. Appropriate pretreatments are generally required for these food materials; typical pretreatment processes include cleaning, enzyme inactivation, and disinfection, as well as packaging and coating. To improve the working efficiency of a central kitchen, novel efficient pretreatment technologies are needed. This article systematically reviews various high-efficiency pretreatment technologies for fresh foods. These include ultrasonic cleaning technologies, physical-field enzyme inactivation technologies, non-thermal disinfection technologies, and modified-atmosphere packagings and coatings. Mechanisms, applications, influencing factors, and advantages and disadvantages of these technologies, which can be used in a central kitchen, are outlined and discussed. Possible solutions to problems related to central-kitchen food processing are addressed, including low cleaning efficiency and automation feasibility, high nutrition loss, high energy consumption, and short shelf life of products. These should lead us to the next step of fresh food processing for a highly demanding modern society. © 2020 Society of Chemical Industry.

Progresses in processing technologies for special foods with ultra-long shelf life

Foods for special applications have recently received much attention due to rapid development of space and military industries as well as to frequent occurrence of natural and man-made disasters. Since the way such foods are processed clearly and directly affects their consumer's acceptability and shelf life, it is of interest to explore in detail how these special foods can be processed. This article presents a review on the difficulties in the processing, application and storage as well as on how to ensure the shelf life and acceptability of special foods through the use of efficient processing technologies. Emphasis is made on the use of both conventional and alternative thermal processing and irradiation technologies. Appropriate packaging technologies for each of the discussed special foods are also mentioned along with the way to overcome the problem of product quality degradation. Through comparison and analysis, it is found that foods with different attributes require different technologies and processes to achieve desirable results. Combined use of multiple technologies has also noted to be advantageous.

A novel approach to develop spray-dried encapsulated curcumin powder from oil-in-water emulsions stabilized by combined surfactants and chitosan

In this study, a novel approach to prepare spray-dried encapsulated curcumin powder was investigated. The effects of surfactants viz. Tween 80 (at 0.25 to 0.75% wt) and lecithin (at 1% wt) and of a stabilizer viz. chitosan (at 0 to 0.375% wt) on the characteristics of curcumin-based emulsions as well as on physicochemical properties of the resulting spray-dried encapsulated powder were determined. The optimal emulsion was noted to be the one formulated with 0.50 and 0.25% wt, respectively, of Tween 80 and chitosan (T0.50/C0.25). Spray-dried powder prepared from the optimal emulsion was compared to that prepared from an emulsion with 0.5% Tween 80 and 0% chitosan (T0.50/C0.00), as well as that from an emulsion with 0.25% Tween 80 and 0.25% chitosan (T0.25/C0.25). Physical properties of all powders were not significantly different. However, the encapsulation efficiency of T0.50/C0.25 powder (72.28%) was significantly higher than those of T0.50/C0.00 (47.19%) and T0.25/C0.25 powder (51.61%). Ferric reducing antioxidant powers of T0.50/C0.25 and T0.25/C0.25 powders were comparable but significantly higher than that of T0.50/C0.00 powder. After reconstitution, the mean particle sizes of T0.50/C0.25 and T0.25/C0.25 remained unchanged due to the protection by chitosan. T0.50/C0.00 powder was noted to exhibit the highest bioaccessibility (89.32%) in the simulated gastrointestinal tract. PRACTICAL APPLICATION: The results of this study can be used as a guideline to develop a stable formulation of curcumin feed emulsion that can later be transformed into an encapsulated powdery form via spray drying. Such a guideline should prove useful for a company looking for a way to produce high-quality functional ingredients and/or products from curcumin.

Comparative evaluation of acrylamide and polycyclic aromatic hydrocarbons contents in Robusta coffee beans roasted by hot air and superheated steam

Although hot air (HA) is a conventional roasting medium for coffee beans, HA roasting is known to result in possible formation of toxic compounds, including acrolein, acrylamide and polycyclic aromatic hydrocarbons (PAHs). Superheated steam (SHS) roasting is therefore proposed as an alternative means to alleviate the formation of these toxic compounds in roasted coffee beans. Robusta coffee beans were roasted either with HA or SHS in a fluidized bed roaster at 210-250 °C until the bean color reached the targeted roast levels. The contents of acrolein, acrylamide and 16 PAHs in the roasted beans were determined; only acrylamide and 5 PAHs were nevertheless found. SHS roasting interestingly resulted in lower acrylamide contents in dark-roasted beans; similar trend was noted in the beans medium-roasted at 250 °C. The contents of three-ring PAHs, namely fluorene, phenanthrene and anthracene, in dark-roasted beans were significantly lower upon SHS roasting at 250 °C.

Investigation on Spontaneous Shape Change of 4D Printed Starch-Based Purees from Purple Sweet Potatoes As Induced by Microwave Dehydration

The time evolution of three-dimensional (3D) printed food structures as affected by their composition and postprinting stimulus is an area of research that has recently received increasing attention. In this study, the spontaneous shape change of 3D printed purple sweet potato purees of different formulations as triggered by microwave dehydration was investigated. The rheological properties, water distribution behavior, and dielectric properties of the purees were first studied. Addition of salt reduced the viscosity, storage modulus, loss modulus, and yield stress but increased the relaxation time of the purees. Addition of fructose syrup resulted in opposite results. Addition of both salt and syrup decreased the dielectric constant but increased the dielectric loss of the purees. Increased microwave power and salt content increased the rates of dehydration and deformation but decreased the maximum deformation degree of the printed samples. The syrup also decreased the maximum deformation degree. A desirable deformation pattern could also be achieved by manipulating the infill parameters. Transformation of two-dimensional planar flowers and butterflies into 3D configurations as a result of varying the aforementioned parameters is illustrated. The proposed technique to induce spontaneous shape change of a 3D printed starch-based product should lay a foundation for further application of four-dimensional food printing.

