Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 148

Молекулярная гастрономия для креативных шеф-поваров (англ. язык)

agent, but its use is usually limited to making jams and jellies because it will only gel in the

presence of acid and a very high sugar content.

· secondly the environment should be sufficiently acidic, (about 3.3) to help extract the pectin

during cooking, and favour its subsequent association.

· thirdly sugar should be present. The presence of sugar in the cooking medium favours the

removal of water from the cells by osmosis. The removal of water and thus turgor from the

cells damages the cells, which therefore release their pectin molecules. Equally, the presence

of sugar in the syrup means that the solution can boil at a temperature as high as 130°C, and

at this high temperature pectin is extracted more quickly. Jam should usually be cooked

covered, to prevent elimination of the volatile components that contribute to the characteristic

taste.

All these factors increase the extraction of pectin. But once the pectin has been extracted, it needs to

gel. Pectins do not gel easily - they prefer to bind to water molecules than to each other. The sugar

added in the syrup thus carries out a third role – the sugar molecules themselves bind the water

molecules, preventing the pectin molecules from binding to them, allowing them to combine more

readily with each other to form the gel.

Cook jam in a copper pot? : It is often recommended that we cook jam in copper pots. Copper is an

excellent heat conductor, so during cooking heat...

often recommended that we cook jam in copper pots. Copper is an

excellent heat conductor, so during cooking heat will be transferred quickly and evenly, causing an

even cooking process. The acidity of a jam mixture will attack the bottom of such a pan, causing

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copper ions to come off the pan and into the jam. Although copper is easily absorbed by the body, it is

only dangerous in high concentrations. In fact, these copper ions actually help to set the jam. Copper

ions have two positive charges and thus help to link two negative pectin molecules together, improving

its 3D network, and better setting the jam. Secondly, the metals ions bind to the fruit pigments,

reorganising their structure by regrouping electrons, and thus causing them to absorb different

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