Azuara Model Research Articles

Modeling of sage (Salvia fruticosa Miller) phenolics diffusion in meat cubes during ultrasound assisted vacuum impregnation

This study aimed to investigate the modelling of the transport of sage phenolics into meat cubes under various vacuum impregnation (VI) conditions (Control, VI-100, VI-250, and VI-500 mbar; ultrasound-assisted (UA) VI-100, VI-250, and VI-500 mbar). Azuara model from five different models has been proposed as a model that can be used successfully in describing kinetic parameters. After 180 min of treatment, the phenolic contents of the samples were determined between 462.7 and 639.8 mg/kg. Although the highest phenolic content (639.8 mg/kg) was obtained in the samples applied UAVI-100, the highest equilibrium phenolic content was calculated in the samples applied VI-100 in the calculations performed with the Azuara model. In addition, the diffusion coefficients calculated for the samples varied between 8.5 × 10−6 and 11.4 × 10−6 m2/s.

Simulation of mass transfer during sucrose extraction from sugar beet using a combined analytical and semi-empirical model

In this study, the leaching of sucrose from sugar beet was investigated in a batch process using distilled water solvent. Extraction kinetics was explored at low and high solutions/solid mass ratios. The experimental data were examined by a mathematical model based on Fick’s second law and the Azuara model as a semi-empirical model to determine diffusion coefficients, equilibrium concentrations, and dissociation coefficient K (the ratio of the concentration at the sample to concentration in solution). Diffusion coefficients were calculated by nonlinear regression of the experimental findings. The diffusion coefficients of sucrose (ranging from 2.4831 × 10−10 to 3.2023 × 10−10 m2/s) were higher in the high solution/solid mass ratios compared to the low ratios (ranging from 0.5231 × 10−10 to 0.8728 × 10−10 m2/s) due to higher mass transfer driving force. Also, the proposed empirical Azuara model could properly describe equilibrium concentrations by predicting results (squared mean square error less than 0.0082) close to experimental data at different operating conditions.

Improving salt diffusion by ultrasound application during wet salting of pork meat: A mathematical modeling approach

AbstractThe objectives of this research were to evaluate the influence of ultrasound (US; power of 600 W; frequency of 20 kHz), and salt concentration (SC) in brine (50 and 100 g of salt·L−1 of water) on salt gain (SG) in salted pork meat and to investigate the applicability of mathematical models to simulate SG. Four treatments were tested: T50SB, static brine with 50 g of salt·L−1 of water; T100SB, static brine with 100 g of salt·L−1 of water; T50US, US‐assisted brine with 50 g of salt·L−1 of water; T100US, US‐assisted brine with 100 g of salt·L−1 of water. After wet salting, the NaCl content was determined by the Mohr method. Five mathematical models (Azuara; Z and L; Simplified Fick Equation; Weibull; Diffusive) were tested to describe SG. US‐assisted brine and increasing SC in the brine increased (p < .05) the NaCl content in the salted meat. The salt diffusion coefficients also increased (p < .05) as a result of the increase in the SC in the brine and by the application of US (TM). All models tested showed predictability of experimental data and confirmed that US accelerated the SG during wet salting. The Azuara model presented the highest coefficients of determination (R2) and was chosen to predict the experimental data due to its best fit and because it has a simple mathematical solution, also enabling the prediction of equilibrium conditions. Therefore, US‐assisted brine is a technology that can shorten the salting time and improve the salt diffusion in pork meat and the Azuara model can be used to simulate wet salting processes.Practical ApplicationsUltrasound is an emerging technology that has shown promising results in the processing of meat and meat products. This study showed that ultrasound‐assisted brine of pork meat improves SG, increasing the salt diffusion coefficient in salted meat. Therefore, ultrasound‐assisted brine has the potential to shorten salting time in the industrial processing of pork meat. The Azuara model successfully described the kinetic parameters of the process and can be used to simulate the static and ultrasound‐assisted brine process.

