Osmotic dehydration kinetics of carrot cubes in sodium chloride solution

Osmotic dehydration kinetics of carrot cubes in sodium chloride solution having concentrations 5%, 10% and 15% (w/v), solution temperature 35, 45 and 55 °C, sample to solution ratio (STSR) 1:4, 1:5 and 1:6 were studied up to 240 min duration. During the experimentation, effect of solution temperature and process duration was significant and that of solution concentration and STSR were non-significant on water loss. Among the different models applied (Penetration model, Magee Model, and Azuara model), Azuara model best fitted to the experimental data for water loss and solute gain during osmotic dehydration. Effective diffusivities of water and solute were calculated by using the analytical solution of Fick's unsteady state law of diffusion by iterative technique with a computer program. For the above conditions, the effective diffusivity of water was found to be in the range between 2.6323 × 10⁻⁹ and 6.2397 × 10⁻⁹ m²/s and that of solute between 3.1522 × 10⁻⁹ and 4.6400 × 10⁻⁹ m²/s.     

Osmotic dehydration pretreatment for improving the quality attributes of frozen mango: effects of different osmotic solutes and concentrations on the samples

The effect of osmotic dehydration pretreatment on the quality attributes (e.g. colour, hardness, drip loss, vitamin C content and pH) of frozen mango cuboids in different osmotic solutions (sucrose, glucose and maltose) and concentrations (30, 45 and 60% (wt/wt)) was investigated. Results revealed that melting temperature of mango cuboids was affected by both solute type and solid mass fraction. In addition, the dehydrofrozen samples pretreated in maltose had higher quality in vitamin C content (increasing by 23.5–73.0%), colour (colour change reducing by 2.6–39.2%) and drip loss (reducing by 0.7–9.7%) than those pretreated in other osmotic solutions. The cuboids pretreated in glucose displayed higher hardness (increasing by 16.4–36.2%). Based on principal component analysis and group distance, osmotic dehydration in 45% maltose was proposed as the most favourable freezing conditions with the highest sensory score (6.8). The current work indicates osmotic dehydration significantly improves frozen mango quality.     

Influence of Modified Atmosphere Packaging and Osmotic Dehydration on the Quality Maintenance of Minimally Processed Guavas

ABSTRACT: The quality of minimally processed guavas ( Psidium guajava L.), osmotically dehydrated and packed under passive modified atmosphere, was evaluated during 24 d of storage at 5 °C. Modified atmosphere packaging (MAP) in polyethylene terephthalate (PET) containers had a strong influence on color preservation and weight loss of the guavas. Significant changes in the texture were found due to osmotic dehydration, but the color of the fresh fruit remained unchanged. Osmotically dehydrated guavas stored in MAP showed good microbial conditions during storage. The combination of storage temperature, modified atmosphere packaging, and the osmotic dehydration process maintained the quality of the guavas during 24 d of storage.     

Osmotic dehydration of pomegranate seeds: mass transfer kinetics and differential scanning calorimetry characterization

Osmotic dehydration of pomegranate seeds was carried out at different temperatures (30, 40, 50 °C) in a 55°Brix solution of sucrose, glucose, and mixture sucrose & glucose (50:50, w/w). The most significant changes of water loss and solids gain took place during the first 20 min of dewatering. During this period, seeds water loss was estimated to 46% in sucrose, 37% in glucose and 41% in mix glucose/sucrose solution. The increase of temperature favoured the increase of water loss, weight reduction, solids gain and effective diffusivity. Differential scanning calorimetry data provided complementary information on the mobility changes of water and solute in osmodehydrated pomegranate seeds. The ratio between % frozen water and % unfreezable water decreased from 5 to 0.5 during the process. That involving the presence of very tightly bound water to the sample, which is very difficult to eliminate with this process. It also appeared that glass transition temperature depends on the types of sugar.     

Osmotic dehydration of the Indian fig (Opuntia ficus indica) with binary and ternary solutions

The objective of this work was to study osmotic dehydration (OD) of the Indian fig with two binary solutions (sucrose/water and glucose/water) and a ternary solution (sucrose/NaCl/water) according to a 2³ factorial design with independent variables: temperature (30–50 °C), immersion time (90–240 min) and concentration (40–60 °Brix). The dependent variables were water loss (WL), solid gain (SG) and dehydration efficiency index. The temperature had greater influence on the WL in the three hypertonic solutions studied; the concentration had greater influence on the SG in the three hypertonic solutions investigated and the best conditions for the OD of the Indian fig were in glucose solution at 40 °Brix, 40 °C and 165 min.     

