Effects of Water Activity and Water Content on Mobility of Food Components, and their Effects on Phase Transitions in Food Systems

1985 ◽  
pp. 153-169 ◽  
Author(s):  
M. Karel
Keyword(s):  
Phase Transitions ◽  
Water Content ◽  
Water Activity ◽  
Food Systems ◽  
Food Components

scholarly journals Penurunan mutu dan pendugaan umur simpan sup krim instan labu kuning diperkaya tempe untuk lansia dengan metode accelerated shelf life testing (ASLT)

2020 ◽  
Vol 8 (2) ◽  
pp. 134-142
Author(s):  
Salma Shafrina Aulia ◽  
Budi Setiawan ◽  
Tiurma Sinaga ◽  
Ahmad Sulaeman
Keyword(s):  
Lipid Oxidation ◽  
Shelf Life ◽  
Water Content ◽  
Water Activity ◽  
Critical Parameter ◽  
Storage Period ◽  
Life Testing ◽  
Quality Of Water ◽  
Long Time

Background: Instant pumpkin cream soup enriched with tempeh had fulfilled 10% Recommended Dietary Allowances (RDA) for elderly so that it can be used as an easy-to-serve snack, but decreasing quality of instant cream soup will be happened if the instant cream soup was stored for a long time. Objectives: This study aimed to analyze quality of water content, water activity and lipid oxidation in instant pumpkin cream soup during storage and estimated the shelf life of pumpkin cream soup enriched with tempeh.Method:  Quality storage was analyzed using of water content, water activity (aw) and lipid oxidation. Estimation of shelf life was analyzed using Arrhenius Accelerated Shelf Life Testing (ASLT) model.Results: The results showed that the water content, aw levels and lipid oxidation of instant pumpkin cream soup increased during the storage period. The critical parameter used in this study was lipid oxidation. Instant cream soup without the addition of tempeh can last 447 days  while the cream soup with the addition of tempeh has a shelf life of 433 days.Conclusion: Quality of instant pumpkin cream soup decreased during the storage period and it would be expired over a year.

scholarly journals A robotic irrigation system for urban gardening and agriculture

2019 ◽  
Vol 50 (4) ◽  
pp. 198-207
Author(s):  
Ioannis Gravalos ◽  
Avgoustinos Avgousti ◽  
Theodoros Gialamas ◽  
Nikolaos Alfieris ◽  
Georgios Paschalidis
Keyword(s):  
Water Content ◽  
Food Systems ◽  
Management Practices ◽  
Irrigation System ◽  
Robotic System ◽  
Urban Gardening ◽  
Irrigation Treatments ◽  
Comparison Of The Results ◽  
Irrigation Technologies ◽  
Sustainable Irrigation

Water supply limits and continued population growth have intensified the search for measures to conserve water in urban gardening and agriculture. The efficiency of water use is depended on performance of the irrigation technologies and management practices. In this study, a robotic irrigation system was developed that consists of a moving bridge manipulator and a sensor-based platform. The manipulator constructed is partly using open-source components and software, and is easily reconfigurable and extendable. In combination to the sensor-based platform this custommade manipulator has the potential to monitor the soil water content (SWC) in real time. The irrigation robotic system was tested in an experimental soil tank. The total surface of the soil tank was divided by a raster into 18 equal quadrants. The water management for maintaining water content in the soil tank within tolerable lower limit (refill point) was based on three irrigation treatments: i) quadrants whose SWC is below the refill point are irrigated; ii) quadrants are irrigated only when the daily mean SWC of the tank is below the refill point and only for those whose actual SWC is lower than that limit; and iii) quadrants are irrigated every two days with constant amount of water. A comparison of the results of the three irrigation treatments showed that the second treatment gave less irrigation events and less applied water. Finally, we could conclude that the performance of the fabricated robotic system is appropriate and it could play an important role in achieving sustainable irrigation into urban food systems.

Transient Water Transport in Nafion Membranes Under Activity Gradients

2010 ◽  
Author(s):  
T. Romero ◽  
W. Me´rida
Keyword(s):  
Water Content ◽  
Water Transport ◽  
Water Activity ◽  
Thickness Variation ◽  
Membrane Thickness ◽  
Membrane Interface ◽  
Rational Representation ◽  
Transport Measurements ◽  
Nafion Membranes ◽  
The Time Domain

Transient water transport experiments on Nafion of different thicknesses were carried out in the temperature range of 30 to 70 °C. These experiments report on water transport measurements under activity gradients in the time domain for liquid and vapour equilibrated Nafion membranes. Using a permeability test rig with a gated valve, the water crossover was measured as a function of time. The typical response is shown as a time dependent flux, and it shows the dynamic transport from an initially dry condition up to the final steady state. Contrarily to previous reports from dynamic water transport measurements, where the activity gradient across the membrane is absent; in this work, the membrane was subjected to an activity gradient acting as the driving force to transport water from an environment with higher water activity to an environment with lower water activity through the membrane’s structure. Measurements explored temperature and membrane thickness variation effect on the transient response. Results showed dependency on temperature and a slower water transport rate across the vapour-membrane interface than for the liquid-membrane interface. These measurements showed the transport dependency on water content at the beginning of the experiment when the membrane was in a close-to-dry condition suggesting a transport phenomenon transition due to a reached critical water content value. The new protocol for transient measurements proposed here will allow the characterization of water transport dependency on membrane water content with a more rational representation of the membrane-environment interface.