Modeling moisture and solids transfer kinetics during a novel microwave assisted water absorption-desorption process of dry red gram (Cajanus cajan L.) splits

The microwave-assisted water absorption and desorption of dry polished red gram splits were done to reduce its anti-nutritional compounds, improve cooking characteristics, save energy and reduce water requirements. The newly developed process was compared with soaking of red gram splits in water at ambient and 60 °C. Peleg model and modified Azuara model were used to study the water absorption and solid loss kinetics while considering the dry matter holding capacity and surface tension of red gram. The process showed 61.40% db moisture gain and 6.30% db solid loss in 7 min. Further, microwave drying at optimum condition (1.25 W/g and 1.5 pulsation ratio) that was determined using response surface methodology resulted in 50 and 10 min of drying and cooking times, respectively. Compared with raw and conventionally treated samples, the microwave process resulted in a product with an improved rehydration ratio and solids dispersion of 3.00 and 31.90%, respectively. The total specific energy consumption in microwave treatment was 93% lesser than the control methods. • Microwave treatment improved the quality and cooking characteristics of red gram splits. • Microwaves accelerated water absorption by reducing the surface tension. • Low solid loss and high dry matter holding capacity was observed after microwave treatment. • The water absorption and solid loss kinetics were best described by Azuara models. • Total energy consumption in microwave processing was 93% lesser than conventional methods.

Ultrasonic induced effect on mass transfer characteristics during osmotic dehydration of aonla (Phyllanthus emblica L.) slices: A mathematical modeling approach

AbstractThe present work aimed to investigate the effect of ultrasound pretreatment on osmotic dehydration of aonla slices. The aonla slices were subjected to an ultrasonic treatment with a frequency of 40 kHz for 10 min and then subjected to osmotic dehydration in 60°Bx sucrose solution for 300 min. Empirical models such as Azuara, Peleg, Weibull, Page, and Crank model were utilized to predict the kinetics of water loss and solid gain. Artificial Neural Network technique was also used to predict the parameters with immersion time and temperature as input. All models were found to have a good fit. From the analysis, the ultrasound pretreated samples were found to have enhanced rate of mass transfer compared to control samples especially at the early stages of the process. From Azuara Model, the equilibrium water loss and solid gain were ranged between 49.95–53.65 g/100 g and 11.10–22.01 g/100 g. From Crank model, the effective moisture diffusivities in osmotic dehydration were observed to be varied between 9.28 × 10−10–12.47 × 10−10 m2/s and 10.06 × 10−10–19.17 × 10−10 m2/s for atmospheric and ultrasonic conditions. While for solid gain, the values were ranged between 2.36–2.67 × 10−10 m2/s (untreated) and 2.49–2.73 × 10−10 m2/s (treated). The Vitamin C content and color of sample were found to be affected by ultrasound pretreatment (p <.05) and temperature (p <.05). The effective diffusivities attributed to have a significant Arrhenius relationship (R2 ≥.92, p ≤.05). The enhanced moisture loss and solid gain in the product can be explained by the microscopic channels and cell disruption caused by ultrasonic waves.Practical ApplicationThe aonla fruit, native to South Asia, is a very important commodity because of its health and nutritional benefits. Despite its advantages, it is less popular as table fruit because of its low shelf life and astringency. Osmotic dehydration can be used to preserve the fruit, and it causes the partial removal of water from the fruit and improves its taste. Osmotic dehydration being a slow process, can be enhanced by the ultrasound application. The data and findings can be applied to produce stable intermediate moisture content food that can be used as dried fruit or additive with other food products. This study investigates the modeling of ultrasound‐induced osmotic dehydration in order to design the process with low energy and cost.