蘑菇渗透脱水规律的研究

对蘑菇片在糖溶液中的脱水规律进行初步的试验研究。通过多因素正交试验，得出影响蘑菇渗透脱水因素的主次顺序及因素间交互作用的关系；通过应用均匀试验，建立了蘑菇渗透脱水的回归数学模型，其理论值与实测值具有很好的一致性；利用回归模型，建立了不同条件下的渗透脱水规律预测表。     

渗透液特性对渗透脱水黄桃质构品质的影响

为明确渗透液特性对渗透脱水黄桃片质构品质的影响,本实验以‘金童8号’黄桃为原料,追踪分析渗透脱水过程中渗透液特性和黄桃质构品质的变化行为。黄桃片经超声或真空处理后,分别浸渍于糖度为30 °Brix的蔗糖、低聚异麦芽糖、果糖和葡萄糖溶液中（25 ℃）,并于0.5、1、2、3、4 h和5 h时进行取样分析。测定渗透脱水过程中渗透液特性,如可溶性固形物（total solid soluble,TSS）含量、渗透压、pH值和浊度以及黄桃果肉质构参数的变化。结果表明,不同溶质的初始渗透液呈现出相同的TSS含量,但浊度、渗透压和pH值明显不同。渗透初期,渗透液渗透压和TSS含量均呈现明显降低的趋势,且超声和真空预处理会明显加速这一降低趋势,随着渗透脱水的进行,渗透后期TSS含量降低缓慢;渗透液pH值在渗透0.5 h后下降至与新鲜黄桃（4.30±0.32）接近的水平,后期未呈现出显著变化;渗透液浊度随着渗透过程中传质的发生,呈现先快速上升后缓慢上升的趋势。追踪分析渗透脱水过程中黄桃片质构品质变化发现,黄桃质构品质明显改变,其中硬度和咀嚼性显著降低（P＜0.05）。利用相关性分析发现,黄桃质构与渗透液渗透压、TSS含量和pH值总体呈显著正相关,与渗透液浊度呈显著负相关。综上,可以从渗透液特性调控入手,辅以合适的预处理,以改善渗透脱水黄桃片的质构品质。     

Effect of osmotic dehydration on the drying kinetics and quality of cashew apple

The effect of different osmotic pretreatments on cashew apple drying kinetics and product quality were investigated. The osmotic pretreatment was carried out in an incubator at constant temperature and agitation. The drying process was conducted in a fixed bed dryer at different temperatures and constant air velocity. Experimental data were fitted successfully using the Page and the two‐term exponential models for dried fresh and pretreated fruit, respectively. It was found that drying rates of osmosed fruits decreased owing to the presence of infused solutes. Evaluation of the final product was performed by means of ascorbic acid content, water activity and sensorial test. The osmotic pretreated samples showed the highest vitamin C losses and the lowest water activity. The samples pretreated in sucrose solution had the highest acceptance.     

不同渗透条件对琯溪蜜柚品质的影响

以琯溪蜜柚为原料,采用正交实验设计,研究不同渗透液含糖量(55%、60%、65%),不同渗透温度(50、55、60℃),不同料液比(1∶6、1∶8、1∶10)对蜜柚品质的影响。测定的指标包括失水率、抗坏血酸保存率、还原糖保存率、蔗糖增加率和总酸保存率。由多指标综合评分法得出的结果表明:渗透液含糖量65%,渗透温度60℃,料液比1∶10为最佳渗透脱水条件。不同渗透条件对蜜柚各营养指标均有影响,且呈现不同的影响效果。      

Effect of osmotic dehydration on dielectric properties,microwave vacuum drying kinetics and quality of mangosteen

