Cold-stirred jams

The advantage of cold-stirred jams is that the fruit flavour is retained better than in boiled products. The disadvantage is the shorter shelf life. Cold-stirred jams cannot be kept for more than 1 month under refrigerated storage conditions. They should therefore be produced as and when required. 

Cold-stirred jams can also be kept frozen. It is preferable, however, to freeze the fruit and make the jam from day-to-day in small batches. 

Selenium [7782-49-2] M 79.0, m 217.4°, d 4 4.81. Dissolve selenium in small portions in hot cone HNO3 (2ml/g), filter and evaporate to dryness to give selenious acid which is then dissolved in cone HCl. Pass SO2 gas through the solution whereby selenium (but not tellurium) precipitates. It is filtered off and washed with cone HCl. This purification process is repeated. The selenium is then converted twice to the selenocyanate by treating with a 10% excess of 3M aqueous KCN (CARE), heated for half an hour on a sand-bath and filtered. Add an equal weight of crashed ice to the cold solution, followed by an excess of cold, cone HCl, with stirring (in an efficient fume cupboard as HCN is evolved) which precipitates selenium powder. This is washed with water until colourless, and then with MeOH and is heated in an oven at 105°. Finally it is fused for 2 hours in vacuo. It is cooled, crashed and stored in a desiccator [Tideswell McCullough JAm Chem Soc 78 3036 1956]. 

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