White light, scaly crystals or granules, odorless or slightly smelly of propionic acid, easy to deliquescence in humid air. Soluble in water, slightly soluble in alcohol, insoluble in ethers, sensitive to light and heat, decomposes into calcium carbonate at 330-340℃.
Calcium propionate decomposes into propionic acid under acidic conditions. The antibacterial spectrum of propionic acid is narrower than that of benzoic acid and sorbic acid, and its antibacterial effect is slightly weaker. Calcium propionate has special effects on enzymes, but has limited effect on bacteria and no effect on yeast.
Propionic acid is obtained by reacting with calcium hydroxide and calcium carbonate.
Calcium hydroxide is generally used as raw material in industry. The calcium hydroxide is adjusted into a suspension, propionic acid is added, the reaction temperature is kept at 70-100 ° C, the reaction is carried out for 2-3 hours, and the pH value of the reaction end point is controlled at about 7-8. After decolorization, pressurized concentration, filtration, washing and drying to obtain the finished product. Calcium propionate can also be prepared from eggshells instead of industrial calcium hydroxide.
It has been reported that the optimal process conditions for preparing calcium propionate by neutralization method using eggshell as calcium source are as follows: eggshell calcination temperature is 1000℃, and after calcination time is 2h, the yield and purity of calcium oxide in ash can reach 1000℃, respectively. 93% and 95%; the eggshell will be divided into lime milk after adding water, and the conditions for the reaction of propionic acid and lime milk are: the reaction temperature is 50 ° C, the mass fractions of lime milk and propionic acid are 5% and 50%, respectively, propionic acid. Excessive 5%, reaction time 1h. Drying and dehydration at 120-140 ℃ in an electric heating constant temperature drying oven, the yield and purity of calcium propionate can reach 96% and 98% respectively.
Some studies have also shown that the use of crustacean biological resources to produce calcium propionate technology is feasible. Decolorization, filtration, concentration, drying (vacuum or spray), quality inspection, packaging, finished products.
The various indicators of calcium propionate produced by crustacean biological resources have reached the national standard, and the production process is simple and feasible, which has practical guiding significance for industrial production.
Calcium propionate is a new type of food additive developed and applied in my country in recent years. Calcium propionate is used as a non-toxic food and feed preservative, which can prolong the fresh-keeping period of food. Calcium propionate does not have the corrosiveness and irritation of propionic acid, which can avoid damage to processing equipment and operators. However, due to the influence of knowledge and habits, only a few units and enterprises in China research and produce calcium propionate, and generally use limestone ore as raw material, so the application is relatively small. In recent years, many factories have used imported propionic acid to produce propionate, which has greatly developed the application of propionate.
It is mainly used as a preservative in the food industry to prolong the fresh-keeping period of food. It has a good anti-kill effect on mold, aerobic spore-producing bacteria and gram-negative bacilli, and is harmless to yeast. This product can also inhibit the production of aflatoxin, widely used in bread, cakes, soy sauce, soy products, jams and canned food anti-mildew and preservative. Calculated as propionic acid, the maximum usage amount of calcium propionate in raw noodle wet products (cut noodles, wonton wrappers) is 0.25g/kg; in bread, vinegar, soy sauce, cakes and soy products, the maximum usage amount is 2.5g/kg.
In foreign countries, calcium propionate is also used as a feed preservative; it can also be used medicinally to make liquid, powder, cream, etc.; it also has a good effect on skin diseases caused by mold. Calcium propionate also has the effect of strengthening calcium, so it can be used to supplement calcium in foods such as bread. Calcium propionate can also inhibit the reproduction of Bacillus subtilis during dough fermentation. When the pH value is 5.0, the minimum inhibitory concentration is 0.01%, and the pH value When it is 5.8, it needs 0.188%, and the optimum pH value should be lower than 5.5.