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2025-02-18
Soy sauce is a condiment made from vegetable proteins such as soybeans or soybean meal. Color is an important appearance attribute of soy sauce and an important sensory attribute for consumers to choose soy sauce. If the color of soy sauce is unstable, it will affect the sales of the product and even have a negative impact. So, what are the requirements for the color of soy sauce? How to measure the color of soy sauce with a colorimeter? The following is an introduction.
soy sauce
Soy sauce, also known as soybean oil, sauce, clear sauce, soy sauce, etc., is a seasoning product made from plant proteins such as soybeans or soybean meal as the main raw materials, supplemented with starchy raw materials such as flour, wheat flour or bran, and fermented by microorganisms. It is rich in various amino acids and nutrients and has a special color, aroma, taste and body. During the soy sauce brewing process, due to the synergistic effect of various microorganisms, the macromolecular substances in the raw materials are decomposed into low-molecular compounds. Not only does it improve the bioavailability of the product, but these low-molecular substances are combined with each other, and multi-level conversion forms a wide variety of flavor, aroma and color substances in soy sauce.
Soy sauce is one of the indispensable condiments in the cooking process. Its main functions are seasoning and coloring. The coloring property of soy sauce is given by the safe and non-toxic brown-red pigment formed during the brewing process of soy sauce. When cooking, especially when cooking braised, braised, stewed and other dishes, adding soy sauce can play the role of coloring, fixing and enhancing the color, making the finished dish ruddy and bright, with attractive color and increasing appetite.
As the main condiment for Chinese people, soy sauce plays a very important role in people's daily life. With the continuous improvement of people's living standards and the gradual development of the market economy in recent years, higher requirements have been put forward for the flavor quality of soy sauce. However, due to the limitations of eating habits and professional knowledge, people often put color first among the color, aroma, taste and body of soy sauce. In order to accurately measure the color of soy sauce and control the color quality of soy sauce, a colorimeter can be used.
Spectrophotometers for measuring liquids
Chinese Soy Sauce Hygiene Standard also gives a brief description of the sensory inspection of soy sauce color: take 2mL of sample in a 25mL stoppered colorimetric tube, add water to the scale, shake and observe the color and clarity, which should be clear and free of sediment; some researchers also use the direct colorimetric method with colorimetric plates, and the descriptive terms used are mainly: thick, light reddish brown or yellowish brown, bright, glossiness, brightness, etc., and use the scoring method to compare the quality. However, the comparative ranking method or other sensory inspection methods can also be used. However, these sensory evaluations are mostly qualitative descriptions, which are affected by people's preferences, sensory sensitivity, psychology, etc. Therefore, the sensory evaluation method is not accurate. In order to accurately measure the color of soy sauce and quantify the soy sauce color data, a liquid colorimeter can be used.
Liquid colorimeter is a common color measurement instrument. It uses the standard light source inside the instrument to illuminate the object to be measured, performs an integral measurement in the entire visible light wavelength range, and obtains the L, a, and b values of the color of the transmitted or reflected object. In the color system CIELAB, L* represents lightness, called the lightness index, L*=100 represents white, L*=0 represents black, and there are 100 levels in between, representing different grayscales. The larger the value, the better the brightness of the soy sauce color and the lighter the black. a* is chroma, +a* represents red, -a* represents green; b* is hue, +b* represents yellow, -b* represents blue; through data conversion, we get: chroma C*=(a*2+b*2)1/2; hue angle h=tan(b*/a*), the larger the absolute value of a*, b*, c*, the more saturated and pure the color.
Compared with the visual method, the color difference method for detecting the color of soy sauce converts the perceptual index into a rational index, which is more accurate and stable. It can be applied to analytical testing and more accurately feedback the fluctuation of color index. Its specific applications are as follows:
1. Detect the accuracy of soy sauce color
In the process of soy sauce production, a variety of different ingredients can be added to achieve the ideal taste, color and other quality requirements. However, in production, due to different batches of raw materials or improper human operation methods, the stability of soy sauce is often adversely affected. Therefore, applying colorimeter detection technology to the detection of soy sauce color will promptly detect whether there is color difference between different batches of soy sauce, so as to adjust the soy sauce production process in advance.
2. Check the color quality of soy sauce before leaving the factory
Newly produced soy sauce can be packaged and shipped after being left for a period of time. Before shipping, the soy sauce should also be tested for color. During the storage process, the soy sauce may lose its gloss, precipitate or fade due to temperature, light, fading of the production container and ingredients themselves. Therefore, color testing is particularly important. Through testing, we can clearly know whether the soy sauce meets the quality standards and whether it can be packaged and shipped.
3. Provide a basis for the shelf life of soy sauce
Maintaining its own color stability is an important indicator of the stability of soy sauce quality. After the product is put on the market, the color stability of soy sauce will be affected by temperature, light and the fading of the pigment itself. If the product is collected regularly, its color difference value is tested, and the degree of fading is observed, it will provide a reliable basis for determining the shelf life of the product.