Modeling of hibiscus anthocyanins transport to apple tissue during ultrasound‐assisted vacuum impregnation

This study reports the mathematical modeling of hibiscus anthocyanins transport to apple tissues under various vacuum impregnation conditions (Control, VI 100, 250, and 500 mbar; ultrasound-assisted VI 100, 250, and 500 mbar). Azuara, Peleg, Diffusive, Z and L, and Weibull mathematical models were used to describe the water gain and anthocyanin gain's mass transfer kinetics. Azuara model successfully described the kinetic parameters of mass transfer during impregnation treatment. The equilibrium anthocyanin and water gain values predicted by the Azuara model varied between 38.4001–58.2536 and 24.0863–33.0245 mg/kg, respectively. Anthocyanin and water diffusion coefficients of the samples ranged between 0.406 × 10−9, −1.68 × 10−9, 0.117 × 10−9, and 0.715 × 10−9 m2/s, respectively. Ultrasound treatment increased moisture and anthocyanin gain during vacuum impregnation. At the end of the 30 min process, the highest anthocyanin content was determined as 38.85 mg/kg in samples treated ultrasound-assisted vacuum at 100 mbar. Novelty impact statement The studies on the modeling of bioactive components transport in the vacuum impregnation are limited although an increase is observed in the studies dealing with the enrichment of fruit and vegetable tissue with bioactive components. In the present study, Azuara model successfully described the kinetic parameters of mass transfer during impregnation treatment. In addition, ultrasound treatment increased anthocyanin content in the apple cubes during vacuum impregnation.

Kinetics and bixine extraction time from achiote (Bixa Orellana L.).

The effects of the use of solvents (96% ethanol and PEG 400), solute ratios: solvent (1: 4 and 1: 6 w/w), extraction temperatures (50 and 60°C) and leaching techniques (conventional and assisted by ultrasound) on the concentration and time of extraction of bixin from Achiote (Bixa Orellana L.) were evaluated. The extraction kinetics were constructed, and their orders were determined. The experimental values were adjusted through the mathematical models of Peleg and Azuara. ANOVA was used based on a 23 design, blocking type of technology. The kinetics showed two stages of extraction: rapid and slow. The reaction orders were decimal numbers, which indicates the complexity of the extraction mechanism. The highest orders of reaction (2.97 and 2.075) were presented with extraction with ultrasound-assisted and ethanol as solvent, at 50 and 60°C and solute solvent ratio 1: 4 and 1: 6, respectively. The concentration of Bixin was increased by approximately 30% by increasing the temperature. The Azuara model presented the highest adjustment with a standard error < 0.1. The conventional leaching with PEG-400 required the lowest activation energy (9.2kJ / mol) and with this treatment in 66min the highest concentration of bixin (2.74 mgBix / gExt) was obtained. It was concluded that ultrasound-assisted leaching facilitates the extraction of bixin pigment, and the use of PEG 400 solvent is useful to obtain higher yields.

Application of ultrasound-assisted vacuum impregnation for improving the diffusion of salt in beef cubes

The aim of this study was to investigate the effect of different vacuum impregnation (VI) conditions (Control, VI-250, VI-500, VI-750, US-VI-250, US-VI-500 and US-VI-750) on the salt gain (SG) and water gain (WG) kinetics of beef cubes. The cubes were immersed in brine solution (4 g NaCl/ 100 g solution) and salted at different levels of vacuum (250, 500 and 750 mbar) using VI method with and without ultrasound. The final moisture and salt contents of the cubes were 78.60% and 1.59%, respectively, and the samples were salted the fastest with US-VI-250. Five kinetic models were selected to evaluate the SG and WG kinetics, and Azuara model exhibited the best fit. In addition, the salt (Ds) and moisture (Dw) diffusion coefficients were in the range of 5.94–8.11 × 10−9 m2/s and 5.17–8.64 × 10−9 m2/s, respectively. It can be concluded that the ultrasound-assisted VI could shorten the brining time by improving the salt diffusion in beef cubes.