Mangosteen (Garcinia mangostana Linn.) with and without osmotic dehydration (OD) in sucrose solution was dried by microwave vacuum drying at 1200, 1440 and 1680 W. Because of water loss (49.12–49.98 g 100 g^?1) and solid gain (9.31–11.62 g 100 g^?1) during OD, dielectric constant, loss factor and loss tangent of mangosteen were significantly increased (P ≤ 0.05) to 24.82–25.12, 11.52–14.18 and 0.47–0.50, respectively. With the decreased initial moisture content and the modified dielectric properties, drying time of osmotically dehydrated mangosteen was shorter than that of mangosteen without OD. Moreover, an increase in microwave power enhanced drying kinetics. With OD, Tg of dried mangosteen was increased from ?7.01, ?3.00 to 11.11–25.96 °C. Hardness and lightness (seedless part) were significantly increased (P ≤ 0.05). Structure of dried seedless mangosteen was well protected, resulting in the improved rehydration ability (P ≤ 0.05). Nonetheless, rehydration ability of the mangosteen containing seed was not improved (P > 0.05).     

真空、脉冲真空和常压下蓝莓渗透脱水的研究

研究了真空渗透脱水、脉冲真空渗透脱水和常压渗透脱水下蓝莓水分含量和水分活度的变化规律，结果表明：真空渗透脱水时，蓝莓的水分含量和水分活度降低得最快。真空渗透脱水、脉冲真空渗透脱水、常压下渗透脱水蓝莓的有效水分扩散率分别为1.6777×10^-9、1.3629×10^-9、0.5679×10^-9m^2/s。真空渗透脱水、脉冲真空渗透脱水、常压下渗透脱水的有效固性物扩散率分别为9.1705×10^-10、6.3919×10^-10、5.1007×10^-10m^2/s。     

Osmotic Dehydration Behavior of Red Paprika (Capsicum Annuum L.)

ABSTRACT: Osmotic dehydration of red paprika was studied using a combined sucrose (5 to 45 g/100 g) and sodium chloride (0 to 15 g/100g) solution. The effective diffusion coefficients for water and solute were determined using the slope method based on the Fickian diffusion model. The effects of concentration of sucrose, sodium chloride and their complex interaction on water and solute diffusion coefficients as well as on equilibrium moisture and solid contents were studied using central composite rotatable design of experiments. The graphical optimization showed that at optimum conditions (sucrose concentration and sodium chloride concentration were 21.86 g/100 g and 2.02 g/100 g, respectively), the following criteria were achieved: water diffusion coefficient (D_ew) 0.80 × 10⁻⁹ m²/s, solid diffusion coefficient (D_es 0.82 × 10⁻⁹ m²/s, equilibrium moisture content (m∞) 6.85 kg/kg, and equilibrium solid content (s∞) 2.00 kg/kg.     

Osmotic dehydration of raspberries with vacuum pretreatment followed by microwave-vacuum drying

Defrozen raspberries were osmotically dehydrated in sucrose solution initially at low pressure (1.33 kPa for 8 min), and then at ambient pressure (4 h). Moisture decreased from 84% to 49% (wet basis), and almost one half of water removal occurred at the vacuum period. Two different transport coefficients were obtained: 19.9 × 10⁻¹⁰ m²/s for transport of water under vacuum, and 3.2 × 10⁻¹⁰ m²/s for water transport at atmospheric pressure. Losses of vitamin C were high (80%) and reutilization of sucrose solution is suggested. Osmotically dried raspberries were microwave-vacuum dried (1.33 kPa for 40 min) under on–off temperature control by varying microwave settings. An undamaged dried product (7.8% wet basis) of high quality (color, taste, structure) was obtained.     

Review: Effect of the combined application of edible coatings and osmotic dehydration on the performance of the process and the quality of pear cubes

The objective of the present work was to evaluate the combined effect of the application of edible coatings (sodium alginate and low methoxyl pectin) and different osmotic dehydration conditions (sucrose solution: 40 and 60 °Brix, temperatures: 20 and 40°C and times: 1, 2, 4, 8 and 16 h) on pear cubes (water loss, solid gain, performance ratio, the total colour differences, mechanical properties, phenolic content and sensory analysis). The results indicated that samples coated with low methoxyl pectin and treated under 60 °Brix for 16 h at both temperatures (20 and 40°C) presented the best process performance. Statistical analysis showed that the application of the coatings resulted in greater firmness and stiffness of the pear cubes at the end of osmotic dehydration. Besides, alginate coating best preserved the phenolic content (31.4%) than uncoated (26.04%) and pectin-coated (20.77%) ones. However, total colour differences were not improved with the use of edible coatings (alginate or pectin). In terms of quality, the samples coated with both hydrogels had good overall acceptability by the evaluators and good mechanical properties. However, further studies are required to decrease the difference in colour and leaching of bioactive compounds in pear cubes due to the osmotic dehydration treatment.     

