Partial Removal Of Water Research Articles

Graphene oxide modifications by X-rays irradiations in air and vacuum

Graphene oxide (GO) foils have been exposed to X-rays in air and in vacuum. The attenuated total reflectance (ATR) method for Fourier Transmission Infrared (FTIR) spectroscopy has been used to analyze the pristine and the irradiated GO foils. The X-ray exposition in air produces oxidation increment, while in vacuum it induces reduction of the oxygen functional groups and partial removal of water. These processes have been investigated as a function of both the irradiation time and X-ray energy distribution highlighting the variations of some functional groups of oxygen. Some interesting applications of the GO reduction will be suggested in the field of ionization dosimetry, detectors, microelectronic devices, and membranes, as presented hereafter.

Novas tecnologias combinadas com desidratação osmótica para aplicação na conservação de frutas: uma revisão

ABSTRACT: Osmotic dehydration (OD) is a technique used for the partial removal of water from foodstuff, including fruit and vegetables, with the aim of producing a desiccated product. The process involves placing the material in a hypertonic solution for several hours and allowing water to move from the cell compartment into the solution by osmosis. OD is influenced by various factors such as the concentration and composition of the osmotic solution, the solution temperature, the type of agitation and the time of exposure, as well as the size, shape and compactness of the food material. The main advantages of OD over conventional drying processes are the superior quality of the dried products and the minimization of shrinkage. In recent years, research effort has focused on the combination of OD with other technologies, such as ultrasound, cryogenic freezing with liquid nitrogen, pulsed electric field, gamma radiation and high hydrostatic pressure. The application of these methods prior to or concomitant with OD accelerates mass transfer and reduces the drying rate of fruit and vegetables by increasing the permeability of cell membranes. In this manner, combined processes tend to be more efficient and economical in comparison with conventional OD because they reduce operating times and; consequently, energy consumption. In addition, the dried products generated by such coupled processes typically exhibit improved nutritional and physicochemical characteristics. This review summarizes the basic principles and applications of OD in combination with other methods, with particular emphasis on the production of dried fruits.

Structural and textural improvements of strawberry fruits by partial water removal prior to conventional freezing process

Structural and textural improvements of strawberry fruits by partial water removal prior to conventional freezing process

Thermodynamic Insight in Design of Methanation Reactor with Water Removal Considering Nexus between CO2 Conversion and Irreversibilities

The inevitable nexus between energy use and CO2 emission necessitates the development of sustainable energy systems. The conversion of CO2 to CH4 using green H2 in power-to-gas applications in such energy systems has attracted much interest. In this context, the present study provides a thermodynamic insight into the effect of water removal on CO2 conversion and irreversibility within a CO2 methanation reactor. A fixed-bed reactor with one intermediate water removal point, representing two reactors in series, was modeled by a one-dimensional pseudo-homogeneous model. Pure CO2 or a mixture of CO2 and methane, representing a typical biogas mixture, were used as feed. For short reactors, both the maximum conversion and the largest irreversibilities were observed when the water removal point was located in the middle of the reactor. However, as the length of the reactor increased, the water removal point with the highest conversion was shifted towards the end of the reactor, accompanied by a smaller thermodynamic penalty. The largest irreversibilities in long reactors were obtained when water removal took place closer to the inlet of the reactor. The study discusses the potential benefit of partial water removal and reactant feeding for energy-efficient reactor design.