Propuesta de mejora del Modelo de Azuara: Aplicación en la cinética de transferencia de masa durante la deshidratación osmótica de anchoveta (Engraulis ringens) y su optimización

Propuesta de mejora del Modelo de Azuara: Aplicación en la cinética de transferencia de masa durante la deshidratación osmótica de anchoveta (Engraulis ringens) y su optimización

The Influence of Natural Basil Seed Gum Coats on the Kinetics of Osmotic Dehydration of Apple Rings

Edible basil seed gum is well known as a safe and beneficial material in the food industry. The effect of the gum concentration was studied as a coating solution on apple rings in the osmotic dehydration process. Water loss, solid gain, water, and solid diffusion coefficients, and performance ratio were selected as important parameters to be studied. Furthermore, different concentrations and temperatures of sucrose solution were investigated as osmotic process parameters. Equilibrium values of solid gain and water loss have been predicted by Azuara model. Mass transfer diffusion coefficients have been appropriately calculated by the analytical solution of Fick’s second law of diffusion. Water and solid diffusion coefficients varied in the ranges of 2.78 × 10−10–13.21 × 10−10(m2/s) and 1.4 × 10−10–5.34 × 10−10(m2/s) respectively, in different operational conditions. The optimal operating condition to gain maximum performance ratio was obtained at 60 °C for concentrations of 0.3 wt.% gum and 60 wt.% osmotic sucrose solutions. Considered conditions resulted in a maximum performance ratio of 9 kg of water removal per 1 kg of solid gain. Coated samples showed 18% lower sucrose absorption in comparison with non-coated apples.

KEHILANGAN AIR DAN PENAMBAHAN PADATAN YANG TERJADI SELAMA PROSES DEHIDRASI OSMOTIK BUAH NAGA

Osmotic dehydration is a method that can be used in the pretreatment of drying by immersing the material in a hypertonic solution. The purpose of this study was to examine the effect of concentration and temperature of the osmotic solution on water loss and solid gain to dragon fruit pieces during the osmotic dehydration process. Dragon fruit slices were immersed in osmotic solution with different concentration and temperature solution (30 oBrix, 50 oBrix, and 70 oBrix, as well as 30 oC, 40 oC, and 50 oC). The WL value for the concentration of 30 oBrix solution varies from 17.42% to 25.26%, for a 50 oBrix concentration is 32.84% to 50.38%, and for a 70 oBrix concentration is 39.89% to 57.99% . Thus, changes in the level of WL, concentration and temperature of the solution, where the higher the concentration and temperature of the solution, the greater the WL of the material. Meanwhile, for SG on materials, values ​​ranged from 2.092% -10.010%. Based on the calculation of the Azuara model, the WL values ​​ranged from 21.551% -75, 187% and 3.899% -17.575% for the SG value. The coefficient of determination for the calculation of the Azuara model is 0.938 - 0.992, thus the Azuara model can be said to be feasible for modeling the WL and SG values ​​on osmotic dehydration of dragon fruit.

Mass transfer modelling in ultrasound assisted osmotic dehydration of kiwi fruit

In this study, the effect of ultrasonic pre-treatment on osmotic dehydration of kiwi slices was investigated. Kiwi fruit slices were subjected to ultrasonic pre-treatment in a sonication water bath at a frequency of 25 kHz for 20 min. Osmotic dehydration of ultrasonic pre-treated samples were conducted for a period of 300 min in 60 Brix sucrose solution. The kinetics of moisture loss and solute gain during osmotic dehydration were predicted by fitting the experimental data with Azuara's model and Weibull's model. The effects of ultrasound application on water loss, sugar gain, effective moisture diffusivity and solute diffusivity of the samples were analysed. The osmotic dehydration process showed a rapid initial water loss followed by a progressive decrease in the rates in the later stages. From the Azuara's model, the predicted equilibrium water loss value for ultrasound pre-treated sample was 58.4% (wb) at 60°C that was nearly 16% higher than the samples treated under atmospheric conditions. Fitting of Weibull model showed that the ultrasound pre-treated and untreated samples had shape parameter (βw) ranging between 0.570–0.616 and 0.677–0.723 respectively. The lower values of shape parameter indicated that sonication caused accelerated water loss resulting faster dehydration rate. Results indicated that the effective moisture diffusivity and solute diffusivity was enhanced in ultrasonic pre-treated samples. The effective moisture diffusivity during osmotic dehydration of ultrasonic pre-treated samples was ranged between 5.460×10−10–7.300×10−10 m2/s and solute diffusivity was varied between 2.925×10−10–3.511×10−10 m2/s within the temperature range 25–60 °C. The enhanced moisture and solute diffusivity in ultrasound pre-treated kiwi slices was due to cell disruption and formation of microscopic channels.

