How to thicken chutney

Liquid becomes solid: jam and co

Are there more fruits in your garden than you can eat? Or have you been given or bought more fruit than you can currently use? Then canning is a good way to preserve the fruits of summer and to preserve them for the cold months. So you can enjoy self-harvested or regional fruit even after the season. In Austria apricots, strawberries, currants and blackberries are among the most popular types of jam. The bESSERwisser have put together useful information about correct filling, the consistency and various gelling aids for jams and jams.

Jam or jam?

In Austria, the name jam is particularly common - regardless of which fruits were used and how finely pureed the product is. The EU already regulated the division into jam and jam a few years ago. Since 2001, in the EU - based on "marmelade" in English - only products made from citrus fruits have been allowed to be labeled as jam, whereas the name jam must be used for jellied fruit puree made from other fruits [4, 5]. So nowadays, on the shelves of Austrian supermarkets, you will mainly find jams made from berries, apricots and other local fruits. In everyday language usage, especially for home-cooked fruit products, the term jam is still used in Austria.

The principle of preserving jam

Today, preserving jam, like in grandma's time, is all the rage and is anything but old-fashioned. The basic ingredient for this is fresh, ripe and perfect fruit. This is cleaned, cored, chopped up and mixed with sugar and / or gelling agent. Then a not too large amount - the information varies between 0.5 and 3 kilograms - of the fruit mass is heated. It is important to always stir evenly so that the gelling agent and sugar are well distributed by the heat and the mass does not lie on the bottom of the pot [1, 2]. Depending on the type of fruit and gelling agent, the fruit mass is boiled for five to ten minutes. If foam forms in the process, it is advisable to skim it off, as bacteria could later collect there [1, 2, 3]. Depending on the desired end result, the fruit mass can be mashed with a hand blender or not while it is cooking.

The all-important question when boiling jam is then: When has the mixture reached the right consistency and is it ready for filling? To test this, the so-called gelation test is made. To do this, a few drops of the hot fruit mass are placed on a cold, smooth plate [1, 2, 6]. If these quickly solidify when cooling, the jam is ready and can be filled. Good hygiene is important to ensure the shelf life of jam: the jars must be thoroughly cleaned and preferably boiled out before the hot jam is poured in, and the lids should be dried well. This prevents mold formation and the jam has a longer shelf life [3].

Tips and tricks when filling

  • So that jam jars do not jump when filled with hot jam due to the rapid temperature change, wash them with hot water beforehand and / or place them on a damp cloth [2].
  • Turn the containers upside down immediately after filling. In this way, the hot jam sterilizes the remaining air - again an important tip for extending the shelf life of the product. A few minutes are sufficient - turn the jars again before the contents have cooled down and can stick to the lid [2, 3].

Physics and chemistry of gelation

The principle when jam is made from liquid becomes solid. In a process known as gelling, water is bound, and a "gel" is created with a firmer, yet soft consistency. Depending on the type, this is called jam, jam, terrine or aspic.

But how does this gelation process work? The decisive factor for this is the structure of the water: water (H2O) is a polar molecule that has a positively and a negatively charged side. In order to bind water, you also need charged molecules that can interact with the water molecules. When preserving jam, this function is fulfilled by long, chain-shaped sugar molecules, especially pectins [6, 7, 8].

Pectins, which are also contained in various gelling agents, can be found in almost all fruits. However, they are mostly obtained from the cell walls of berries and pome fruit - preferably apples [2, 6]. Pectins are multiple sugars, i.e. molecules of the same simple sugar that are strung together via special bonds. The negatively charged, long-chain pectin molecules repel each other - but this reaction can be prevented by the presence of acid. The charges of the pectin chains are neutralized by naturally contained fruit acid or by adding lemon juice when boiling. The long-chain molecules can then hook into a network and bind the aqueous sugar solution. This gives the product the desired consistency: it gels from [6].

Known gelling aids

Preserving sugar

Gelling sugar is a mixture of sugar and gelling agents - especially pectin, which is obtained from fruits. The ratio of 1: 1, 2: 1 or 3: 1 indicated on the package indicates how much preserving sugar should be added in relation to the fruit mass. The first-mentioned number denotes the fruit content. The larger this is, the less sweet the corresponding preserving sugar is. However, it contains more gelling agent to guarantee the desired result. In addition, preservatives such as sorbic acid are added to low-sugar preserving sugars in order to make the end product more durable [7]. When using this gelling agent, it is particularly important to weigh the fruit before you start making the jam. Because what many do not know: The stated ratio of preserving sugar to fruits mostly relates to the gross weight of the fruits and includes the shell, seeds and casing. It is therefore essential to weigh the fruit before pitting and cutting [2]. The pectin contained in the gelling sugar loses its gelling power over time. Preserving sugar should therefore no longer be used after the expiry date, as the desired effect may no longer be achieved.