Ultrasonic induced effect on mass transfer characteristics during osmotic dehydration of aonla (Phyllanthus emblica L.) slices: A mathematical modeling approach

AbstractThe present work aimed to investigate the effect of ultrasound pretreatment on osmotic dehydration of aonla slices. The aonla slices were subjected to an ultrasonic treatment with a frequency of 40 kHz for 10 min and then subjected to osmotic dehydration in 60°Bx sucrose solution for 300 min. Empirical models such as Azuara, Peleg, Weibull, Page, and Crank model were utilized to predict the kinetics of water loss and solid gain. Artificial Neural Network technique was also used to predict the parameters with immersion time and temperature as input. All models were found to have a good fit. From the analysis, the ultrasound pretreated samples were found to have enhanced rate of mass transfer compared to control samples especially at the early stages of the process. From Azuara Model, the equilibrium water loss and solid gain were ranged between 49.95–53.65 g/100 g and 11.10–22.01 g/100 g. From Crank model, the effective moisture diffusivities in osmotic dehydration were observed to be varied between 9.28 × 10−10–12.47 × 10−10 m2/s and 10.06 × 10−10–19.17 × 10−10 m2/s for atmospheric and ultrasonic conditions. While for solid gain, the values were ranged between 2.36–2.67 × 10−10 m2/s (untreated) and 2.49–2.73 × 10−10 m2/s (treated). The Vitamin C content and color of sample were found to be affected by ultrasound pretreatment (p <.05) and temperature (p <.05). The effective diffusivities attributed to have a significant Arrhenius relationship (R2 ≥.92, p ≤.05). The enhanced moisture loss and solid gain in the product can be explained by the microscopic channels and cell disruption caused by ultrasonic waves.Practical ApplicationThe aonla fruit, native to South Asia, is a very important commodity because of its health and nutritional benefits. Despite its advantages, it is less popular as table fruit because of its low shelf life and astringency. Osmotic dehydration can be used to preserve the fruit, and it causes the partial removal of water from the fruit and improves its taste. Osmotic dehydration being a slow process, can be enhanced by the ultrasound application. The data and findings can be applied to produce stable intermediate moisture content food that can be used as dried fruit or additive with other food products. This study investigates the modeling of ultrasound‐induced osmotic dehydration in order to design the process with low energy and cost.

Design of Roll‐In Margarine Analogous by Partial Drying of Monoglyceride‐Structured Emulsions

AbstractA novel process is proposed to turn soft gelled emulsions containing saturated monoglyceride (MG), sunflower oil, and water into a fat material with the typical water content (20 g/100 g) and rheological properties of roll‐in margarine. A gentle drying procedure at 30 °C is proposed to allow partial water removal from the emulsions, without causing phase separation. Upon water removal, the soft emulsion, initially stabilized by a highly hydrated liquid crystalline lamellar phase of MG, converts into a high internal phase oil–water emulsion (HIPE) stabilized thanks to the presence of MG crystals around gelled oil particles, which are interconnected via polar groups of MG. HIPE at the highest MG content (13.7 g/100 g) shows rheological properties (Gʹ = 4.6 × 105 Pa, critical stress = 634 Pa) comparable to those of commercial roll‐in margarine and is successfully used in baking trials of puff pastry.Practical Applications: The last years have seen an increasing demand for strategies for the nutritional improvement of lipid‐containing foods, due to the emerging health concern related to the consumption of unbalanced saturate/unsaturated fats. Moreover, sustainability issues have arisen due to the abundant use of tropical fats in foods. However, the unique technological and sensory properties of fats make this task very challenging, especially considering the production of laminated products requiring the use of plastic fat materials with peculiar rheological properties. The results obtained in this study are very promising, as they show that the novel fat can be used as an alternative to traditional laminating margarine.

Comparison of extractive distillation flowsheets for methanol–tetrahydrofuran–water mixtures