Kinetic Analysis of Osmotic Dehydration Carried Out with Reused Sucrose Syrup

ABSTRACT Processing times required to achieve a target level of soluble solids were determined in apple pieces during sequential osmotic dehydrations carried out with reused sucrose syrup, in which new loads of fruits were charged in each turn. Effective diffusivities for water and sucrose in apple pieces were experimentally determined as a function of syrup soluble solids. A computer program was written to predict soluble solids change both in apple pieces and in syrup during the sequential osmotic dehydration process. Experimental data on the change of soluble solids for apples and syrup for 10 batches arranged in 2 sets of 5 were obtained. A good agreement between observed and predicted values of soluble solids in both fruit and the syrup was obtained, with root mean square values ranging from 1.3% to 4.6%.     

Solute Transfer in Osmotic Dehydration of Vegetable Foods: A Review

While various mechanisms have been proposed for the water transfer during osmotic dehydration (OD), little progress has been made to understand the mechanisms of solute transfer during osmotic dehydration. The transfer of solutes has been often described only by the diffusion mechanism; however, numerous evidences suggest the participation of a variety of mechanisms. This review deals with the main issues of solute transfer in the OD of vegetables. In this context, several studies suggest that during OD of fruits and vegetables, the migration of solutes is not influenced by diffusion. Thus, new theories that may explain the solute transport are analyzed, considering the influence of the plant microstructure and its interaction with the physicochemical properties of osmotic liquid media. In particular, the surface adhesion phenomenon is analyzed and discussed, as a possible mechanism present during the transfer of solutes in OD.     

渗透脱水循环处理对糖液及桃片理化特性的影响

以白桃片为实验材料,追踪分析了单阶段(糖液浓度不变)和多阶段(糖液浓度逐渐增加)渗透脱水循环处理后糖液特性和桃片理化特性的变化。糖液循环利用5次,期间不做任何调整。结果表明:随着糖液循环利用次数的增加,单阶段渗透脱水处理过程中糖液黏度降低、稀化现象严重,导致渗透压力差减小,使桃片水分损失率和固形物增加率逐渐降低,同时桃片中可溶性物质的溶出致使糖液电导率、浊度、色差值显著增加;多阶段渗透脱水循环处理基于多浓度糖液组合利用,有效降低了循环利用过程中糖液稀化现象的发生,保持了较好的渗透压力差,进而有利于桃片更多固形物的获得和更多水分的散失,且糖液的电导率、浊度等特性得到了较好的保持,但是多阶段渗透脱水循环处理会使桃片与空气接触更多,不利于产品色泽的保持,且长时间的高渗透压导致桃片中可滴定酸含量显著改变。从糖液循环利用中桃片渗透脱水效率和糖液特性保留角度出发,多阶段渗透处理可在桃片渗透方式的选择上提供一种新颖的思路,具有良好的应用前景。     

Calcium lactate effect on the shelf life of osmotically dehydrated guavas

The effect of calcium lactate on osmodehydrated guavas in sucrose and maltose solutions was monitored during storage under passive modified atmosphere for 24 d at 5 °C. Sample texture and color characteristics, microbial spoilage, sensory acceptance, structural changes, and gas composition inside the packages were periodically evaluated. Calcium lactate inhibited microbial growth on guavas, with yeast and mold counts in the order of 10(2) CFU/g throughout storage. The calcium salt reduced respiration rate of guava products, showing O(2) and CO(2) concentrations around 18% and 3% inside the packages. A firming effect on fruit texture, with up to 5 and 2 times higher stress and strain at failure values and tissue structure preservation could also be attributed to calcium lactate use. However, fruits treated with calcium lactate, osmodehydrated in maltose and sucrose solutions, showed sensory acceptance scores below the acceptability limit (4.5) after 13 and 17 d of storage, respectively.