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Hållbarhetsförlängning av skuren isbergssallat genom paketering i modifierad atmosfär

Kvist, Peter LU (2012) MVEK03 20112
Studies in Environmental Science
Abstract
Problem definition:
The production, sale and consumption of ready to eat-vegetables and salads have increased at a frantic pace over the last decade and this trend shows signs of continuing. This very much depends on that ready to eat-salads are minimally processed and contain no artificial additives. They also retain a large amount of their nutrients after harvest and do not require any preparation before consumption which is both convenient and timesaving.
The importance of these foods as a source of infection has increased during the 2000s compared to the 1900s. It has been confirmed that the sales growth of ready to eat-salads have coincided with the number of cases caused by foodborne diseases. The consumption is done by the... (More)
Problem definition:
The production, sale and consumption of ready to eat-vegetables and salads have increased at a frantic pace over the last decade and this trend shows signs of continuing. This very much depends on that ready to eat-salads are minimally processed and contain no artificial additives. They also retain a large amount of their nutrients after harvest and do not require any preparation before consumption which is both convenient and timesaving.
The importance of these foods as a source of infection has increased during the 2000s compared to the 1900s. It has been confirmed that the sales growth of ready to eat-salads have coincided with the number of cases caused by foodborne diseases. The consumption is done by the consumer without warming up, rinse, or use some other steps that can reduce the number of microorganisms. Therefore it is vital that the previous step in the process, such as irrigation, harvesting and processing, are carried out with Good Agricultural Practice (GAP) and Good Manufacturing Practice (GMP)to avoid contamination of the salad and that any illness to the consumer doesn’t occur.
Microorganisms and pathogens affect the shelf life of lettuce by starting different spoilage processes. The shelf life of lettuce can, in addition to working with good practices in all areas before, during and after harvest, be extended by package it in an atmosphere where the gas mixture has been modified to slow the growth of microorganisms. Vegetables are living material and after harvest they still have an active metabolism, hence they continue to respire. Respiration accelerates the biological processes that cause spoilage which affects the lettuce taste, nutritional value, texture and appearance. During the respiration nutrients and water from the vegetable’s own storage are used, that over time will decrease. The respiration rate is influenced by several factors such as maturity, type of product, harvest method and harvest time. A cut product also has a high respiratory rate, and the cutting also causes fluid loss and release of nutrients which promote growth of microorganisms.
If the vegetable’s respiration rate is reduced, its lifetime and shelf life
will be extended. By packaging in a modified atmosphere this can be achieved. Since many factors affect the respiration rate, one must by practical trials determine what type of permeable packaging film, gas mixture and storage temperature is most suitable for a particular product to give the longest possible shelf life.

Purpose: The company Norrvidinge Boställe AB wants to launch cut iceberg lettuce together with different kinds of baby leaf, because there is a large market potential but also to become more competitive. To economically justify a launch of this type a product it requires that the iceberg lettuce has a shelf life of at least 9 days. This means that the product must be fresh and clean and can be consumed, but also that its appearance is acceptable, in this case not discoloured at the end of th product's shelf life. My task and purpose of this essay is to extend the shelf life of cut iceberg lettuce by package it in a modified atmosphere.

Method: To determine the longest possible shelf life, a number of trials were conducted where test packages were produced with different packaging films, lettuce blends and gas mixtures. These packages were then stored in different temperatures. The monitoring of the lettuces’ shelf life has been followed by photographing, which also has helped in the evaluation of the different types that were produced. Sensory analyzes were performed on the last day of storage for all types. A microbiological analysis was carried out on the date of expiration to ensure food safety of the lettuces' in the packages that showed the best results.

