Effect Of Osmotic Pretreatment Research Articles

Effect of osmotic pretreatment and drying temperature on drying kinetics, antioxidant activity, and overall quality of taikor (Garcinia pedunculata Roxb.) slices.

Taikor (Garcinia pedunculata Roxb.) is an underutilized, however nutritious fruit, typically found in Bangladesh and northeast parts of India. Taikor slices (1 ± 0.25 cm thickness) were pretreated for 10 min in 10% sucrose, 10% fructose, and 2% brine solution. Three different temperatures, such as 45, 50, and 55 °C were used to perform the drying operation at 30% constant relative humidity (RH). The thin-layer dehydration characteristics of taikor slices were analyzed using the Newtonian, Page, and Henderson and Pabi’s model. The changes in pH, total acidity, color, β-carotene, vitamin C, B vitamins, antioxidant activity, and microbial load calculation were done to compare the comprehensive quality of untreated and pre-treated dried taikor. After assessing the coefficient of determination (R2) and root mean square error (RMSE) values, the Page model was obtained as the best-suited model. For this model, the R2 and RMSE values were found to be approximately 1 and below 0.1094, respectively. Among the pretreatments, sucrose helped retain quality characteristics like ascorbic acid (115.25 ± 0.19 mg/100 g), antioxidant activity (33.25 ± 0.07%) more in the dried samples. The brine pretreated sample had minimum microbial growth. Fructose pretreated taikor samples dried at 45 °C exhibited maximum value of B vitamins (B1 0.025 ± 0.002 mg/100 g, B2 0.016 ± 0.002 mg/100 g, B3 0.011 ± 0.001 mg/100 g), total phenolic content (15.78 ± 0.15 mg GAE/100 g), total flavonoid content (11.11 ± 0.08 mg QE/100 g). Overall, fructose pretreated sample dried at 55 °C was found to be the best method for preserving the maximum physical and chemical quality of dried Garcinia pedunculata.

Effects of osmotic pretreatment and frying conditions on quality and storage stability of vacuum‐fried pumpkin chips

SummaryThe effects of osmotic (OP), ultrasound‐assisted osmotic pretreatment (UAOP) and frying conditions on quality and storage stability of vacuum fried pumpkin chips were investigated. The pumpkin samples were pretreated in maltodextrin solution and subsequently fried at different temperatures (90–110 °C) and time periods (10–30 min). The results demonstrated that the moisture content, water activity, lightness, yellowness and carotenoid content of the fried chips decreased, while oil content, hardness and a* (dark brown colour) value increased with increasing frying temperature and time. UAOP reduced about 16.0% of oil absorption and enhanced approximately 70% of carotenoid retention in the fried chips. UAOP samples were also more stable during storage than the untreated ones, indicated by lower degradation kinetics constants of key quality parameters. The proposed pretreatment could be an effective method for food industries to develop vacuum fried pumpkin chips with improved quality and stability.

Mango dehydration: influence of osmotic pre-treatmentAnd addition of calcium chloride

Abstract Mango (Mangifera indica L.) can be characterized as a greatly accepted fruit due to its sensory attributes of flavor and aroma. However, it has a large production during the harvest season and requires preservation through processing. Osmotic pretreatment, followed by drying, provides products with higher quality and stability. The present study explored the effects of osmotic pretreatment with and without addition of calcium chloride in the nutritional characteristics and sensorial acceptance of dehydrated mango. Four different osmotic treatments were applied in mango slices followed by drying. Drying without osmotic treatment was considered control. Dried samples pre-treated with calcium had lower sugar content and higher retention of acids in the fruit. The increase of sucrose and glucose content during osmotic treatment contributed to maintaining nutritional quality and color of the product when compared with control treatment. Products dehydrated with osmotic pre-treatment were the most preferred, presenting higher purchase intention. The combination of osmotic pretreatment with convective drying provided higher acceptance of dehydrated mango due to its higher quality.