Apple pectin

If sugar is not to be added to particularly sweet fruits, pure apple pectin is also suitable as a gelling aid. Apples have a very high concentration of this polysaccharide, and some varieties such as Granny Smith contain a particularly large amount of it. The use of apple pectin has the advantage that the fruit mass only needs a few minutes to gel with this preparation [1, 6].

Agar Agar

A vegetable alternative to gelatine - another gelling aid made from animal connective tissue - is agar-agar. This is also a long-chain polysaccharide, which is obtained from red algae. This gelling agent is characterized by its neutral taste. As with apple pectin, no sugar has to be added to agar-agar so that the mass gels. Another advantage of this gelling agent, which is particularly widespread in Asia: the product gels even at higher room temperatures and has a significantly higher gelling capacity than the alternatives mentioned above. Agar-agar only needs to be boiled for at least two minutes - then it starts to solidify [1, 6].

Gelling without a gelling agent

The production of jams without added gelling agent is an original method that is still used today, especially in France. The pectin stored in the fruit itself causes the gelling process: In the presence of sugar, it dissolves from the cells when the fruit mass is cooked. However, gelling only works if the starting material contains enough pectin [6]. The rule of thumb is: the more unripe a fruit, the higher its pectin content. Overripe fruits, on the other hand, do not contain enough of this natural gelling agent [2].

Enzymes can also trigger the gelling reaction. For example, pudding can be prepared with ginger without adding any gelling agent.

When boiling jam, it doesn't always have to be the classic preserving sugar. There are quite a few alternatives that are especially interesting if you want to make less sweet products. The choice of the right gelling agent is primarily a matter of taste.


Another way of processing fruits - and vegetables - and making them durable is to boil them down to make chutney. This product from India is also called spiced jam and describes a sauce that can be spicy, (sweet) sour, piquant or hot. Fruit and vegetables are preserved by adding sugar and vinegar. Chutney consists of well-balanced mixtures of fruit, vegetables, herbs and spices and, when cooked, gets a consistency similar to jam. It is eaten with meat, fish dishes and curries and, especially in India, it is served with almost every dish [9, 10, 11]. Incidentally, the full taste of a chutney only develops after a few weeks of storage [10].


The processing of fruit into jam and the like is well suited to still be able to feed on the fruits of summer in winter. Preserving is an old tradition that has lost none of its relevance today. There are numerous ways to get fruit pulp to gel. Above all, low-sugar alternatives to classic preserving sugar are enjoying increasing popularity. In addition to the traditional single-variety jams, mixes of different types of fruit such as apple-elderberry, apricot-peach and others provide a breath of fresh air.

In addition to the traditional single-variety jams, mixes of different types of fruit such as apple-elderberry, apricot-peach and others provide a breath of fresh air. And to give the jam that certain something, you can experiment: For example, spices such as ginger, cinnamon or chilli can be added to conventional fruit spreads during preparation. A shot of alcohol - liqueur, cognac or Grand Marnier - and the addition of herbs such as thyme or rosemary give the jam a special note [2, 3].


[1] Rupp C .: Preserving fruit and vegetables: 10 tips., accessed on July 31, 2018

[2] Questions and answers about canning., accessed on July 31, 2018

[3] Kutos J .: The best tips and tricks for successful jam. (07/06/2017), accessed on 07/31/2018

[4] Schiltz CB: Why jam has to be called jam now (04/07/2008), accessed on 08/07/2018

[5] Council Directive 2001/113 / EC of December 20, 2001 on jams, jellies, marmalades and chestnut cream for human consumption. (December 20, 2001), accessed on August 7, 2018

[6] Vilgis T .: The Molecular Kitchen: Physics and Chemistry of Fine Taste. S. Hirzel Verlag Stuttgart (2013), 9th corrected edition

[7] Thakur BR, Singh RK and Handa AK: Chemistry and uses of pectin – a review. Crit Rev Food Sci Nutr 1997 Feb; 37 (1): 47-73. doi: 10.1080 / 10408399709527767

[8] Lara-Espinoza C., Carvajal-Millán E., Balandrán-Quintana R. et al .: Pectin and Pectin-Based Composite Materials: Beyond Food Texture. Molecules. 2018 Apr; 23 (4): 942.

[9] Preserving, drying, soaking: that's how it works. (07/07/2016), accessed on 31/07/2018

[10] Preserving, pickling and preserving fruit and vegetables. (June 23, 2016), accessed on July 31, 2018

[11] Preserving fruit and vegetables., accessed on July 31, 2018

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