Objectives. Synthesis and comparative analysis of the extractive distillation flowsheets for aqueous mixtures of solvents utilized in pharmaceutical industries using the example of a methanol−tetrahydrofuran−water system with various compositions. The ternary system contains two minimally boiling azeotropes that exist in a vapor–liquid phase equilibrium. To evaluate the selective effect of glycerol, the phase equilibria of the methanol–tetrahydrofuran–water and methanol–tetrahydrofuran–water–glycerol systems at 101.32 kPa were studied.Methods. The calculations were carried out in the Aspen Plus V.9.0 software package. The vapor–liquid equilibria were simulated using the non-random two-liquid (NRTL) equation with the binary interaction parameters of the software package database. To account for the non-ideal behavior of the vapor phase, the Redlich–Kwong equation of state was used. The calculations of the extractive distillation schemes were carried out at 101.32 kPa.Results. The conceptual flowsheets of extractive distillation are proposed. The flowsheets consist of three (schemes I–III) or four (scheme IV) distillation columns operating at atmospheric pressure. In schemes I and II, the extractive distillation of the mixtures is carried out with tetrahydrofuran isolation occurring in the distillate stream. Further separation in the schemes differs in the order of glycerol isolation: in the third column for scheme I (traditional extractive distillation complex) or in the second column for scheme II (two-column extractive distillation complex + methanol/water separation column). Sсheme III caters to the complete dehydration of the basic ternary mixtures, followed by the extractive distillation of the azeotropic methanol–tetrahydrofuran system, also with glycerol. Sсheme IV includes a preconcentration column (for the partial removal of water) and a traditional extractive distillation complex.Conclusions. According to the criterion of least energy consumption for separation (the total load of the reboilers of distillation columns), sсheme I (a traditional complex of extractive distillation) is recommended. Additionally, the energy expended for the separation of the basic equimolar mixture using glycerol as the extractive agent was compared with that expended using another selective agent: 1,2-ethanediol. Glycerol is an effective extractive agent because it reduces energy consumption, in comparison with 1,2-ethanediol, by more than 5%.

Electro-demulsification of water-in-oil suspensions enhanced with implementing various additives

A huge amount of various oily suspensions that frequently display properties of stable emulsions are produced per day in upstream and downstream petroleum industries. As this waste is considered potentially harmful to the environment, their management and disposal require particular attention. While current treatment processes, such as partial water removal via the separation of phases by centrifuging result in decreased waste volumes for disposal, a significant volume of water and oil remains trapped in the form of water-in-oil emulsion. Therefore, the electrokinetic method for oil-water separation came into consideration for the improvement of the quality and volume of separated products. This paper discusses the impacts of additives, namely, ferric chloride, alum, cationic polymer, clay, and a mixture of clay and cationic polymer on the electrokinetic treatment of suspensions. The tests were conducted at a lab scale using an array of steel electrodes and low voltage. The objective of this study was to observe the impact of voltage gradients on electro-demulsification, in conjunction with employing additives into the separation and recovery of water, light, and heavy oil. An optimal recovery of light oil by 28%–52% in addition to heavy oil and water in the presence of ferric chloride under a constant voltage gradient of 1 V/cm, was achieved. Furthermore, the same system revealed an excellent clarity of extracted water. The results from this study can be implemented at a larger scale in upstream and downstream petroleum industries.

Impact of initial moisture content levels, freezing rate and instant controlled pressure drop treatment (DIC) on dehydrofreezing process and quality attributes of quince fruits