Effect of Osmotic Pre-treatment and Temperature Storage Conditions on Water Activity and Colour of Dried Apple

Abstract The cylinders of apples cv. Braeburn were subjected to osmotic dehydration in a sucrose solution with the addition of chokeberry juice concentrate. After osmotic pre-treatment the pieces of apples were dried by two methods: freeze-drying and air-drying. The storage results of dried apples at temperature 25–45 °C for 7 and 12 months were satisfactory. Mass changes were very minor. During storage dried apples obtained by both methods exhibited microbiological stability even after 7 and 12 months of storage, due to the fact that the water activity did not exceed the value of 0.4. Under the influence of the technological processes application, as well as storage conditions, appearance changes in the samples occurred. Higher temperature of storage had an increase impact in colour changes of control samples (without osmotic pre-treatment) and also osmotically dehydrated into sucrose solution, mainly in the case of samples which had dried using freeze-drying. Previously immersed in chokeberry juice concentrate, dried apples had colour changes comes from colour of solution.

Effect of osmotic pretreatment on quality of mango chips by explosion puffing drying

The effect of osmotic dehydration pretreatment duration (30, 60 and 120 min) on the glass transition, texture, color, expansion, rehydration and other properties of mango chips was investigated. Mango slices were immersed into 65 °Bx sucrose solution at 30 °C and then predried to a moisture content of 30 g water/100 g by hot-air-drying at 50 °C. The mango chips were then obtained by explosion puffing drying. The osmotic pretreatment improved the color of mango chips, whereas sucrose impregnation resulted in a hard and brittle texture. The non-pretreated samples had a higher glass transition temperature, expansion ratio and rehydration ratio and lower hardness and crispness values than the pretreated samples. With increasing immersion time, the glass transition temperature decreased and the water activity simultaneously increased for the chips. Sensory evaluation showed that the pretreated samples were of better overall quality than the non-pretreated samples, although this difference is slight.

Effect of Osmotic Pre-Treatment on Drying Characteristics of Pomegranate (Punica granatum L.)

This study was conducted to determine the effect of osmotic dehydration on air drying characteristics of pomegranate arils. Osmotic dehydration was performed at different time and temperatures combinations. Mass transfer parameters were studied using response surface methodology. After osmotic dehydration, the arils were air dried till moisture content became 8.0%. Page model of drying was fitted on experimental data. Osmotic pretreatment decreased the exponential coefficient of the model. Osmotic dehydration conditions and air drying constant were combined in a single mathematical model with optimization at lowest time for overall dehydration. This goal was achieved when the arils were pretreated for 93 minutes at 39°C. This research might help to choose drying conditions for pomegranate arils on an industrial scale.

Modeling of Microwave Drying of Fruits. Part II: Effect of Osmotic Pretreatment on the Microwave Dehydration Process

The heat and mass transfer during the combined process of osmotic–microwave drying (OD-MWD) of fruits was studied theoretically and experimentally through modeling and numerical simulation. With the aim of describing the transport phenomena involved in the combined dehydration process, the mass and energy microscopic balances were set out. For the first step (OD), two models with different levels of complexity were proposed, an osmotic–diffusive and a countercurrent flow diffusive model. For MWD, the energy and mass balances were solved, using moisture- and temperature-dependent properties; inner heat generation due to transformation of the electromagnetic energy was accounted for by using the approximation of Lambert's law. The numerical solution obtained from OD was incorporated as initial values for the simulation of MWD. The model validation was satisfactorily carried out in pears, both fresh and osmodehydrated for 2 h in sucrose solutions and then irradiated in a microwave oven at 500 W. From the res...

