Drying Kinetics and Quality Control in Food Processing

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Food Process Engineering".

Deadline for manuscript submissions: closed (25 November 2023) | Viewed by 94607

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Guest Editor
Food Science and Biotechnology, Kangwon National University, Chuncheon 24341, Republic of Korea
Interests: mathematical modelling in food and bioprocesses; computer simulations; biopolymer rheology
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Food Science, Fu Jen Catholic University, New Taipei City 24205, Taiwan
Interests: novel food ingredients; innovative food processing technology; texture tailoring; sustainable upcycling
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Kinetic characteristics of food quality during dehydration plays an important role in the final product quality as well as the cost of operation. The physico-chemical changes during drying are highly related to the drying temperature and time as well as the food compositions and matrix. The unstable properties of food could be accelerated under various drying circumstances. The drying related researches have focused on characterizing the relations between the moisture content changes and drying conditions such as drying temperature and time. The analytical, semi-empirical, and numerical models to predict the moisture contents during drying have been well developed. However, relatively few studies on the mathematical or empirical analysis on the kinetic characters of food quality during rehydration have been reported. The kinetics character of food quality is a key connection between the drying operations and the final quality of dried food.

This Special Issue on ‘Drying Kinetics and Quality Control in Food Processing’ aims to integrate the novel advances in the development and application of mathematical modeling of drying opeations and kinectic changes of food quality during drying. Topics include but are not limited to the following:

  • Integrated (or multidisciplinary) studies on quality changes of food or bioresource product during dryings;
  • Novel technologoies to control food quality during drying;
  • Optimization of quality prameters invloved in drying operations;
  • Fundamental and applied aspect of drying and dryers;
  • Transport phenomena in food- or bio-porous media;
  • Design, scale-up, and control of dryers in food or bioproduct processing.

Prof. Dr. Won Byong Yoon
Prof. Dr. Meng-I Kuo (Marie)
Guest Editors

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Keywords

  • drying
  • rehydration
  • mass transfer
  • food
  • porous media
  • kinetics
  • quality
  • mathematical model
  • semi-empirical model
  • simulation
  • empirical model
  • texture
  • anthocyanin
  • vitamin
  • energy
  • optimization

Published Papers (27 papers)

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17 pages, 4419 KiB  
Article
Physical, Sensorial, and Physicochemical Characteristics of Arabica Coffee Dried under Two Solar Brightness Conditions
by Aida Esther Peñuela-Martínez, Ingrid Paola Hower-García, Alvaro Guerrero, Lina Marcela Agudelo-Laverde, Henry Betancourt-Rodríguez and Jhully Martínez-Giraldo
Processes 2023, 11(10), 3016; https://doi.org/10.3390/pr11103016 - 20 Oct 2023
Viewed by 994
Abstract
The solar drying process is a critical postharvest stage for preserving coffee quality and is widely used in coffee-producing countries. A descriptive exploratory study was carried out in zones with different annual solar brightness to determine the climate variability influence on solar drying. [...] Read more.
The solar drying process is a critical postharvest stage for preserving coffee quality and is widely used in coffee-producing countries. A descriptive exploratory study was carried out in zones with different annual solar brightness to determine the climate variability influence on solar drying. Variables related to the evolution of drying, physical and sensory quality, and the physicochemical characteristics of the Castillo® coffee variety were analyzed. Coffee quality was assessed by means of SCA protocol. An automatic system was designed to record variables inside the dryers and mass loss. The drying rates were different by climatic zone above and below 0.52%∙h−1. Drying time was significantly longer in less solar brightness zones (Wilcoxon test). An inverse linear relationship between rewetting percentage and bean moisture was observed. Regarding coffee quality, the average scores were 81.37 and 80.93 SCA points for the climatic zones with the lowest and highest solar brightness, respectively. The bean color, water activity, acidity, and fat content did not vary between climatic zones. The coffee quality was not affected by solar drying in contrasting climatic conditions, despite the differences in drying time. Solar drying behaviors were identified that allow for the development of strategies for improving the process efficiency and management of coffee. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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23 pages, 4539 KiB  
Article
Monitoring Temperature Profile and Drying Kinetics of Thin-Layer Banana Slices under Controlled Forced Convection Conditions
by Baher M. A. Amer, Mostafa M. Azam and AbdelGawad Saad
Processes 2023, 11(6), 1771; https://doi.org/10.3390/pr11061771 - 10 Jun 2023
Cited by 1 | Viewed by 1996
Abstract
The drying kinetics of banana slices were examined in a forced convection dryer using an infrared camera to monitor the temperature profile and drying kinetics under control conditions. The air temperature was tested at 40 °C, 50 °C, 60 °C, and 70 °C [...] Read more.
The drying kinetics of banana slices were examined in a forced convection dryer using an infrared camera to monitor the temperature profile and drying kinetics under control conditions. The air temperature was tested at 40 °C, 50 °C, 60 °C, and 70 °C and the air velocity at 0.2 m/s, 0.5 m/s, and 0.75 m/s, with initial moisture contents of the banana ranging from 76–80% wet basis. The thicknesses of the banana slices being dried were 2, 4, 6, and 8 mm. The optimum drying conditions for the highest drying rate and best color were found to be a temperature of 70 °C, an air velocity of 0.75 m/s, a low relative humidity of 5 to 7%, and banana slices with a thickness of 2 mm. As the air temperature increased, the drying rate and shrinkage also increased. Shrinkage varies concerning moisture loss, and the reduction in radial dimension of banana slices was around 17–23% from the original slice before drying. An empirical mathematical equation was derived by applying the technique of multiple linear regression analysis to the whole dataset of the many experiments of the experimental work. The moisture diffusivity was between 7.88 × 10−10 to 1.04 × 10−10 m2/s, and the average activated energy of the banana was 34.29 kJ/mol. The experimental data were used to fit the drying models. The Midilli model was predicted to produce the closest results to the experimental data. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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15 pages, 1754 KiB  
Article
Drying Kinetics and Quality Analysis of Coriander Leaves Dried in an Indirect, Stand-Alone Solar Dryer
by Hemanatha Jayasuriya, Pankaj B. Pathare, Zahir Al-Attabi and Anfal Al-Hamdani
Processes 2023, 11(6), 1596; https://doi.org/10.3390/pr11061596 - 23 May 2023
Cited by 5 | Viewed by 2154
Abstract
In this study, coriander leaves were subjected to three different drying techniques; direct sun, shade, and using an indirect solar dryer. In the developed dryer, hot air obtained from a black-body solar collector was pushed by a blower powered by a solar panel, [...] Read more.
