Tristimulus Color Research Articles

Standardization of vacuum frying techniques for the development of low-fat beetroot finger chips

Beetroot (Beta vulgaris L. ssp), is a popular root crop grown for its fleshy roots and is a nutritious and mostly consumed fresh vegetable. It is a perishable product of just two to three days after the mature stage. The beetroot can be used for the preparation of value-added products like juice, dehydrated powder, soup mix, chips, etc. The chips out-turn of beetroot finger chips under vacuum frying was about 20 %. The vacuum-fried beetroot finger chips with corn powder coating absorbed relatively less frying oil (16.79 %) when compared to those without corn powder coating chips (18.25 %). The tristimulus color of vacuum-fried beetroot finger chips with corn powder coating chips were improved. Among the vacuum-fried chips prepared under various combinations of vacuum (constant 640 mm Hg), frying temperature (3 levels), and frying duration (3 levels), it was found that the beetroot finger chips prepared with corn coating at 110 °C frying temperature for 15 minutes frying time were the best in terms of all quality parameters. The beetroot finger chip manufacturing cost was determined to be Rs. 235 per kg, and the benefit-cost ratio of production was found to be 1:1.70.

Optimization of Execution Microscopic Extrusion Parameter Characterizations for Color Polycarbonate Grading: General Trend and Box–Behnken Designs

This research article concentrates on process conditions in addition to improving color selections in polymer compounders and developing more accurate simulation models. The feed rate (FR), temperature (T) and screw speed (SS) are three processing variables that the research investigates using general trends (GTs) and Box–Behnken design (BBD) response surface methodology. The identical set of processing settings was tweaked at three separate phases independently of one another. This study uses the experimental design to investigate process parameters’ optimization while holding all other parameters constant. This design was given the name GT. To develop this design and its statistical optimization, this study used the software of the design expert method. A regression model was run in this design, which displayed collective as well as individual effects of the parameters on color images. The values of tri-stimulus color with the best optimization had the smallest proper color variance (dE*). To obtain information on pigment characteristics, an SEM image analysis was conducted, which aids in improving future designs and overcoming manufacturing issues that affect color fluctuation properties and waste reduction for various chemical grades, both of which enhance environmentally friendly processes.

A non-contact colour correction system on mobile display under various light sources

Human recognize perceived color on the display device of a smart phone under various types of light sources and illuminance differently even though the display represents the same color. This study investigated the relationship between input RGB code and output color tristimulus (XYZ) on two types of smartphone displays under various types of light sources and illuminances. A non-contact color correction system to transfer similar color with actual object was then proposed under various types of light sources and illuminances. Furthermore, the color correction model was validated by input color RGB predicted for representing the desired color and a survey test on displays of two types of smartphone, iPhone 13 Pro and Galaxy S22.

Use of an Integrating Cavity Spectrometer to Easily Determine Beer SRM Color Without Filtration, Centrifugation or Numerical Correction

Quantification of beer color of craft unfiltered, hazy, seltzer, and fruited beer styles can be problematic due to turbidity and unconventional ingredients. A novel integrating cavity spectrometer (ICS), designed to eliminate the effect of light scatter by the sample was employed to determine if it was able to more accurately quantify beer color compared to a conventional scanning spectrophotometer (CSS). A CSS was employed to measure the absorbance and transmission of 15 filtered and unfiltered craft brewery beer samples to determine the SRM color value and tristimulus color values. The ICS measures absorbance with a 430 nm LED to determine the single-point SRM value for each beer. The SRM values of unfiltered or 0.2 µm filtered beer samples were compared using Bland-Altman analysis and regression fits. Filtered and very clear beers showed strong agreement between the methods and Bland-Altman analysis confirmed their equivalence, particularly for SRM <25. Using the ICS alone, filtered beer versus unfiltered beer showed highly correlated values and narrow limits of agreement, successfully negating the effects of turbidity. In conclusion, SRM determination by ICS is equivalent to standard spectrophotometer single-point methods and superior in accurately determining the SRM color of hazy beers without filtration or centrifugation.

