Evaluation of pork color by colorimeter

The colorimeter is used to detect the difference between the colors of different objects. It generally uses the principle of filter to judge the color. The filter is made of glass or plastic and added with special dyes. The refractive index of the unstained glass is similar to that of air, and all colored light can pass through. The molecular structure of the dyed glass will change, and the refractive index is also different. The red filter can only let red light pass through, and the green filter can only let through The filter can only let green pass, and the blue filter can only let blue pass.

Now the colorimeter can detect the color information of many products, including food. Meat products are the most common food in our daily life, and controlling the quality of its raw materials is also what many manufacturers are pursuing now. The color control of early meat products was obtained by comparing the naked eye with the standard meat color plate, but this method is not perfect, and is often controlled by various factors. Therefore, the color difference instrument is becoming more and more popular in the detection of pork color.

The naked eye control meat color plate evaluation method and the color difference instrument evaluation method were used for the alignment pigs (HH), Suhuai white pigs (75% large Yorkshire pigs+25% Xinhuai pigs, SHB), and large Yorkshire pigs × Huai pig (YH), Landrace × A total of 23 pigs from 5 breeds (lines) or hybrid combinations, including Huai pig (LH) and Chang Da (DLY), were evaluated for meat color after slaughter. The results of the two methods were compared and analyzed. The results showed that the reference value of b * in the evaluation of meat color was small; When the individual meat color difference is small, such as (3.0~3.5 points), the evaluation results of the color difference instrument evaluation method and the naked eye comparison evaluation method are inconsistent; When the individual flesh color difference is large, the evaluation structure of the two methods is basically the same.

The traditional evaluation method of pork meat color is to use the naked eye to compare the meat color plate score, and take the cross section of the longest muscle in the background (also known as eye muscle) at the last rib as the evaluation site. The standard meat color plate was used to assess the normal light in the daytime 1~2h after slaughter. The standard meat color plate is 5~6 color levels (6 color levels in Japanese standard, 5 color levels in American standard), 1~2 light color (PSE meat), 3~4 normal, 5~6 deep color (DFD meat). This evaluation method is highly subjective. The results of the same meat sample and different people may differ by 0.5~1 color grade. In addition, the results vary greatly under different light conditions. In short, the color of the flesh is divided into 5 to 6 levels, and the detection results are rough and the reliability is low only by the naked eye. It is necessary to improve the detection method.

At present, foreign countries mostly use colorimeter to detect meat color. The colorimeter is a high-precision electronic instrument that can distinguish different colors. It can measure the L *, a * and b * values of pork color. Lab color space is to represent any color with the values of L *, a *, and b *. Where L * represents brightness, and the value is 0~100. The higher the value, the greater the brightness; A * and b * are positive and negative,+a * represents redness, – a * represents greenness,+b * represents yellowness, and – b * represents blueness. The L *, a *, and b * values of any color can be measured with a color difference meter, and the difference of different colors can be judged according to the measured L *, a *, and b * values. In addition, the chromaticity (C) and hue (H) can be measured simultaneously by the colorimeter. The H value can be calculated by the color difference calculation formula of LISUN colorimeter.

The use of colorimeter to determine meat color has the advantages of high data accuracy, strong objectivity, and convenient operation, which is worthy of promotion. In this experiment, the two methods of Shanghai Lishan color difference instrument and meat color plate were used to evaluate the meat color of pork at the same time, and the relationship and difference between the two methods were analyzed to provide reference for the practical application of pork color evaluation.

Experimental method:
Determination of meat color plate by colorimeter
Six color levels in the meat color plate were measured with LISUN colorimeter, and each color level was measured 10 times. The measured L *, a *, and b * values were recorded for statistical analysis to determine the average and standard deviation of the L *, a *, and b * values of the six color levels. Then get the H value according to the conversion formula, and then judge the pork quality problem according to the range of L *, a *, b *, C and H values.

Control test for meat color determination:
Slaughtering and meat color evaluation shall be conducted according to unified standards. Within 1~2 hours after slaughter, the meat color of fresh meat samples was evaluated with the meat color plate and 3nh colorimeter. The score of the flesh color plate is to compare the cross section of the longissimus dorsi at the last rib with the standard flesh color plate with the naked eye when the outdoor light is sufficient in the daytime (but avoid direct sunlight), with an accurate value of 0.5 points. The measurement method of chromatic aberration meter is to place the lens of chromatic aberration meter vertically on the longest cross section of the back at the last rib. The lens mouth is close to the flesh surface (no light leakage). Each sample is measured for 5 to 8 times. It is required to consciously distribute the measurement position evenly on the cross section of the eye muscle, record the L *, a *, b * values, calculate the degree of excellence C and the hue angle H values according to the conversion formula, and then statistically analyze the result data with SPSS software.

LISUN lauched Portable Colorimeter/Chroma Meter is an innovation color measuring tool with powerful configuration to make color measurement easier and more professional; It support Bluetooth to connect with Android and ISO devices, Portable Colorimeter/Chroma Meter will take you into a new world of color management; It can be widely used to measure color value, color difference value and find similar color from color cards for printing industry, paint industry, textile industry, etc.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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