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Heat-Induced Cell Membrane Injury of Vegetable Tissues -An applied study on potatoes

Gonzalez-M, Gerardo LU (2003)
Abstract (Swedish)
Popular Abstract in Swedish

Värmebehandling av vegetabilier medför att man värmer till temperaturer över växtens ursprungliga fysiologiska och naturliga temperaturgränser och därmed förändras den enskilda grönsakens vävnadsstruktur. Detta leder till en serie händelser på cellnivå som i sin tur bestämmer transportegenskaperna hos vävnaden. En av cellens viktigaste komponenter för masstransport är cellmembranet som utgör den fysiska barriären för transport av näringsämnen till och från cellen. Potatis har använts som modell för att studera hur cellmembranets fysiologiska egenskaper påverkas och förändras vid värmebehandling. In vitro studier av plasmamembranets H+-ATPas aktivitet har gett en pseudo-första-ordningens modell... (More)
Popular Abstract in Swedish

Värmebehandling av vegetabilier medför att man värmer till temperaturer över växtens ursprungliga fysiologiska och naturliga temperaturgränser och därmed förändras den enskilda grönsakens vävnadsstruktur. Detta leder till en serie händelser på cellnivå som i sin tur bestämmer transportegenskaperna hos vävnaden. En av cellens viktigaste komponenter för masstransport är cellmembranet som utgör den fysiska barriären för transport av näringsämnen till och från cellen. Potatis har använts som modell för att studera hur cellmembranets fysiologiska egenskaper påverkas och förändras vid värmebehandling. In vitro studier av plasmamembranets H+-ATPas aktivitet har gett en pseudo-första-ordningens modell som karaktäriseras av summan av två oberoende och simultana processer uppkomna vid olika ATPas nivåer. Studier av ATPas aktivitetens temperaturberoende har visat att cellmembranets funktion börjar att upphöra vid 55°C. Den förändrade funktionen karaktäriseras av en snabb sänkning av H+-ATPas aktiviteten och en drastisk sjufaldig minskning av aktiveringsenergi (Ea). Som en följd av den minskade aktiveringsenergin påverkas den H+-drivna processen som behövs för att underhålla cellens aktiva transportmekanismer och därmed cellens förmåga att behålla cytoplasmans lösningar. Eftersom H+-ATPas spelar en viktig roll för transporten genom cellmembranet, visar resultaten att temperaturer över 55°C påverkar både passiv och aktiv transport på cellnivå. Cellmembranets funktion har mätts på olika djup från ytan och in till mitten av potatisbitar som värmebehandlats på olika sätt. Datasimuleringar med finita-element metoden (programvara Femlab) har genomförts för att beräkna temperaturprofiler i de värmebehandlade potatisbitarna. Beräkningar och analysresultat visar hur olika temperaturer bestämmer graden av skador på cellmembranen. Värmebehandlingens skador på cellmembranet följde samma utveckling som de för H+-ATPas aktiviteten. Kinetiken för cellmembranets förändringar följer en pseudo-första-ordningens modell vilket tyder på att cellmembranets tillstånd i vävnaden är kopplad till värmestabiliteten hos växtens plasmamembran med avseende på H+-ATPase aktiviteten. Inaktiveringen av cellmembranet följer inte Arrhenius lag, utan ett sigmoidalt mönster vilket innebär en svag minskning vid låga processtemperaturer följda av en plötslig och snabb minskning efter det att vävnaden nått 50°C. Även PME:s resterande enzymaktivitet i vävnaden mättes på olika djup i den värmebehandlade potatisbiten och temperaturprofilerna beräknades med hjälp av Femlab. Enzymaktiviteten visade ett starkt samband med både temperaturnivån och hastigheten för värmepenetrationen i vävnaden. Förändringar i enzymaktiviteten observerades för vävnadstemperaturer över 52°C. Att värmeaktiveringen av enzymet sker samtidigt, dvs i samma temperaturområde som den drastiska nedgången av cellmembranets funktion kan bero på ett samband mellan de två processerna. Aktiveringen av enzymet PME i vävnaden kan vara en konsekvens av cellmembranets förändringar och efterföljande läckage av cytoplasmalösning till cellväggen. (Less)
Abstract
Heat processing of vegetables involves the use of temperatures above the physiological limit which affect the cellular structures of the tissue and induce a series of events at cell level that will in turn be reflected in the transport properties of the tissue. One of the most important cellular structures from the mass transport point of view is the cell membrane since it represents the physical barrier to the transport of nutrients into and out of the cell. The effect of heat treatment above physiological limits on the cell membrane of vegetable tissues was studied using potatoes as a model tissue. In vitro studies of the thermal deactivation kinetics of the plasma membrane H+-ATPase showed a pseudo-first-order model characterized by the... (More)
