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Quality Aspects of Modified Atmosphere Packaged Broccoli

Jacobsson, Annelie LU (2004)
Abstract (Swedish)
Popular Abstract in Swedish

Grönsaker andas och efter skörd innebär det att de börjar brytas ner. Broccoli är en grönsak som bryts ner snabbt på grund av sin höga andningshastighet, även kallad respirationshastighet. För att förlänga hållbarheten förpackas den ofta i plastförpackningar med syfte att förhindra nedbrytningen och sänka andingshastigheten. Plastfilmer har olika genomsläpplighet för gaser, så som syre, koldioxid och vattenånga. Detta innebär att en atmosfär olik den från luften kommer att bildas inuti förpackningen på grund av att broccolin förbrukar syre och bildar koldioxid. Hur atmosfären inuti förpackningen modifieras beror på broccolins respiration och plastens egenskaper. Lagringstemperaturen har också... (More)
Popular Abstract in Swedish

Grönsaker andas och efter skörd innebär det att de börjar brytas ner. Broccoli är en grönsak som bryts ner snabbt på grund av sin höga andningshastighet, även kallad respirationshastighet. För att förlänga hållbarheten förpackas den ofta i plastförpackningar med syfte att förhindra nedbrytningen och sänka andingshastigheten. Plastfilmer har olika genomsläpplighet för gaser, så som syre, koldioxid och vattenånga. Detta innebär att en atmosfär olik den från luften kommer att bildas inuti förpackningen på grund av att broccolin förbrukar syre och bildar koldioxid. Hur atmosfären inuti förpackningen modifieras beror på broccolins respiration och plastens egenskaper. Lagringstemperaturen har också väldigt stor betydelse för broccolins hållbarhet, en låg temperatur sänker andningshastigheten och broccolin håller sig fräsch längre.



I den här avhandlingen har olika förpackningslösningar för broccoli undersökts för att kunna föreslå ett alternativ som bibehåller broccolins kvalitet under lagring. Lagringsförsök med olika plastförpackningar och temperaturer gjordes för att studera hur atmosfären runt broccolin modifierades och hur broccolins färg, textur, lukt och smak påverkades. Broccolins lukt undersöktes både när broccolin var rå och efter kokning.



Broccolins hållbarhet kunde förlängas väsentligt, mellan 8 och 14 dagar, med hjälp av rätt förpackning. De förpackningar som studerades påverkade de broccolins färg, textur, lukt och smak på olika sätt, t.ex. blev broccolin gul fortare i en av förpackningarna, medan den i en annan förpackning blev mjukare men bibehöll sin gröna färg. Syre och koldioxid halterna i förpackningen påverkade också broccolins produktion av föreningar som påverkar dess lukt och smak. En del av dessa förändringar var inte märkbara förrän efter kokning av broccolin. Temperaturvariationer under lagringstiden visade sig också påverka produktionen av lukt och smakämnen.



Valet av förpackningsmaterial är väldigt viktigt, för att uppnå lång hållbarhet. Det kan vara svårt att ta hänsyn till alla de olika kvalitetsaspekterna, men förändringar hos broccolin som endast är märkbara efter kokning bör undvikas, eftersom broccoli oftast äts kokt. (Less)
Abstract
The modified atmosphere packaging (MAP) of vegetables is used with the aim of prolonging the shelf-life of the packaged produce. The packaging material consists of a permeable film and as a result of the respiration of the produce and gas diffusion through the film, the O2 decreases and the CO2 increases inside the package. This thesis has focused on the MAP of broccoli and the effect of the packaging material on the quality of broccoli. The influence of temperature was also investigated. The quality parameters studied were flavour, aroma, weight, colour and texture.



Oriented polypropylene (OPP), polyvinyl chloride (PVC), and two different low-density polyethylene (LDPE) films were used as packaging materials. One of the... (More)
The modified atmosphere packaging (MAP) of vegetables is used with the aim of prolonging the shelf-life of the packaged produce. The packaging material consists of a permeable film and as a result of the respiration of the produce and gas diffusion through the film, the O2 decreases and the CO2 increases inside the package. This thesis has focused on the MAP of broccoli and the effect of the packaging material on the quality of broccoli. The influence of temperature was also investigated. The quality parameters studied were flavour, aroma, weight, colour and texture.



Oriented polypropylene (OPP), polyvinyl chloride (PVC), and two different low-density polyethylene (LDPE) films were used as packaging materials. One of the LDPE packages contained an ethylene-absorbing sachet. In all the studies, significantly different atmospheres developed inside the different packaging materials. At steady state, the O2 levels ranged between 2-18 % while the CO2 concentration was between 4-13 %.



MAP was found to significantly affect the investigated quality parameters of the broccoli. Significant differences in the smell and flavour of cooked broccoli were found, depending on the packaging material used to store the raw broccoli. However, no such differences could be found in raw broccoli prior to cooking. A high CO2 level of 10-14 %, in combination with an O2 level of 12-14 % differed significantly from the other material used when raw as well as after heat treatment. The high CO2 level enhanced the sulphur compounds of the broccoli. The different atmospheres were also found to influence the weight, colour, appearance and texture of the raw broccoli. The texture of the broccoli was affected differently, depending on the storage atmosphere, and softening occurred at a CO2 level above 10 % in combination with an O2 level of 12-14 %. The yellowing of the broccoli decreased upon introducing an ethylene- absorbing sachet into the package. It was observed that the quality parameters did not change at the same rate during storage. Thus, the shelf-life of the broccoli was found to be dependent not only on the choice of packaging material, but also on the choice of quality parameter. The shelf-life was prolonged by up to 14 days using MAP. However, the quality parameter limiting the shelf-life differed between the packaging materials.