ULTRASOUND‐ASSISTED OSMOTIC DEHYDRATION OF CRANBERRIES: EFFECT OF FINISH DRYING METHODS AND ULTRASONIC FREQUENCY ON TEXTURAL PROPERTIES

ABSTRACTIn this study, the effect of osmotic pretreatments (with or without ultrasound) in combination with hot‐air or microwave‐assisted hot‐air drying methods on the texture, microstructure, color and water activity of dried cranberries were investigated. Osmotic pretreatments were done in a ternary solution (sucrose–NaCl–water) under three different temperatures: 30, 40 and 50C. The concentrations of osmotic solutions were 40, 50 and 60% of sucrose and 0, 4 and 8% of NaCl. Also, the influence of the two levels of frequency of ultrasound (35 and 130 kHz) on the quality properties was investigated. Our results showed lower hardness and water activity (aw) when higher temperature, sucrose and salt were used. Applying ultrasound reduced the hardness and aw of samples. With increasing the frequency of ultrasound, hardness (N) and aw were decreased. Microwave energy reduced drying time and can modify the structure, texture strength and color of the final product.PRACTICAL APPLICATIONSCranberry contains high levels of phytochemicals, which have health‐promoting properties. Some of these phytochemicals, such as anthocyanins, act as an antioxidant, reducing the oxidative damage to cells, which can lead to cancer, heart disease and other degenerative diseases. Recently, cranberry products have been used with the hope of preventing or treating urinary tract infections or Helicobacter pylori infections, which can lead to stomach ulcers, or to prevent dental plaque. Osmotic dehydration is a suitable way to produce shelf‐stable products or partially dehydrated foods without enduring heat damage. The osmotically dehydrated cranberries can be consumed as healthy snacks or can be suited to a wide range of food formulations, including jams or sweets.

Effects of osmotic pretreatments on oxidative stress, antioxidant profiles and cryopreservation of olive somatic embryos

A three-day pretreatment of olive somatic embryos (SE) with 0.75 M sucrose, combined with cryoprotection (0.5 M DMSO, 1 M sucrose, 0.5 M glycerol and 0.009 M proline) and controlled rate cooling, supported regrowth (as 34.6% fresh weight gain) and resumption of embryo development after cryopreservation. Pretreatment with mannitol or sorbitol did not support regrowth. Profiles of sugars, proline, antioxidant enzymes, Reactive oxygen species (ROS), secondary oxidation products and ethylene were constructed for the most successful (0.75 M) pretreatment series. Sucrose was the optimal pretreatment for supporting recovery, it also elevated glutathione reductase (GR) activity compared to controls, whereas superoxide dismutase (SOD), catalase and guaiacol peroxidase activities remained relatively unchanged. Superoxide dismutase activity was higher in SE pretreated with sucrose, compared with those pretreated with polyols; H 2O 2 was enhanced in SE pretreated with sorbitol and sucrose compared to mannitol. The overall trend for ethylene and OH production revealed their levels were highest in SE pretreated with polyols albeit, for individual treatments this was not always the case. Generally, pretreatments did not significantly change embryo secondary oxidation profiles of Thio Barbituric Acid Reactive Substances (TBARS) and Schiff's bases. In combination these studies suggest oxidative processes may influence regrowth of cryopreserved olive SE and that optimal pretreatments could, in part, increase tolerance by an overall enhancement of endogenous antioxidants (particularly GR), proline and sugars.

