Measuring Transpiration Rates of Tomato and Other Detached Fruit

A method was developed to measure transpiration rates and apparent water-vapor permeability coefficients (P'H2O) of detached fruit using an analytical balance equipped with a humidity chamber, wide-range humidity-generating and sensing devices, and a datalogger. The system was designed to monitor weight changes with time and, hence, weight loss of individual fruit during exposure to specific relative humidities (RHs) and temperatures. Weight loss was corrected for loss due to respiratory exchange of 02 and CO2 before calculating P'H2O. Values of P'H2O for tomatoes obtained using this method over periods of 5 minutes to 24 hours ranged from 3 to 12 nmol·cm-2·s-1·kPa-1 at 20C, depending on the experimental conditions. These values are similar to previously published values and to those obtained in a conventional weight-loss experiment, which involved intermittent weighing. P'H20 for tomatoes dropped ≈15% in 24 hours. P'H20 increased with a transient increase in RH; the extent of the increase was variable from fruit to fruit, ranging from 5% to 100% over 30% to 90% RH. The change was reversible in that P'H2O increased and decreased within minutes following shifts in RH. Similar changes were found for strawberry P'H20. The increase in P'H2O may be due, in part, to a direct effect of water vapor on the water transport properties of the cuticular polymer and surface temperature depression as a result of evaporative cooling. At 50% RH and 20C, water vapor diffuses from tomatoes 50 times faster than O2 enters on a molar basis. This information will be useful for modeling RH changes in modified-atmosphere packages.

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Preparation, properties and applications of wheat gluten edible films

Agricultural and Food Science ◽

10.23986/afsci.5650 ◽

2000 ◽

Vol 9 (1) ◽

pp. 23-35 ◽

Cited By ~ 24

Author(s):

P. TANADA-PALMU ◽

H. HELÉN ◽

L. HYVÖNEN

Keyword(s):

Weight Loss ◽

Tensile Strength ◽

Water Vapor ◽

Wheat Gluten ◽

Single Layer ◽

Water Vapor Permeability ◽

Edible Films ◽

Bilayer Film ◽

Vapor Permeability ◽

Elongation At Break

Edible films from wheat gluten were prepared with various amounts of glycerol as a plasticizer. Water vapor permeability, oxygen permeability, tensile strength and percentage elongation at break at different water activities ( aw ) were measured. Films with low amounts of glycerol had lower water vapor and oxygen permeabilities, higher tensile strength and lower elongation at break. Wheat gluten coatings reduced weight loss during two weeks of storage for cherry tomatoes and sharon fruits compared to uncoated controls. A bilayer film of wheat gluten and beeswax significantly lowered weight loss from coated cheese cubes compared to single layer coating of wheat gluten.;

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Water Vapor Permeability and Sorption of Hevea Latex Films

Rubber Chemistry and Technology ◽

10.5254/1.3543435 ◽

1952 ◽

Vol 25 (4) ◽

pp. 1006-1016

Author(s):

William W. Bowler

Keyword(s):

Water Vapor ◽

Adsorption Layer ◽

Structural Difference ◽

Water Vapor Permeability ◽

Negative Temperature ◽

Vapor Permeability ◽

Careful Study ◽

Latex Films ◽

Wide Range ◽

Very High

Abstract A considerable structural difference exists between Hevea latex films vulcanized after drying and those vulcanized in the latex state. Since these two types of films differ considerably in water vapor permeability and sorption, a careful study has been made of these phenomena. The weight of water permeating an uncompounded film was inversely proportional to the thickness of the film over a wide range of thicknesses, and directly proportional to Δp, the vapor pressure difference across the film, except at very high values of Δp. However, films cast from vulcanized latex were much more permeable to water vapor, sorbed considerably less water, and had a greater negative temperature dependence of permeability than uncompounded or dry vulcanized films. These experiments indicate that diffusion takes place in prevulcanized films by an activated diffusion through capillary holes and in dry vulcanized films by an activated diffusion through the polymer itself or the adsorption layer.

