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Studies of the Effects of Industrial Processing on Fruit

Viberg, Uno LU (1998)
Abstract (Swedish)
Popular Abstract in Swedish

Industriell produktion av bärkonserver innefattar flera enhetsoperationer, vilka alla påverkar sensoriska så väl som näringsmässiga kvaliteter hos produkten. Upptiningen är ett speciellt kritiskt steg eftersom förändringar i både kemisk sammansättning och textur sker. Upptining av jordgubbar i designade lösningar visade att bärens fasthet såväl som viktsförlusterna gick att påverka under upptiningen.Vid blandning av jordgubbar och socker förändrades sockersammansättningen, pga invertasaktivitet, samt storleken hos jordgubbarna, beroende på skillnader i osmotiskt tryck. Modeller för båda förloppen presenteras.



Färska frukter och bär anses vara goda källor för antioxidanter. Den... (More)
Popular Abstract in Swedish

Industriell produktion av bärkonserver innefattar flera enhetsoperationer, vilka alla påverkar sensoriska så väl som näringsmässiga kvaliteter hos produkten. Upptiningen är ett speciellt kritiskt steg eftersom förändringar i både kemisk sammansättning och textur sker. Upptining av jordgubbar i designade lösningar visade att bärens fasthet såväl som viktsförlusterna gick att påverka under upptiningen.Vid blandning av jordgubbar och socker förändrades sockersammansättningen, pga invertasaktivitet, samt storleken hos jordgubbarna, beroende på skillnader i osmotiskt tryck. Modeller för båda förloppen presenteras.



Färska frukter och bär anses vara goda källor för antioxidanter. Den totala antioxidativa kapaciteten i jordgubbar bestämdes före infrysning, värmebehandling samt efter en accelerad lagring (40 C, en vecka). Förlusterna i den totala antioxidativa kapaciteten befanns vara små och korrelerade till förlusterna av askorbinsyra. I en avslutande studie undersöktes hur några utvalda antioxidanter i svartvinbärssylt (askorbinsyra, beta-karoten och antocyaner) påverkades vid tillverkning och lagring (13 månader) under olika lagringsförhållanden. Sylten som lagrats vid 8 C kunde efter lagringen fortfarande anses vara en god källa för askorbinsyra (mer än 7 mg/MJ). Lagring vid högre temperaturer ökade förlusterna. Förluster av antocyanerna var också temperaturberoende. Halten beta-karoten ändrades inte under lagringen. (Less)
Abstract
The industrial production of preserves includes several unit operations which all affects sensorial properties as well as the nutritional value of the final product. Thawing is a crucial unit operation, since then both chemical and physical changes take place.



Thawing strawberries in selected aqueous media could gave both firmer strawberries and smaller weight loss than if air was used as the thawing medium.



Upon mixing with sugar solution juice will diffuse out of the strawberries and into the solution. At the same time, some solids will be taken up from the solution. A model for the final volume of the strawberries is presented. Also, the composition of the sugar will change due to the invertase... (More)
The industrial production of preserves includes several unit operations which all affects sensorial properties as well as the nutritional value of the final product. Thawing is a crucial unit operation, since then both chemical and physical changes take place.



Thawing strawberries in selected aqueous media could gave both firmer strawberries and smaller weight loss than if air was used as the thawing medium.



Upon mixing with sugar solution juice will diffuse out of the strawberries and into the solution. At the same time, some solids will be taken up from the solution. A model for the final volume of the strawberries is presented. Also, the composition of the sugar will change due to the invertase activity in the strawberries. The inversion affects both the natural sucrose as well as that added. The extent of inversion depends on the shape of the strawberries and on the duration of the immersion. The reaction takes place inside or in contact with the strawberry tissue. The reaction is important since the composition of the sugar affect the essential qualities of the final jam product.



Fresh berries and fruits are considered to be good sources of antioxidants. The antioxidative capacity in strawberries was measured before freezing and after an accelerated storage 40 C for 7 days. The loss of antioxidative capacity was small and could be related to the reduction of ascorbic acid.



In a final study blackcurrant jam was stored for 13 months during which time changes in ascorbic acid, beta-carotene and anthocyanins were monitored. After storage at 8 C the jam could still be considered a good source of ascorbic acid. In jam stored at a higher temperature the content of ascorbic acid was lower. Also the amount of anthocyanins were negatively affected by an elevated storage temperature. The amount of beta-carotene did not change during storage. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Sereno, Alberto M.C., University of Porto, Porto, Portugal
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Food and drink technology, antioxidants, invertase, thawing, blackcurrant, strawberry, fruit, berry, Livsmedelsteknik
pages
154 pages
publisher
Food Engineering, Lund Univeristy
defense location
Lecture hall C, Center for Chemistry and Chemical Engineering
defense date
1998-04-04 10:15
external identifiers
  • Other:ISRN: LUTKDH/(TKLT-1026)-154
language
English
LU publication?
yes
id
c13d0831-8d94-458e-8e6b-6d21578bfd87 (old id 38502)
date added to LUP
2007-10-14 17:46:59
date last changed
2016-09-19 08:45:05
@misc{c13d0831-8d94-458e-8e6b-6d21578bfd87,
  abstract     = {The industrial production of preserves includes several unit operations which all affects sensorial properties as well as the nutritional value of the final product. Thawing is a crucial unit operation, since then both chemical and physical changes take place.<br/><br>
<br/><br>
Thawing strawberries in selected aqueous media could gave both firmer strawberries and smaller weight loss than if air was used as the thawing medium.<br/><br>
<br/><br>
Upon mixing with sugar solution juice will diffuse out of the strawberries and into the solution. At the same time, some solids will be taken up from the solution. A model for the final volume of the strawberries is presented. Also, the composition of the sugar will change due to the invertase activity in the strawberries. The inversion affects both the natural sucrose as well as that added. The extent of inversion depends on the shape of the strawberries and on the duration of the immersion. The reaction takes place inside or in contact with the strawberry tissue. The reaction is important since the composition of the sugar affect the essential qualities of the final jam product.<br/><br>
<br/><br>
Fresh berries and fruits are considered to be good sources of antioxidants. The antioxidative capacity in strawberries was measured before freezing and after an accelerated storage 40 C for 7 days. The loss of antioxidative capacity was small and could be related to the reduction of ascorbic acid.<br/><br>
<br/><br>
In a final study blackcurrant jam was stored for 13 months during which time changes in ascorbic acid, beta-carotene and anthocyanins were monitored. After storage at 8 C the jam could still be considered a good source of ascorbic acid. In jam stored at a higher temperature the content of ascorbic acid was lower. Also the amount of anthocyanins were negatively affected by an elevated storage temperature. The amount of beta-carotene did not change during storage.},
  author       = {Viberg, Uno},
  keyword      = {Food and drink technology,antioxidants,invertase,thawing,blackcurrant,strawberry,fruit,berry,Livsmedelsteknik},
  language     = {eng},
  pages        = {154},
  publisher    = {ARRAY(0x9293880)},
  title        = {Studies of the Effects of Industrial Processing on Fruit},
  year         = {1998},
}