In this study, coriander leaves were subjected to three different drying techniques; direct sun, shade, and using an indirect solar dryer. In the developed dryer, hot air obtained from a black-body solar collector was pushed by a blower powered by a solar panel, and sent to the drying chamber with multiple trays for thin-layer drying. Experiments were conducted for summer and winter seasons, and temperature and relative humidity variations in the drying chamber were measured using a data acquisition system. Indirect solar dryer performance was evaluated and compared with sun drying and shade drying for drying kinetics, moisture diffusivity, and product quality. The drying rate curves show a linear falling rate throughout the drying process. The drying kinetic models are well-fitted with the Midilli and Kucuk thin-layer drying model. The effective moisture diffusivity of the dried coriander shows a decreasing trend, sun drying (2.63 × 10−10 m2/s and 1.05 × 10−10 m2/s) followed by solar dryer (1.31 × 10−10 m2/s and 6.57 × 10−10 m2/s), and shade drying (6.57 × 10−11 m2/s and 3.94 × 10−11 m2/s) for winter and summer seasons, respectively. Green color changes from −7.22 to −0.056, −7.22 to 3.15, and −7.22 to −0.35 in indirect solar, direct sun, and shade drying, respectively. The hue angle and Chroma are reduced by 12% and 32% in indirect solar drying, respectively. The total phenol content (TPC) value increases with drying, with summer showing the highest values (365 to 852 mg caffeic acid/100 g dry weight) while the antioxidant capacity reaches 3.41 and 3.53 in winter and summer, respectively from 0.22 μmol Trolox/g dry matter of fresh leaves. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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14 pages, 886 KiB  
Article
Effect of Different Drying Techniques on Total Bioactive Compounds and Individual Phenolic Composition in Goji Berries
by Busra Turan, Zeynep Hazal Tekin-Cakmak, Selma Kayacan Çakmakoglu, Salih Karasu, Muhammed Zahid Kasapoglu and Esra Avci
Processes 2023, 11(3), 754; https://doi.org/10.3390/pr11030754 - 03 Mar 2023
Cited by 1 | Viewed by 1731
Abstract
In recent years, interest in the consumption of dried goji berries has increased due to its high bioactive properties. Alternative drying methods that provide faster drying and better preservation of bioactive properties should be developed. This study aims to investigate the effect of [...] Read more.
In recent years, interest in the consumption of dried goji berries has increased due to its high bioactive properties. Alternative drying methods that provide faster drying and better preservation of bioactive properties should be developed. This study aims to investigate the effect of different drying methods on the drying time and quality characteristics of the goji berry; namely, hot-air drying (HAD), ultrasound-assisted vacuum drying (USVD), vacuum drying (VD), freeze-drying (FD), and ultrasound-pretreated freeze-drying (USFD). The drying kinetic, total phenolic content, antioxidant capacity, phenolic profile, carotenoid profile, and color change of the goji berry fruit were determined. The drying times for VD, USVD, and HAD varied between 275–1330 min. USVD treatment showed faster drying behavior than the other two drying methods. The total phenolic content (TPC) value of dry samples varied between 1002.53–1238.59 mg GAE/g DM. USVD treatments exhibited a higher total phenolic content (TPC) value than all other drying methods. DPPH and CUPRAC values varied between 15.70–29.90 mg TE/g DM and 40.98–226.09 mg TE/g DM, respectively. The total color change (ΔE) value ranged between 4.59 and 23.93 and HAD dried samples showed the highest ΔE of all samples. The results of the phenolic profile were consistent with TPC analysis. HAD caused higher phenolic compound degradation than VD, USVD, and FD. The results of this study showed that different drying techniques significantly affected the drying rate and retention of bioactive components of the goji berry fruit, and the USVD and VD methods could be used as an alternative to the HAD method. This study concluded that USVD and FD could be considered as suitable drying methods and could be used as alternatives to HAD in the drying of goji berries. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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20 pages, 8397 KiB  
Article
Generalized Mathematical Model of the Grain Drying Process
by Ryszard Myhan and Marek Markowski
Processes 2022, 10(12), 2749; https://doi.org/10.3390/pr10122749 - 19 Dec 2022
Cited by 2 | Viewed by 2099
Abstract
Convective cereal grain drying is an energy-intensive process. Mathematical models are applied to analyze and optimize grain drying processes in different types of dryers and in different stages of drying to improve final grain quality and reduce energy consumption. The aim of the [...] Read more.
Convective cereal grain drying is an energy-intensive process. Mathematical models are applied to analyze and optimize grain drying processes in different types of dryers and in different stages of drying to improve final grain quality and reduce energy consumption. The aim of the present study was to develop a generalized mathematical model of the grain drying process that accounts for all drying stages, including loading and unloading of unprocessed grain, drying, and cooling of dry grain. The developed mathematical model is a system of algebraic equations, where the calculated coefficients are determined by the thermophysical and diffusive properties of dried grain. The model was validated for batch drying of wheat, canola, and corn grain, as well as continuous flow drying of wheat grain. The results were compared with published findings. The relationships between energy consumption during drying and drying time vs. air temperature at the dryer inlet and air stream volume were determined. Dryer capacity and drying conditions specified by the manufacturers, as well as loading and unloading capacity, were considered during batch drying. Continuous flow drying simulations were conducted in counter-flow, parallel-flow, and cross-flow mode. Simulation results indicate that the proposed models correctly depicted process flow in both batch and continuous flow dryers. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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24 pages, 3803 KiB  
Article
Mathematical Modeling of Thin Layer Drying Kinetics and Moisture Diffusivity Study of Pretreated Moringa oleifera Leaves Using Fluidized Bed Dryer
by Shobhit Ambawat, Alka Sharma and Ramesh Kumar Saini
Processes 2022, 10(11), 2464; https://doi.org/10.3390/pr10112464 - 21 Nov 2022
Cited by 6 | Viewed by 1924
Abstract
Investigations were undertaken to study the drying kinetics of pretreated and unblanched leaves of Moringa oleifera dried in a fluidized bed dryer (FBD) using nine established thin layer drying mathematical models. The statistical software tool Statistica was utilized to carry out regression analysis, [...] Read more.
Investigations were undertaken to study the drying kinetics of pretreated and unblanched leaves of Moringa oleifera dried in a fluidized bed dryer (FBD) using nine established thin layer drying mathematical models. The statistical software tool Statistica was utilized to carry out regression analysis, and the model constants were evaluated using nonlinear regression. In nonlinear regression, the R2 and reduced χ2 were employed to evaluate the goodness of fit of several mathematical models to the data generated experimentally. The model with the highest R2 and the lowest reduced χ2 and root mean square error (RMSE) values was adjudged as best fit to the drying curves. The drying kinetics of drumstick leaves was best explained by the Midilli–Kucuk model, followed by the Logarithmic model. The R2, reduced χ2, and RMSE values of the Midilli–Kucuk model under fluidized bed drying varied from 0.9982–0.9997, 0.00003–0.00029, and 0.0059–0.0166 in pretreated and 0.9945–0.9961, 0.00019–0.00054 and 0.0136–0.227 in unblanched Moringa leaves dried at 50–70 °C, respectively. The diffusivity (Deff) values ranged between 2.96 × 10−9–3.59 × 10−9 m2 s−1 and 2.92 × 10−9–3.04 × 10−9 m2 s−1, and activation energy varied from 13.67–14.07 (KJ/mol) and 13.85–14.11 (KJ/mol) for pretreated and unblanched dried leaves at 50–70 °C drying temperatures, respectively. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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18 pages, 1883 KiB  
Article
Mathematical Modeling to Describe Drying Behavior of Kyoho (Vitis labruscana) Skin Waste: Drying Kinetics and Quality Attributes
by Kandi Sridhar and Albert Linton Charles
Processes 2022, 10(10), 2092; https://doi.org/10.3390/pr10102092 - 16 Oct 2022
Cited by 3 | Viewed by 1269
Abstract
Grape skin (Kyoho: Vitis labruscana), a by-product of processed grapes, was experimentally investigated for its drying behavior at different drying temperatures with five thin layer drying models. Moreover, we determined the effect of drying temperature on the bioactive capacity of Kyoho skin. [...] Read more.
Grape skin (Kyoho: Vitis labruscana), a by-product of processed grapes, was experimentally investigated for its drying behavior at different drying temperatures with five thin layer drying models. Moreover, we determined the effect of drying temperature on the bioactive capacity of Kyoho skin. The experimental moisture ratio decreased with increasing drying temperature. The drying process was predicted by mathematical models, such as Page (303.15 K: R2 = 0.9815, 333.15 K: R2 = 0.9685) and two-term (313.15 K: R2 = 0.9639, 323.15 K: R2 = 0.9737) models. Moisture diffusivity (Deff) ranged from 2.87 × 10−8 to 9.82 × 10−8 m2/s, with an activation energy (Ea) of 33.78 ± 1.06 kJ/mol. Total phenolic compounds (0.37 ± 0.04 to 0.23 ± 0.03 mg GAE/g) and antioxidant activities (DPPH activity of 93.06 to 73.31%) of Kyoho skin were significantly affected by drying temperature. Thus, this study concluded that the drying process decreased the bioactive potential of grape skin; therefore, we recommend that the food processing industry needs to consider drying variables during the processing of grape skin-based value-added products for improved food production. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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15 pages, 2315 KiB  
Article
Kinetic Model of Moisture Loss and Polyphenol Degradation during Heat Pump Drying of Soursop Fruit (Annona muricata L.)
by Ngoc Duc Vu, Nhi Thi Yen Tran, Truong Dang Le, Nguyet Thi Minh Phan, Phu Le An Doan, Long Bao Huynh and Phat Tan Dao
Processes 2022, 10(10), 2082; https://doi.org/10.3390/pr10102082 - 14 Oct 2022
Cited by 10 | Viewed by 1590
Abstract
The aim of this study is to investigate the impact of time and temperature of the heat pump drying process of soursop slices at different levels on moisture content and total polyphenol content (TPC). Twelve types of classical kinetic models have been used [...] Read more.
The aim of this study is to investigate the impact of time and temperature of the heat pump drying process of soursop slices at different levels on moisture content and total polyphenol content (TPC). Twelve types of classical kinetic models have been used in this work to describe the suitability of experimental data with models. The conformity is assessed based on statistical values (e.g., coefficient of determination (R2), Chi–square value (X2), etc.). The loss of moisture in the material is described in accordance with Fick’s diffusion law. Value of moisture rate (MR), and effective moisture diffusivities (Deff) have been identified. Experimental results show that MR value depends on the time and drying temperature, Deff increases when increasing the drying temperature from 20–50 °C with values of 1.24 × 10−9, 1.85 × 10−8, 7.69 × 10−8, and 5.54 × 10−7 m/s2. The Singh et al. model is the best option to describe the moisture of the sliced soursop drying process at 30 °C (R2 = 0.97815). The largest TPC decomposition occurs at a temperature of 50 °C. The ability to decompose TPC is proportional to the drying temperature. The TPC decomposition dynamic model follows a first–order reaction when drying at 20 °C with a determinant coefficient R2 = 0.9693. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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15 pages, 3674 KiB  
Article
Preparation of Rice Bran Protein (RBP) Powder Using Spray Drying Method at the Optimal Condition and Its Protein Quality
by Mohd Rizuan Mansor, Mohd Sharizan Md Sarip, Nik Muhammad Azhar Nik Daud, Syahrul Affandi Saidi, Mohd Al Hafiz Mohd Nawi and Mohd Aminudin Jamlos
Processes 2022, 10(10), 2026; https://doi.org/10.3390/pr10102026 - 07 Oct 2022
Cited by 2 | Viewed by 1485
Abstract
Rice bran is a by-product of the rice milling process. It contains a high concentration of protein. Rice brans are frequently utilized as feed cattle, fertilizer, and fuel. However, their application as human nutrition supplements is uncommon, and the necessary process for this [...] Read more.
Rice bran is a by-product of the rice milling process. It contains a high concentration of protein. Rice brans are frequently utilized as feed cattle, fertilizer, and fuel. However, their application as human nutrition supplements is uncommon, and the necessary process for this purpose is yet to be established, including the drying process. This study aims to evaluate the effect of the spray-drying parameters, the inlet temperature, inlet flowrate, and inlet air flowrate, on rice bran protein (RBP) powder and optimize it using response surface methodology (RSM). A thermal water-based extraction method was utilized prior to the drying process. The correlation between the spray-drying parameters, i.e., the inlet temperature (120 to 210 °C), feed flowrate (5 to 55%), and air flowrate (246 to 670 L/h), and the RBP yield were investigated. The quality of the RBP powder was evaluated based on acid amino profiling in the mixture through de novo peptide sequencing. The optimized operating conditions for the maximum yield of RBP powder (25.7 g RBP/100 g RRB) are 178 °C, feed flowrate of 25%, and air flowrate of 450 L/h. The main peptides that contribute to RBP powder protein are globulin and glutelin; meanwhile, prolamin is believed to degrade during the drying process. The process also produced protein sugar, helping to produce fine particles powder without the drying agent. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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11 pages, 5559 KiB  
Article
Drying Characteristics of a Combined Drying System of Low-Pressure Superheated Steam and Heat Pump
by Yuan Yao, Zhenneng Lu, Yulie Gong, Song Guo, Chupeng Xiao and Wenbo Hu
Processes 2022, 10(7), 1402; https://doi.org/10.3390/pr10071402 - 19 Jul 2022
Viewed by 1710
Abstract
The present study aimed at investigating the use of a drying system combining the concept of low-pressure superheated steam drying and heat pump drying for fish. The effects of various drying medium pressures on the temperature field, airflow field, drying time, equipment performance [...] Read more.