Box-Behnken Design for Polycarbonate-Pigment Blending: Applications and Characterization Techniques.

Incorporating pigments into polymers can be done for various purposes, including the introduction of color, interfacial effects, or aesthetics. If these pigments are to disperse properly, then the process of extrusion must be optimized. During polymer compounding extrusion, three effective processing factors were investigated: feed rate (FR), speed (Sp.) and temperature (temp.) for a colored compounded polycarbonate (PC) grade (30/70%). The processing design techniques were obtained by applying design experiments in a response surface methodology (RSM) to blend two polycarbonates with pigments and optimize the processing temperatures at center points. The first study decided to utilize the response surface approach of Box-Behnken design (BBD) to design an experiment to optimize the process parameters. Statistical significance was demonstrated by the model passing all diagnostic tests. Furthermore, the three processing factors strongly impacted the characteristics of the tri-stimulus color, according to the results from a variance analysis. The second study identified process variables for the same PC grade at the center level, 25 kg/h FR, 750 rpm speed, and (255 °C) temp. The characterization and scanning morphology were examined using MicroCtscanner image analysis, SEM, DOM, rheology, FT-IR, and color-pigmented values were measured using a color spectrometer. The output response was significantly impacted when excellent color dispersion was observed with few agglomerates and less differences in colors at the center point. By characterizing these results and having good insight into color difference output and processing condition relationships, which have an adverse effect on color variation characteristics and minimize recycling compounds of different grades, results in cleaner environments benefits.

Roast level and brew temperature significantly affect the color of brewed coffee.

Beverage color significantly affects perceived sensory quality and consumer preference. Although the color of coffee beans is well known to vary strongly with roast level, little work has examined how roast level and brewing conditions affect the color of the final beverage. Here, we report that the color of full immersion brewed coffee is significantly affected by both roast level and brewing temperature. Coffees from three different origins were each roasted to three different levels (light, medium, and dark) and then brewed at three different temperatures (4, 22, and 92°C). Each sample was brewed toward full extraction and then diluted to precisely 2% total dissolved solids so that differences in concentration would not confound color measurements. Absorbance spectra (UV‐vis) and color tristimulus values (L*a*b*) were then collected and analyzed. We find that roast level had the strongest impact on brew color, and that brew temperature had a significant impact on color for light and medium roasts, with less impact on dark roasts. Qualitatively, the cold brewed coffees tended to be redder, while the hot brewed coffees were blacker. The results suggest that there is an opportunity to manipulate and brand brewed coffee color through judicious choices of roast level and brewing temperature.Practical ApplicationColor serves as an indicator of coffee quality and potentially could affect perceived sensory characteristics. Our results suggest that appropriate control of roast level and brew temperature could yield desired colors for novel coffee products.

An Integrative Simulation for Mixing Different Polycarbonate Grades with the Same Color: Experimental Analysis and Evaluations

The processing parameters’ impact such as temperature (Temp.), feed rate (F.R.), and speed (S.) at three distinct grades of the same color was explored in this study. To investigate the effect of the characteristics on color formulations, they were each adjusted to five different levels. For these grades, which were all associated with the same color, an intermeshing twin-screw extruder (TSE) was used. The compounded materials were molded into flat coupons then evaluated with a spectrophotometer for their CIE (L*, a*, b*, and dE*) values. A spectrophotometer was used to determine the color of a compounded plastic batch, which measured three numbers indicating the tristimulus values (CIE L*a*b*). The lightness axis, which ranged from 0 (black) to 100 (white), is known as the L*-axis (white). Redness-greenness and yellowness-blueness were represented by the other two coordinates, a* and b*, respectively. The color difference deviation (Delta E*) from a target was dimensionless, when dE* approached zero. However, the most excellent favorable color difference value occurred and different processing impact factors on polycarbonate grade were investigated. Using the response service design (RSD) software of Stat-Ease Design-Expert® (Minneapolis, MN, USA), historical data were gathered and evaluated. To reduce the value of dE*, the impacts of these processing factors were investigated with the three processing parameters. The whole tristimulus color value could be simulated. Parameters were adjusted on 45 different treatments, using a five-level controlled response method to investigate their impact on color and detect non-optimal responses. The ANOVA for each grade was used to build the predicted regression models. The significant processing parameters were subjected to experimental running to simulate the regression models and achieve the best color, reducing waste.