Dehydrofreezing process involves water partial removal before freezing. This treatment has been proposed in order to reduce the negative impacts of conventional or even accelerated freezing, especially on the textural quality of high water content fruits and vegetables. Indeed, in such cases, freezing and thawing processes result in severe damage of the integrity of product’s cell structure due to the formation of ice crystals. For this purpose, quince fruits (7 g H2O/g db) were subjected to convective air drying of 40 °C and 3m/s to reach different water content levels of 2, 1, and 0.3 g H2O/g db. Freezing profiles obtained at various freezing rates (V1, V2, and V3) for different water contents allowed the main freezing characteristics such as the Initial Freezing Temperature (IFT), the Practical Freezing time (PFt), and the Specific Freezing time (SFt) to be assessed. The impact of freezing rate was important on PFt and SFt, and more pronounced for high water contents (W between 7 and 2 g H2O/g db (dry basis)). Furthermore, IFT decreased sharply when initial sample water content decreased. Indeed, it started at −0.8 °C for W = 7g H2O/g db, while it reached a value of −8.2 °C for samples of W = 1g H2O/g db. Since convective air drying normally triggers shrinkage which causes a detrimental deformation of fruit structures, instant controlled pressure drop (DIC) treatment was used to improve the texture and enhance the whole dehydrofreezing performance and the final frozen-thawed product quality. Moreover, DIC implied a slight increase of PFt compared to untreated ones. On the other hand, quality attributes were estimated through the assessment of thawed water exudate (TWE g H2O/100 g db), color and texture (maximum puncture force as index of firmness): freezing rate and water content had great impacts on TWE. Hence, the lower the water content, the weaker the TWE. Furthermore, the TWE of the pre-dried quince (0.3 g H2O/g db) had higher value for DIC-textured samples than for the un-treated ones. Indeed, DIC-texturing leads to a well-controlled structure expansion of the cell wall. These textural changes resulted in more lixiviation of residual water. Consequently, water becomes more available, hence more releasable after thawing. Finally, the partial removal of water by air drying before freezing remarkably reduced the negative impact of freezing/thawing processes on final quince color. Decisively, the firmness of quince fruit increased with the decrease of water content level.Abbreviations: DMC: Dry Matter Concentration (%); DIC: Instant controlled pressure drop; W: Water content dry basis (g H2O/g db); IFT: Initial Freezing Temperature (°C); PFt: Practical Freezing time (min); SFt: Specific Freezing time (min); TWE: Thawed Water Exudate (g H2O/100 g db); L, a, and b: Color coordinates; (L): The degrees of lightness; (a) and (–a): The redness (a) or greenness (−a), respectively; (b) and (−b): The yellowness (b) or blueness (−b), respectively; ΔE*ab: Total color difference; L0, a0, and b0: Color coordinates of fresh or dried quince samples; SD: Standard Deviation; ANOVA: Analysis of variances; LSD: Least Significant Differences; cp: Specific Heat of the product depending on composition (dry material and water content)(KJ/kg K); cpd: Specific Heat of the dry material (KJ/kg K); cpW: Specific Heat of water (KJ/kg K); V1: Freezing rate without insulation; V2: Freezing rate with a food stretch film insulation with thickness e2 = 3 mm and thermal conductivity λ2 = 0.17 W/m K; V3: Freezing rate with a versatile flexible insulation (Armacell) with thickness e3 = 13mm and weak thermal conductivity λ3 = 0.036 W/m K; vd: Volume of dry material of quince sample (mm3); vH2O: Volume of quince sample water (mm3); vt: Total volume of quince sample (mm3); e0: Quince sample thickness (mm); e2: Insulation thickness in the case V2; = 3 mm; ; e3: Insulation thickness in the case V3; = 13 mm; ; λ0: Quince sample conductivity (W/m K); λ2: Insulation conductivity in the case V2; = 0.17 W/m K; ; λ3: Insulation conductivity in the case V3; = 0.036 W/m K; λd: Conductivity of quince sample dry material (W/m K); λH2O: Conductivity of water (W/m K); λequiv: Equivalent conductivity of quince sample versus water content (W/m K); mi and mf: Weights of the frozen and thawed samples, respectively

Recent advances in postharvest technology ofthe wine grape to improve the wine aroma.

Postharvest techniques are widely used for the handling and storage of fresh horticultural crops. Some of these techniques are interesting for use with wine grapes to improve the quality of wine. In this review, we consider the postharvest techniques that are already commercially used in the wine sector and others that may be significant in inducing or extracting the aroma from grapes to produce high-quality wines. Precooling consists of rapidly lowering the grape temperature, which allows the preservation/increase of volatile organic compounds (VOCs). We also discuss sustainability. Partial dehydration consists of the partial removal of water from grapes, and if a suitable environment is adopted it can be used to produce and extract berry VOCs. As a solid, carbon dioxide is used in wine processing for the rapid cooling of grapes and, as a gas, it is used for carbonic maceration. Ozone has been used for sanitation purposes in wineries for a long time, but more recently it has been used to produce wine without sulfite addition and to increase the aromatic quality of wine grapes. Ethylene application is not used commercially for wine grapes, but promising results in terms of phenolic extraction and aromatic changes in grapes are discussed. A comparison among the proposed techniques is reported in terms of grape aromatic quality and process features. The proposed techniques could help a winemaker to maintain or induce aromatic compounds in grape berries before the vinification process. The choice depends on the desired wine and economic consistency. © 2018 Society of Chemical Industry.