REHYDRATION KINETICS OF PEAR AS AFFECTED BY OSMOTIC PRETREATMENT AND TEMPERATURE

ABSTRACT The effect of osmotic pretreatments was analyzed as a way to optimize the quality loss of pear slices (cv. Blanquilla) during dried and/or rehydration processes. Pear slices, osmotically pretreated and non‐treated were dried at 45C, until about 10% final moisture, and rehydrated at 45, 55 and 65C in water. The rehydration kinetics of air‐dried pear slices were analyzed by means of Peleg and Fick's models. Kinetics parameters obtained for both models can adequately predict the sample's behavior during rehydration process. Osmotic treatment seemed to slow down the kinetics of dried pear rehydration in terms of water gain and solute loss, with no significant effect on the final solute concentration of the fruit liquid phase. This could be related with the greater viscosity of the fruit liquid phase associated with the sugar gain during the osmotic step and the total loss of this sugar during rehydration. PRACTICAL APPLICATIONSRehydration is a complex process and its main purpose consists of restoring the properties of the dry raw material. The capacity of the dry material to be rehydrated depends on certain intrinsic properties of the vegetal tissue and also, on how the rehydration process is carried out (process conditions) and on the previous pretreatments applied to the product. These pretreatments are usually used to obtain a better quality of the final product (i.e., better preserved from undesirable changes) and in this sense, applying an osmotic dehydration step prior to the rehydration process could be interesting. Thus, the process optimization of pretreated products, rehydrated under several conditions and pretreatments, is a desirable and useful tool to reformulate and obtain high‐quality products.

DRYING KINETIC OF FRESH AND OSMOTICALLY DEHYDRATED MUSHROOM (AGARICUS BLAZEI)

ABSTRACTThe aim of this study was to model the drying kinetics of fresh and osmotically pretreated mushroom slices (Agaricus blazei). Besides the effects of drying air temperature and air velocity, the effect of osmotic pretreatment on drying kinetics and color of dried mushrooms was also determined. The osmotic treatment was carried out at 20C with a 10% (w/w) salt solution, 80 rpm agitation and 60 min immersion time. The fresh and osmosed mushrooms were dried in a vertical bed dryer with forced airflow at different temperatures (40, 60 and 80C) and air velocities (1.0, 1.75 and 2.5 m/s). Drying curves obtained from the experimental data were fitted to the different thin layer‐drying models (Fick's, Page's and logarithmic models). Drying rates of osmosed mushroom decreased due to the presence of infused solids. Increasing the drying temperature and air velocity caused shorter drying times. Osmotically pretreated mushroom presented lower luminosity values (L*) when compared with fresh mushroom, indicating that the osmotic dehydration was not efficient to prevent color loss. Temperature strongly affected the color parameters luminosity L* (or lightness) and chroma C* (or color intensity).PRACTICAL APPLICATIONSBiological materials are highly perishable due to their high moisture content. Therefore, these materials must be processed to improve their shelf life. Among the several methods employed for preservation, drying is a process in which the water activity of the food is reduced by the removal of water, minimizing chemical, enzymatic and microbiological reactions. Several pretreatments are commonly used to minimize adverse changes occurring during drying. Osmotic dehydration is used for the partial removal of water from the food by immersion in a hypertonic solution reducing the physical, chemical and biological changes during drying at higher temperatures. Thus, this study intends to contribute in understanding the behavior of undesirable color quality degradation during the process.

128. Effect of osmotic pretreatments on oxidative stress and antioxidant profiles in olive somatic embryos cryopreserved using controlled rate cooling

128. Effect of osmotic pretreatments on oxidative stress and antioxidant profiles in olive somatic embryos cryopreserved using controlled rate cooling

Effect of osmotic pretreatment on air drying characteristics and colour of pepper (Capsicum spp) cultivars

Air-drying characteristics of fresh and osmotically pretreated (40°B, 50°B and 60°B sucrose solutions for 9h) four pepper cultivars namely, Rodo (Capsicum annuum), Shombo (Capsicum frutescens), Bawa (Capsicum frutenscens) and Tatashe (Capsicum annuum), and CIE L*a*b* parameters of air-dried (50, 60, 70 and 80°C) peppers were investigated. Moisture diffusivity and activation energy (Ea) were calculated from Fick's law and analogous Arrhenius equation, respectively. Colour difference, chroma and hue angle of fresh- and osmo-oven dried peppers were evaluated. Drying rates occurred predominantly in the falling rate. Moisture diffusivity varied from 8.071 × 10(-10)-1.048 × 10(-8), 7.710 × 10(-11)-1.018 × 10(-9), 9.807 × 10(-9)-1.746 × 10(-8) and 8.748 × 10(-10)-1.464 × 10(-9)m(2)/s for Bawa, Rodo, Shombo, and Tatashe, respectively. Ea for moisture diffusion during drying of peppers varied from 53.86 to 84.86kJ/mol and was affected by cultivars and osmotic pretreatment concentration. Osmotic pretreatment and drying temperature had significant effect (p < 0.05) on a*, b*, chroma and hue angle values of dried peppers.

