Optimisation of osmotic dehydration process of carrot cubes in mixtures of sucrose and sodium chloride solutions

In the optimisation of the osmotic dehydration process of the carrot cubes in mixtures of sucrose and sodium chloride by response surface methodology, using face-centred central composite design (CCF), it was shown that the independent process variables for osmotic dehydration process were osmotic solution concentrations (5–15% w/v sodium chloride in 50 °Brix sucrose syrup), temperature (35–55 °C) and process duration (120–240 min). Statistical analysis of results showed that the linear terms of all the process variables have a significant effect on all the responses. The optimum osmotic dehydration process conditions for maximum water loss, minimum solute gain, maximum retention of colour, and sensory score were: 50 °Brix + 15% w/v sodium chloride solution, 54.8 °C solution temperature and 120 min process duration.     

Optimization of osmotic dehydration of diced green peppers by response surface methodology

Osmotic dehydration of diced green peppers was optimized with respect to temperature (20-40 °C), time (15-600 min), salt (0-10 g/100 g) and sorbitol (0-10 g/100 g) concentrations through response surface methodology. Water loss (WL), solids gain (SG), salt uptake (SA) and sorbitol uptake (SO) were the responses in a 2⁴ central composite rotatable design. Models developed for all responses were significant (p ≤ 0.01) without significant lack of fit. Results suggested that optimum processing conditions of 5.5 g salt/100 g and 6 g sorbitol/100 g at 30 °C after 240 min would result in WL = 23.3%, SG = 4.1%, SA = 8 g/100 g dry pepper and SO = 2.4 g/100 ml extract.     

Optimisation of vacuum pulse osmotic dehydration of blanched pumpkin

Pulsed vacuum osmotic dehydration (PVOD) is an efficient process for obtaining semi‐dehydrated food. The effects of temperature (30–50°C), solute concentration (NaCl 0–15 kg per 100 kg solution, sucrose, 15–35 kg per 100 kg solution) and vacuum pulse application (50–150 mbar and 5–15 min) on water loss (WL), solid gain (SG), water activity (a_w) and total colour difference (?E) of previously blanched pumpkin slices were assessed through Plackett–Burman experimental design. Temperature was not statistically significant in the process. Later, with the aid of a central composite design (CCD), it was found that concentration of sucrose and NaCl was influent on the WL, SG, a_w and ?E, and the pressure and time of application of vacuum were influent on WL and SG. The optimal conditions of process were stabilised with the desirable function, and the simulated data were similar from the experimental ones.     

Optimisation of osmotic dehydration of carrot cubes in sucrose-salt solutions using response surface methodology

Osmotic dehydration of carrot cubes in ternary solution of water, sucrose and sodium chloride at different solution concentrations, temperatures and process durations were analysed for water loss and solute gain during osmotic dehydration. The osmotically pre-treated carrot cubes were further dehydrated in a cabinet dryer at 65 °C and were then rehydrated in water at ambient temperature of water for 10–12 h and were analysed for rehydration ratio, shrinkage and overall acceptability after rehydration. The process was optimised for maximum water loss, rehydration ratio and overall acceptability of the rehydrated product, and for minimum solute gain and shrinkage of rehydrated product by response surface methodology. The optimum conditions of various process parameters are 50°B+10% w/v aqueous sodium chloride concentration, 46.5 °C solution temperature and 180 min process duration.     

Effects of brine concentration and temperature on equilibrium distribution coefficients during osmotic dehydration of sardine sheets

Effects of brine concentration (0.15-0.27 gNaCl/g) and temperature (32-38°C) on equilibrium distribution coefficients of sardine sheets were studied during osmotic dehydration. The equilibrium distribution coefficients of water and salt were determined using the mass transfer dynamic. The distribution coefficient for water and salt ranged from 0.5008 to 0.6254 and from 0.5286 to 0.7783, respectively. At a constant brine concentration, distribution coefficient of water decreased and distribution coefficient of salt increased with the increasing temperature. At a constant temperature, distribution coefficients of water and salt decreased with the increase in brine concentration. A multiple linear regression fitted (P=0.001; R²=0.877-0.966) distribution coefficient as a function of brine concentration and temperature.     

Osmotic dehydration of Aloe vera (Aloe barbadensis Miller)

Aloe vera possess immunomodulatory, anti-inflammatory, antibacteria effects and wound and burn healing properties, but it is a very unstable product due to its high water content. Osmotic dehydration can be used to obtain stable products from aloe. In this work the effect of osmotic dehydration (OD) on Aloe vera (Aloe barbadensis Miller) leaves was studied. Peeled and unpeeled Aloe vera slices (15 × 50 mm), were immersed in sucrose solutions at 35, 50 and 65 °Brix at 25 and 40 °C. Moisture, effective diffusion coefficients and mass fluxes (water loss, solids gained and weight reduction) were determined. Osmotic dehydration experiments were conducted at atmospheric pressure. The best conditions for the OD of Aloe slices with the highest effect on diffusivity were obtained using a temperature of 40 °C for peeled samples. The analysis of the effect of temperature on mass transfer kinetics showed that unpeeled samples were more effected than peeled samples.     

