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Optical Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
A colloid is a substance consisting of particles between 1 and 1000 nm, forming a suspension in a fluid, such as smokes, fogs, foams (a substance that is formed by trapping many gaseous bubbles in a liquid or solid), aerosols (submicron to several micron particles in suspension in the atmosphere), etc., comprising a dispersed phase surrounded by a dispersion medium. A colorimeter is a device for measuring color, particularly hue, saturation, and luminous intensity. Hue is one of the main properties of a color, defined technically as the degree to which a stimulus can be described as similar to or different from stimuli that are described as red, green, blue, and yellow (the unique hues). Saturation refers to the dominance of hue in the color.
Sensing for the Color of the Perfect Tomato
Published in Denise Wilson, Sensing the Perfect Tomato, 2019
A less expensive alternative to the spectrophotometer is a colorimeter, which measures a small number of wavelength bands (colors) consistent with the human perception of color. The CIELAB color space, introduced by Commision Internale de L'Eclairage, provides a unified and standardized framework for making these color measurements along three axes of perception: light to dark (L*), red to green (a*), and blue to yellow (b*). Measurements along these three axes vary during ripening (Figure 5.2b). The ratio between a* and b* (Arias et al. 2000), the hue angle calculated from a* and b* (Hobson et al. 1983), and all three axis values (López Camelo and Gómez 2004) have been used to differentiate various stages of tomato ripening and determine the optimal time to harvest. Colorimetry in the CIELAB color space has also been successfully used for monitoring tomato firmness (Batu 2004) and total soluble solids inside the fruit itself (Saad et al. 2016).
Laboratory tutorials
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
Spectrophotometers and colorimeters make use of the transmission of light through a solution to determine the concentration of a solute within the solution. A spectrophotometer differs from a colorimeter in the manner in which light is separated into its component wavelengths. A spectrophotometer uses a prism to separate light, while a colorimeter uses filters. Both are based on a simple design of passing light of a known wavelength through a sample and measuring the amount of light energy that is transmitted. This is accomplished by placing a photocell on the other side of the sample. All molecules absorb radiant energy at one wavelength or another. Those that absorb energy from within the visible spectrum are known as pigments. Proteins and nucleic acids absorb light in the UV range. The design of the single-beam spectrophotometer involves a light source, a prism, a sample holder, and a photocell. Connected to each are the appropriate electrical or mechanical systems to control the illuminating intensity and the wavelength and for conversion of energy received at the photocell into a voltage fluctuation. The voltage fluctuation is then displayed on a meter scale, is displayed digitally, or is recorded via connection to a computer for later investigation.
Optimization of explosion puffing drying for high-value yellow-fleshed peach crisps using response surface methodology
Published in Drying Technology, 2019
Jiangfeng Song, Gorby Gonzalles, Jun Liu, Zhuqing Dai, Dajing Li, Chunquan Liu, Min Zhang
The moisture content of yellow-fleshed peach crisps was determined according to weight loss after drying 5 g samples in a forced air oven at 105 °C for 24 h. The crispness of the yellow-fleshed peach crisps was measured using a texture analyzer (CT3-Brookfield, Texture Analyzer, Brookfield Engineering Laboratories., Inc., MA) fitted with a spherical probe (P/0.25). The pretest, test, and posttest speed set at 8.0 mm/s. The deformation ratio was 80%. A force time curve was recorded and analyzed by the software of TexturePro CT V1.6 Build 26 (Brookfield) to calculate the peak force. For color measurement, the colorimeter was calibrated against a standard white plate before each actual color measurement. Mean values of three measurements for each sample were recorded by three hunter color parameters, namely, L* (lightness), a* (redness/greenness), and b* (yellowness/blueness). The ΔE value represents the total color difference between raw (L0*, a0*, b0*) and crisps (L*, a*, b*) and it was calculated according to Equation 1:[20]
Potential of Ozonated Water at Different Temperatures to Improve Safety and Shelf-Life of Fresh Cut Lettuce
Published in Ozone: Science & Engineering, 2018
Ilkin Yucel Sengun, Perihan Kendirci
Color parameters of treated and untreated samples were analyzed by using Konica Minolta CR-400 (Japan) colorimeter as described in Kramer and Twigg (1984). Lightness to darkness (L*), redness to greenness (a*), yellowness to blueness (b*), net color difference (ΔE*), chroma (C) and hue (H) values were quantified. Colorimeter was calibrated by using standard white plate (Y: 89,0; x: 0,3175 and y: 0,3346) before each measurement. Measurements were taken three times from three different parts (edge, middle and stem) of two lettuce leaves (total 18 measurements for each sample) and the average color values were calculated.
Effect of drying method on post-processing stability and quality of 3D printed rose-yam paste
Published in Drying Technology, 2021
Chunyan Feng, Min Zhang, Zhenbin Liu, Arun Mujumdar, Yuchuan Wang, Lu Chang
Colorimeter (Chroma Meter CR-400; Konica Minolta Sensing, Tokyo, Japan) was used to measure the L* (brightness), a* (redness), b* (yellowness) of dried products. L* suggests lightness, with 0 for black and 100 for white. a* is from red (positive value) to green (negative value), and b* is from yellow (positive value) to blue (negative value).[13,16,17] The calculation formulation of color difference (△E) is as follows: