scholarly journals Drying Kinetics, Quality Changes and Shrinkage of Two Grape Varieties of Italy

2014 ◽  
Vol 553 ◽  
pp. 362-366 ◽  
Author(s):  
Wijitha Senadeera ◽  
G. Adilettta ◽  
M. di Matteo ◽  
P. Russo

Two varieties of grapes, white grape and red grape grown in the Campania region of Italy were selected for the study of drying characteristics, moisture diffusion, quality changes (colour) and shrinkage behaviour. Comparisons were made with treated and untreated grapes under constant drying condition of 50o C in a conventional drying system. This temperature was selected to represent farm drying conditions. Grapes were purchased from a local market from the same supplier to maintain the same size of grapes and same properties. An abrasive physical treatment was used as pretreatment. The drying curves were constructed and drying kinetics was calculated using several commonly available models. It was found that treated samples shows better drying characteristics than untreated samples. The objective of this study is to obtain drying kinetics which can be used to optimize the drying operations in grape drying.

Author(s):  
Ali Ersan ◽  
Nurcan Tugrul

The main purpose of this study was to research the influence of different drying methods on the physical and quality properties of dried shrimps. Shrimps were dried with conventional methods at 60, 70 and 80?C between 330 to 210 minutes and 190 to 110 minutes, in an oven and vacuum oven respectively. Drying time is shortened with the use of vacuum pump. The drying kinetics of the shrimp were studied, and effective moisture diffusion and activation energy were calculated for both methods. The Alibas model and the Midilli & Kucuk model provided the best experimental data with a high coefficient of determination (R2) for oven and the vacuum-oven techniques, respectively. The final dried products were characterized by investigating the colour characteristics, heavy metal content and by carrying out protein analyses. Rehydration ratio was also determined for the dehydrated shrimps. Drying conditions affected the colour features so that shrimps dried in ovens and vacuum ovens showed an increase in brightness and yellowness values and decrease in redness values. The concentration of As, Pb, Cd, Hg, Cu, Zn and Fe in the dried shrimp were within acceptable limits. The protein content of dried shrimp (~85%) is higher than undried shrimp (~20%).


Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 647
Author(s):  
Cristina M. González ◽  
Rebeca Gil ◽  
Gemma Moraga ◽  
Alejandra Salvador

Persimmon (Diospyros kaki L.f.) crop has markedly increased in Spain, and “Rojo Brillante” persimmon is the main cultivated variety. This astringent cultivar requires de-astringency treatment before commercialization, which may involve an extra cost. Its short commercial season implies handling large volumes of fruits with consequent postharvest losses. Therefore, the development of derived added-value products is of much interest. In this study, astringent and non-astringent “Rojo Brillante” persimmons were dehydrated by following a natural drying method used in Asia. The drying kinetics and physico-chemical properties were analyzed for 81 days. The results indicated subsequent reductions in weight, water content, and water activity throughout the drying process, and the equatorial diameter decreased. All the employed thin-layer mathematical models were suitable for representing the drying characteristics of both products with similar behavior. The effective water diffusivity values were 5.07 × 10−11 m2 s−1 and 6.07 × 10−11 m2 s−1 for astringent and non-astringent persimmon samples, respectively. The drying treatment significantly decreased the soluble tannins content, and the astringent samples obtained similar values to those obtained for the non-astringent samples in 20 days. The external and internal flesh of the astringent fruit remained orange through the drying period, while brown coloration in the non-astringent fruit was observed after 57 drying days. Therefore, prior de-astringency treatment would not be necessary.


2008 ◽  
Vol 19 (2) ◽  
pp. 127 ◽  
Author(s):  
S.B. BAKAL ◽  
K.H. GEDAM ◽  
G.P. SHARMA

In developed countries, more than 50% potatoes are consumed as processed products. As drying is the vital phenomenon in processing, it is necessary to investigate the drying characteristics and its kinetics. In this experimental study, drying kinetics of Potato in two different shape of cuboidal & cylindrical with three aspect ratio was investigated as a function of drying conditions. Experiments were conducted using air temperatures of 50, 60 and 70 ºC, at velocity of 7 ms-1. The experimental moisture data were fitted to Page and simple models available in the literature, and a good agreement was observed. The Page model gave better fit than simple model. In the ranges covered, the values of the effective moisture diffusivity, Deff were obtained between 2.278 × 10-9 to 3.314 × 10-8 m2s-1 from the Fick's diffusion model. Using Deff, the value of activation energy (Ea) was determined assuming the Arrhenius-type temperature relationship.


2018 ◽  
Vol 6 (2) ◽  
pp. 552-565 ◽  
Author(s):  
Eunice Akello Mewa ◽  
Michael Wandayi Okoth ◽  
Catherine Nkirote Kunyanga ◽  
Musa Njue Rugiri

The objective of the present study was to determine the drying kinetics, moisture diffusivity and sensory quality of convective air dried beef. The effect of temperature of drying (30-60°C) and thickness of samples (2.5-10 mm) on the convective thin-layer drying kinetics of beefdried in a cabinet dryer was evaluated. Five semi-theoretical models were fit to the drying experimentaldata with the aim of predicting drying characteristics of beef and fitting quality of models determined using the standard error of estimate (SEE)and coefficient of determination (R2). Determination ofeffective moisture diffusivity (Deff) from the experimental drying datawas done and sensory quality of the optimized dried cooked and uncookedbeef samplesevaluated. Drying time and rate of drying increased with an increasing temperature but decreased with increased slice thickness. However, there was overlapping of drying curves at 40-50°C. Among the selected models, Page model gave the best prediction of beef drying characteristics. Effective moisture diffusivity (Deff) ranged between 4.2337 x 10-11 and 5.5899 x 10-10 m2/s, increasing with an increase in air temperature and beef slice thickness.Of all the sensory parameters evaluated, texture was the only attribute that gave significantly different (P > 0.05) scores between the cooked and uncooked dried beef samples.