بررسی اثرتعداد لایهها و غلظتهای مختف پوششهای خوراکی کربوکسیمتیلسلولز و کاراگینان بر کارایی فرایند خشک کردن اسمزی سیب زرد لبنانی

در طی فرایند آبگیری اسمز، مواد جامد محلول توسط بافت ماده غذایی جذب شده و اثرات نامطلوبی بر خروج آب، خصوصیات تغذیه‌ای و حسی می‌گذارد. لذا برای بهبود فرایند اسمز از پوشش‌های خوراکی استفاده می‌شود. بهترین شاخص برای ارزیابی یک پوشش، کارایی فرایند (نسبت خروج آب به جذب مواد جامد) است. در این پژوهش از دو پوشش کربوکسی‌متیل‌سلولز و کاراگینان در سه غلظت 5/0، 1 و 5/1 درصد، به‌صورت یک‌لایه و دو لایه، جهت پوشش‌دهی قطعات مکعبی سیب زرد لبنانی و محلول اسمزی ساکارز با غلظت 30، 45 و 60 % استفاده شد. نتایج نشان داد که نمونه یک بار پوشش داده شده با کاراگینان 1% و تیمار شده در ساکارز 60 % و نمونه‌های یک و دو لایه پوشش داده شده با کربوکسی‌متیل‌سلولز 5/0% بیشترین میزان کارایی فرایند را داشته‌اند و به‌عنوان تیمارهای برگزیده به‌دست آمدند. این نمونه‌ها میزان جذب مواد جامد را کاهش داده و تاثیر قابل توجهی بر روی خروج آب نگذاشته‌اند. همچنین نتایج بیان‌گر این موضوع است که با افزایش غلظت محلول اسمزی ساکارز از 30 به 60% میزان حذف آب و جذب مواد جامد افزایش می‌یابد.

Mass Transfer Kinetics of the Osmotic Dehydration of Yacon Slices with Polyols

Osmotic dehydration using different polyols was studied. Yacon slices were immersed in solutions of xylitol, maltitol, erythritol, isomalt and sorbitol. The kinetics of solid gain (SG), water loss (WL) and water activity (aw) were evaluated (0, 10, 30, 45, 60, 90 and 120 min). The effective diffusion coefficients of water (Dₑffw) and solids (Dₑffₛ) were calculated with the models of Fick and Barbosa Junior et al. At the end of the process, the highest SG was obtained with erythritol solutions; the lowest with sorbitol and maltitol and intermediate values of SG were acquired in osmotic processes with solutions of isomalt and xylitol. The samples treated in sorbitol, xylitol and erythritol solutions presented the highest Dₑffw and were more effective at increasing WL and reducing aw. The model of Barbosa Junior et al. presented the best fitness. The Dₑffw/Dₑffₛ ratio showed better results for osmotic processes involving sorbitol and xylitol. PRACTICAL APPLICATIONS: Yacon tuber is typical from Latin America. It is considered an important source of fructooligosaccharides (FOS). This class of carbohydrate is employed on the control of diseases such as obesity and diabetes, due its low glycemic index. However, yacon roots are highly perishable and techniques for conservation are required. Osmotic dehydration is a pretreatment process that provides partial water removal from a food product, with low energy consumption. Polyols are widely employed as osmotic agents due their low caloric value. The kinetics of mass transfer on osmotic process are function of process variables, sample matrix characteristics, molecular weight of osmotic agents and others. This study investigate the water loss, solid gain, effective diffusivity and water activity of the OD of yacon with five different polyols and provide information about mass transfer kinetics of osmotic processes using two different empirical models.

