Texture of Vacuum Microwave Dehydrated Apple Chips as Affected by Calcium Pretreatment, Vacuum Level, and Apple Variety

Sham, Patricia Wai Ying; Scaman, Christine H.; Durance, T.D.

doi:10.1111/j.1365-2621.2001.tb15212.x

Cited by 119 publications

(85 citation statements)

References 18 publications

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“…Regarding the crispness, the F3 and F4 samples were spongy and were not crispy. These textural properties were similar to those reported for freeze-dried apple chips, which have a very porous structure (38). As shown in Fig.…”

Section: Texture Analysis Of the Freeze-dried Foamssupporting

confidence: 75%

Physical characterization of freeze-dried foam prepared from aloe vera gel and guar gum

Santacruz-Vázquez

Cortés

2015

Vitae

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Background: Foams are colloidal dispersions of a gas suspended in a dispersing phase, which consisting of a semi-freeze-dried or viscous liquid phase. The physical properties of food foams are the result of the bubble characteristics and their spatial arrangement. Objectives: The aim of this work was to obtain foams of A. vera gel and guar gum and describe the changes in their physical properties and microstructure during freeze-drying using the fractal dimension concept and image analysis techniques. Methods: The porosity, density, and volume expansion factor of the fresh foams that were based on the A. vera foams were determined. The kinetics of foam texture, color, porosity and microstructure of the freeze-dried foams were obtained. The fractal texture dimension of surface (FD SDBC ) and microstructure (FD ESEM ) of the foams were determined as indicators of structural changes after freeze-drying. The guar gum concentrations used to obtain the A. vera prefoam were expressed in w/w as F1 (control sample without gum), F2 (2%), F3 (4%) and F4 (6%). Results: We obtained stable freeze-dried foams of Aloe vera gel and guar gum. The porosity, density and volume expansion factor of the fresh and freeze-dried foams were affected by the addition of the guar gum. Changes in the topology of the freeze-dried foam surface during the drying process resulted in a high rugosity compared with the original smooth surface. The microstructure of the dried foam samples suggested a relationship between the gum concentration of the prefoam A. vera gel mixture and the physical properties before and after freeze-drying, such as an increase in the microstructural alterations and surface roughness during freeze-drying. The roughness of the freeze-dried foam surface, described by the FD SDBC represented the macroscopic physical changes of the samples and correlated with the changes in the foam microstructure, which were described by the fractal dimension of the Environmental Scanning Electron Microscopy ESEM microphotographs (FD ESEM ). Conclusions: The digital analysis of the structure and porosity of the freeze-dried foam can be used to quantify the effect of gum concentrations on the morphological features and physical properties of foams during freeze-drying.

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Section: Texture Analysis Of the Freeze-dried Foamssupporting

confidence: 75%

Physical characterization of freeze-dried foam prepared from aloe vera gel and guar gum

Santacruz-Vázquez

Cortés

2015

Vitae

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“…As a consequence, the rate of drying is considerably higher than in traditional methods of dehydration [12]. The puffing phenomenon that accompanies the rapid process of dehydration creates a porous texture of the food and facilitates obtaining a crispy and delicate texture [13], and in this way it reduces the product's density as well as its shrinkage.…”

Section: Introductionmentioning

confidence: 98%

The Effect of Selected Fruit Juice Concentrates Used as Osmotic Agents on the Drying Kinetics and Chemical Properties of Vacuum-Microwave Drying of Pumpkin

Lech

Figiel

Michalska

et al. 2018

Journal of Food Quality

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The study examined the osmotic dehydration of pumpkin slices in chokeberry, flowering quince, and raspberry concentrated juices. Products obtained were subjected to vacuum-microwave finish drying (VMD). The objective of the study was to evaluate the drying kinetics and the chemical properties, that is, total polyphenolics content and antioxidant capacity of the vacuum-microwave-dried pumpkin products. The concentration and temperature of the juices were 40 ∘ Brix and 45 ∘ C, respectively. The pumpkin slices were pretreated in concentrated juices for 0.5, 1, 2, 3, and 6 hours. Vacuum-microwave finish drying was carried out at the power of magnetrons that ensured the maintenance of the safe temperature (below 90 ∘ C) of the slices measured with the use of infrared camera. The results of the study showed that the moisture content of samples during the pretreatment in concentrated juices was decreasing until the equilibrium stage. The logarithmic model was used to describe the drying kinetics of pumpkin during VMD. Osmotic pretreatment resulted in a decrease in colour coordinates, improved the antioxidant activity of dried product, and prolonged the duration of VMD.

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“…This process, well-known as the microwave puffing phenomenon, creates a porous texture of the food. Further, it reduces the density of the material (Sham et al 2001). Hence, the dried samples become hard and crispy.…”

Section: Convective Vacuum-microwave Dryingmentioning

confidence: 99%

Combined Drying of Apple Cubes by Using of Heat Pump, Vacuum-Microwave, and Intermittent Techniques

Chong

Figiel

Law

2013

Food Bioprocess Technol

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Apple cubes of 15 mm were dried naturally without adding any chemical preservative using various drying methods namely intermittent hot air-dehumidified air drying with cyclic temperature profile and step-up temperature profile, heat-pump-assisted (HP) drying, convective vacuum-microwave (C/VM) drying, and heat pump vacuum-microwave (HP/VM) drying. The drying kinetics of apple samples dehydrated by different methods was divided into characteristic drying periods and fitted with empirical models, which gave high value of determination coefficient. The application of C/VM in drying of fruits gave the shortest drying time compared to other drying methods (about 50 % of the total drying time). The drying time was affected by effective diffusivity ranging from 3.522×10 −8 to 1.431×10 −6 m 2 /min depending on the drying technique used. It was found that combined drying which apply vacuum microwave (C/VM, HP/VM) gave the lowest values in hardness and chewiness. In addition, HP/VM drying gave the highest retained total polyphenol content, antioxidant activity, and the best appearance quality.

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Texture of Vacuum Microwave Dehydrated Apple Chips as Affected by Calcium Pretreatment, Vacuum Level, and Apple Variety

Cited by 119 publications

References 18 publications

Physical characterization of freeze-dried foam prepared from aloe vera gel and guar gum

Physical characterization of freeze-dried foam prepared from aloe vera gel and guar gum

The Effect of Selected Fruit Juice Concentrates Used as Osmotic Agents on the Drying Kinetics and Chemical Properties of Vacuum-Microwave Drying of Pumpkin

Combined Drying of Apple Cubes by Using of Heat Pump, Vacuum-Microwave, and Intermittent Techniques

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