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Ultraviolet blocking and antioxidant polyvinyl alcohol films incorporated with baicalin extraction from Scutellaria baicalensis Georgi

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0071 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Jinshu Liu ◽

Xiaoyan Ma ◽

Wenzhao Shi ◽

Jianwei Xing ◽

Chaoqun Ma ◽

...

Keyword(s):

Water Vapor ◽

Polyvinyl Alcohol ◽

Radical Scavenging Activity ◽

Antioxidant Properties ◽

Radical Scavenging ◽

Water Vapor Permeability ◽

Scutellaria Baicalensis ◽

Vapor Permeability ◽

Protective Film ◽

Uv Blocking

Abstract Baicalin, an active flavonoid ingredient of Scutellaria baicalensis Georgi, was extracted by heat reflux extraction and showed the same significance UV absorption property with standard baicalin. Active films were prepared from polyvinyl alcohol (PVA) containing baicalin extract by casting method. The effect of baicalin extracts on the UV-blocking, optical, antioxidant property, water vapor permeability, swelling and mechanical properties of the films were studied. UV–vis transmittance spectra showed that PVA films incorporated with baicalin extract blocked ultraviolet light range from 280–400 nm even with low concentration of baicalin (0.5 wt%) and maintain the high transparency in visible spectrum. The outstanding UV-blocking properties of PVA films incorporated with baicalin extract were also confirmed by Rhodamine B degradation. Baicalin conferred antioxidant properties to PVA films as determined by DPPH radical scavenging activity. Due to the interaction between hydroxy groups of baicalin and PVA molecule, water vapor permeability, swelling and elongation at break of the films were decreased accompanied with the increasing in tensile strength and Young’s modulus. FTIR reveal that the interaction between PVA molecules was significant changed by the introduction of baicalin. These results suggest that PVA film incorporated with baicalin extract can be used for the development of functional protective film.

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The Effect of Extraction Conditions on the Barrier and Mechanical Properties of Kefiran Films

Coatings ◽

10.3390/coatings11050602 ◽

2021 ◽

Vol 11 (5) ◽

pp. 602

Author(s):

Carmen Rodica Pop ◽

Teodora Emilia Coldea ◽

Liana Claudia Salanţă ◽

Alina Lăcrămioara Nistor ◽

Andrei Borşa ◽

...

Keyword(s):

Water Vapor ◽

Conformational Changes ◽

Water Vapor Permeability ◽

Edible Films ◽

Film Structure ◽

Water Soluble ◽

Vapor Permeability ◽

Water Molecules ◽

Compact Structure ◽

Technology Applications

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.

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Development of PE/PCL Bilayer Films Modified with Casein and Aluminum Oxide

Molecules ◽

10.3390/molecules26113090 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3090

Author(s):

Anita Ptiček Siročić ◽

Ana Rešček ◽

Zvonimir Katančić ◽

Zlata Hrnjak-Murgić

Keyword(s):

Mechanical Properties ◽

Thermal Properties ◽

Water Vapor ◽

Aluminum Oxide ◽

Water Vapor Permeability ◽

Vapor Permeability ◽

Mechanical And Thermal Properties ◽

Oxide Compound ◽

Bilayer Films ◽

Oxide Particles

The studied samples were prepared from polyethylene (PE) polymer which was coated with modified polycaprolactone (PCL) film in order to obtain bilayer films. Thin PCL film was modified with casein/aluminum oxide compound to enhance vapor permeability as well as mechanical and thermal properties of PE/PCL films. Casein/aluminum oxide modifiers were used in order to achieve some functional properties of polymer film that can be used in various applications, e.g., reduction of water vapor permeability (WVTR) and good mechanical and thermal properties. Significant improvement was observed in mechanical properties, especially in tensile strength as well as in water vapor values. Samples prepared with aluminum oxide particles indicated significantly lower values up to 60%, and samples that were prepared with casein and 5% Al2O3 showed the lowest WVTR value.