Shrinkage, density, porosity and shape changes during dehydration of pumpkin (Cucurbita pepo L.) fruits

The aim of this work was to study the changes in volume, density, porosity and shape factors of pumpkin tissue during osmotic dehydration (OD) and air drying (AD). Pumpkin cylinders with length/diameter ratio of 5/3 were used. OD experiments were carried out with solutions of sucrose, sodium chloride and mixtures of both solutes at different temperatures. AD experiments were conducted at 70 °C. Volume of samples decreased linearly with weight reduction (WR). Bulk density varied in a restricted range (5-13%) during dehydration and for all the methods maximum values were found. Particle density increased during both processes. Porosity increased at advanced degrees of dehydration, showing a minimum value at the beginning of OD and AD. The proposed models to evaluate shrinkage, bulk and particle densities and porosity from WR were satisfactorily applied. Image analysis showed that shrinkage of samples during OD was isotropic. Pumpkin cylinders increased elongation and decreased roundness and compactness during osmotic dehydration.     

Osmotic dehydration of apples in sugar/salt solutions: Concentration profiles and effective diffusion coefficients

Apples (Fuji variety) were treated in aqueous sucrose (50% w/w) and salt (NaCl, 10% w/w) solutions for 2, 4 and 8 h (27 °C). Concentration profiles were determined as a function of the distance, considering the unidirectional and normal diffusion to the exposed face of the immersed fruit. The density, water, sugar and salt contents were determined for each piece of apple. A mathematical model was fitted to the experimental data for the water, sucrose and salt contents. A numerical method of finite differences allowed for the calculation of the effective diffusion coefficients as a function of concentration, using the material coordinates to consider tissue shrinkage. The coefficients were obtained by simultaneously integrating the three differential equations (for water, sucrose and salt). The behavior of the apple cellular tissue was also studied using light microscopy techniques to obtain images of the osmotically treated pieces.     

Application of microwaves dielectric spectroscopy for controlling long time osmotic dehydration of parenchymatic apple tissue

Dielectric spectroscopy studies have been performed on fresh and osmotically dehydrated Granny Smith apples. The osmotic treatment consisted on immerse the samples into 65% (w/w) sucrose aqueous solution at 30 °C during different exposure times lasted from 3 h to 16 days. Some physical-chemical parameters were measured in fresh, treated and reposed (24 h at 30 °C) samples. Dielectric spectra were measured in the frequency range from 500 MHz to 20 GHz by an Agilent 85070E Open-ended Coaxial Probe connected to an Agilent E8362B Vector Network Analyzer in the fresh, treated and reposed samples. It has been demonstrated that the dielectric properties are a good tool to control the surface water activity by using the loss factor at relaxation frequency. This relation of dielectric properties with the water activity allows controlling the shrinkage level and determines the moment when the driving forces change from diffusional to mechanical behaviors. This value corresponds to 12.25 ± 0.16 and represents a practical control value to decide if the final dehydrated samples shrink or swell. Moreover, the quantity of adsorbed water was estimated by the subtraction between the overall moisture and the water content in liquid phase estimated by using dielectric loss factor at relaxation frequency.     

Optimization of microwave frying of osmotically dehydrated potato slices by using response surface methodology

Microwave frying of osmotically dehydrated potatoes was optimized by using response surface methodology. Osmotic dehydration was applied prior to microwave frying in order to reduce oil uptake and to evaluate the effect of osmotic dehydration on quality of microwave fried potatoes. Moisture content, oil content, hardness and color of the fried potatoes were used as quality parameters. Microwave power level (400, 550, 700 W), frying time (1.5, 2.0, 2.5 min) and osmotic dehydration time (15, 30, 45 min) were the independent variables in the study. Osmotic dehydration treatment was conducted using 20% (w/w) sodium chloride solution at 30 °C. Moisture content of the fried potatoes decreased whereas oil content, hardness and ΔE value of potatoes increased with increasing frying time and microwave power level. The increase in osmotic dehydration time reduced moisture content and oil content and increased hardness of fried potatoes. The optimum condition was found as frying at 400 W microwave power level for 1.5 min after 39 min of osmotic dehydration time.     

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.     