Kinetic modeling of microwave osmotic dehydration of mangoes under continuous flow medium spray conditions using sucrose and maltodextrin (10-18 DE) solute mixtures

Microwave osmotic dehydration of mango (Mangifera indica) was carried out under continuous spray mode (MWODS) with four osmotic solute mixtures (sucrose (S), sucrose in combination with maltodextrin (MD) 10 dextrose equivalent (DE), 15DE, and 18DE), at two temperatures (40 °C, 60 °C) and two concentrations (40%, 60%) and four contact times (10, 20, 30, 40 min). The mass transfer kinetics were fitted to a first-order kinetic model, by way of an empirical parameter (k) representing an overall mass transfer coefficient. Azuara model was also evaluated to describe the mass transfer kinetics. The results showed that the overall mass transfer coefficients for moisture and solids contents were influenced by temperature, concentration and, more importantly, the solute composition. The highest mass transfer coefficient for moisture loss (1.56 E−2) and lowest for solids gain (8.60 E−3) observed with sucrose + maltodextrin 10DE (S + MD 10DE) combination at 60%/60 °C and 40%/40 °C, conditions, respectively. In addition, the Azuara model well fitted the experimental data for mass transfer kinetics (R2 > 0.92). The highest moisture loss (ML) along with lower solids gain (SG) was associated with the solute sucrose + maltodextrin 10DE combination. The highest ML/SG ratio of 10 and weight reduction of 55.5% were observed with S + MD 10DE at 40 °C/60%/40 min and 60 °C/60%/40 min, respectively, with S + MD 10DE solute mixture. Overall, it was possible to successfully describe the mass transfer kinetics using empirical first order and Azuara models and MWODS with S + MD 10DE facilitated the maximum moisture loss and low solids uptake, both desirable from osmotic dehydration point of view.

Osmotic dehydration kinetics of biofortified yellow-flesh cassava in contrast to white-flesh cassava (Manihot esculenta).

In recent times, the cultivation, processing and consumption of biofortified yellow-flesh cassava is of significant interest to breeders and food processors due to its relatively high pro-vitamin-A content, compared to the conventional white-flesh cassava. In light of this, osmotic dehydration (OD) kinetics of a recently released biofortified yellow-flesh cassava was compared to that of a white-flesh cassava, using salt, sugar, and salt-sugar solutions at different temperatures (30, 45, 60°C) and fixed cube/solution-ratio. Water loss (WL) and solids gain (SG) data were fitted by non-linear regression using four models (Page, Weibull, Azuara, and Peleg). Azuara model was most appropriate in describing OD kinetics for both cultivars. Azuara estimates for equilibrium WL and equilibrium SG, respectively, ranged between 0.101-0.120 and 0.049-0.094g/g for salt solution, 0.158-0.212g/g and 0.107-0.268g/g for sugar solution and 0.234-0.306g/g and 0.189-0.276g/g for salt-sugar solution. The best conditions for OD of both cultivars by salt solution and sugar solution was at 60°C and 45°C, respectively, while that for salt-sugar solution varied with cultivar. Increasing temperature increased water loss and solids gain. Salt-OD conformed to Arrhenius temperature dependence of diffusivity, but sugar-OD and salt-sugar-OD did not. Micrographs reveal biofortified yellow-flesh cassava was more susceptible to cell wall collapse than white-flesh cassava. Extent of dehydration by OD agents ranked: salt-sugar > sugar > salt. Osmotic dehydration may be useful as a means of dehydration for cassava prior to drying, and is especially relevant for the carotenoids-rich biofortified yellow cassava.

