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The effectivity of vacuum impregnation with glycerol and secondary metabolites on electroporated arugula leaves to improve freezing stability.

de Kuijer, Oscar LU (2021) KLTM01 20201
Food Technology and Nutrition (M.Sc.)
Abstract
Freeze damage is a common issue in many food items. The cellular dehydration caused by freezing can be prevented through addition of a cryoprotectant. Research has shown that it is possible to improve the freezing tolerance of plant materials by addition of cryoprotectants, which forms hydrogen bonds with water molecules. However, the cryoprotect needs to be in the cell to function. Which is where vacuum impregnation can be applied. Vacuum impregnation is a method of transfecting substances through pressure fluctuations. As the pressure drops, gas will be forced out of the intracellular space and solutes can be transfected into the intracellular space until an equilibrium is formed. However, the cryoprotectant needs to be within the cell... (More)
Freeze damage is a common issue in many food items. The cellular dehydration caused by freezing can be prevented through addition of a cryoprotectant. Research has shown that it is possible to improve the freezing tolerance of plant materials by addition of cryoprotectants, which forms hydrogen bonds with water molecules. However, the cryoprotect needs to be in the cell to function. Which is where vacuum impregnation can be applied. Vacuum impregnation is a method of transfecting substances through pressure fluctuations. As the pressure drops, gas will be forced out of the intracellular space and solutes can be transfected into the intracellular space until an equilibrium is formed. However, the cryoprotectant needs to be within the cell membrane, where the vacuole is. Small pores can be formed on the cell membrane by using pulsed electric field technology (PEF). Hydrophilic pores are formed in the lipid bilayer of a cell membrane when exposed to electric pulses. As a result, hydrophobic pores are formed in the cell membrane by spontaneous thermal fluctuations of membrane lipids. If the voltage is too high or the number of pulses is too high, the cell dies. In some cases, with the right parameters, reversible electroporation can be achieved. This means that the cell is able to recover to its original state, with a closed cell membrane.
In this study, the effect of vacuum impregnation of arugula with glycerol solutions with secondary metabolites, in combination with PEF on the recovery rate, PEF survival rate, and freezing survival rate of arugula cells was studied.
The electroporation causes solutes to leech out of the cell, which can be measured by measuring the resistance. 100 Hz was used to measure the resistance of the arugula. At higher frequencies, the electrical current goes through the cell, whereas with lower frequencies, the electrical current goes around the cell, where the leeched out solutes will reduce the resistance. This reduction in resistance can be picked up by measuring the resistance over time, and as the cell recovers, the solutes are taken up by the cell and the resistance increases again.
Microscopy showed that bipolar electroporation with a pulse width of 1000µs, a pulse space of 20µs at 1000 V/cm with 1000 loops gave homogenous electroporation in arugula cells. Using these pulsed electric field and vacuum impregnation with different substances it has been shown that after only electroporation 40% of the leaves survived and recovery of the cells took 8 hours, no leaves survived the freezing experiment. Vacuum impregnation of different substances reduced the recovery time up to 3 hours and increased the freezing resistance from 0% to 10%. (Less)
Popular Abstract
Increasing cell metabolism by vacuum impregnation of secondary metabolites in electroporated arugula.
This study will delve into the effects of vacuum impregnation of substances in combination with pulsed electric field on the cell behavior in arugula cells. This data will be used in order to develop freeze resistant arugula.
Arugula, commonly known as rucola or rocket, is a popular mustard green and is a staple food in Mediterranean areas. Which like many, does not like to be frozen. Freezing is one of the most well-known processes for food preservation. Unfortunately, it also has its drawbacks. When you freeze food products, freeze damage occurs. This often degrades product quality through dehydration of the cells. This is why it would... (More)
Increasing cell metabolism by vacuum impregnation of secondary metabolites in electroporated arugula.
This study will delve into the effects of vacuum impregnation of substances in combination with pulsed electric field on the cell behavior in arugula cells. This data will be used in order to develop freeze resistant arugula.