低温快速电解磷化工艺研究

介绍低温电解磷化技术及钢丝表面快速形成磷酸锌涂层的工艺。利用磷化膜面质量对电解磷化膜进行评估,研究电流密度、时间和温度对电解磷化的影响。使用XRD和SEM分析电解磷化膜的成分主要为四水磷酸锌,形成的晶粒为球状结构,磷化膜细腻。优化后的工艺条件:电流密度为3～4 A/dm2,时间为20～40 s,温度为30～40℃,磷化膜面质量8～10 g/m2。实际应用表明该电解磷化技术具有无渣的特点。该电解磷化膜既可用于水箱式拉拔,压缩率超过90%以上,拉拔速度达到8 m/s,也适用于干式拉拔,拉拔速度可达13 m/s。     

Application of microwaves dielectric spectroscopy for controlling osmotic dehydration of kiwifruit (Actinidia deliciosa cv Hayward)

Dielectric spectroscopy studies have been performed on fresh and osmotically dehydrated kiwifruits (Actinidia deliciosa cv Hayward). The osmotic treatment consisted on the immersion the samples into 65% (w/w) sucrose aqueous solution at 30 °C during different treatment times from 5 to 1440 min. Some physical–chemical parameters were measured in fresh, treated and reposed (24 h at 30 °C) samples. Dielectric spectra were measured in the frequency range from 500 MHz to 20 GHz by an Agilent 85070E Open-ended Coaxial Probe connected to an Agilent E8362B Vector Network Analyzer in the fresh, treated and reposed samples. It has been demonstrated that the dielectric technique is a good method to control the osmotic treatment in kiwifruit.Industrial relevance: The results of this research article are demonstrated to be useful for controlling candying of kiwifruits in bakery industries. Thus, the industrial relevance is clear in order to optimize the osmotic dehydration times and the final quantity of sugars added by using a non destructive technique that can be implemented in process line. Dielectric spectroscopy, which can be considered an emerging technology, has the advantage of being an objective and a rapid technique. For all these reasons we are sending to this journal “Innovative Food Science and Emerging Technologies” our results.     

Optimization of the process variables for the preparation of processed paneer using response surface methodology

Models capable of predicting the quality and yield of processed paneer have been developed using response surface methodology to determine the optimum processing conditions. Three and four-dimensional response surfaces were drawn and the individual contour plots of the different responses were superimposed, and regions meeting the maximum sensory score (29.50–30.75) and yield (9.50–10.50 g/100 g) were identified at 70.1±2.0 °C at 4.85±0.23 pH and 2.908±0.113 g/kg stabilizer concentration. These predicted values for optimum process conditions were in good agreement with experimental data.     

羊毛低温染色新工艺的研究

低温染色法可降低染色过程对羊毛纤维的损伤.文章探讨了采用新工艺,即氨-羊毛蓬松剂PS22预处理-低温染色促进剂DK510法对羊毛进行低温染色,得到了较高的上染率及表观得色量,显著降低了羊毛的强力损伤.同时,此配方和工艺成本较低、工艺简单易行且清洁无污染,可作为羊毛低温染色的较佳工艺.     

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.     

Optimization of the pistachio nut roasting process using response surface methodology and gene expression programming

Roasted pistachio nuts are consumed as snack foods and used as ingredients in confectionery, chocolates and ice-cream industries. Response surface methodology (RSM) and Gene Expression Programming (GEP) were used to optimize the roasting process for production of the pistachios in shell, kernel, and ground-kernel forms over a range of temperature (100-180 °C) and for various times (10-60 min). The moisture content and color parameters (L, a, b and yellowness index (YI)) were evaluated during roasting and modeled by RSM and GEP. The moisture content changes of the pistachios during roasting were successfully described by RSM and GEP models. The results showed that the L, a and b values could be used as parameters for the development of the predictive models during roasting of in shell pistachios, but the color of kernel and ground-kernel pistachios could be monitored by measuring only a and a, b values, respectively. The quadratic models developed by RSM adequately described the changes in selected color parameters during roasting. The GEP models were found to be slightly better than RSM models. The response surface of desirability function was used successfully in optimization procedure of pistachio nut roasting.     

低温保存对超干烟草种子活力的影响

将在低温条件下保存的超干烟草种子的活力与在原干燥器内和常温常湿（自然条件）下继续保存的种子进行比较,结果表明超干燥的烟草种子最适合在４℃下继续保存,其次是在－８℃低温下保存,再其次是在干燥器内继续保存,最不利于在常温常湿下继续保存。由此说明超干烟草种子可以安全地向低温冷藏库转移,而且其种子寿命长于继续进行超干燥保存的种子,而经过超干燥处理后的烟草种子不宜在自然条件下保存。     

An alternative method for the industrial monitoring of osmotic solution during dehydration of fruit and vegetables: A test-case for tomatoes

In this paper, an alternative procedure for in situ and continuous monitoring of the status of the hypertonic solutions used in industrial osmotic dehydration (OD) process of fruit and vegetables is presented and validated. The proposed method, which is based on microwave reflectometry technique, circumvents the limitation of traditional control methods, since it discovers the relation between the characteristic parameters of osmotic solutions and the corresponding measured reflection coefficients. In fact, as the OD proceeds, the dielectric characteristics of the solution, associated to the reflectometry measurements, can be directly related to the variation of the water activity (a_w), which is the parameter that is typically considered to assess the dewatering capacity of the solution. As a result, through the method presented herein, a continuous monitoring of the dewatering capacity of the osmotic solution, associated to its qualitative status, is possible, which, in turn, is useful also for optimizing the OD industrial process. The proposed method was preliminarily validated on reference aqueous solutions of sucrose. Successively, the method was tested also in a typical industrial application, involving the OD process of tomatoes.