Influence of bioprocessing treatments on phytochemical and functional properties, in vitro digestibility, protein secondary structure and morphological characteristics of Indian barnyard millet flour

SummaryThe objective of the present investigation was to assess the effects of different bioprocessing treatments on Indian barnyard millet (Echinochloa frumentacea) at preliminary optimised conditions including soaking (12 h at 25 °C), germination (48 h at 25 °C), lactic acid fermentation (20 h at 38 °C) and combination of aforesaid treatments. Anti‐nutritional factors were significantly (P &lt; 0.05) lowered (5–70% reduction) during different treatments. Enhanced enzymatic activity further resulted in liberation of bound phytochemical compounds (phenolic acid and flavonoids) in addition to their synthesis, which enhanced the antioxidant potential by several folds. Variation in the hydrophobic‐hydrophilic characteristics of barnyard millet flour during given treatments modified the techno‐functionality in terms of hydration properties, surface characteristics, gelation and tristimulus colour parameters. In vitro starch and protein digestibility were significantly (P &lt; 0.05) improved from 6.49 to 23.65 mg maltose released per 100 g and 72.21 to 80.48 g hydrolysed protein per 100 g, respectively. Morphological changes as revealed by scanning electron microscopy showed that bioprocessing of barnyard millet flour disrupted the starch‐protein matrix, cell wall constituents and starch‐fibre association which made the protein and starch molecules susceptible to in vitro digestibility conditions. Further, Pearson’s correlation matrix was employed to determine the relationship among different observations.

Temperature Effect on the Physical Properties of Enamel Paint Layer on Cement Plaster

The heating effect on the stability and visual colour of enamel paint on cement plaster is evaluated through light intensity ratio of three primary colours (RGB). The painted cement plaster is isochronally heated in an electric resistance furnace at different temperatures for one hour. The investigation of optical images reveals that the original colour of the paint layer on the plaster samples remains more or less unchanged up to heating at 100°C. However, thermal degradation of the samples becomes evident in colour when they are heated beyond 200°C and at 350°C the colour becomes already burned. The microstructural images of the samples at room temperature show fine and uniform grains. But at higher heating condition the microstructure of the colour sample is characterized by coarsening grain. The colour of the heated samples are then studied through tristimulus colour ‘L*’, ‘a*’ ‘b*’ and ‘E*’ values which were analyzed and evaluated in MATLAB software. The results show that after 200°C the hunter ‘L*’ value starts to decrease greatly up to 250°C. The hunter ‘a*’ value shows an increasing trend up to 100°C and then begins to decrease until 200°C. After 200°C the same increasing character is showed till 300°C. The change of hunter ‘b*’ value remains insignificant up to 100°C and shows decreasing trend between 100°C-250°C range and an increase after 250°C up to 300°C. It is graphically shown that the proportion of all three colours decreases with the increasing temparature. The overall change of colour ‘E*’ occurs with increasing heating temperature due to moisture releasing, chemical changes and thermal degradation simulteneously. The thickness of enamel paint layer comply the above degradation by showing the nature of decresing trend.&#x0D; Journal of Engineering Science 12(2), 2021, 103-108

Preview the Products on Display at Display Week 2021

Preview the Products on Display at Display Week 2021

New Freeze-Dried Andean Blueberry Juice Powders for Potential Application as Functional Food Ingredients: Effect of Maltodextrin on Bioactive and Morphological Features.

