What we found

The pick of the jams

Top jam by a clear margin was Anathoth Raspberry Jam, leading the rankings for taste and overall quality.

"Very sweet, lovely rich colour and very similar to my homemade raspberry jam" summed up the tasters’ comments. That’s not surprising – Anathoth consists simply of equal quantities of raspberries and sugar. The other jams had added ingredients (see below).

Barker’s Raspberry Jam and Select Raspberry Jam (sold in Woolworths and Countdown supermarkets) rated well for taste and overall quality – but some of our tasters thought they were overly sweet.

The rest

Tasters also commented on the sweetness of Craig’s Raspberry Jam: it was one of the sweetest on trial. Those who preferred a tarter flavour went for the low-sugar Jok’n’Al Raspberry Jam Spread.

All the jams except Anathoth and Jok’n’Al contained added pectin to help setting. This sometimes meant the jam separated into a firm jelly surrounded by a runny syrup – particularly noticeable in Pam’s Raspberry Jam and Rose’s Sweet Raspberry Gourmet Conserve.

St Dalfour “Rhapsodie de Fruit” Raspberry was the most expensive jam in the trial. It was also the least liked, with the lowest rating for taste – and some tasters found its brownish colour off-putting.

Added ingredients

To make raspberry jam at home, you simply take equal quantities of fruit and sugar and boil them together. After that it gets tricky. If you don’t boil the jam for long enough it won’t set. Boil it too long and it becomes stiff and gummy.

Jam manufacturers deal with these problems by adding other ingredients. These must be listed on the label (despite dark hints from tasters we found no mention of apple pulp, rhubarb or sugar beet).

Sugar develops the jam’s flavour by providing sweetness. Fructose (a sugar which occurs naturally in fruit) and grape juice concentrate have the same energy content (kilojoules) as ordinary table sugar but are sweeter – so manufacturers sometimes add them because smaller quantities are needed.

Sugar also inhibits the growth of bacteria. Before fridges, making jam was one of the few ways to preserve fruit. The low-sugar Jok’n’Al Raspberry Jam Spread contains a preservative to delay deterioration once the jar is opened

Pectin or calcium chloride may be added to set the jam. An acidity regulator such as citric acid also helps to form a gel.