Effect of Osmotic Dehydration on Microwave Freeze-Drying Characteristics and Quality of Potato Chips

In this study, the effects of osmotic pretreatment on microwave freeze-drying (MFD) characteristics and quality of potato chips were studied. Potato slices were pretreated by immersion in salt solution (5, 10, 15% w/w) or sucrose solution (30, 40, 50% w/w) at 20°C for 6 h prior to MFD. Results showed that osmotic pretreatment significantly improved the MFD drying rate compared with MFD of fresh samples under the same operating conditions. However, there is an optimal level of osmotic dehydration beyond which it has an adverse effect on product quality. Osmotic pretreatment with salt concentration below 5% and/or sucrose concentration below 30% prior to MFD drying resulted in dried products of good quality with shorter total drying times relative to MFD of untreated samples.

Effect of osmotic pre-treatment and microwave heating on lycopene degradation and isomerization in cherry tomato

Cherry tomato were dehydrated by a combination of different techniques (osmotic dehydration, convective drying, and microwaves assisted air drying) in order to evaluate the effect of the process variables on the degradation and isomerization of lycopene, as well as on the optical properties. Specifically, the effect of prior osmotic treatment, air drying temperature (40, 55, and 80 °C) and level of microwave energy (0, 1, and 3 W/g) were studied. Obtained results showed that the osmotic pre-treatment limited the isomerization during the later stage of drying, whereas both the loss of total lycopene and the trans – cis isomerization, mainly to the 13- cis form, were favored by an increase in temperature and the microwave power. Furthermore, a positive correlation between the degree of isomerization experienced by the samples during drying and the hue ( h *) were obtained. This correlation was reflected in the colour of the sample with predominantly more orange tones and less reddish ones.

Optimization of coffee ( Coffea arabica ) transformation parameters using uidA and hpt genes: effect of osmotic pre-treatment, helium pressure and target distance

The aim of this work was to optimize the biolistic delivery parameters that affect the DNA delivery and stable expression of marker genes into coffee tissues (Coffea arabica. L. cvs. Caturra and Catuai). The effect of osmotic preculture length, osmotic concentration of medium, Helium pressure and target distance on transient expression of the uidA gene in coffee leaves and somatic embryos were tested. The highest transient uidA expression was obtained when Caturra (18.3±2.8) and Catuai (6.8±2.0) leaves and Catuai embryos (80.0±7.4) were cultured for 5h on Yasuda medium complemented with 0.5M Mannitol +0.5M Sorbitol. The combination of 1100psi and a target distance of 9cm resulted in the highest number of blue spots per Caturra leaf segment (23.6±3.9), whereas for the Catuai variety the combination of 1100psi and a target distance of six (10.2±1.9) and nine (8.2±1.9) cm gave the highest number of blue spots per leaf segment. The optimized protocol was tested with pCAMBIA 1 301 (uidA gene and the hpt gene), pCAMBIA 1 305.2 (uidA version GUSPlus ™ and the hpt gene) and pCAMBIA 1 301-BAR (uidA gene and the bar gene). The highest number of blue spots was obtained when Caturra (54.6±5.7) and Catuai (28.9±4.3) leaves were bombarded with pCAMBIA 1 305.2. Selection of bombarded coffee tissues with 100mg/l hygromicyn caused the oxidation of tissues.

