Making Potato Jam

Frozen-storage spinach can be divided into two types: ordinary frozen storage and ventilated cool storage.

(1) Ordinary frozen storage method: choose a shaded, dry place, set up a shade barrier along an east-west orientation, and dig one or several trenches within the shaded area on the north side of the barrier. Their specifications vary with the regional climate conditions. In the Beijing area, the trench depth is mostly about 15 cm, and the width depends on the size of the spinach bundles and the quantity placed, generally about 30 cm. Then spread a layer of fine sand on the bottom of the trench. Wait until the temperature steadily drops below 0°C, then bundle the spinach into bunches and place them in, immediately covering with a layer of fine sand. As the weather gets colder, cover with soil in stages; the thickness and number of soil coverings depend on the regional climate conditions. In the Beijing area, soil is mostly applied in 2 to 3 rounds, with a total thickness of 17 to 20 cm. In severe cold seasons, straw mats can be added on top to ensure the temperature in the trench is -6 to 8°C, so that the leaves freeze but the roots do not freeze.

(2) Ventilated trench frozen storage method: this method is basically the same as the ordinary frozen storage method. The difference is that the trench is 12 to 15 cm deep and 100 to 200 cm wide. Along the bottom of the trench, dig 2 to 3 ventilation channels each 20 cm deep and 20 cm wide, and lay a single layer of sorghum stalks across the ventilation channels. Place spinach on top, then apply a thin layer of covering over the spinach, and later cover in stages. The soil-covering method is the same as the ordinary frozen storage method. The ventilation channels in the trench are exposed above ground and should be opened at first to help lower the temperature so the spinach freezes, then gradually blocked as the weather gets colder. After the beginning of spring, as the ground temperature rises, gradually remove the straw bundles from the ventilation channels.

Before the frozen-stored spinach is marketed, take it out of the trench and place it in a vegetable cellar or indoors at slightly above 0°C for 3 to 5 days to thaw naturally. After it has fully recovered, sort it and sell it.