Butyl 4-Hydroxybenzoate CAS 94-26-8

There is no doubt that butylparaben is an efficient, safe and broad-spectrum food preservative. The reason why the domestic food industry has not promoted its use is related to the physical and chemical properties of this substance. Regarding the physical and chemical properties of parabens, most of the literature has the following introduction: colorless fine crystals or white crystalline powder. Almost odorless, slightly numb tongue. The melting point is 69~72°C. Very poorly soluble in water (0.2g/L, 25°C). Soluble in ethanol (2.10g/mL), ether (2.10g/g), acetone (2.40g/g) and propylene glycol (1.10g/g). Insoluble in glycerol (0.002g/g). Among them, the two properties of slightly numb tongue and extremely difficult to dissolve in water constitute two physical and chemical weaknesses of Butyl 4-Hydroxybenzoate, which directly hinder the selection of this substance by technical personnel in the food industry. The reasons are: first, common sense of life prompts People, for most foods, tongue numbness is a peculiar smell, unless a certain food needs to have a spicy flavor. Therefore, once a food preservative is told that it has a numb tongue, the technicians in the food processing department will try to give up using this variety, so as not to affect the flavor of the food. Secondly, according to biological principles, the growth and reproduction of microorganisms is not only dependent on suitable temperature, active water is also a key factor. If a certain food is in a relatively dry state, even if it is contaminated with microorganisms, it is not easy to spoil. Therefore, most food preservatives need to be dissolved in water before they can be evenly distributed to all parts of the food, and make the moisture contained in the food unsuitable for the growth of microorganisms. Preservatives that are poorly soluble in water will become unsuitable for most foods. Although butylparaben is an efficient, safe and broad-spectrum food preservative, to be widely used in the food industry, technical means that can overcome its physical and chemical weaknesses must be found. The experimental results prove that finding the taste threshold of Butyl 4-Hydroxybenzoate and realizing the sodium salt of Butyl 4-Hydroxybenzoate is an effective way to overcome the two physical and chemical weaknesses of Butyl 4-Hydroxybenzoate.

First, experimentally determine the taste threshold of Butyl 4-Hydroxybenzoate. Any substance with taste or smell has a concentration detection range for its taste or smell. When the taste or smell of a certain taste substance is below a certain level, individuals with normal sense of taste or smell cannot detect the presence of the taste substance. Taste substances can only be perceived by most people if the taste or smell is higher than this amount. According to the threshold definition proposed by the American Society for Testing and Materials, the so-called taste threshold is the most dilute aqueous solution concentration of taste substances that people can taste. The sensory taste method was used to measure the taste threshold, and the test results were processed by statistical methods. For example, 0.08% saline solution is the lowest concentration at which 50% (or 75%) of the subjects can feel the salty taste, and it is set as the threshold concentration of table salt. Sensory tasting experiments showed that the taste threshold concentration of butylparaben was 0.012%. Accordingly, there are three ways to overcome the tongue numbness of butylparaben. One is to use butylparaben and propylparaben in combination, not only can the concentration of the former be controlled within 0.012%, but also can make the two preservatives produce a synergistic effect, improve the antibacterial strength of the preservative, and expand Bacteriostatic range of preservatives. The second is to use butylparaben in combination with other acid-type preservatives, and the concentration of butylparaben can also be controlled within 0.012%. Even if there is no synergistic effect between paraben ester preservatives and commonly used acid preservatives, at least there will be no mutual masking. The third is to use butylparaben in foods with obvious flavor characteristics, and use it as little as possible in light foods.

Second, the sodium salification of butylparaben is realized by spray drying process.

Although paraben esters are organic substances with high molecular weight, they lack water solubility. However, because its molecular structure contains a highly reactive hydroxyl group, it has very close properties to benzoic acid and sorbic acid, and it is easy to neutralize with sodium hydroxide, derivate into sodium paraben ester, and become into water-soluble substances. Its reaction formula is as follows:

The aqueous solution of paraben sodium salt is alkaline and is an unstable substance. If it is left for a long time, the hydrolysis reaction of paraben will occur, and part of the paraben in the solution will be reduced to p-hydroxybenzoic acid. . In order to prevent the hydrolysis of parabens, the method adopted by Japanese companies in the early years was to mix and use the sodium paraben solution immediately. Due to the popularization of spray drying technology in recent years, several domestic enterprises began to quickly dry the prepared sodium paraben solution into fine powder from the beginning of 2000, which not only overcomes the problem of poor water solubility of paraben, but also effectively avoids the Hydrolytic reduction of parkinyl esters. In short, the two major physical and chemical weaknesses of Butyl 4-Hydroxybenzoate have now found an effective way to overcome them, and people don’t have to follow the old ideas and hold conservative opinions on the promotion and application of Butylparaben.