Effect of Osmotic Pretreatment on Hot Air Drying Kinetics and Quality of Chilean Papaya (Carica pubescens)

The effect of osmotic pretreatment on the mass transfer kinetics and quality of dried rehydrated Chilean papaya was researched. Osmotic treatments were sucrose solutions of 40, 50, and 60% w/w and dried at 60°C; non-pretreated samples were dried at different temperatures (40, 60, and 80°C). Quality parameters were analyzed: proximal composition, rehydration ratio, water-holding capacity, color, vitamin C content, firmness, and microstructure. Non-pretreated samples showed a clear turgor loss, color loss. and low ascorbic acid retention when rehydrated. Osmotic pretreatment improved the quality of rehydrated papayas, showing higher ascorbic acid retention and best firmness and color. Microstructure is better preserved in the pretreated papayas than in the non-pretreated samples, although this difference is minimal.

Effect of Osmotic Pre-Treatment on the Air-Drying Behavior and Quality of Plum Tomato Pieces

The air-drying behavior and quality of plum tomato pieces after pre-treatment with different osmotic solutions was investigated. Four pre-treatment solutions (comprised of salt, sugar and/or calcium lactate), three sample geometries (halves, quarters and eighths) and two air-drying temperatures (55 and 65°C) were studied. During osmotic pre-treatment, the moisture loss of the tomato pieces decreased with osmotic pressure. The proportion of skin to cut surface area was found to be important for osmotic moisture loss. As the percentage of cut surface area decreased (59.6%, 47.6% and 25.3% for the eighths, quarters and halves, respectively) and the percentage of skin on the sample increased, the percentage osmotic moisture loss also decreased. At an air-drying temperature of 55°C, the critical moisture content for storage (15%, wet basis) for the pre-treated halves, quarters and eighths was reached after 25-27, 15-18 and 9-12 hours, respectively. At 65°C, the critical moisture content was reached after 16-19, 9-13 and 6-8 hours, respectively. In both cases, the osmotic pre-treatment reduced the critical drying time. The reduction in moisture ratio over time was described by an exponential model (R2 values ? 0.92). The specific drying rate increased with osmotic pre-treatment and was more affected by air-drying temperature than the type of osmotic solution, while the geometry of the samples had no significant effect. Air-dried samples with osmotic pre-treatment were closer to the color of fresh tomato than samples without pre-treatment.

Effect of osmotic pretreatment on equilibrium moisture content of dehydrated carrot cubes

SummaryThe equilibrium moisture contents were determined for carrot cubes osmotically pretreated in salt, sucrose and salt plus sucrose combined solution using static method at 10, 25, 40 and 50 °C over a range of relative humidities from 14% to 95%. Six isotherm equations were applied for analysing the experimental data. Modified exponential equation, is the best equation for predicting the equilibrium moisture contents (EMC) of the dehydrated carrot cubes preosmosed in salt and sucrose plus salt solution, whereas modified Hasley equation is suitable for dehydrated carrot cubes preosmosed in sucrose solution over the relative humidity range of 14–95%. The EMC of carrot cubes osmotically pretreated with salt was highest among all pretreatments, and was lowest for un‐osmosed samples.

Effect of osmotic pretreatment and microwave frying on acrylamide formation in potato strips

AbstractBACKGROUND: The presence of acrylamide, a probable carcinogen, is currently a major concern relating to the consumption of fried products. Therefore, recent frying studies have focused on ways of reducing the acrylamide content. The main objective of the present study was to determine the effects of microwave frying and osmotic treatment prior to frying on acrylamide formation in potato strips.RESULTS: Potatoes fried using 400 W microwave power for 1.0 min had an 87.85% lower acrylamide content than potatoes fried conventionally for 4.5 min (i.e. an 81.82% reduction in frying time) but a comparable moisture content. The acrylamide content of fried potatoes treated osmotically prior to both microwave and conventional frying was found to be lower than that of fried potatoes not pretreated osmotically. However, the reduction in acrylamide content was lower when osmotic treatment was applied before microwave frying.CONCLUSION: As a result of this study, it was concluded that microwave frying can be an alternative to conventional frying. Copyright © 2007 Society of Chemical Industry