Color and molecular structure alterations of brazilein extracted from Caesalpinia sappan L. under different pH and heating conditions

Brazilein extract from sappan wood (Caesalpinia sappan L.) has potential for use as natural food colorant since it has no unique flavor and taste. Although brazilein has long been applied in several traditional foods and beverages, information on its stability, which is of importance for practical application, is still limited. In this work, brazilein was isolated from sappan wood; its purity was confirmed by nuclear magnetic resonance spectroscopy. Relations between molecular structures and color as well as thermal stabilities of brazilein in aqueous solutions at pH 3, 7 and 9 were for the first time investigated. At the lowest pH, zero net-charge structure of brazilein, which exhibited yellow color, was predominantly found. The deprotonated and fully deprotonated structures of brazilein, which exhibited orange and red colors, respectively, were found when pH of the aqueous solutions increased. The forms of brazilein existing at the higher pH suffered extensive degradation upon heating, while the form existing at the lowest pH possessed higher stability. Heat-induced deprotonation and degradation were confirmed by UV-visible and Fourier-transform infrared spectra as well as losses of brazilein content.

Effect of carbon dots in combination with aqueous chitosan solution on shelf life and stability of soy milk

Use of carbon dots (CDs) in combination with aqueous chitosan solution to extend shelf life and improve stability of soy milk was investigated. Soy milk samples with chitosan solution (0.00%, 0.08%, 0.12%, 0.16% and 0.20%) and banana-based CDs (4%, 6% and 8%) were prepared and stored at room temperature (25-30 °C) for shelf life evaluation. Soy milk with 0.16% chitosan solution exhibited improved stability as evident by increased viscosity, stability coefficient, zeta potential and decreased centrifugation rate compared with soy milk without chitosan. The suitable amount of carbon dots could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Soy milk with 0.16% chitosan and 8% CDs exhibited longer shelf life and significantly lower total bacterial count after storage at room temperature for up to 4 days. Electronic nose-based flavor characteristics of all treated soy milk samples were not far from that of the control sample.

Correction: Evolution of important glucosinolates in three common Brassica vegetables during their processing into vegetable powder and in vitro gastric digestion

Correction for 'Evolution of important glucosinolates in three common Brassica vegetables during their processing into vegetable powder and in vitro gastric digestion' by Thitima Kuljarachanan et al., Food Funct., 2020, DOI: 10.1039/c9fo00811j.

Synthesis of Dimethyl Ether via CO2 Hydrogenation: Effect of the Drying Technique of Alumina on Properties and Performance of Alumina-Supported Copper Catalysts

Thermal treatment during catalyst preparation is one of the important factors affecting the characteristics and performance of a catalyst. To improve the catalytic performance of an alumina-supported copper catalyst prepared by an impregnation method for dimethyl ether (DME) synthesis from CO₂, the effects of the use of hot air and infrared drying as well as calcination at 600 and 900 °C to prepare alumina supports were investigated. Infrared drying could shorten the required drying time by 75% when compared with hot air drying. Infrared drying could also help maintain the pore size and pore volume of the supports, leading to their larger surface areas. Different drying techniques were additionally noted to result in different sizes and shapes of the pores as well as to different copper distributions and intensities of acid sites of the catalyst. An increase in the calcination temperature resulted in a decrease in the surface area of the supports because of particle aggregation. The drying technique exhibited a more significant effect than calcination temperature on the space-time yield of DME. A catalyst utilizing the support prepared by infrared drying and then calcined at 600 °C exhibited the highest yield of DME (40.9 g_DME kg_cat ^-1 h^-1) at a reaction temperature of 300 °C. Stability of the optimal catalyst, when monitored over a 24 h period, was noted to be excellent.

Evolution of important glucosinolates in three common Brassica vegetables during their processing into vegetable powder and in vitro gastric digestion

Evolution of important glucosinolates (GLSs), namely, sinigrin, glucoraphanin, glucoerucin and glucobrassicin, in three commonly consumed Brassica vegetables viz. white cabbage, Chinese cabbage and bok choy during their processing into vegetable powder was investigated. Drying was noted to be a major processing step causing significant losses of GLSs. Interestingly, different GLSs and even the same GLSs in different vegetables showed different thermal stabilities during drying. The stability of GLSs in vegetable powder during in vitro gastric digestion was also studied. Glucoraphanin exhibited the highest stability while glucobrassicin was the most vulnerable GLS under in vitro gastric conditions. White cabbage is found to be a promising material for the production of vegetable powder as it contains high contents of GLSs, especially glucoraphanin and glucoerucin, which are important precursors of anticarcinogenic compounds, namely sulforaphane and erucin. These two GLSs were also noted to be stable during in vitro gastric digestion.