scholarly journals How NaCl and water content determine water activity during ripening of Gouda cheese, and the predicted effect on inhibition of Listeria monocytogenes

2016 ◽  
Vol 99 (7) ◽  
pp. 5192-5201 ◽  
Author(s):  
E. Wemmenhove ◽  
M.H.J. Wells-Bennik ◽  
A. Stara ◽  
A.C.M. van Hooijdonk ◽  
M.H. Zwietering
Keyword(s):  
Listeria Monocytogenes ◽  
Water Content ◽  
Water Activity ◽  
Gouda Cheese

scholarly journals Effects of Imprinting and Water Activity on Transesterification and Thermostability with Lipases in Ionic Liquid

2021 ◽  
Vol 35 (1) ◽  
pp. 57-63
Author(s):  
M. Matsumoto ◽  
K. Nakao ◽  
Y. Tahara
Keyword(s):  
Ionic Liquid ◽  
Water Content ◽  
Benzyl Alcohol ◽  
Vinyl Acetate ◽  
Water Activity ◽  
Maximum Rate ◽  
The Other ◽  
Organic Media ◽  
Catalytic Activities ◽  
Michaelis Constants

The effect of bio-imprinting and water activity on catalytic activities and the thermostability of lipases was investigated for transesterification using vinyl acetate and benzyl alcohol as substrates in ionic liquid, [Cnmim][PF6] (n=4,6,8), and benzene. The catalytic activities were enhanced by imprinting in benzene and [C4mim][PF6], and the relations between the transesterification activities and the water activity in both solvents were approximately bell shaped. The reactivity of the transesterification in benzene was higher than that in [C4<br /> mim][PF6]. The effects of water activity and imprinting on the kinetic parameters in [C4mim][PF6] were examined. Without controlling the water content, the values of Km,VA and Km,BA (Michaelis constants of vinyl acetate and benzyl alcohol, respectively) decreased, and the values of Vm (maximum rate) increased by imprinting. On the other hand, by controlling the water content in the organic media, the values of Vm, Km,VA, and Km,BA increased by imprinting. The activities of lipase in ionic liquid are more strongly affected by water activity and imprinting than those in benzene. We observed effects of water activity on thermostability but none from imprinting.

Fermentation Problem in Spanish North-Coast Honey

1995 ◽  
Vol 58 (5) ◽  
pp. 515-518 ◽  
Author(s):  
SUSANA SANZ ◽  
GLORIA GRADILLAS ◽  
FUENCISLA JIMENO ◽  
CONSUELO PEREZ ◽  
TERESA JUAN
Keyword(s):  
Water Content ◽  
Water Activity ◽  
Microbiological Quality ◽  
Free Water ◽  
High Water ◽  
North Coast ◽  
High Water Content ◽  
Free Water Content ◽  
Cantabrian Coast ◽  
Mold And Yeast

Twenty-one samples from the Cantabrian coast were analyzed to establish their microbiological quality and fermentation tendency. In a food with a very low free-water content like honey, microbiological growth is only possible when there is an increase in water activity. Since most of the samples studied were not extensively granulated, the risk of fermentation is mostly due to high water content. Among our samples, only two had a water content below 17.1% (no risk of fermentation), whereas the high water activity of the rest of the samples indicates the possibility of microbial growth. In fact, four of the samples analyzed showed a moisture content over the Spanish maximum legal limit, which means a high risk of fermentation. The absence of Enterobacteriaceae, coliforms, and Escherichia coli in our samples indicates an appropriate cleanliness during extractions and handling of honey. No Salmonella or Shigella were found. The relationship between water activity and mold and yeast counts found for the honeys analyzed allowed us to divide our samples in two groups: honeys with a high or a low risk of fermentation. Changes observed during storage of the samples confirmed this classification.

Water-sensitive phase-transition of a carbon dot–calcium carbonate composite for moisture detection in organic solvents

2019 ◽  
Vol 11 (20) ◽  
pp. 2634-2638 ◽  
Author(s):  
Haijun Yu ◽  
Haoxiang Li ◽  
Chao Chen ◽  
Shengmin Zhou ◽  
Ping Wang
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Calcium Carbonate ◽  
Water Content ◽  
Organic Solvents ◽  
Carbon Dot ◽  
Sensitive Phase ◽  
Moisture Detection

Sensitive and broad range water content detection in organic solvents based on phase transitions of a calcium carbonate nanocomposite is accomplished.

scholarly journals Water activity in liquid food systems: A molecular scale interpretation

2017 ◽  
Vol 237 ◽  
pp. 1133-1138 ◽  
Author(s):  
Andrew J. Maneffa ◽  
Richard Stenner ◽  
Avtar S. Matharu ◽  
James H. Clark ◽  
Nobuyuki Matubayasi ◽  
...  
Keyword(s):  
Water Activity ◽  
Food Systems ◽  
Liquid Food ◽  
Molecular Scale
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