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Chitosan Films Obtained from Brachystola magna (Girard) and Its Evaluation on Quality Attributes in Sausages during Storage

Molecules ◽

10.3390/molecules26061782 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1782

Author(s):

Juan Manuel Tirado-Gallegos ◽

Paul Baruk Zamudio-Flores ◽

Miguel Espino-Díaz ◽

René Salgado-Delgado ◽

Gilber Vela-Gutiérrez ◽

...

Keyword(s):

Weight Loss ◽

Lipid Oxidation ◽

Meat Products ◽

Water Vapor Permeability ◽

Good Alternative ◽

Quality Attributes ◽

Vapor Permeability ◽

Biodegradable Films ◽

Molecular Weights ◽

Chitosan Films

High molecular weight chitosan (≈322 kDa) was obtained from chitin isolated from Brachystola magna (Girard) to produced biodegradable films. Their physicochemical, mechanical and water vapor permeability (WVP) properties were compared against commercial chitosan films with different molecular weights. Brachystola magna chitosan films (CFBM) exhibited similar physicochemical and mechanical characteristics to those of commercial chitosans. The CFBM films presented lower WVP values (10.01 × 10−11 g/m s Pa) than commercial chitosans films (from 16.06 × 10−11 to 64.30 × 10−11 g/m s Pa). Frankfurt-type sausages were covered with chitosan films and stored in refrigerated conditions (4 °C). Their quality attributes (color, weight loss, pH, moisture, texture and lipid oxidation) were evaluated at 0, 5, 10, 15 and 20 days. Sausages covered with CFMB films presented the lowest weight loss (from 1.24 to 2.38%). A higher increase in hardness (from 22.32 to 30.63 N) was observed in sausages covered with CFMB films. Compared with other films and the control (uncovered sausages), CFMB films delay pH reduction. Moreover, this film presents the lower lipid oxidation level (0.10 malonaldehyde mg/sample kg). Thus, chitosan of B. magna could be a good alternative as packaging material for meat products with high-fat content.

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Reduction of Water Vapor Permeability in Food Multilayer Biopackaging by Epitaxial Crystallization of Beeswax

Food and Bioprocess Technology ◽

10.1007/s11947-021-02628-9 ◽

2021 ◽

Author(s):

Florencia Cruces ◽

María Guadalupe García ◽

Nelio Ariel Ochoa

Keyword(s):

Water Vapor ◽

Water Vapor Permeability ◽

Vapor Permeability ◽

Epitaxial Crystallization

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Upcycling of Vine Shoots: Production of Fillers for PHBV-Based Biocomposite Applications

Journal of Polymers and the Environment ◽

10.1007/s10924-020-01884-8 ◽

2020 ◽

Cited By ~ 1

Author(s):

Grégoire David ◽

Laurent Heux ◽

Stéphanie Pradeau ◽

Nathalie Gontard ◽

Hélène Angellier-Coussy

Keyword(s):

Water Vapor ◽

Gas Phase ◽

Mechanical Performance ◽

Low Cost ◽

Water Vapor Permeability ◽

Contact Angles ◽

Vapor Permeability ◽

Water Contact ◽

Median Diameter ◽

Cost Of Materials

Abstract This paper aims at investigating the potential of vine shoots (ViSh) upcycling as fillers in novel poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV) based biocomposites. ViSh particles of around 50 µm (apparent median diameter) were obtained combining dry grinding processes, and mixed with PHBV using melt extrusion. Thermal stability and elongation at break of biocomposites were reduced with increasing contents of ViSh particles (10, 20 and 30 wt%), while Young’s modulus and water vapor permeability were increased. It was shown that a surface gas-phase esterification allowed to significantly increase the hydrophobicity of ViSh particles (increase of water contact angles from 59° to 114°), leading to a reduction of 27% in the water vapor permeability of the biocomposite filled with 30 wt% of ViSh. The overall mechanical performance was not impacted by gas-phase esterification, demonstrating that the interfacial adhesion between the virgin ViSh particles and the PHBV matrix was already good and that such filler surface treatment was not required in that case. It was concluded that ViSh particles can be interestingly used as low cost fillers in PHBV-based biocomposites to decrease the overall cost of materials.

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