The present study aimed at investigating the use of a drying system combining the concept of low-pressure superheated steam drying and heat pump drying for fish. The effects of various drying medium pressures on the temperature field, airflow field, drying time, equipment performance as well as the power consumption of the drying process were investigated and discussed. Four comparative tests with different initial pressures were carried out according to a specified drying process by the combined drying system. The results showed that when the vacuum was high, the temperature field and airflow field in the drying chamber were more uniform. Due to the poor heat transfer performance of the drying medium at high vacuum, the drying time increased with a decrease in initial pressure. It was also found that with the decrease in drying medium pressure, the power consumption of the heat pump and the axial fans was reduced, while the power consumption of the electric heater went up. Overall, the total power consumption is directly proportional to the drying medium pressure. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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15 pages, 2099 KiB  
Article
Heat Pump Drying of Kelp (Laminaria japonica): Drying Kinetics and Thermodynamic Properties
by Qian Zhang, Shiyu Li, Minqi Zhang, Gang Mu, Xiuchen Li, Guochen Zhang and Shanbai Xiong
Processes 2022, 10(3), 514; https://doi.org/10.3390/pr10030514 - 04 Mar 2022
Cited by 6 | Viewed by 2555
Abstract
The main objective of this research is the study of the drying kinetics and thermodynamic properties of kelp using heat pump drying technology. The effects of the independent variables of temperature (20–50 °C), air velocity (0.3–1.3 m/s), humidity (20–50%), and thickness (0.8–4.2 mm) [...] Read more.
The main objective of this research is the study of the drying kinetics and thermodynamic properties of kelp using heat pump drying technology. The effects of the independent variables of temperature (20–50 °C), air velocity (0.3–1.3 m/s), humidity (20–50%), and thickness (0.8–4.2 mm) on the drying time, moisture uniformity, effective moisture diffusivity (Deff), activation energy (Ea), enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) were investigated. The results show that the Page model was effective in describing the moisture content change of kelp during heat pump drying. The Deff varied from 1.00 × 10−11 to 13.00 × 10−11 m2/s and the temperature, air velocity, humidity, and thickness had significant effects on drying time and moisture uniformity. Higher temperature and air velocity with proper humidity shortened the drying time and lessened the influence of thickness on moisture uniformity. The Ea (16.38–26.66 kJ/mol) and ΔH (13.69–24.22 kJ/mol) were significantly increased by thickness. When the temperature was 40 °C, air velocity 1.3 m/s, and air humidity 40%, the moisture content was reduced to 18% in 5 h, with a homogeneous moisture content. This study clarifies the regularity of moisture change inside kelp and provides a theoretical reference for the development of macroalgae drying technology. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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19 pages, 3259 KiB  
Article
Short- and Medium-Wave Infrared Drying of Cantaloupe (Cucumis melon L.) Slices: Drying Kinetics and Process Parameter Optimization
by Antai Chang, Xia Zheng, Hongwei Xiao, Xuedong Yao, Decheng Liu, Xiangyu Li and Yican Li
Processes 2022, 10(1), 114; https://doi.org/10.3390/pr10010114 - 06 Jan 2022
Cited by 15 | Viewed by 2258
Abstract
The main objective of the present work was to study the drying kinetics and obtain the optimum process parameters of cantaloupe slices using short-and medium-wave infrared radiation (SMIR) drying technology. The effect of three independent variables of infrared radiation temperature (55–65 °C [...] Read more.
The main objective of the present work was to study the drying kinetics and obtain the optimum process parameters of cantaloupe slices using short-and medium-wave infrared radiation (SMIR) drying technology. The effect of three independent variables of infrared radiation temperature (55–65 °C), slice thickness (5–9 mm) and radiation distance (80–160 mm) on the L value, color difference (∆E), hardness and vitamin C content were investigated by using the Response Surface Methodology (RSM). The results showed that the Page model can adequately predict the moisture content between 55 and 65 °C (R2 > 0.99). The effective moisture diffusivity (Deff) varied from 5.26 × 10−10 to 2.09 × 10−9 m2/s and the activation energy (Ea) of the SMIR drying was 31.84 kJ/mol. Infrared radiation temperature and slice thickness exerted extremely significant effects on L value and color difference (ΔE) (p < 0.01), with higher infrared radiation temperature and thin slice thickness leading to a decrease in the L value and an increase in ΔE. Hardness and vitamin C content were significantly affected by infrared radiation temperature, slice thickness and radiation distance, of which the slice thickness was the most distinct factor affecting the hardness value. Higher infrared radiation temperature and larger slice thickness and radiation distance resulted in higher vitamin C degradation. For the given constraints (maximized vitamin C content and L value, minimized ΔE and hardness value), the optimum drying parameters were infrared radiation temperature 58.2 °C, slice thickness 6 mm and radiation distance 90 mm. Under the optimum drying combination conditions, the experimental values were 65.58 (L value), 8.57 (∆E), 10.49 N (hardness) and 106.58 mg/100 g (vitamin C content), respectively. This study is beneficial to the development of the cantaloupe food processing industry and provides more insights for the application of SMIR drying technology to improve the drying rate and product quality of cantaloupe. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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17 pages, 2615 KiB  
Article
Experimental Study and Mathematical Modeling of Convective Thin-Layer Drying of Apple Slices
by Mohammad Jafar Royen, Abdul Wasim Noori and Juma Haydary
Processes 2020, 8(12), 1562; https://doi.org/10.3390/pr8121562 - 27 Nov 2020
Cited by 25 | Viewed by 2939
Abstract
This work represents an experimental study and mathematical modeling of convective apple slice drying. The influence of multiple process parameters such as temperature, air humidity, air velocity and slice thickness on process kinetics, product water activity and parameters of empirical models has been [...] Read more.
