Effect Of Osmotic Dehydration Pretreatment Research Articles

Modeling the Effects of Osmotic Dehydration Pretreatment Parameters and Lyophilization Kinetics on Mass Transfer and Selected Nutritive Parameters of Peaches

The effects of the osmodehydration pretreatment parameters on successive lyophilization mass transfer kinetics of the peaches, dehydrated in the combined dehydration process, were investigated and mathematically modelled. The obtained results showed the statistically significant effect of osmotic dehydration pretreatment and its parameters on the final dry matter content and water activity values of the dehydrated peaches. The maximum dry matter content and minimal water activity values of dehydrated peach samples were 84.60 % and 0.423, respectively, produced in osmodehydration pretreatment in molasses of 80 % concentration, at 50 °C, during a 5-hour process and subsequent 6-hour lyophilization. With the increase of all osmodehydration pretreatment parameters it is possible to reduce the duration of the lyophilization process, reducing the high energy demand of the dehydration method (lyophilization) and substituting it with low energy demanding dehydration method (osmodehydration) without compromising the quality of the final product, regarding the dry matter content and water activity values. Mathematical models describing the effect of the duration of the lyophilization on the dry matter content and water activity values of the fresh and dehydrated peaches were developed. They showed a good correlation between calculated and experimental values, allowing a good prediction of the investigated responses. In the combined method, protein, sugar, K and Fe content of the dehydrated peach samples were enriched and further enhanced in prolonged lyophilization stages.

Effect of Osmotic Dehydration Pretreatment on the Drying Characteristics and Quality Properties of Semi-Dried (Intermediate) Kumquat (Citrus japonica) Slices by Vacuum Dryer.

The effect of osmotic dehydration (OD) pretreatments at different temperatures and immersion times on drying characteristics, total phenolic content (TPC), total antioxidant activity (TAA) (DPPH and CUPRAC methods), and color of kumquat slices dried under vacuum conditions (70 °C-100 mbar) was investigated. The OD pretreatment was performed in a sucrose solution (45 °Bx) at the temperatures of 40 and 50 °C and immersed at times of 30, 60, and 90 min. OD before vacuum drying decreased the total required drying time by up to 70 min compared to the control non-pretreated samples. Page, Modified Page, Henderson Pabis, and Two Terms Exponential models were found to satisfactorily describe the drying behavior of thin layer dried kumquat slices. The minimum and maximum values of effective moisture diffusivity (Deff) for semi-dried kumquat slices were 5.04 × 10−8 to 7.19 × 10−8, respectively. OD treatments induced a decline in TPC (5.30–33.92%) and TAA (23.63–59.34% and 4.17–31.67% for DPPH and CUPRAC assays, respectively) of kumquat slices. It was observed that OD pre-treatment can decrease the gross drying time, and make the color and sensorial attributes of dried kumquats better.

The effect of osmotic dehydration pretreatment with sweetenerson the quality of dried aronia berries

Aronia (Aronia melanocarpa) berries are rich in polyphenols. However, they are extremely astringent, which reduces their commercial viability. This study suggests a treatment method to produce more commercial aronia products. In this method, the berries were pretreated with osmotic dehydration and then dried with hot air or lyophilized to reduce their astringency. Sucrose, glucose, and xylitol were used as the pretreatment solutions. The products were prepared and grouped as follows: raw aronia (CON), freeze-dried (FD), osmo-dehydrated using sucrose solution and freeze-dried (FDS), osmo-dehydrated using glucose solution and freeze-dried (FDG), osmo-dehydrated using xylitol solution and freeze-dried (FDX), hot-air-dried (HD), osmo-dehydrated using sucrose solution and hot-air-dried (HDS), osmo-dehydrated using glucose solution and hot-air-dried (HDG), and osmo-dehydrated using xylitol solution and hot-air-dried (HDX). Water loss was highest in aronia berries that were osmo-dehydrated using sucrose solution (16.36%), followed by berries that were dehydrated using glucose solution (14.26%), and those that were osmo-dehydrated using xylitol solution (12.83%). Moisture contents and total soluble solid contents of the FD products were 3.83-7.45% and 6,908.47 °Brix, respectively. FDS and FDX showed relatively high phenolic compound contents and antioxidant activities. FDG and FDS showed better texture and redness. FDS received the highest score for sweetness (5.07) and overall preference (5.13). Hence, FDS proved to be the most appropriate pretreatment, because it allows a better control of the moisture content and maintenance of their appearance and texture, with a relatively low reduction of their phenolic contents. Hence, it affords better preservation efficiency to aronia products.