Andean blueberry (Vaccinium meridionale Swartz) fruits are an underutilized source of anthocyanins and other valuable bioactive phytochemicals. The purpose of this work was to obtain Andean blueberry juice powders via freeze-drying processing and evaluate the effect of maltodextrin as a drying aid on their physicochemical, technological, microstructural, and bioactive characteristics. Andean blueberry juices were mixed with variable proportions of maltodextrin (20–50%); freeze-dried; and characterized in terms of their tristimulus color, Fourier transform infrared spectra (FTIR), moisture content, water activity, morphology, water solubility, flow properties, total polyphenols and anthocyanins content, and DPPH•-scavenging capacity. The powders obtained presented suitable characteristics in terms of their water activity (<0.5), solubility (>90%), and bioactive compound recovery (>70% for total phenolics, and >60% for total monomeric anthocyanins), with antioxidant activities up to 4 mg equivalent of gallic acid/g of dry matter. Although an increased content of maltodextrin resulted in lower concentrations of phytochemicals, as expected, it also favored an increased % recovery (over 90% of total phenolics at the highest maltodextrin proportion) and improved their flow properties. Freeze-dried juice powders are a potential alternative for the stabilization and value addition of this fruit as a new source of functionality for processed foods.

Physical Behaviour of Thermally Affected Bronze and Brass

The physical behavior of thermally affected cast copper, aluminium bronze and brass has been studied by subjecting to heating isochronally for one hour at a range of 600°C. It shows that solid-solution hardening takes place into the Al added bronze and Zn added brass metal. Due to heating Al forms hard and brittle intermetallic of copper aluminites into bronze metal which responses some age hardening effects. The electrical conductivity of the metals increases initially through heat treatment due to stress relieving and finally decreases due to formation of intermetallic precipitates. The color of the heated samples are also studied through tristimulus color ‘L*’, ‘a*’ and ‘b*’ values which were analyzed and evaluated in MATLAB software. It is found that incorporation of Al and Zn affects the colour of cast Cu. The overall change of color occurs with increasing heating temperature due to chemical changes like oxidization, intermetallic formation, dissolution of phases, precipitation coarsening and recrsystallization. Due to change of hardness and microstructural properties of the experimental metals the sound intensity level also decreases at high heating temperature. A microstructural study confirms that the cast alloys contents the different phases of grains and bring about re-crystallized state after heating at 500°C for one hour.

A comparative study of chemical and physical properties of copper and copper alloys affected by acidic, alkaline and saline environments

Chemical and physical behavior including corrosion performance, thermal conductivity and visual color change of the copper-based alloys brass and bronze have been studied prior and after corrosion in acidic, alkaline and saline media. The concentrations of 0.5 M H2SO4, 0.5 M NaOH and 0.5 M NaCl were used in which copper and copper-alloy samples were immersed and left to corrode at room temperature for 28 days. The experiments were performed prior and after corrosion, using conventional gravimetric measurements accompanied with measurements of thermal conductivity, microstructure and optical properties. The color change of different samples was also studied through tristimulus color parameter (L*, a* and b*) values. It is concluded that the corrosion rate of copper and copper alloys is greater in acidic than in salt and alkaline media. This is due to the extent of disruption of the passive film formed on the surfaces. In the cases of alkaline and salt media, the passive films on the surface remain stable to a large extent. Small increase of thermal conductivity takes place due to formation of a very thin film of oxide and hydroxide bonded to the surface. The environment also affects the color of copper and copper alloys by chemical changes like oxidation and formation of different intermetallics on the surfaces. A microstructural study of experimental materials confirms that corrosion after 28 days results in formation of pores on the surfaces in acidic environment, and passive film that grows thicker on the surfaces in alkaline and saline environments. Aluminum oxide that is more stable than zinc oxide causes better anti-corrosion performance and minimal color variation of bronze compared to brass, especially in acidic environment.