Evaluation of the Shrinkage Effect on the Modeling Kinetics of Osmotic Dehydration of Sweet Potato (Ipomoea batatas (L.))

The kinetics of water loss (WL), solid gain (SG) and water activity (aw) of the osmotic dehydration of sweet potato (Ipomoea batatas (L.)) slices were investigated. Three osmotic solutions, sucrose, sorbitol and fructose, were used with two different water activities, 0.900 and 0.940. The diffusivities of both water and solute were evaluated by using Crank's analytical solution to Fick's second law and according to the models of Azuara and Barbosa Júnior et al. The shrinkage effect was considered to estimate the water and solid diffusion. A lower aw of the osmotic solutions resulted in higher mass transfer parameters (WL and SG) and a lower aw of the product. Sorbitol promoted higher WL and sorbitol and fructose, higher SG. The shrinkage was directly proportional to moisture reduction. Among the tested mathematical models, the Barbosa Júnior et al. presented the best fit. The shrinkage resulted in lower water and solid diffusivity values. Practical Applications Brazil is the largest producer of sweet potatoes (Ipomoea batatas (L.)) in Latin America. This root is considered as the fifth most important crop in developing countries. Like most vegetables, its shelf life is short and its storage is difficult. Therefore, improved techniques for conservation are welcome. Osmotic dehydration is a pretreatment process that provides partial water removal from a food product, with low energy consumption. In the literature, there are few studies on osmotic dehydration with nonionic agents and considering the shrinkage that occurs during the process in sweet potatoes. This study investigates the effects of different osmotic agents and water activities of osmotic solutions on the drying kinetics and effective diffusivities. The mathematical models provide information about the processes. Three different empirical models were employed and one approach investigates the shrinkage that occurs during the process.

Infusion of fructooligosaccharide in Indian gooseberry (Emblica officinalis) fruit using osmotic treatment and its effect on the antioxidant activity of the fruit

Osmotic dehydration is the most reliable method for the partial removal of water from fruits and vegetables because it is less energy intensive and retains the natural colour, texture and flavour of the food materials. The present work deals with the infusion of fructooligosaccharide (FOS) into Indian gooseberry (amla) fruit. The infusion of FOS was found to increase over a range of temperatures from 30 to 50 °C. The water loss and solid gain during the infusion process were higher at higher temperatures. Furthermore, the antioxidant activity and phenolic as well as flavonoid contents of the FOS osmotic dehydrated samples were also found to be significantly higher as compared to fresh fruits in both in vitro and cell line assays. The present study indicated that the osmotic treatment can be used as a method for the infusion of FOS in solid food matrix such as Indian gooseberry.

Dehydrofreezing of Apple Fruits: Freezing Profiles, Freezing Characteristics, and Texture Variation

The present study deals with the dehydrofreezing of apples. Fresh samples (700 % db) and samples dehydrated up to different water contents (200, 100, and 30 % db) were frozen at high practical freezing rate (PFR+) and low practical freezing rate (PFR−). The effects of water content (W) and practical freezing rate (PFR) were investigated in terms of freezing characteristics: initial freezing temperature (IFT), practical freezing time (PFT), specific freezing time (SFT), thaw exudate water (TEW), and texture (maximum puncture force as index of firmness). Only high W samples (700 and 200 % db) had a significant impact of PFR in terms of PFT, SFT, and TEW. IFT decreased sharply with the decrease in the sample W. PFT greatly depended on PFR for fresh apples. PFT varied from 86 to 329 min for fresh apples at PFR+ and PFR−, respectively, whereas it was lower than 32 min for samples with W = 30 % db. SFT decreased, equally, with sample W decrease. The TEW of fresh frozen samples, during thawing, was approximately 12 g/100 g water for low PFR (PFR−), whereas it was lower than 3 g/100 g water for samples with W = 200 % db at the same PFR. Moreover, the impact of PFR on TEW was significant and very important for high W samples. Finally, the firmness increased when W decreased for both PFR+ and PFR−. Nevertheless, an insignificant impact of PFR on apple firmness was found. Thus, partial removal of water constitutes a promising solution to prevent the negative impacts of freezing on apple fruit firmness.

