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.     

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。     

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.     

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).     

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.     

高稳定性番石榴果汁饮料的研制

近年来番石榴果汁受到消费者的欢迎,但生产过程中存在果肉沉淀、果汁氧化褐变及稳定性差等问题。本研究通过对果汁原料的控制及不同胶体复配稳定体系的构建,基本解决了番石榴果汁产品在货架期内的沉淀问题;通过采用维生素C结合天然抗氧化剂的复合使用,有效地减少了浅色系番石榴果汁产品在货架期内色泽褐变和口味氧化问题。     

国内外果蔬渗透脱水的研究进展

阐述了果蔬渗透脱水的定义和技术特点,介绍了渗透脱水在国内外的研究和应用现状,探讨了该技术在生产应用中存在的问题和应用前景。     

Analysis of minority honey components: Possible use for the evaluation of honey quality

The minerals (Al, B, Ca, Cu, Mg, Mn, Ni, Zn) of 24 authentic Czech nectar and honeydew honey samples (2003 and 2004 harvests) were determined, to find the relationship between their content and the origin or type of honey. The concentrations of analytes in the digests, obtained via optimised dry decomposition of honey samples, were measured by flame atomic absorption spectrometry (F-AAS), as well as optical emission spectrometry with inductively coupled plasma (ICP-OES). With regard to its speed of analysis and cost, ICP-OES was the more favourable method. By combining the analytical data and electrolytic conductivities of samples, the honey samples could be divided into two groups – honeydew honeys and nectar honeys. Like Slovak and Polish honeys, samples of Czech honeys had higher nickel levels than honeys originating from other parts of the world.     

辣椒果肉的渗透脱水效果研究

研究了不同渗透溶液对辣椒果肉的脱水效果,从失水率、固形物增加率、含盐量和色泽变化等方面综合分析了不同浓度的纯糖溶液(50%和65%)、纯盐溶液(10%和20%)和糖盐混合溶液(10%盐,50%糖)的作用效果。结果表明,蔗糖和盐混合溶液的脱水效果最好,8h的失水率可以达到54.20%,可溶性固形物增加率仅有7.53%,且含盐量更是低于纯盐溶液的含盐量变化,只增加了2.62g/100g干基。在渗透后的颜色方面,混合溶液渗透后的变化差异没有纯溶液渗透后的明显。     

蓝莓渗透脱水的研究

在不同的渗透温度 ( 4 5～ 65℃ )条件下 ,高果糖浆和蔗糖的有效水分扩散率 (Dm)分别为( 4 90 60～ 5 2 3 66)× 1 0 - 10 m2 /s和 ( 3 5 5 1 8～ 4 0 1 0 9)× 1 0 - 10 m2 /s,有效固形扩散率 (Ds)分别为( 2 7740～ 3 691 5 )× 1 0 - 10 m2 /s和 ( 1 3 1 63～ 2 691 5 )× 1 0 - 10 m2 /s的规律。在渗透脱水处理过程中Dm 和Ds 随处理温度升高而增加。经高果糖浆 ( 70°Brix)渗透脱水的蓝莓的平均体积比随温度升高而稍微下降。其相对密度随温度的升高也略有增加     

真空、脉冲真空、超声波对芒果渗透脱水的影响

为研究真空、脉冲真空和超声波对芒果渗透脱水动力学的影响,将大小为26mm×26mm×5mm的块状样品浸于65°Brix果葡糖浆溶液中,渗透脱水处理180min。结果表明,菲克扩散模型能很好地描述渗透脱水过程中芒果失水率和固增率的变化规律;真空、脉冲真空和超声波均促进了水分和固形物的扩散,其中超声波作用使水分扩散系数具有最大值,而真空处理导致了固形物扩散系数最高。     

果蔬渗透脱水的研究进展及应用前景

主要论述了果蔬渗透脱水的研究进展 ,总结了影响渗透脱水效果的主要因素 ,概括了渗透脱水在果蔬的品质保持和节能方面的优势 ,它将作为果蔬加工的前处理方法而具有广阔的应用前景。     

Drying of plums (Prunus sp,c.v Gulfblaze) treated with KCl in the field and subjected to pulsed vacuum osmotic dehydration

The pulsed vacuum osmotic dehydration (PVOD) promotes more homogeneous concentration profiles in the product and quality improvement of several fruits. The objective of this work was to study the drying of plums submitted to treatments of plants manure with KCl and PVOD (5” c.a., 10 min). Experimental planning was done with the following independent variables: doses of KCl (400, 700 and 1000 g/plant), concentration of sucrose solution (40; 50 and 60 ºBrix) and drying temperature (50, 60 and 70C). The tested variables were: color, shrinkage, visual quality and rehydration. Temperature leads to a skin browning at fruit pulps and lower visual quality. The treatment with KCl leads to final products with lower moisture content. The higher the values of all the independent variables, the lower the shrinkage and the rehydration capacity. Plums submitted to convective drying with previous PVOD promote a new product with good visual quality and satisfactory shrinkage.