Green preservation of pickled vegetables
During the pickling process, vegetables gradually lose their green color, turning yellow-green or gray-green, or even yellow-brown, which greatly reduces the color quality of pickled products. This color change is called chlorosis, which is caused by the properties of chlorophyll itself. decided. Chlorophyll can remove magnesium ions under acidic conditions and is replaced by hydrogen ions to form pheophytin and lose its green color. However, under alkaline conditions, alkaline substances can alkalinize chlorophyll ester bases to generate chlorophyllate and keep green . When pickling weakly fermented pickles, because the water contained in the vegetables is weakly acidic (about pH 6), if the acid water is not discharged and salted, the acidic vegetable water will turn the chlorophyll into pheophytin. The original bright green is also lost.
For example, kimchi and sauerkraut produce lactic acid due to fermentation. Under acidic conditions, the green color of the raw vegetable itself cannot be maintained and becomes chlorosis, making the product appear yellow-green and yellowish brown. On the contrary, if the pickles or pickles are properly treated with alkaline substances, they can keep green. For example, when pickling cucumbers, first soak the cucumbers in slightly alkaline water with a pH of 7.4 to 8.3, change the water several times, and then pickle them with salt; or when pickling cucumbers, in the salt solution Adding appropriate amount of weakly alkaline substances such as lime milk, sodium carbonate, sodium bicarbonate or magnesium carbonate, etc., can keep the green of pickled cucumbers.