Influence of thermal treatment on the stability of phenolic compounds and the microbiological quality of sucrose solution following osmotic dehydration of highbush blueberry fruits.

Osmotic dehydration is a process of the partial removal of water which is based on immersion of material having cellular structure in a hypertonic solution. Osmotic dehydration is used as a pretreatment for the dehydration of foods before they are subjected to further processing such as freezing, freeze drying, vacuum drying. Management of spent syrup is one of the most important problems related to osmotic dewatering. Osmotic solutions are heavily polluted with of carbohydrates, remains of the dehydrated material and microorganisms. The aim of this study was to determine the effect of thermal treatment on the content of phenolic compounds and the microbiological quality of sucrose solution used in 15 cycles of osmotic dehydration of highbush blueberry (Vaccinium corymbosum L.) fruits. The tested material was 65.0 ±0.5°Brix sucrose solution used for 15 cycles of osmotic dehydration of highbush blueberry (Vaccinium corymbosum L.). Osmotic dehydration was conducted at 40°C for 120 min using fruits previously subjected to enzymatic pretreatment. The thermal treatment of sucrose solution was conducted at 70, 80, 90, 100 and 115°C for 20, 40 and 60 s. The sucrose solution was analysed in terms of total polyphenols, particular polyphenols using high performance liquid chromatography and microbiological analysis was subjected. Thermal treatment at 70-115°C for 20 s caused degradation of 8.5% to 12.7% of polyphenols, while as much as 23.1% of polyphenols were degraded at 115°C after 60 s. The present paper proposes heating parameters that are optimal from the point of view of phenolic compound retention and microbiological quality: thermal treatment of syrup at 100°C for 40 s. Under these conditions, total polyphenols retention was 94.5%, while the retention of individual phenolic compounds varied from 89.2% to 37.2%, and that of flavan-3-ols amounted to 89.5%. The studied manner of syrup treatment eliminated the problem of syrup contamination with yeasts and molds (reducing their levels to less than 1 CFU/mL).

A Novel Biodiesel Production Method Consisting of Oil Extraction and Transesterification from Wet Microalgae

Microalgae biodiesel is one of the most promising alternatives to fossil fuels. However, how to quickly and cost-effectively obtain a large quantity of oil form microalgae is always a challenge. In this study, a novel method was developed for biodiesel production. This method was composed of microwave disruption, partial water removal, oil extraction and transesterification. The wet microalgal biomass with a moisture content of about 80 wt% was used as the feedstock for biodiesel production. The results show that the moisture of the wet microalgae after microwave disruption and partial water removal decreased to nearly 50 wt%. The oil recovery in oil extraction from the pretreated microalgae was over 90%, and the conversion in transesterification was higher than 90%. Moreover, the test for the large amount of microalgae sludge (400 g) shows that this method was suitable for the use in large-scale microalgae-based biodiesel production.

Osmotic dehydration of fruits in food industrial: A review

Osmotic dehydration (OD) is an operation used for the partial removal of water from plant tissues by immersion in a hypertonic solution, sugar and/or salt solution, to reduce the moisture content of foods before actual drying process. Research applications of osmotic dehydration to food processing in technology and in component transfer mechanisms are being carried out in several countries. This technique is a partial dehydration process to give the product a quality improvement over the conventional drying process. Osmotic dehydration is affected by several factors such as osmotic agent, solute concentration, temperature, time, size, and shape and tissue compactness of the material, agitation and solution/sample ratio. The osmotic dehydration step can be done before, during or after the conventional drying process to enhance the mass transfer rate or to shorten the duration of drying time the quality of osmotically dehydrated products is better and shrinkage is considerably lower as compared to products from conventional drying processes. This technique helps to conserve the overall energy relative to other drying procedures. In this review, the mechanism of osmotic dehydration is described. In addition, some factors that affect on mass transfer during osmotic dehydration reviewed. The major objective of this paper is to discuss the advantage of osmotic dehydration in terms of energy reduction.

