How Does A Curved Surface Gloss Meter Measure The Glossiness Of Apples?

The glossiness of apples is one of the important appearance traits and also the main economic trait. Generally speaking, apples with good color are loved by people. However, the glossiness of apples is a difficult to measure appearance parameter and it is often impossible to accurately evaluate it with the naked eye. This article introduces the method of measuring the glossiness of apples with a curved surface gloss meter.

Necessity of apple gloss measurement:

Apple is one of the fruits with the largest cultivation area and the highest yield in the world, and it is also the most common fruit in daily life. Glossiness is an important sensory indicator of apples, which can indirectly reflect the maturity, freshness and intrinsic quality of fruits and vegetables, and is also an important reference for consumers to judge the value of apples. Manufacturers use edible films to treat apples, which can not only maintain freshness, but also increase the glossiness of the fruit. Apples with high glossiness can stimulate consumers' desire to buy and have higher added value. With the development of fruit and vegetable commercialization, the glossiness of apples has become an indicator that attracts more and more attention.

Glossiness is the degree to which the surface of an object approaches a mirror. When exposed to daily light sources, apples with high glossiness will have strong mirror reflections on their surfaces. The human eye can observe that there are large reflective areas on the surface of fruits and vegetables. The detection of apple glossiness is generally completed through manual sorting, which is highly subjective and easily affected by uneven lighting conditions and the color of the apple itself. The measurement error is large and it is not suitable for large-scale glossiness evaluation, which is not conducive to large-scale classification of enterprises. With the development of photoelectric instruments, the emergence of professional gloss measurement instruments has overcome this limitation, allowing the glossiness of apples to be quantified in digital form.

YG60M Curved Surface Gloss Meter

Method for measuring the glossiness of apples using a curved surface gloss meter :

In the early days, the glossiness of apples was generally measured using a conventional gloss meter. The measuring aperture of this gloss meter could not cover the measuring surface, which easily led to inaccurate measurement results. With the development of science and technology, people have developed a small-aperture gloss meter, also called a curved surface gloss meter. This gloss meter has a small measuring aperture and can approximate the curved surface to a flat surface, which improves the accuracy of the measurement.

From the detection principle of the gloss meter, we can know that the gloss detection is to emit stable light from the light source, illuminate the object to be measured through the lens, and then reflect the reflected light back to the sensor through the lens and filter, and determine the gloss by receiving the reflected light. This objectively requires that the propagation path of light should not be disturbed by external light. The special feature of the small-caliber gloss meter is that the measuring aperture at the bottom is smaller than the conventional one, which can fit more closely when measuring the gloss of irregular (curved) surfaces. Small-caliber gloss meters are now widely used in industrial production. Some special hardware and plastic workpieces have curved surfaces or small areas, which cannot be detected by conventional gloss meters, so small-caliber gloss meters can also be used.

Take 3nh's small aperture gloss meter YG60M as an example. The instrument adopts a micro-pore design and uses a very small measurement aperture of 2x4mm, which is suitable for the detection of gloss of samples such as curved surfaces, irregular objects, and small objects. In addition, the instrument adopts a 60° universal angle design, with a measuring range of up to 1000GU, simple operation, and strong portability. It is widely used in gloss measurement and quality inspection in paints and inks, coatings, paper printing, plastic electronics, furniture, ceramics, electroplating, hardware, marble and other industries. 

The steps to use the YG60M micro-pore gloss meter to measure the gloss of apples are as follows:

1. Sample Preparation

Select representative fruits with uniform maturity and size, remove cracked fruits before measurement, wash the fruit surface with tap water or wipe it with a clean cloth to keep the fruit surface clean and free of stains.

2. Instrument startup and calibration

Turn on the instrument according to the measurement amount. After turning on, the instrument will enter the calibration interface and calibrate as required. The YG60M gloss meter has an automatic calibration function. The instrument will automatically calibrate after turning on, and you can also choose manual calibration.

3. Sample Measurement

The YG60M gloss meter was placed on the surface of the apple fruit to prevent light leakage. Multiple points were randomly selected for measurement on each fruit, and then the average value was calculated.

4. Data Analysis

The glossiness of apple fruits is graded according to the size of the glossiness value; generally speaking, when the glossiness value is higher than 35, it indicates that the apple fruit has high gloss; when the glossiness value is lower than 25, it indicates that the apple fruit is dull and has no luster; apple fruits with a glossiness value between 25-35 have a certain glossiness.