Arugula, commonly known as rucola or rocket, is a popular mustard green and is a staple food in Mediterranean areas. Which like many, does not like to be frozen. Freezing is one of the most well-known processes for food preservation. Unfortunately, it also has its drawbacks. When you freeze food products, freeze damage occurs. This often degrades product quality through dehydration of the cells. This is why it would be beneficial to invent a treatment after which arugula can be frozen. One theory for this is by using pulsed electric field and vacuum impregnation technology. Pulsed electric field is where small short pulses of electricity are fired through the arugula leaves which damages the plant tissue. This damage creates pores in the cell, which can be used to transport substances into the cell. The cell is then able to rebuild the cell over a period of time. Which can also be improved by adding secondary metabolites, which are substances that are naturally found in the plant cells, but in lower quantities. But how do we transport the substances? With vacuum impregnation. Vacuum impregnation is a method that uses pressure levels to introduce substances into products. The arugula is placed into a substance that helps improve the freezing resistance. When the pressure drops, gas in the cell expands. And when the pressure rises again, the gas will shrink and due to pressure differences inside the product, it will draw in the substance.
In this study, the combination of vacuum impregnation and pulsed electric field technology on the recovery after pulsed electric field technology was studied.
This was done by first vacuum impregnating the leaves with secondary metabolites and glycerol (glycerol improves the freezing resistance) and then treating the arugula with pulsed electric field technology. After this, the recovery of the arugula was studied. This was done by measuring the electrical resistance. The electrical resistance was measured because the damage of the pulsed electric field, causes substances to leech out of the cells, which reduces the electrical resistance. But as the cell recovers, the electrical resistance will increase again because the cell is taking up the substances again.
Results showed that vacuum impregnation with the secondary metabolites reduced the time the plant needed to recover after electroporation. It also showed to increase the survival rate after pulsed electric field treatment. (Less)
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author
de Kuijer, Oscar LU
supervisor
organization
course
KLTM01 20201
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Pulsed electric field PEF, Arugula, Electroporation, Secondary metabolites, Glycerol, Food engineering, Livsmedelsteknik
language
English
id
9030901
date added to LUP
2020-11-09 09:29:36
date last changed
2020-11-09 09:29:36
@misc{9030901,
  abstract     = {Freeze damage is a common issue in many food items. The cellular dehydration caused by freezing can be prevented through addition of a cryoprotectant. Research has shown that it is possible to improve the freezing tolerance of plant materials by addition of cryoprotectants, which forms hydrogen bonds with water molecules. However, the cryoprotect needs to be in the cell to function. Which is where vacuum impregnation can be applied. Vacuum impregnation is a method of transfecting substances through pressure fluctuations. As the pressure drops, gas will be forced out of the intracellular space and solutes can be transfected into the intracellular space until an equilibrium is formed. However, the cryoprotectant needs to be within the cell membrane, where the vacuole is. Small pores can be formed on the cell membrane by using pulsed electric field technology (PEF). Hydrophilic pores are formed in the lipid bilayer of a cell membrane when exposed to electric pulses. As a result, hydrophobic pores are formed in the cell membrane by spontaneous thermal fluctuations of membrane lipids. If the voltage is too high or the number of pulses is too high, the cell dies. In some cases, with the right parameters, reversible electroporation can be achieved. This means that the cell is able to recover to its original state, with a closed cell membrane. 
In this study, the effect of vacuum impregnation of arugula with glycerol solutions with secondary metabolites, in combination with PEF on the recovery rate, PEF survival rate, and freezing survival rate of arugula cells was studied. 
The electroporation causes solutes to leech out of the cell, which can be measured by measuring the resistance. 100 Hz was used to measure the resistance of the arugula. At higher frequencies, the electrical current goes through the cell, whereas with lower frequencies, the electrical current goes around the cell, where the leeched out solutes will reduce the resistance. This reduction in resistance can be picked up by measuring the resistance over time, and as the cell recovers, the solutes are taken up by the cell and the resistance increases again.
Microscopy showed that bipolar electroporation with a pulse width of 1000µs, a pulse space of 20µs at 1000 V/cm with 1000 loops gave homogenous electroporation in arugula cells. Using these pulsed electric field and vacuum impregnation with different substances it has been shown that after only electroporation 40% of the leaves survived and recovery of the cells took 8 hours, no leaves survived the freezing experiment. Vacuum impregnation of different substances reduced the recovery time up to 3 hours and increased the freezing resistance from 0% to 10%.},
  author       = {de Kuijer, Oscar},
  keyword      = {Pulsed electric field PEF,Arugula,Electroporation,Secondary metabolites,Glycerol,Food engineering,Livsmedelsteknik},
  language     = {eng},
  note         = {Student Paper},
  title        = {The effectivity of vacuum impregnation with glycerol and secondary metabolites on electroporated arugula leaves to improve freezing stability.},
  year         = {2021},
}