The influence of chokeberry juice and inulin as osmotic-enriching agents in pre-treatment on polyphenols content and sensory quality of dried strawberries

The objective of this study was to explain the effect of osmotic dehydration pre-treatment (chokeberry juice or inulin) and drying method (microwave-convective drying or freeze-drying) on polyphenols content, antioxidant activity and sensory properties of dried strawberries. The addition of a chokeberry juice concentrate to the osmotic solution significantly influenced the increase of polyphenols content in the fruit. Their content was significantly higher in the samples treated via osmotic dehydration in solutions containing the chokeberry juice concentrate, followed by freeze-drying and also by microwave-convective method. The ability to bind DPPH• radicals ranged from 40% in the dried strawberries without osmotic dehydration to 82% in fruit osmo-dehydrated in a mixture of inulin and the chokeberry juice concentrate and dried by freeze-drying. Study results indicate that the concentrated chokeberry juice and inulin can be used as beneficial osmotic substances. The dried strawberries can represent an alternative to snacks or may be attractive component of other products. One of the very attractive proposals for today’s increasingly demanding consumers can therefore be dried fruit snacks enriched with natural bioactive ingredients.

Mass transfer and morphometric characteristics of fresh and osmodehydrated white mushroom pilei during convective drying

The effect of osmotic dehydration pretreatment (25% NaCl, 80 °C, 180 min) on the mass transfer and morphometric characteristics of white mushroom pilei during convective drying (50, 65 and 80 °C, 2.0 m/s) is investigated. Samples were characterized during process in terms of their cross-sectional area, inner-to-outer radius ratio and roundness by using image analysis. Drying data were modeled by an unsteady state 2D-diffusion model where product was considered as a hemispherical shell. A novel shrinkage algorithm was applied to move inner and outer radial boundaries at a different rate to reduce geometry mismatch during simulation and reproduce both the change in size and proportions of product. Results indicated that OD pretreatment affected mass transfer characteristics of product by significantly lowering (p < 0.05) estimated water diffusivities in comparison to those observed in fresh samples (1.1–2.9 × 10−10 m2/s vs. 2.6–7.2 × 10−10 m2/s).

Effect of osmotic dehydration pretreatment and glassy state storage on the quality attributes of frozen mangoes under long-term storage.

Changes in the quality of frozen mango cuboids were investigated during long-term glassy state storage with and without osmotic dehydration pretreatment. The mango cuboids were dehydrated in mixed solutions (sucrose: glucose: fructose in a ratio of 3.6:1:3) of different concentrations (30, 40, and 50% (wt/wt)) prior to freezing and then stored at -55°C (in the glassy state) for 6months. The results revealed that compared with the untreated samples, osmotic pretreatment decreased total color difference (reduced by 15.6-62.3%), drip loss (reduced by 8.2-29.5%) and titration acidity (reduced by 1.3-9.4%), while increasing hardness (increased by 48.8-82.3%), vitamin C content (increased by 72.5-120.6%) and total soluble solids (increased by 21.8-53.7%) of frozen mangoes after 6months. Dehydration with a sugar concentration of 40% was considered as the optimal pretreatment condition. In addition, a storage temperature of -55°C provided better retention of quality than rubbery state storage at -18°C. With prolonged storage time, the quality of frozen mangoes continued to change, even in the glassy state. However, the changes in quality of the osmotic-dehydrated samples were less than those of the untreated samples. The current work indicates that osmotic pretreatment and glassy state storage significantly improved the quality of frozen mangoes during long-term storage.

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

SummaryThe 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.

Impact of pretreatment on colour and texture of watermelon rind

Impact of pretreatment on colour and texture of watermelon rind The effect of osmotic dehydration pretreatment on water loss, solid gain, colour and textural change was investigated. Watermelon rind 1 x 1 cm size was immersed in sucrose solution of 40, 50 and 60° Brix after pretreatment with microwave and conventional boiling in water for 1, 3, and 5 min, respectively. Water loss and solid gain increased with the time of cooking and sugar concentration. Microwave pretreated samples showed higher water loss and solid gain. Increase in the time of cooking decreased the brightness of all the samples. Microwave pretreated samples showed higher ‘b’ values than conventionally pretreated ones. There was no significant difference (P≤0.05) in texture profile analysis parameters except for hardness. Hardness decreased with increase in time of cooking and sugar concentration. Second order regression model was developed for water loss and solid gain of microwave and conventional pretreated watermelon rind.