0086 18165740359Fish color measurement is crucial in the aquaculture industry because color directly reflects the freshness, quality, processing status and consumer acceptance of fish. The following is a detailed discussion of fish color measurement, covering its importance, measurement methods, practical applications and precautions.
The meaning and importance of fish color
The color of fish meat is mainly determined by myoglobin, fat content and processing process. Myoglobin and hemoglobin in fish muscle form the basis of color, and their degree of oxidation directly determines the color change. During cold chain transportation, a temperature fluctuation of 0.5°C will cause the myoglobin oxidation rate to double, causing the brightness of the fish meat (L value) to drop rapidly . Malondialdehyde produced by fat oxidation combines with protein to form fluorescent substances, causing the yellow-blue value (b*) to shift. Hydrogen sulfide produced by microbial metabolism combines with myoglobin, causing gray-green patches to appear on the surface of fish meat. This color change often occurs 12-24 hours earlier than the odor.
The color change reflection can be summarized as follows :
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Fresh fish: Usually white, pink or light red (such as salmon, trout), indicating freshness and lack of oxidation.
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Processed fish: Fish that has been cured, smoked or frozen may appear off-white, brown or orange and needs to maintain consistency.
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Spoiled fish: may turn dark or yellow after prolonged storage or oxidation, indicating a decline in quality.
How to measure fish color?
Fish meat is usually an opaque solid sample, so a reflected light measurement method is required. It is recommended to use a professional spectrometer or colorimeter, such as the instrument provided by 3nh. The following are the specific measurement steps:
1. Sample Preparation
Select fresh or processed fish samples (e.g. salmon, herring, cod) and cut into thin, flat slices (5-10 mm thickness is recommended).
Make sure the sample surface is clean and free of scale, fat or excess moisture that could interfere with the measurement.
If there is frost on the surface of the fish (frozen fish), it needs to be thawed naturally and wiped dry before measurement to avoid moisture influence.
2. Instrument selection and calibration
3nh offers a variety of instruments suitable for fish color measurement. The following are recommended equipment and their features:
NS800 Spectrophotometer 45°/0°
Features: Portable design, lightweight and portable, convenient for on-site measurement, meeting the needs of different working environments. 45/0 optical geometry, supports a variety of color indicators and light sources, good repeatability.
Application scenarios: It can be used for detailed studies of meat color changes, such as the effects of oxidation, aging or processing on color.
Features: Equipped with a large 20mm aperture, suitable for measuring uneven surfaces with high accuracy.
Applicable scenarios: Especially suitable for large pieces of meat or meat products with irregular surfaces (such as steaks and sausages) to ensure color consistency detection.
Features: Portable instrument, provides spectral data, high measurement accuracy.
Applicable scenarios: Suitable for high-precision analysis of meat color, such as fat content, doneness or color change after pickling, and can be used in quality control and research laboratories.
3. Measurement and recording
the selected 3nh instrument , place the measuring port close to the meat surface and press the measuring key. The instrument captures the color of the meat surface through reflected light and generates L * a * b* values:
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L * value: Lightness (0-100, with high values indicating brighter colors and low values possibly indicating spoiled meat).
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a* value: red-green hue (positive values indicate a reddish tint, negative values indicate a greenish tint, and fresh meat is usually reddish).
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b* value: Yellow-blue hue (positive values indicate a yellowish tint, negative values indicate a bluish tint, used to assess subtle color differences in meat).
Record the Lab* value for each measurement. It is recommended to take the average value of multiple measurements to improve accuracy.
4. Environmental Control
Measure in a room without direct light to avoid interference from light sources. Keep the measurement environment temperature stable (20-25°C is recommended) and ensure that the sample surface is dry.
Common problems and solutions in measurement
Problem 1: Surface moisture or frost
Impact: Moisture or frost can change the reflected light, causing distorted color readings.
Solution: Thaw the fish naturally and gently wipe the surface of the sample with an oil-free paper towel to make sure it is dry before measuring.
Problem 2: Sample is not uniform
Impact: Uneven distribution of fat, skin or scales may interfere with color measurement.
Solution: Select a uniform area of fish flesh for measurement, or take samples from multiple points and average the results.
Problem 3: Ambient light interference
Impact: External light may change the measurement results.
Solution: Perform measurements in a dark room or a stable light-controlled environment.
Problem 4: Fish is spoiled or oxidized
Impact: Long-term storage causes the color to darken or turn yellow, affecting the judgment of freshness.
Solution: Measure fresh samples as soon as possible, or record measurement time and storage conditions to assess the extent of oxidation.
In short, fish color measurement is a key link in quality control and consumer trust in the aquaculture industry. By using professional instruments such as NR20XE, TS7600 and NS800 from 3nh, combined with L * a * b * value analysis, producers can accurately evaluate the freshness and processing quality of fish to ensure product consistency and market competitiveness. Whether it is solving practical problems in measurement or looking forward to the trend of intelligence, this technology provides strong support for fish production.
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