Chemical and Microbiological Changes in Blueberries and in Hypertonic Solution during Osmotic Dehydration Employing Reused Concentrate

AbstractDehydration was carried out in 65°Brix sucrose solution at 40C for 120 min. The solution was used 15 times, each time a new batch of fruits was processed. Prior to dehydration, the fruits were subjected to pretreatment by immersion in solutions containing pectinolytic and lipolytic enzymes. Following dehydration, the dehydrated material and osmotic solution were tested for the content of dry matter (36.6 ± 3.3% [w/w] and 58–61°Brix, respectively), total polyphenols (1,738 ± 289 mg/100 g initial dry matter [IDM]), anthocyanins (606 ± 58 mg/100 g IDM) and flavan‐3‐ols (695 ± 139 mg/100 g IDM). The highest retention of anthocyanins was observed for cyanidin‐3‐O‐glucoside (over 81%), petunidin‐3‐O‐glucoside, malvidin‐3‐O‐arabinoside and malvidin‐3‐O‐glucoside (over 74%). The average retention of procyanidins in fruits was 77%. The pH value of the hypertonic solution remained at the level of 3.4–3.7. The syrup used for osmotic dehydration was characterized by a relatively low quantity of mesophilic bacteria (<103 cfu/mL) but a higher contamination with osmotolerant yeasts and molds (from 1 × 103 to 2.5 × 104 cfu/mL).Practical ApplicationsThe article deals with osmotic dehydration, which is a method that allows a partial removal of water from plant material. Using this method, one can obtain high‐quality products because the water removal is conducted without phase change. However, considerable amounts of hypertonic solution (used for osmotic dehydration) pose a problem. Management of spent syrup is one of the most important problems related to osmotic dewatering. Thus, repeated use of hypertonic solution is indispensable; however, it may have an influence on the product quality. The paper presents the chemical and microbiological changes that occur during osmotic dehydration of highbush blueberry fruits over 15 cycles employing reused sucrose solution. Prior to dehydration, the fruits were subjected to pretreatment by immersion in solutions containing pectinolytic and (which is a new approach to pretreatment before osmotic dehydration) lipolytic enzymes. The results indicate that applied procedure enables to obtain osmodehydrated berries without a large decrease in the product quality.

Retention of crystallinity in bis(guaninium) sulfate hydrate upon partial and full dehydration

Crystals of bis(guaninium) sulfate hydrate ((GH)2SO4. 2.5H2O) have been isolated via slow solvent evaporation. This compound adopts the triclinic space group P1¯ with unit cell parameters a = 9.6300(19) Å, b = 9.8613(19) Å, c = 10.5872(19) Å, α = 78.627(15)°, β = 71.518(15)°, γ = 63.260(14)° and unit cell volume 849.8(3) Å3 at 150 K. The crystal structure displays intricate hydrogen bonding interactions between the guaninium cations, the sulfate anions and water. Guaninium cations are held together in approximately planar ribbons by hydrogen bonds. These ribbons are stacked parallel to the [230] direction and held together by hydrogen bonding to sulfate and water. Channels are formed between the hydrogen-bonded cations and the anions that are filled with water molecules. Remarkably, partial and complete removal of water from this structure is possible without wholescale loss of crystallinity. Partial removal of water to yield (GH)2 SO4. 1.5H2O happens with very limited change to the structure. It is possible to remove all of the water to yield the apohost, G(GH)3(SO4H)SO4 which retains many structural features of the hydrate but contains a different hydrogen bonding chain. The three structures and the relationship between them are described.