Main conclusions: The first and second trial showed that the arugula was more durable than iceberg lettuce and that the shelf life of iceberg lettuce was not adversely affected in the presence of arugula. A packaging film with an OTR-value between 500-750 cm3/m2/24h per package depending on
the length of the package, gave iceberg lettuce the longest shelf life in both trial 1 and 2. The differences in shelf life between the best and worst types were at most 6 days. A high concentration of carbon dioxide, 20 and 30 %, gave the most number of packages the longest shelf life and 0 to 5 % the least. An initial oxygen concentration of around 2,5 % gave a shelf life of 15 days in experiment 3 when stored at 3 ° C. However, lettuce should be packaged in packaging films that have lower OTR-values which are a measure of the amount of oxygen that penetrates or passes through a film at specified temperature- and humidity conditions. (Less)
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author
Kvist, Peter LU
supervisor
organization
course
MVEK03 20112
year
type
M2 - Bachelor Degree
subject
language
Swedish
id
3364949
date added to LUP
2013-01-21 16:34:00
date last changed
2013-01-21 16:34:00
@misc{3364949,
  abstract     = {Problem definition: 
The production, sale and consumption of ready to eat-vegetables and salads have increased at a frantic pace over the last decade and this trend shows signs of continuing. This very much depends on that ready to eat-salads are minimally processed and contain no artificial additives. They also retain a large amount of their nutrients after harvest and do not require any preparation before consumption which is both convenient and timesaving.
The importance of these foods as a source of infection has increased during the 2000s compared to the 1900s. It has been confirmed that the sales growth of ready to eat-salads have coincided with the number of cases caused by foodborne diseases. The consumption is done by the consumer without warming up, rinse, or use some other steps that can reduce the number of microorganisms. Therefore it is vital that the previous step in the process, such as irrigation, harvesting and processing, are carried out with Good Agricultural Practice (GAP) and Good Manufacturing Practice (GMP)to avoid contamination of the salad and that any illness to the consumer doesn’t occur.
Microorganisms and pathogens affect the shelf life of lettuce by starting different spoilage processes. The shelf life of lettuce can, in addition to working with good practices in all areas before, during and after harvest, be extended by package it in an atmosphere where the gas mixture has been modified to slow the growth of microorganisms. Vegetables are living material and after harvest they still have an active metabolism, hence they continue to respire. Respiration accelerates the biological processes that cause spoilage which affects the lettuce taste, nutritional value, texture and appearance. During the respiration nutrients and water from the vegetable’s own storage are used, that over time will decrease. The respiration rate is influenced by several factors such as maturity, type of product, harvest method and harvest time. A cut product also has a high respiratory rate, and the cutting also causes fluid loss and release of nutrients which promote growth of microorganisms.
If the vegetable’s respiration rate is reduced, its lifetime and shelf life
will be extended. By packaging in a modified atmosphere this can be achieved. Since many factors affect the respiration rate, one must by practical trials determine what type of permeable packaging film, gas mixture and storage temperature is most suitable for a particular product to give the longest possible shelf life.

Purpose: The company Norrvidinge Boställe AB wants to launch cut iceberg lettuce together with different kinds of baby leaf, because there is a large market potential but also to become more competitive. To economically justify a launch of this type a product it requires that the iceberg lettuce has a shelf life of at least 9 days. This means that the product must be fresh and clean and can be consumed, but also that its appearance is acceptable, in this case not discoloured at the end of th product's shelf life. My task and purpose of this essay is to extend the shelf life of cut iceberg lettuce by package it in a modified atmosphere. 

Method: To determine the longest possible shelf life, a number of trials were conducted where test packages were produced with different packaging films, lettuce blends and gas mixtures. These packages were then stored in different temperatures. The monitoring of the lettuces’ shelf life has been followed by photographing, which also has helped in the evaluation of the different types that were produced. Sensory analyzes were performed on the last day of storage for all types. A microbiological analysis was carried out on the date of expiration to ensure food safety of the lettuces' in the packages that showed the best results.

Main conclusions: The first and second trial showed that the arugula was more durable than iceberg lettuce and that the shelf life of iceberg lettuce was not adversely affected in the presence of arugula. A packaging film with an OTR-value between 500-750 cm3/m2/24h per package depending on
the length of the package, gave iceberg lettuce the longest shelf life in both trial 1 and 2. The differences in shelf life between the best and worst types were at most 6 days. A high concentration of carbon dioxide, 20 and 30 %, gave the most number of packages the longest shelf life and 0 to 5 % the least. An initial oxygen concentration of around 2,5 % gave a shelf life of 15 days in experiment 3 when stored at 3 ° C. However, lettuce should be packaged in packaging films that have lower OTR-values which are a measure of the amount of oxygen that penetrates or passes through a film at specified temperature- and humidity conditions.},
  author       = {Kvist, Peter},
  language     = {swe},
  note         = {Student Paper},
  title        = {Hållbarhetsförlängning av skuren isbergssallat genom paketering i modifierad atmosfär},
  year         = {2012},
}