This work represents an experimental study and mathematical modeling of convective apple slice drying. The influence of multiple process parameters such as temperature, air humidity, air velocity and slice thickness on process kinetics, product water activity and parameters of empirical models has been investigated. Drying characteristics of apple slices were monitored at temperatures of 40, 45 and 50 °C, air velocities of 0.6, 0.85 and 1.1 m/s., slice thicknesses of 4, 6, 8, 10 and 12 mm, and in relative air humidity ranges of 25–28, 35–38 and 40–45%. During the process, samples were dried from an initial moisture content of 86.7% to that of 20% (w.b), corresponding to product water activity of 0.45 ± 0.05. By increasing the temperature from 40 to 50 °C, the time for reaching the required product water activity decreased by about 300 min. Sample thickness is the most significant parameter; by increasing the slice thickness from 4 to 12 mm, the time required to achieve the required water activity increased by more than 500 min. For all experimental runs, parameters of five different thin-layer empirical models were estimated. A thin-layer model sensible to process conditions such as temperature, air velocity, layer thickness and air relative humidity was developed and statistically analyzed. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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17 pages, 4913 KiB  
Article
Modeling and Optimization for Konjac Vacuum Drying Based on Response Surface Methodology (RSM) and Artificial Neural Network (ANN)
by Zhiheng Zeng, Ming Chen, Xiaoming Wang, Weibin Wu, Zefeng Zheng, Zhibiao Hu and Baoqi Ma
Processes 2020, 8(11), 1430; https://doi.org/10.3390/pr8111430 - 09 Nov 2020
Cited by 11 | Viewed by 2413
Abstract
To reveal quality change rules and establish the predicting model of konjac vacuum drying, a response surface methodology was adopted to optimize and analyze the vacuum drying process, while an artificial neural network (ANN) was applied to model the drying process and compare [...] Read more.
To reveal quality change rules and establish the predicting model of konjac vacuum drying, a response surface methodology was adopted to optimize and analyze the vacuum drying process, while an artificial neural network (ANN) was applied to model the drying process and compare with the response surface methodology (RSM) model. The different material thickness (MT) of konjac samples (2, 4 and 6mm) were dehydrated at temperatures (DT) of 50, 60 and 70 °C with vacuum degrees (DV) of 0.04, 0.05 and 0.06 MPa, followed by Box–Behnken design. Dehydrated samples were analyzed for drying time (t), konjac glucomannan content (KGM) and whiteness index (WI). The results showed that the DT and MT should be, respectively, under 60 °C and 4 mm for quality and efficiency purposes. Optimal conditions were found to be: DT of 60.34 °C; DV of 0.06 MPa and MT of 2 mm, and the corresponding responses t, KGM and WI were 5 h, 61.96% and 82, respectively. Moreover, a 3-10-3 ANN model was established to compare with three second order polynomial models established by the RSM, the result showed that the RSM models were superior in predicting capacity (R2 > 0.928; MSE < 1.46; MAE < 1.04; RMSE < 1.21) than the ANN model. The main results may provide some theoretical and technical basis for the konjac vacuum drying and the designing of related equipment. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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15 pages, 3937 KiB  
Article
Effects of Different Drying Methods and Temperature on the Drying Behavior and Quality Attributes of Cherry Laurel Fruit
by Fatma Turkmen, Salih Karasu and Ayse Karadag
Processes 2020, 8(7), 761; https://doi.org/10.3390/pr8070761 - 29 Jun 2020
Cited by 16 | Viewed by 4904
Abstract
This study aimed to investigate the effect of different drying methods and drying temperature on the drying kinetics, total bioactive compounds, phenolic profile, microstructural properties, rehydration kinetics, and color change of cherry laurel fruit. For this aim, hot air drying (HAD), ultrasound-assisted vacuum [...] Read more.
This study aimed to investigate the effect of different drying methods and drying temperature on the drying kinetics, total bioactive compounds, phenolic profile, microstructural properties, rehydration kinetics, and color change of cherry laurel fruit. For this aim, hot air drying (HAD), ultrasound-assisted vacuum drying (USV), and freeze-drying (FD) were conducted on drying of cherry laurel. HAD and USV were conducted at 50, 60, and 70 °C. Drying times of the samples were 1980, 1220, and 770 min for HAD at 50, 60 and 70 °C, and 950, 615, and 445 min at 50, 60, and 70 °C, respectively, for USV. The total bioactive compound was significantly affected by both drying methods and temperature (p < 0.05). FD exhibited the highest total phenolic (TPC), total flavonoid (TFC), total anthocyanin (TAC), and antioxidant capacity value USV showed a higher amount of bioactive compounds than those of HAD at the same drying temperature. The content of total bioactive compounds significantly increased as the temperature increased for both HAD and USV (p < 0.05). The chlorogenic acid was identified as a major phenolic, and its amount significantly depended on drying methods (p < 0.05). SEM images described the surface characteristic of dried samples. HAD dried products showed higher shrinkage compared to FD and USV. All drying methods significantly affected the total color difference (ΔE) values (p < 0.05). This study proposed that USV could be as an alternative method to HAD due to higher bioactive compounds retention and rehydration ratio, shorter drying time, less color change, and shrinkage formation. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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19 pages, 1916 KiB  
Article
Mathematical Modelling of Blanch-Assisted Drying of Pomegranate (Punica granatum) Arils in a Hot-Air Drier
by Adegoke Olusesan Adetoro, Alemayehu Ambaw Tsige, Umezuruike Linus Opara and Olaniyi Amos Fawole
Processes 2020, 8(5), 611; https://doi.org/10.3390/pr8050611 - 20 May 2020
Cited by 6 | Viewed by 3421
Abstract
The effect of blanching conditions on the hot-air drying kinetics of three pomegranates (cvs. “Acco”, “Herskawitz” and “Wonderful”) were assessed. Water blanching conditions considered were 90 °C for 30 s, 90 °C for 60 s, 100 °C for 30 s and 100 °C [...] Read more.