Heat processing of vegetables involves the use of temperatures above the physiological limit which affect the cellular structures of the tissue and induce a series of events at cell level that will in turn be reflected in the transport properties of the tissue. One of the most important cellular structures from the mass transport point of view is the cell membrane since it represents the physical barrier to the transport of nutrients into and out of the cell. The effect of heat treatment above physiological limits on the cell membrane of vegetable tissues was studied using potatoes as a model tissue. In vitro studies of the thermal deactivation kinetics of the plasma membrane H+-ATPase showed a pseudo-first-order model characterized by the sum of two independent and simultaneous processes occurring at different rates. Study of the temperature dependence of the activity loss showed that the potato cell membrane undergoes functional breakdown at 55°C, which is characterized by a sharp drop in the H+-ATPase activity and a drastic 7-fold decrease in the energy of activation (Ea). As a result, the proton-motive force needed to provide the energy for the active solute transport is greatly affected and the ability of the cell to retain cytoplasmic solutes decrease. Since the H+-ATPase plays a key role in the transport of solutes across the cell membrane, results indicate that processing temperatures above 55°C affect both mediate and active transport at cellular level. The cell membrane integrity of potato tissue was measured at different depths from the surface to the centre of a sample exposed to different heat treatments. Computer simulations using the finite-element method were performed in order to estimate the temperature distribution within the tissue during heat treatment. Treatment conditions were found to affect the degree of cell membrane integrity in the tissue, especially after heat treatment above 55°C. In similarity to the thermal deactivation of the plasma membrane H+-ATPase, the kinetics of the reduction in cell membrane integrity was found to follow a pseudo-first-order model indicating theta the cell membrane integrity of the tissue is coupled to the thermal stability of the plant plasma membrane H+-ATPase. The temperature dependence of the cell membrane integrity after heat treatment did not follow Arrhenius’ law but a sigmoid pattern, as demonstrated by a slight decrease at low tissue temperatures followed by a sudden sharp decrease after the tissue reached temperatures above 50°C. The absolute residual pectin methylesterase activity of the tissue was also measured at different depths and related the simulated temperature of the tissue. The activity of the enzyme was found to be strongly dependent on the degree of heat penetration and temperature distribution within the tissue. Thermally induced activation of the enzyme was detected at tissue temperatures above 52°C. The simultaneous occurrence of thermal activation of the enzyme and the sharp decrease in cell membrane integrity of the tissue in the same temperature range suggest a coupling of the two processes. The activation of pectin methylesterase enzyme in the tissue may be the consequence of cell membrane disruption and subsequent leakage of cytoplasmic solutes towards the cell wall. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Oliveira., Fernanda, Head of Process Engineering. Department of Process Engineering. Room 310 Food Science Building. University College Cork, Ireland
organization
alternative title
VÄRMEINDUCERADE SKADOR PÅ CELLMEMBRAN I VEGETABILISKA VÄVNADER -en studie tillämpad på potatis-
publishing date
type
Thesis
publication status
published
subject
keywords
Livsmedelsteknik, Food and drink technology, PME, active transport, Cell membrane injury, potatoes
pages
75 pages
publisher
Food Engineering, Lund Univeristy
defense location
lecture hall B, Centre for Chemistry and Chemical Eng, Lund Institute of Technology
defense date
2003-10-16 10:15
external identifiers
  • Other:ISRN: LUTKDH/(TKLT-1026)-154
ISBN
91-628-5833-5
language
English
LU publication?