Development and quality evaluation of banana‐rice‐bean porridge as weaning food for older infants and young children

AbstractAmong low‐income families in developing countries, foods fed to infants and young children are rich in carbohydrates but limiting in protein and important micronutrients. Our objective was to develop a high‐protein weaning food (porridge), with enhanced nutritional contents and acceptable sensory attributes. Cooked light red kidney beans and brown rice and semi‐ripe Cavendish bananas were air‐dried (60°C, 8–16 hr) and milled into flours to formulate seven banana‐rice‐bean (BRB) porridge premixes; 80:10:10, 70:10:20, 70:20:10, 60:25:15, 55:20:25, 50:30:20, and 45:40:15 BRBs, respectively. The premixes were analyzed for nutritional (protein, dietary fiber, resistant starch, minerals) and physical properties (moisture, color, density, water solubility, oil and water absorption capacity). Four prepared porridges were evaluated for selected sensory attributes by 31 African/Asian mothers. All BRB porridge premixes met the World Health Organization recommended levels of protein for complementary foods (5.70–8.52 g/100 g). Resistant starch and dietary fiber contents were 6.35–9.21 and 10.1–11.82 g/100 g, respectively. The oligosaccharide (raffinose, stachyose) ranged from 0.19 to 0.46 mg/g and 3.49–6.27 mg/g, respectively. The Tristimulus color values showed a mixed trend, with significant differences among porridges for CIE L*and a* values and Hue angle, whereas no differences were observed for CIE b* value and Chroma. The sensory quality of all prepared porridges was shown to be acceptable, with scores of 6.5–7.1, on a 9‐point Hedonic scale. Twenty‐nine panelists indicated that they would feed BRB porridge to a child under 5 years old. Overall, the results of this study demonstrated that the BRB porridge could be used as a nutritious weaning food.

Digital photography as a tool for microscale mapping of soil organic carbon and iron oxides

Digital cameras are becoming increasingly popular in environmental sciences and proximal soil sensing as low cost, but high quality and high-resolution sensors. The high spatial resolution of the images shows a great potential for mapping predicted soil properties at small scales, from soil profiles to the microscale. To explore the potential of digital cameras for the morphometric analysis at a fine scale, we took 50 samples plus 3 microplate scale excavations from a profile wall of a Luvisol and analyzed samples for soil organic carbon (SOC) and Fe content for model calibration. Images of sieved and ground soil samples were taken under standardized laboratory conditions. After image correction, RGB colors were obtained for each sample and transformed into different color space models. Based on the obtained soil colors, different regression models were built to predict SOC and Fe content. Simple regression produced predictions with R2adj values of 0.90 for SOC (using HSV V) and 0.70 for Fe (using CIE a*) for ground soil samples. For sieved samples, R2adj values were lower with 0.69 for SOC using HSV V and 0.61 for Fe using CIE a*. Multiple linear regression models with interaction terms could improve those predictions for sieved samples to R2adj values of 0.94 for SOC and 0.89 for Fe, using the complete HSV and CIELab color tristimulus, respectively. Based on the best pedotransfer functions, we predicted SOC and Fe contents for the excavated microplates at a 1 × 1 mm resolution. With this method we were able to map the microscale variability of SOC and Fe content with great accuracy. This study showed, that accurately calibrated digital images can be a cost-effective method to map the distribution of SOC and Fe and potentially other soil physical and chemical parameters at a very fine scale.

Narrowband angle filter.

Narrowband pass filters are generally poor as narrowband angle filters. A tilted narrowband pass filter, however, is an improved narrowband angle filter, but only for rays in one plane of incidence. It is shown that a combination of two tilted narrowband pass filters will select light from all narrow angle patches in an incident cone. Furthermore, a design is presented for a narrow-angle filter for three wavelengths, enabling transmission of tristimulus color gamut images, while rejecting out-of-band sources and off-angle sources.