Modeling of osmotic treatment of ostrich meat coated by tragacanth and salep

This study involved coating of ostrich meat pieces (30 × 30 × 20 mm) with tragacanth gum (0.25%, 0.5%, and 1%) and salep gum (1%, 2%, and 3%) before osmotic treatment with salt solution (5, 15, and 27%) with the immersing duration of 1, 2, 4, 12, and 24 h to accelerate the transfer of moisture and minimize solid gain. This study also involved the investigation of the efficiency of the Peleg's model, Azuara's model, and diffusion equation in modeling water gain/loss and solid gain in meat pieces. Water gain/loss and solid gain were significantly affected by osmotic and coating concentrations during osmotic treatment. The Peleg's model had the best efficiency in the prediction of water loss at 5% and 27% concentrations and solid gain at 27% concentration. Diffusion model showed a favorable performance in the prediction of water loss and solid gain at 27% and 15% concentrations, respectively. It can be concluded that coating pre-treatment could control solid gain and facilitate water loss/gain.

Modelling of mass transfer kinetics of sapota (&lt;i&gt;Achraszapota&lt;/i&gt;) in ternary solutions of sugar and calcium salt during osmotic dehydration

The mass transfer kinetics of sapota in ternary solution was studied at an optimised condition derived using the Box-Behnken design of response surface methodology (RSM). The optimised conditions were found for minimising solid gain and water activity and maximising water loss, weight reduction and overall acceptability. The osmotic dehydration kinetics data were fitted in viz. the Magee model, Page's model and Azuara model. In a comparative study of mass transfer kinetics of sapota between three models viz. the Magee model, Page's model and Azuara model. Page's model was found to fit more effectively to Sapota, for the prediction of water loss and solid gain kinetics during the osmotic dehydration.The simplified solution of Fick's second law of diffusion for a slab geometry was used to calculate the average values of apparent diffusion coefficient (Deff), namely 4.49 × 10−08 m2/s for WL and 4.27 × 10−08 m2/s for SG.

Ultrasound-Assisted Osmotic Treatment of Model Food Impregnated with Pomegranate Peel Phenolic Compounds: Mass Transfer, Texture, and Phenolic Evaluations

Food impregnation with nutraceutical components due to the health beneficial property is of great importance for food processing industry. In this study, osmotic dehydration was used to impregnate model food with phenolics extracted from pomegranate peel. Intermittent acoustic treatment was applied to enhance mass transfer. This process was carried out at three sucrose concentrations of 40, 50, and 60% and two levels of power ultrasound, 50 and 100% in an experimental setup, which was equipped with a pump circulating osmotic solution frequently. Results showed that increase in sucrose concentration resulted in an increase in the amounts of water loss and solutes gain. Additionally, application of higher power ultrasound led to higher values of water loss and solid gain. Mass transfer modeling using Azuara model predicts water loss and solid gain values at equilibrium. Results revealed the good correlation of experimental values with the model (due to the R2 values greater than 0.94). The microstructure of samples was investigated using scanning electron microscopy (SEM). Images revealed pores and cavities made by ultrasound waves as the result of spongy effects. Texture profile analysis (TPA) was applied for the determination of hardness, springiness, and gumminess of the samples. Results also showed significant effects of the sucrose concentration and ultrasound power on textural properties. Measurements of total phenolic content and antiradical activity, which were carried out by a colorimetric method and antiradical scavenging assay, EC50, respectively indicated that osmotic dehydration is a possible way for uptaking phenolic compounds of pomegranate peel presented in osmotic solution into food matrices.

Effects of Ultrasound on Mass Transfer Kinetics, Structure, Carotenoid and Vitamin C Content of Osmodehydrated Sweet Potato (Ipomea Batatas)

The effects of ultrasound pretreatments on mass transfer kinetics, microstructure, carotenoid and vitamin C contents of sweet potato were investigated. Sweet potato samples were treated in distilled water with ultrasound (DWU), osmotic dehydration without ultrasound (OD) and ultrasound-assisted osmotic dehydration (UOD). Samples were subjected to ultrasound probe of 2 cm diameter, frequency of 28 kHz at 300 W maximum power at different pretreatment times of 20, 30, 45 and 60 min. The Azuara model used in this study fitted the experimental data well with high coefficient of correlation ranging from 0.92 to 0.98, low values of chi-square ( 70%) in sweet potato samples treated in DWU and UOD.