The effect of blanching conditions on the hot-air drying kinetics of three pomegranates (cvs. “Acco”, “Herskawitz” and “Wonderful”) were assessed. Water blanching conditions considered were 90 °C for 30 s, 90 °C for 60 s, 100 °C for 30 s and 100 °C for 60 s. The drying experiments were carried out at 60 °C, 19.6% relative humidity and at a constant air velocity of 1.0 m s−1. The experimental curves were fitted to seven different drying models. For the Acco cultivar, the drying behaviour was best predicted by the Logarithmic and Page model for blanched (R2 ranging between 0.9966 and 0.9989) and unblanched (R2 = 0.9918) samples, respectively. Furthermore, for the Herskawitz cultivar, Logarithm, Page and Midili models were most suitable for predicting drying behaviour of both blanched and unblanched samples. Also, for the Wonderful cultivar, Logarithm and Midili models were most accurate for predicting the drying behaviour for both blanched and unblanched samples amongst other models. The blanched samples dried faster with shorter drying times: “Acco” (7 h), “Herskawitz” (8 h), and “Wonderful” (7 h), compared to the unblanched samples, which dried after 15, 20 and 11 h, respectively. Effective diffusion coefficient of moisture in pomegranate arils ranged from 4.81 × 10−9 and 1.11 × 10−8 m2 s−1 for the Acco cultivar, for the Herskawitz cultivar; 3.29 × 10−9 and 1.01 × 10−8 m2 s−1 and for the Wonderful cultivar; 5.83 × 10−9 and 1.09 × 10−8 m2 s−1. Overall, blanching resulted in low energy consumption during drying of pomegranate arils. In addition, the Logarithmic model generally showed an appropriate model for blanched samples regardless of cultivar. For unblanched samples, the Page model was more appropriate for “Acco” and “Herskawitz”, while the Midili model was appropriate for “Wonderful”. Therefore, this study provided science-based and practical drying conditions for the investigated pomegranate cultivars. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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18 pages, 4260 KiB  
Article
Effects of Low-Temperature Drying with Intermittent Gaseous Chlorine Dioxide Treatment on Texture and Shelf-Life of Rice Cakes
by Timilehin Martins Oyinloye and Won Byong Yoon
Processes 2020, 8(3), 375; https://doi.org/10.3390/pr8030375 - 23 Mar 2020
Cited by 4 | Viewed by 4518
Abstract
We investigated the effect of chlorine dioxide (ClO2) under low temperature drying to suppress rice cake stickiness during the cutting process by initiating the onset of retrogradation until the stickiness is minimized for shelf-life extension. The intermittent ClO2 application at [...] Read more.
We investigated the effect of chlorine dioxide (ClO2) under low temperature drying to suppress rice cake stickiness during the cutting process by initiating the onset of retrogradation until the stickiness is minimized for shelf-life extension. The intermittent ClO2 application at low-temperature drying was conducted at 10 °C for different drying periods (0, 6, 12, 18, and 24 h). Texture analysis showed significant differences with increasing values of hardness (901.39 ± 53.87 to 12,653 ± 1689.35 g) and reduced values of modified adhesiveness (3614.37 ±578.23 to 534.81 ± 89.37 g). The evaluation of rice cake stickiness during the cutting process revealed an optimum drying period of 18 h with no significant difference (p ≤ 0.05) compared to the 24 h drying process. Microbial contamination during the drying process increased, with microbial load from 6.39 ± 0.37 to 7.94 ± 0.29 CFU/g. Intermittent ClO2 application at 22 ppm successfully reduced the microbial load by 63% during drying process. The inhibitory property of ClO2 was further analyzed on a sample with high initial microbial load (3.01 ± 0.14 CFU/g) using primary and modified secondary growth models fitted to all experimental storage temperatures (5–25 °C) with R2 values > 0.99. The model demonstrated a strong inhibition by ClO2 with microbial growth not exceeding the accepted population threshold (106 CFU/g) for toxin production. The shelf-life of rice cake was increased by 86 h and 432 h at room temperature (25 °C) and 5 °C respectively. Microbial inactivation via ClO2 treatment is a novel method for improved food storage without additional thermal sterilization or the use of an additional processing unit. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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21 pages, 883 KiB  
Article
Model-Based Real Time Operation of the Freeze-Drying Process
by Carlos Vilas, Antonio A. Alonso, Eva Balsa-Canto, Estefanía López-Quiroga and Ioan Cristian Trelea
Processes 2020, 8(3), 325; https://doi.org/10.3390/pr8030325 - 10 Mar 2020
Cited by 22 | Viewed by 6977
Abstract
Background: Freeze-drying or lyophilization is a dehydration process employed in high added-value food and biochemical goods. It helps to maintain product organoleptic and nutritional properties. The proper handling of the product temperature during the operation is critical to preserve quality and to reduce [...] Read more.
Background: Freeze-drying or lyophilization is a dehydration process employed in high added-value food and biochemical goods. It helps to maintain product organoleptic and nutritional properties. The proper handling of the product temperature during the operation is critical to preserve quality and to reduce the process duration. Methods: Mathematical models are useful tools that can be used to design optimal policies that minimize production costs while keeping product quality. In this work, we derive an operational mathematical model to describe product quality and stability during the freeze-drying process. Model identification techniques are used to provide the model with predictive capabilities. Then, the model is used to design optimal control policies that minimize process time. Results and conclusion: Experimental measurements suggest splitting the process into two subsystems, product and chamber, to facilitate the calibration task. Both models are successfully validated using experimental data. Optimally designed control profiles are able to reduce the process duration by around 30% as compared with standard policies. The optimization task is introduced into a real time scheme to take into account unexpected process disturbances and model/plant mismatch. The implementation of the real time optimization scheme shows that this approach is able to compensate for such disturbances. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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13 pages, 1705 KiB  
Article
Effect of Dehydration on the Rheological Measurement of Surimi Paste in Cone-Plate Rheometry: Heat and Mass Transfer Simulation
by Hyeon Woo Park, Jae Won Park and Won Byong Yoon
Processes 2020, 8(2), 234; https://doi.org/10.3390/pr8020234 - 19 Feb 2020
Cited by 2 | Viewed by 2631
Abstract
Moisture transfer characteristics of Alaska pollock (AP) surimi were investigated at various temperatures. The effective moisture diffusivity increased from 5.50 × 10−11 to 2.07 × 10−9 m2/s as the temperature increased from 30 °C to 90 °C. In order [...] Read more.