Storage at a combination of 4 and 10 °C for one week was found to affect the aroma production of MAP broccoli differently to storage solely at 10 °C. A change in temperature during storage resulted in the presence of dimethyl sulphide in raw broccoli and an increased amount of methanethiol in cooked broccoli, which could not be found for broccoli stored solely at 10 °C. The altered aroma production resulted in noticeable differences in the smell and flavour of the cooked broccoli.



In addition to the quality evaluations, the precooling of broccoli using forced-air cooling was simulated in order to predict the airflow rate and the cooling time of the broccoli. The study showed that the porous media approach to flow could be extended to irregularly shaped produce, i.e. broccoli. However, simulations of the heat transfer of irregular produce were more difficult than for regularly shaped products, e.g. potatoes. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof. Hotchkiss, Joseph H., Cornell University, Ithaca, USA
organization
alternative title
Kvalitetsförändringar hos färsk broccoli förpackad i en modifierad atmosfär
publishing date
type
Thesis
publication status
published
subject
keywords
Livsmedelsteknik, Food and drink technology, heat transfer, mass transport, quality, flavour, aroma, modified atmosphere packaging, broccoli
pages
150 pages
publisher
Annelie Jacobsson, Lokföraregatan 15C, 222 37 Lund, Sweden, or SIK, Box 5401, 40229 Göteborg, Sweden,
defense location
Chemical centre lecture hall C, Lund Institute of Technology
defense date
2004-03-19 10:15
ISBN
91-628-5923-4
language
English
LU publication?
yes
id
ac048d3b-dc91-435d-a6d0-bd55de9a23dd (old id 466738)
date added to LUP
2007-10-13 14:00:29
date last changed
2016-09-19 08:45:02
@misc{ac048d3b-dc91-435d-a6d0-bd55de9a23dd,
  abstract     = {The modified atmosphere packaging (MAP) of vegetables is used with the aim of prolonging the shelf-life of the packaged produce. The packaging material consists of a permeable film and as a result of the respiration of the produce and gas diffusion through the film, the O2 decreases and the CO2 increases inside the package. This thesis has focused on the MAP of broccoli and the effect of the packaging material on the quality of broccoli. The influence of temperature was also investigated. The quality parameters studied were flavour, aroma, weight, colour and texture.<br/><br>
<br/><br>
Oriented polypropylene (OPP), polyvinyl chloride (PVC), and two different low-density polyethylene (LDPE) films were used as packaging materials. One of the LDPE packages contained an ethylene-absorbing sachet. In all the studies, significantly different atmospheres developed inside the different packaging materials. At steady state, the O2 levels ranged between 2-18 % while the CO2 concentration was between 4-13 %.<br/><br>
<br/><br>
MAP was found to significantly affect the investigated quality parameters of the broccoli. Significant differences in the smell and flavour of cooked broccoli were found, depending on the packaging material used to store the raw broccoli. However, no such differences could be found in raw broccoli prior to cooking. A high CO2 level of 10-14 %, in combination with an O2 level of 12-14 % differed significantly from the other material used when raw as well as after heat treatment. The high CO2 level enhanced the sulphur compounds of the broccoli. The different atmospheres were also found to influence the weight, colour, appearance and texture of the raw broccoli. The texture of the broccoli was affected differently, depending on the storage atmosphere, and softening occurred at a CO2 level above 10 % in combination with an O2 level of 12-14 %. The yellowing of the broccoli decreased upon introducing an ethylene- absorbing sachet into the package. It was observed that the quality parameters did not change at the same rate during storage. Thus, the shelf-life of the broccoli was found to be dependent not only on the choice of packaging material, but also on the choice of quality parameter. The shelf-life was prolonged by up to 14 days using MAP. However, the quality parameter limiting the shelf-life differed between the packaging materials.<br/><br>
<br/><br>
Storage at a combination of 4 and 10 °C for one week was found to affect the aroma production of MAP broccoli differently to storage solely at 10 °C. A change in temperature during storage resulted in the presence of dimethyl sulphide in raw broccoli and an increased amount of methanethiol in cooked broccoli, which could not be found for broccoli stored solely at 10 °C. The altered aroma production resulted in noticeable differences in the smell and flavour of the cooked broccoli.<br/><br>
<br/><br>
In addition to the quality evaluations, the precooling of broccoli using forced-air cooling was simulated in order to predict the airflow rate and the cooling time of the broccoli. The study showed that the porous media approach to flow could be extended to irregularly shaped produce, i.e. broccoli. However, simulations of the heat transfer of irregular produce were more difficult than for regularly shaped products, e.g. potatoes.},
  author       = {Jacobsson, Annelie},
  isbn         = {91-628-5923-4},
  keyword      = {Livsmedelsteknik,Food and drink technology,heat transfer,mass transport,quality,flavour,aroma,modified atmosphere packaging,broccoli},
  language     = {eng},
  pages        = {150},
  publisher    = {ARRAY(0x8f40cf8)},
  title        = {Quality Aspects of Modified Atmosphere Packaged Broccoli},
  year         = {2004},
}