Osmotic dehydration of lemon (Citrus limon L.) slices: Modeling mass transfer kinetics correlated with dry matter holding capacity and juice sac losses

ABSTRACTOsmotic dehydration of lemon slices was performed using hypertonic NaCl solution. Due to low dry matter holding capacity (DHC) of lemon, the moisture loss, salt gain, and solid loss kinetics during osmotic dehydration were studied by considering the loss of juice sacs from lemon. The slices were immersed in the osmotic solutions maintained with four concentrations of NaCl (5–20%, w/v) and three temperatures (30, 40, and 50°C) for predetermined time intervals (10–180 min). The sample to solution ratio was maintained at 1:10. Azuara model based on Peleg model was used to determine the equilibrium moisture loss and salt gain. Apart from the moisture loss and salt gain, it was found that the loss of solid constituents and juice sacs from the fruit into the osmotic solution was significant. Therefore, the DHC was determined to correlate the rate of solid loss. The DHC was found to be greatly affected by temperature as lemon was less capable to withhold its cell integrity at higher temperature. A combined correlation model was used to determine the effect of osmosis time, solution concentration, and temperature on moisture loss, salt gain, and solid loss. High temperature is not preferable for osmotic dehydration of lemon as it increases losses. The optimal condition was found to be 20% salt concentration and 30°C osmotic solution for 180 min to attain high moisture loss, less solid loss, and required salt uptake within allowable limits.

Acceleration of mass transfer rates in osmotic dehydration of elephant foot yam (Amorphophallus paeoniifolius) applying pulsed-microwave-vacuum

Abstract The elephant foot yam slices were processed with combined pulsed-microwave-vacuum osmotic drying. Osmotic dehydration at ambient (28 °C and 45% RH) was carried out using different levels of sucrose concentration (30, 40, 50 and 60% w/w), salt concentration (5, 7.5, 10 and 12.5% w/w) and dehydration time (10, 20, 30, 50, 70, 90 and 120 min). During the osmotic dehydration, pulsed microwave vacuum (15 kPa pressure, 1 W/g power density and 1.853 pulsating ratio) was maintained for 2 min over the sample and solution to enhance the mass transfer. For this purpose, the osmotic dehydration experiments were conducted in the microwave-vacuum cavity. Azuara model predicted the moisture loss and solid gain by elephant foot yam slices during osmosis. It was observed that both the moisture loss and the solid gain increased with increasing concentration of the osmotic solution. The optimum conditions found in the process were 40% w/w sucrose concentration, 6% w/w salt concentration and 70 min osmotic dehydration time, resulting in to 42.80% moisture loss (initial weight) and 14.65% solid gain (initial weight). Further, samples were dried using microwave vacuum dryer up to moisture content of 5–6% d.b. by varying microwave power density (2, 4, 6 and 8 W/g) and pulsating ratio (1.312, 1.625, 1.983 and 2.250). Page model was fitted to the data to study the microwave vacuum drying kinetics. The microwave vacuum drying at 1.625 pulsating ratio with microwave power density 4 W/g yielded a product with the highest overall acceptability score. Guggenheim, Anderson and deBoer (GAB) model was used in the study of the sorption behavior of dehydrated elephant foot yam and shelf life prediction. Industrial relevance The production of elephant foot yam in India and South East Asia is comparatively higher than other vegetables. Although, it is nutritious product and good source of energy, food industries are not interested to process elephant foot yam using a time consuming traditional osmotic dehydration process followed by hot air drying. Therefore, present research work was undertaken from industry suggestion to develop accelerated osmotic dehydration process for elephant foot yam using novel pulsed-microwave-vacuum combination followed by finish drying by microwave-vacuum. This research has been carried out to decrease industrial processing time, energy consumption and improving quality of the product. Industry will start adopting this new hybrid process of drying elephant foot yam on large scale.