Moisture transfer characteristics of Alaska pollock (AP) surimi were investigated at various temperatures. The effective moisture diffusivity increased from 5.50 × 10−11 to 2.07 × 10−9 m2/s as the temperature increased from 30 °C to 90 °C. In order to investigate the mass and heat transfer characteristics of AP surimi, the simulation model was developed and evaluated by root-mean-square error (RMSE) (<2.95%). Rheological properties of AP surimi were investigated at different heating rates (1 °C/min, 5 °C/min, 10 °C/min, 20 °C/min and 30 °C/min). As heating rate increased to 20 °C/min and 30 °C/min, elastic modulus (G’) significantly diminished. The diminished G’ could be explained by impaired gel during temperature sweep supported by the predicted temperature distribution in the simulation model. Changes in moisture content of AP surimi during temperature sweep were also measured and predicted by the simulation model. The results showed the decreased amount of moisture content significantly increased as heating rate increased. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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19 pages, 2673 KiB  
Article
Evaluation of Thermal Effects on the Bioactivity of Curcumin Microencapsulated with Porous Starch-Based Wall Material Using Spray Drying
by Chenwei Huang, Shengwen Wang and Huaiwen Yang
Processes 2020, 8(2), 172; https://doi.org/10.3390/pr8020172 - 04 Feb 2020
Cited by 6 | Viewed by 3134
Abstract
Curcumin was microencapsulated by porous starch using a spray dryer with a particle size between 1.5 and 2.0 µm and subjected to water bath (40–100 °C) and oven heating (150–200 °C) in comparison to non-encapsulated samples. The minimum possible encapsulation rate ranged from [...] Read more.
Curcumin was microencapsulated by porous starch using a spray dryer with a particle size between 1.5 and 2.0 µm and subjected to water bath (40–100 °C) and oven heating (150–200 °C) in comparison to non-encapsulated samples. The minimum possible encapsulation rate ranged from 26.75 to 52.23%. A reasonable thermal stability was observed after water bath heating with regard to 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging activity. On the other hand, the increase in oven heating temperature caused significant alterations compared with the control samples (p < 0.05). The encapsulated particles subjected to oven heating at 170 °C demonstrated serious collapse. The DPPH scavenging activity of non-encapsulated curcumin was significantly reduced (p < 0.05) from 48.94% ± 3.72% (control, 0 °C) to 40.42% ± 2.23% (oven heating, 160 °C); however, remained stable for the encapsulated samples (51.18% ± 4.86%–50.02% ± 1.79%) without significant difference (p < 0.05). The ABTS scavenging activity was promoted as a function of the oven heating temperature. Both DPPH and ABTS free radical scavenging activities remained stable after water bath. Nevertheless, the color of microencapsulated curcumin was better preserved in comparison to the controls. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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18 pages, 1901 KiB  
Article
Effect of Drying on Lettuce Leaves Using Indirect Solar Dryer Assisted with Photovoltaic Cells and Thermal Energy Storage
by Pedro Cerezal Mezquita, Aldo Álvarez López and Waldo Bugueño Muñoz
Processes 2020, 8(2), 168; https://doi.org/10.3390/pr8020168 - 03 Feb 2020
Cited by 8 | Viewed by 3816
Abstract
The thin layer drying behavior of lettuce leaves was investigated using an indirect pilot solar dryer with thermal energy storage in water, equipped with solar collectors and photovoltaic cells. The drying procedure consisted of shredded lettuce leaves, temperature ≤ 52 °C, airspeed, 1.0 [...] Read more.
The thin layer drying behavior of lettuce leaves was investigated using an indirect pilot solar dryer with thermal energy storage in water, equipped with solar collectors and photovoltaic cells. The drying procedure consisted of shredded lettuce leaves, temperature ≤ 52 °C, airspeed, 1.0 m∙s−1, and process time ~10.0 h. Fifteen drying models were adjusted to the experimental data obtained; three models with maximum values of coefficient of determination (R2)—Page, Midilli, and Kucuk, and Weibull Distribution, whose values of R2 ≥ 0.998, and other statistical parameters, χ2, SSE, and RMSE values closer to zero were chosen. The initial browning index BI = 120.5 ± 0.7 decreased compared to the dry sample BI = 78.99 ± 0.5, with chromatic coordinate degradations a* and b*; but not the luminosity L*; where ΔE = 8.26; whose meaning is that the dry sample is a “more opaque brownish color” due to the difference in the chroma ΔC = 6.65, and with a change from the yellow-green to yellow-red zone, and a difference in hue angle, Δh° = 14.27, between the fresh and the dried sample. Deff values for shredded lettuce leaves were 1.8 × 10−9 m2 s−1 for values ≤ 52 °C. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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21 pages, 825 KiB  
Article
3-D Modeling of Dehydration Kinetics and Shrinkage of Ellipsoidal Fermented Amazonian Cocoa Beans
by Alessandra Adrover and Antonio Brasiello
Processes 2020, 8(2), 150; https://doi.org/10.3390/pr8020150 - 24 Jan 2020
Cited by 3 | Viewed by 2359
Abstract
A recently proposed moving-boundary model for food isothermal dehydration was applied to analyze the dehydration kinetics of ellipsoidal cocoa beans, characterized by a moderate shrinkage and a non-uniform initial distribution of water content between the core and the shell of the bean. The [...] Read more.
A recently proposed moving-boundary model for food isothermal dehydration was applied to analyze the dehydration kinetics of ellipsoidal cocoa beans, characterized by a moderate shrinkage and a non-uniform initial distribution of water content between the core and the shell of the bean. The aim is to predict the influence of air velocity and non-uniformity of the initial water distribution on the dehydration rates, as well as the temporal evolution of the water content in the core and in the shell and of the characteristic lengths of the ellipsoidal bean. The model proved capable of accurately describing the two-phases dehydration process: an initial fast dehydration of the shell, characterized by higher dehydration rates, followed by a slower dehydration of the core, characterized by a linear relationship j d = δ ( T ) X r between the dehydration rate j d and the moisture ratio X r . A shortcut method to estimate the effective water diffusivity D is also proposed, deriving from the basic observation that the asymptotic exponential behaviour of the dehydration curve X r ( t ) for an ellipsoidal bean coincides with that of an equivalent sphere, with the same surface-to-volume ratio. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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12 pages, 1609 KiB  
Article
Physicochemical Properties of Guava Snacks as Affected by Drying Technology
by Yuri M. Leiton-Ramírez, Alfredo Ayala-Aponte and Claudia I. Ochoa-Martínez
Processes 2020, 8(1), 106; https://doi.org/10.3390/pr8010106 - 14 Jan 2020
Cited by 15 | Viewed by 5397
Abstract
Guava is widely consumed because of its agro-industrial use, and its antioxidant properties attributed to vitamin C and carotenoids content. However, it has a short shelf life. Guava has been dried by atomization, fluidized bed, lyophilization (FD) and convective drying (CD). CD requires [...] Read more.
