Preservation of Fruits - blueberry jam and canned pineapple

Hello everyone!

I just started my semester abroad in Volda, Norway where I’m taking a class in Norwegian Food Culture. In this course we’re taking a more hands-on approach to learning about food and I’ll be using this blog to document my progress.
In the first sessions we discussed how due the landscape in the area large scale agriculture is impossible and the winters are so cold there are no plants to eat. Therefore, the preservation of fruits and vegetables during the harvest season is of utmost importance. 


For my assignment I decided to work on fruits, canning them and making jam. 



Blueberry Jam 


Ingredients needed: 

  • 400gr Blueberries

  • 150gr Sugar 

  • 9g Jam Sugar (alternative name: Gelling Sugar)

Process: 




Before starting your jam-making journey please sterilize your future jam container. The glass part of the jar should go into an oven at 100 degrees Celcius for 15-20min, while the lids take a boiling hot bath in a pot of water. 

 







Weigh 400gr of Blueberries and add them to your medium sized pot on the stove. Slowly heat the blueberries, they should start melting after a few minutes.

Stir every once in a while to make sure the blueberries don’t burn at the bottom of the pot. 






Once the blueberries are mushy you can start adding sugar in small portions while continuing to stir. At this point, the blueberries will start smelling very tasty - please don’t eat them all now. When the blueberries are mostly liquid with some bits you can take a potato masher and mash the biggest bits into a puree to avoid large pieces in your jam. Once this is done you can add the gelling sugar and continue stirring. 

If you’re uncertain about the consistency of your jam you can dip a spoon into the jam and let it cool off, if it jellifies and doesn’t drip off the spoon the consistency is perfect.

Note: Due to my lack of mathematical skills I accidentally added double the amount of gelling sugar and the jam jellified already on the spoon before cooling off. Please make sure you don’t imitate my mistakes and take the time to double check your measurements. 




Once you achieve the right consistency, take the pot away from the stove and take your jar out of the oven (without touching the rim to avoid spreading bacteria). Fill the jar until the ridge at the top, close the lid and put the jar upside down to cool. 

After cooling you can put the jar right side up and the lid should be indented to show that it's properly sealed. If your jam remains stuck at the top of the jar after multiple hours right side up - you added too much gelling sugar. 


You can find the original recipe here, although I altered it and partially followed the instructions on the gelling sugar. 

Canned Pineapples 



Ingredients: 

  • 1 pineapple 

  • 500ml water

  • 150gr sugar 


Process:


Sterilisation of jar + lid 


Like for your jam jar please sterilise your jar by putting it into an oven at 100C for 15-20 and boil the lids in a pot of water. Keep both in their hot environment until right before canning. 


Sugar water:




First you need to prepare the sugar-water solution in which your pineapple will be preserved. For this boil 500ml of water with 150gr of sugar. Stir to avoid it sticking to the bottom of the pan. Let it simmer while you start preparing the pineapple. 







Pineapple preparation 


While the sugar solution is on the stove you can start cutting up your pineapple. Start by cutting the green part on top off and slide your knife along the side of the fruit to remove the rind. 

If you would like to preserve it as slices you’ll need a cookie cutter to remove the core. The smallest one I had on hand was still too big and caused too much food waste, so I decided to go with pineapple chunks. 




Canning

Once you’re done cutting up your pineapple you can take your sterilised jar out of the oven (without touching the rim to avoid the spread of bacteria!) and put the pieces of pineapple in. Then take the sugar solution and funnel it into the jar until the start of the mouth of the jar. Close the lid tightly.
Now you can put the jar into a large pot of water and bring it to 85C, keep it there for about 35min. 

Once that is over you can strain the water and put the glass to the side to cool. 







You can find the original recipe in German here (slightly altered to taste and due to type of jar) 


When canning fruits you may have to add lemon juice to avoid risks of botulism, however this is only necessary with fruits with a ph-level of 4.6 or above. (C.Brown, 2019) Since pineapple is part of the most acidic fruits with an average ph-level between 4.0 and 3.2 the use of lemon juice is not necessary.



References: 

Biohof Achleitner. (n.d.). Ananas eingeweckt | Rezept Biohof Achleitner. Retrieved August 29, 2025, from https://www.biohof.at/rezepte/Ananas-eingeweckt-122

C. Brown, A. (2019). Food Preservation. In Understanding Food: Principles and Preparation (6th ed.). Cengage.

Siggi. (n.d.). Blaubeer-Marmelade. einfachbaken.de. Retrieved August 29, 2025, from https://www.einfachbacken.de/rezepte/blaubeer-marmelade-kochen-schnell-einfach?portions=2
Location: Volda Municipality, Norway

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