2012 ◽  
Vol 45 (2) ◽  
pp. 5-14 ◽  
Author(s):  
R. Chayjan ◽  
H. Agha-Alizade ◽  
H. Barikloo ◽  
B. Soleymani

Modeling Some Drying Characteristics of Cantaloupe Slices This study investigated thin layer drying of cantaloupe slices under different drying conditions with initial moisture content about 18.53 (d.b.). Air temperature levels of 40, 50, 60 and 70°C were applied in drying of samples. Fick's second law in diffusion was applied to compute the effective moisture diffusivity (Deff) of cantaloupe slices. Minimum and maximum values of Deff were 4.05x10-10 and 1.61x10-9 m2/s, respectively. Deff values increased as the input air temperature was increased. Activation energy values of cantaloupe slices were found between 30.43 and 36.23 kJ/mol for 40°C to 70°C, respectively. The specific energy consumption for drying cantaloupe slices was calculated at the boundary of 1.01x105 and 9.55x105 kJ/kg. Increasing in drying air temperature in different air velocities led to increase in specific energy value. Results showed that applying the temperature of 70°C is more effective for convective drying of cantaloupe slices. The aforesaid drying parameters are important to select the best operational point of a dryer and to precise design of the system.


2011 ◽  
Vol 179-180 ◽  
pp. 285-288
Author(s):  
Liang Qing Yang ◽  
Yi Xing Liu ◽  
Ying Chun Cai ◽  
Qing Feng Sun

This Study Investigated the Conventional Drying Characteristics of Birch (Betula Costata) Tree Disk Impregnated with NaCl Solution. the Results Showed that NaCI Content in Wood Was Depending on Impregnated Times, and the Relationship between them Was Linear Dependence. the Drying Duration of Treated Disk Was Longer by 25% than that of Untreated Disk. Na+ and Cl-, which Were Easy to Enter the Cell Wall and Combined with Microfibril, which Was the Major Reason for Enhancing Tensile Strength Perpendicular to the Grain and Restrain Cracks.


2013 ◽  
Vol 372 ◽  
pp. 463-466
Author(s):  
Kiattisak Suntaro ◽  
Khwanruedi Sangchum ◽  
Supawan Tirawanichakul ◽  
Yutthana Tirawanichakul

The objectives of this research are to determine the evolution of moisture transfer for germinated Thai jasmine Khao Dawk Mali 105 (KDML105) brown rice variety using impingement drying by eight commonly empirical drying modeling and artificial neural network (ANN) method. The experiments were carried out with drying temperatures of 80-100°C, initial moisture content of KDML105 rice samples soaking with turmeric solution was of 54-55% dry-basis and the desired final moisture content for each drying conditions was fixed at 14-16% dry-basis. The air flow rate was fixed at 7.0 m/s. The measured data in each drying conditions were simulated for getting drying equation by non-linear regression analysis. The results showed that the rice soaking with herb turmeric solution had no effect to drying kinetics and the simulated data using empirical drying equation of Henderson model had the best fitting to all measured data (R2of 0.9978-0.9995 and RMSE of 0.0001441-0.000414). For applying ANN modeling approach, the drying temperature and drying time were considered as the input variables for the topology of neural network while the moisture ratio was the output layer. The simulation results concluded that the simulated values of the ANN model, which was not concerned with any complicated physical properties of grain rice kernels, could be used for prediction drying kinetics and was relatively high accuracy compared to those predicted results of empirical models. So the ANN method without any complicated properties related of rice samples can approach for good prediction their drying kinetics as well as the complicated drying simulations method.


2021 ◽  
pp. 215-223
Author(s):  
Natalia Ageyeva ◽  
Anastasia Tikhonova ◽  
Boris Burtsev ◽  
Svetlana Biryukova ◽  
Ekaterina Globa

Introduction. Grape pomace is the most important by-product of winemaking that can be used as an additional raw material. There is a need for an optimal storage technology so that pomace can be further processed to obtain new types of products. We aimed to study the effect of grape pomace treatment on its microflora. Study objects and methods. We identified and quantified microflora on the fresh and one-month-stored pomace samples from white and red grape varieties. The samples were exposed to conventional drying at 60–65°C, infrared drying at 60–65°C, as well as sulfitation with sulfur dioxide and sodium metabisulfite. Results and discussion. The pomace microflora can be considered a microbial community. Almost all the samples stored for one month in an open area contained Saccharomyces cerevisiae yeasts, higher concentrations of filmy yeasts of the Candida, Pichia, Hansenula, Hanseniaspora/Kloeckera, and Torulaspora genera, as well as conidia of Mucor, Aspergillus niger, and Penicillium molds. Prevalent bacteria included acetic acid (mainly Acetobacter aceti) and lactic acid (Lactobacillus plantarum, Pediococcus, Leuconostoc) bacteria. These microorganisms significantly changed concentrations of volatile and non-volatile components, decreasing total polysaccharides, phenolic compounds, and anthocyanins 1.7–1.9, 3.7–4.0, and 4.0–4.5 times, respectively. The contents of micromycetes and bacteria in the one-month-stored samples were significantly higher than in the fresh pomace. Predrying and sulfitation decreased bacterial contamination, but to a lesser extent compared to micromycetes. Conclusion. Long-term storage spoiled pomace, leading to significant changes in its chemical composition. Sulfitation reduced microorganism growth during storage, but did not provide long-term preservation (over a month), while pre-drying at 60–65°C promoted longer storage.


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