Using moments to represent bounded signals for spectral rendering

We present a compact and efficient representation of spectra for accurate rendering using more than three dimensions. While tristimulus color spaces are sufficient for color display, a spectral renderer has to simulate light transport per wavelength. Consequently, emission spectra and surface albedos need to be known at each wavelength. It is practical to store dense samples for emission spectra but for albedo textures, the memory requirements of this approach are unreasonable. Prior works that approximate dense spectra from tristimulus data introduce strong errors under illuminants with sharp peaks and in indirect illumination. We represent spectra by an arbitrary number of Fourier coefficients. However, we do not use a common truncated Fourier series because its ringing could lead to albedos below zero or above one. Instead, we present a novel approach for reconstruction of bounded densities based on the theory of moments. The core of our technique is our bounded maximum entropy spectral estimate. It uses an efficient closed form to compute a smooth signal between zero and one that matches the given Fourier coefficients exactly. Still, a ground truth that localizes all of its mass around a few wavelengths can be reconstructed adequately. Therefore, our representation covers the full gamut of valid reflectances. The resulting textures are compact because each coefficient can be stored in 10 bits. For compatibility with existing tristimulus assets, we implement a mapping from tristimulus color spaces to three Fourier coefficients. Using three coefficients, our technique gives state of the art results without some of the drawbacks of related work. With four to eight coefficients, our representation is superior to all existing representations. Our focus is on offline rendering but we also demonstrate that the technique is fast enough for real-time rendering.

Physicochemical, Thermal and Rheological Properties of Native and Oxidized Starch from Corn Landraces and Hybrids

Native starch was isolated from three corn landraces and a hybrid variety. The starches were oxidized with several concentrations of NaOCl (0.8, 2 and 5% w/w active chlorine). The physicochemical and functional properties of oxidized starches were compared with those of native starches of the same source. The oxidation treatment increased the content of carboxyl and carbonyl content in the starches confirming that NaOCl effectively oxidized the polysaccharides. The oxidation treatment decreased the content of non-starch components and increased the whiteness (L* values of tristimulus color) of starches. The oxidation also increased the water retention capacity of starches. The values of the thermal and rheological properties of starches decreased as the oxidation intensity increased. The high number of carbonyl and carboxyl groups in oxidized starches favored starch depolymerization and increased the affinity of starch for water. The crystallinity of starches was not affected by oxidation, where the most intense diffraction peaks in both native and oxidized corn starches were observed at 2θ = 15, 17, 18 and 23°. The hardness of starch gels decreased with oxidation.

An application of spectrophotometer for ADMI color measurement

The ADMI color scale is developed to measure the color of wastewater as an indicator of water quality. ADMI color is a metric quantity based on the Adams Nickerson color difference between the APHA/Pt-Co/Hazen liquid standards and distilled water. The Adams Nickelson color formula is obtained by transforming CIE tristimulus color indices into a uniform metric color scale that is independent of hue. If two colors of different hues are different to the same degree from the reference colorless water, then the difference will be the same. For a general purpose spectrophotometer with a measuring range of 360 nm to 830 nm and the wavelength resolution of 1 nm, we developed an ADMI color application based on APHA 2120F weighted-ordinate spectrophotometric method for measuring the color of wastewater in the range of 0 ADMI to 500 ADMI.

Accurate color imaging of pathology slides using holography and absorbance spectrum estimation of histochemical stains.

Holographic microscopy presents challenges for color reproduction due to the usage of narrow-band illumination sources, which especially impacts the imaging of stained pathology slides for clinical diagnoses. Here, an accurate color holographic microscopy framework using absorbance spectrum estimation is presented. This method uses multispectral holographic images acquired and reconstructed at a small number (e.g., three to six) of wavelengths, estimates the absorbance spectrum of the sample, and projects it onto a color tristimulus. Using this method, the wavelength selection is optimized to holographically image 25 pathology slide samples with different tissue and stain combinations to significantly reduce color errors in the final reconstructed images. The results can be used as a practical guide for various imaging applications and, in particular, to correct color distortions in holographic imaging of pathology samples spanning different dyes and tissue types.