Pickles are typical of processed foods that use salt in their manufacture. We examined a method for assuring the quality of the end product by controlling the use of salt in the manufacturing process.
In this study, we used the process for producing Japanese pickled plums as a model, and investigated how the amount of sodium chloride in the finished plum product could be controlled by the addition of salt and the type of salt that was used. We also examined how the amount of citric acid could be controlled by immersing the plums in a salt solution.
Our results indicated that the amount of sodium chloride that transferred into the fruit changed according to the difference between the sodium chloride concentration in the fruit and that in the salt water.
By adjusting the amount of salt and using different types of salt so as to vary the sodium chloride concentration of the liquid in which the plums were immersed, we showed that it is possible to control the amount of sodium chloride in the finished plum product.
On the other hand, although the citric acid concentration also changed according to the difference between the citric acid concentration in the fruit and that in the liquid, relative to the sodium chloride, the rate of transfer was low.
By making the difference between the concentration of the citric acid in the plums and that in the liquid sufficiently great, however, we found that we were able to control the citric acid concentration to a satisfactory degree.
“Kari-kari ume” is a product of Japanese apricot (ume fruit) brined mixing with calcium compounds, and its crispy texture is very unique. Ume fruit should be harvested in the early stage of maturation. It means the content of citric acid is low, and the ratio of hydrochloride acid soluble pectin to water soluble pectin is high. The concentration of calcium ions should be more than 0.16％ to the fresh fruit weight to attain sufficient crispness, but not more than 0.32％ to avoid bitterness. It is necessary for calcium ions to uniformly disperse from the peel to the end of the flesh. Polysaccharides of cell wall bounded to each other by the linkage of calcium ions provide appropriate hardness (crispness) of fruit flesh. Calcium reagents such as calcium hydroxide, calcium lactate, calcium oxide are utilized, and calcium carbonate shows less effect on hardening flesh. Various materials such as egg shell incinerated at more than 720℃ and oyster shell incinerated at more than 1000℃, which contain calcium oxide, are also utilized. The concentration of sodium chloride reached 20％ after brining, and the fruit is desalting once and then seasoned using a sodium chloride solution at a lower concentration (about 9％).
We studied the enhancing effects of citric acid and ume in a water solution and a solid on saltiness. The citric acid solution enhanced saltiness; however, its effect depended on the concentrations of salt solution and citrate. We prepared ume salt, ume powder added salt and ume vinegar added salt, and examined their enhancing effects on saltiness by means of sensory evaluation. The results were that these ume salts enhanced saltiness as well as the addition of citric acid.
A rapid and simple method for determining the total amount of cyanide in de-icing salt (sodium chloride and calcium chloride) was developed. In a sealed vial used for headspace sampling, sodium chloride was heated to liberate free cyanide from the cyanogen complexes. The amount of free cyanide that was recovered was equivalent to or greater than that possible using the official method. The free cyanide was chlorinated with chloramine-T and the resulting cyanogen chloride was quantified using a gas chromatography-mass spectrometer (with a detection limit of 0.001 mg/L). When this method was applied to calcium chloride de-icing salt, however, the recovered amount was less. The recovery of cyanide could be improved by removing the calcium through precipitation as calcium hydroxide.
To establish a method for inspecting road deicing salt, we examined a simple method for determining total nitrogen content, which is one of the markers for toxicity.
As a result, we found that the total amount of nitrogen in road deicing salt can be measured with a high degree of accuracy by using a thermal decomposition method and a total nitrogen analyzer.
Using this method, we believe that the total amount of nitrogen can be measured simply and quickly, relative to the current summation method.
To develop a method for determining the aflatoxin content of edible salt, we studied a “direct method” whereby the amount of aflatoxin in dissolved edible salt was directly measured by LC/MS, and a “desalination method” whereby the aflatoxin was measured by LC/MS after being extracted from the salt solution by an immuno-affinity column. With the desalination method, the aflatoxin was efficiently extracted from the salt solution regardless of the concentration of the solution. We applied the desalination method to determine the aflatoxin content of edible salt. We showed that aflatoxin degraded at a high pH and that aflatoxins easily adsorbed onto any insoluble matter in edible salt. To prevent the adsorption onto any such insoluble matter, the sample was dissolved in a mixed solution of 20％ acetonitrile and water. This method enabled us to determine the aflatoxin content of edible salt containing insoluble matter.
The influence of salt concentration and type of edible salt on the texture of meat gels was examined. It was found that every gel’s water holding capacity increased with salt concentration, although the change in gel strength with salt concentration differed depending on the meat gel. When the type of edible salt was varied, it was found that the purity of edible salt affected the firmness and yield of beef gel, but hardly affected the firmness, yield, or density of either chicken or pork gel. Therefore, the addition of salt prevents the separation of fat and the elution of gravy in any meat. It was found that the addition of salt to pork gel produced a soft texture, while adding it to chicken gel resulted in an elastic texture akin to that of kamaboko. Adding it to beef gel, however, did not affect the texture.