Guava is widely consumed because of its agro-industrial use, and its antioxidant properties attributed to vitamin C and carotenoids content. However, it has a short shelf life. Guava has been dried by atomization, fluidized bed, lyophilization (FD) and convective drying (CD). CD requires long operation times and the product characteristics are not desirable. In contrast, FD produces high quality products, but requires long processing times, high energy consumption and high operation costs. As an alternative, the Refractance Window® (RW) drying is relatively simple and cheap technique. The objective of this study was to compare the effect of CD, FD and RW techniques, on the moisture content, water activity, color, porosity, volume change, vitamin C and carotenoids content in guava samples. The samples dried by RW required less time to reduce the moisture content and exhibited smaller changes in color than CD or FD. There were greater losses of carotenoids and vitamin C when drying by CD whereas RW had similar losses than FD. Lyophilized products exhibited minor change in volume and greater porosity. RW results in better retention of properties, compared with other drying techniques. Based on this, RW is a promising technique for the development of guava snacks. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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17 pages, 4418 KiB  
Article
Effect of Loading on Wheat Germ Drying in a Batch Fluidized Bed for Industrial Production
by Der-Sheng Chan and Meng-I Kuo
Processes 2019, 7(12), 864; https://doi.org/10.3390/pr7120864 - 20 Nov 2019
Viewed by 2958
Abstract
A high loading production in the manufacturing process of wheat germ (WG) drying is important for reducing the production costs. From a cost perspective, the drying performance become more effective in a batch process when the loading increases. The objective of this investigation [...] Read more.
A high loading production in the manufacturing process of wheat germ (WG) drying is important for reducing the production costs. From a cost perspective, the drying performance become more effective in a batch process when the loading increases. The objective of this investigation was to evaluate the drying performance of WG with different loadings, from 2 to 9 kg, at 120 °C in a fluidized bed dryer. The moisture content, according to the American Association of Cereal Chemists (AACC) method, and the water activity using a thermal hygrometer were measured. The absolute humidity, diffusivity of moisture, and thermal efficiency were analyzed using a mathematical model. An analysis of the dehydration flux demonstrated a linear relationship between dehydration time and WG loading using a fluidized bed dryer. The kinetics of WG drying were observed with a simple exponential model used to match the experimental observation, indicating that the drying rate constant decreases with an increase in WG loading. A linear relationship was obtained between the WG loading and heating time (heating time = −0.212 + 0.577 × WG loading). On this basis, a process optimization was developed for industrial operation, and for predicting the drying performance of WG for industrial-scale production. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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Review

Jump to: Research

14 pages, 2125 KiB  
Review
Reassessment of Thin-Layer Drying Models for Foods: A Critical Short Communication
by Sencer Buzrul
Processes 2022, 10(1), 118; https://doi.org/10.3390/pr10010118 - 07 Jan 2022
Cited by 23 | Viewed by 2790
Abstract
Modeling the thin-layer drying of foods is based on describing the moisture ratio versus time data by using a suitable mathematical model or models. Several models were proposed for this purpose and almost all studies were related to the application of these models [...] Read more.
Modeling the thin-layer drying of foods is based on describing the moisture ratio versus time data by using a suitable mathematical model or models. Several models were proposed for this purpose and almost all studies were related to the application of these models to the data, a comparison and selecting the best-fitted model. A careful inspection of the existing drying data in literature revealed that there are only a limited number of curves and, therefore, the use of some models, especially the complex ones and the ones that require a transformation of the data, should be avoided. These were listed based on evidence with the use of both synthetic and published drying data. Moreover, the use of some models were encouraged, again based on evidence. Eventually, some suggestions were given to the researchers who plan to use mathematical models for their drying studies. These will help to reduce the time of the analyses and will also avoid the arbitrary usage of the models. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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23 pages, 1960 KiB  
Review
Effect of Freeze-Drying on Quality and Grinding Process of Food Produce: A Review
by Timilehin Martins Oyinloye and Won Byong Yoon
Processes 2020, 8(3), 354; https://doi.org/10.3390/pr8030354 - 20 Mar 2020
Cited by 86 | Viewed by 16559
Abstract
Freeze-drying is an important processing unit operation in food powder production. It offers dehydrated products with extended shelf life and high quality. Unfortunately, food quality attributes and grinding characteristics are affected significantly during the drying process due to the glass transition temperature (during [...] Read more.
Freeze-drying is an important processing unit operation in food powder production. It offers dehydrated products with extended shelf life and high quality. Unfortunately, food quality attributes and grinding characteristics are affected significantly during the drying process due to the glass transition temperature (during drying operation) and stress generated (during grinding operation) in the food structure. However, it has been successfully applied to several biological materials ranging from animal products to plants products owning to its specific advantages. Recently, the market demands for freeze-dried and ground food products such as spices, vegetables, and fruits are on the increase. In this study, the effect of the freeze-drying process on quality attributes, such as structural changes, the influence of glass transition during grinding, together with the effect on grinding efficiency in terms of energy requirement, grinding yield, and morphological changes in the powder as a result of temperature, drying time were discussed. An overview of models for drying kinetics for freeze-dried food sample, and grinding characteristics developed to optimize the drying processes, and a prediction of the grinding characteristics are also provided. Some limitations of the drying process during grinding are also discussed together with innovative methods to improve the drying and grinding processes. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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15 pages, 312 KiB  
Review
Drying Applications during Value-Added Sustainable Processing for Selected Mass-Produced Food Coproducts
by Huaiwen Yang, Tulakorn Sombatngamwilai, Wen-Yao Yu and Meng-I Kuo
Processes 2020, 8(3), 307; https://doi.org/10.3390/pr8030307 - 06 Mar 2020
Cited by 11 | Viewed by 4522
Abstract
Developing circular value chains for continuing the use of and reducing the waste of the resources of industrial processing would eliminate impairments to the environment. The generation of nutrient-dense byproducts and coproducts with high-moisture contents are considered to be an issue for global [...] Read more.
Developing circular value chains for continuing the use of and reducing the waste of the resources of industrial processing would eliminate impairments to the environment. The generation of nutrient-dense byproducts and coproducts with high-moisture contents are considered to be an issue for global food industries. These byproducts and coproducts spontaneously undergo chemical, biochemical, or microbial deteriorations due to high storage-temperatures, and consequently are turned into direct animal feed sources or even just treated as waste with eutrophication activity. This review provides an overview of selected mass-produced botanical food byproducts and coproducts (BFBC) including soybean okara, wheat germ, banana, and spent coffee grounds, with respect to value-added sustainable processing via proper drying technologies being employed. This review includes the current production of the above-mentioned agricultural products, the nutritional aspects of them, and the sustainable utilization of their coproducts. Additionally, the possible drying kinetics for value-added prospects are discussed. Full article
(This article belongs to the Special Issue Drying Kinetics and Quality Control in Food Processing)
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