yes
id
20e9a833-43eb-4826-bf71-f2379c6077b5 (old id 466216)
date added to LUP
2007-10-14 13:43:30
date last changed
2016-09-19 08:45:03
@phdthesis{20e9a833-43eb-4826-bf71-f2379c6077b5,
  abstract     = {Heat processing of vegetables involves the use of temperatures above the physiological limit which affect the cellular structures of the tissue and induce a series of events at cell level that will in turn be reflected in the transport properties of the tissue. One of the most important cellular structures from the mass transport point of view is the cell membrane since it represents the physical barrier to the transport of nutrients into and out of the cell. The effect of heat treatment above physiological limits on the cell membrane of vegetable tissues was studied using potatoes as a model tissue. In vitro studies of the thermal deactivation kinetics of the plasma membrane H+-ATPase showed a pseudo-first-order model characterized by the sum of two independent and simultaneous processes occurring at different rates. Study of the temperature dependence of the activity loss showed that the potato cell membrane undergoes functional breakdown at 55°C, which is characterized by a sharp drop in the H+-ATPase activity and a drastic 7-fold decrease in the energy of activation (Ea). As a result, the proton-motive force needed to provide the energy for the active solute transport is greatly affected and the ability of the cell to retain cytoplasmic solutes decrease. Since the H+-ATPase plays a key role in the transport of solutes across the cell membrane, results indicate that processing temperatures above 55°C affect both mediate and active transport at cellular level. The cell membrane integrity of potato tissue was measured at different depths from the surface to the centre of a sample exposed to different heat treatments. Computer simulations using the finite-element method were performed in order to estimate the temperature distribution within the tissue during heat treatment. Treatment conditions were found to affect the degree of cell membrane integrity in the tissue, especially after heat treatment above 55°C. In similarity to the thermal deactivation of the plasma membrane H+-ATPase, the kinetics of the reduction in cell membrane integrity was found to follow a pseudo-first-order model indicating theta the cell membrane integrity of the tissue is coupled to the thermal stability of the plant plasma membrane H+-ATPase. The temperature dependence of the cell membrane integrity after heat treatment did not follow Arrhenius’ law but a sigmoid pattern, as demonstrated by a slight decrease at low tissue temperatures followed by a sudden sharp decrease after the tissue reached temperatures above 50°C. The absolute residual pectin methylesterase activity of the tissue was also measured at different depths and related the simulated temperature of the tissue. The activity of the enzyme was found to be strongly dependent on the degree of heat penetration and temperature distribution within the tissue. Thermally induced activation of the enzyme was detected at tissue temperatures above 52°C. The simultaneous occurrence of thermal activation of the enzyme and the sharp decrease in cell membrane integrity of the tissue in the same temperature range suggest a coupling of the two processes. The activation of pectin methylesterase enzyme in the tissue may be the consequence of cell membrane disruption and subsequent leakage of cytoplasmic solutes towards the cell wall.},
  author       = {Gonzalez-M, Gerardo},
  isbn         = {91-628-5833-5},
  keyword      = {Livsmedelsteknik,Food and drink technology,PME,active transport,Cell membrane injury,potatoes},
  language     = {eng},
  pages        = {75},
  publisher    = {Food Engineering, Lund Univeristy},
  school       = {Lund University},
  title        = {Heat-Induced Cell Membrane Injury of Vegetable Tissues -An applied study on potatoes},
  year         = {2003},
}