(1) Choose fresh vegetables. Pickled vegetables should use fresh and mature vegetables as raw materials. Vegetables that have been piled up for a long time and have a high temperature, especially those that have turned yellow, are not suitable for use because of their high nitrite content. The content of nitrite can be reduced by washing and drying vegetables before curing. If you choose Chinese cabbage that already contains nitrite, the nitrite will almost disappear after three days of sun exposure.
(2) Salt for pickled vegetables should be appropriate. When curing vegetables, using too little salt will increase the content of nitrite and speed up the production. The experimental results showed that 3% salt had little inhibition on the fecundity of spoilage bacteria. 6% salt can prevent the propagation of spoilage bacteria, but it can reproduce lactic acid bacteria and yeast, so it can be used as the concentration of pickling fermentation. Salt 12%~15% lactic acid bacteria can't move, and most bacteria can't reproduce. It is suitable for long-term storage and pickling.
(3) Strictly control the mildew spots on the surface of pickled vegetable liquid. When pickling vegetables, strict anti-mildew measures should be taken to prevent mildew on the surface of pickling solution, such as keeping pickled vegetables from exposing the pickling surface and contacting the air as little as possible; Use clean special tools when taking vegetables; Once the pickle liquid is moldy or the mold film sinks, it must be heated or replaced with a new liquid.
(4), keep the bacterial film on the surface of pickled vegetables. Generally, the biofilm on the surface of pickled vegetable liquid should not be salvaged, let alone stirred, so as not to sink and cause the vegetable liquid to rot and produce amine substances.
(5) Preserved pickles should be sealed with film. For pickled vegetables to be stored for a long time, before mildew spots appear in the jar, cover the jar mouth with plastic film and seal it with salt mud to prevent pickled vegetables from contacting with the outside air. In order to facilitate the discharge of carbon dioxide in the cylinder, a small hole can be left on the mud cover.
(6) It is best to pickle vegetables for one month, at least not less than 2 days before eating. In addition to pickling thoroughly, pickles should be washed with water several times before eating to minimize the nitrite content in pickles.
(7) Check the pH value (pH value) of pickle liquor frequently. If the pH value of pickle liquor rises (acidity increases) or mildew is found, handle it quickly. It can't be stored any longer. Otherwise nitrosamines will grow rapidly.
(8) The water quality for pickled vegetables should meet the requirements of national hygiene standards. Pickled vegetables should never be used in well water containing nitrite.