Differences In Color Values Research Articles

Blend of guar/acacia gum as a partial substitute of lecithin in white chocolate: Optimization, characterization, and shelf-life evaluation

Lecithin is potentially used in various food applications due to its emulsifying and stabilizing properties. However, overconsumption of lecithin may cause several diseases and side effects in the human body. Therefore, in this study, we used a blend of guar and acacia gums as a partial replacement for lecithin in white chocolate. Different concentrations of the blend (25–75 %) were used to replace lecithin and white chocolate containing 75 % lecithin, 15 % acacia gum and 10 % guar gum blend (75GAGL) exhibited comparable rheological properties as compared to the control sample. Consequently, the selected sample was characterized using different analytical techniques. FTIR results showed a similar peak of various functional groups of sugars, proteins, and uronic acids for 75GAGL and control samples. Physicochemical analysis and shelf-life evaluation were conducted during the 150-day storage period. Lower fat content (41.64 ± 1.23 %) and highest protein content (5.41 ± 0.08 %) were observed for the 75AGGL sample as compared to the control on the 0th day and a non-significant difference was shown on the 150th day. Overall, physicochemical data revealed minor changes in the nutritional aspects for both control and 75GAGL samples. DSC and TGA data proved that 75GAGL and the control sample have similar heat stability (melting point) and the peak was observed at 36.93 °C for 75GAGL and 37.11 °C for control. The addition of gum blend in chocolate 75GAGL (9985 g force in 2.24 Sec) displayed similar hardness as compared to the control sample (12,448 g force in 2.68 Sec). Results of texture analysis for 5AGGL and control samples exposed similar hardness values. Furthermore, the color assessment showed a non-significant difference in color values of both chocolates during 150 days of storage. 75AGGL received comparable scores to the control sample during sensory analysis. Overall, it could be proven that plant-derived gums can be effectively used for the partial replacement of lecithin for white chocolate production with desirable textural and sensory properties.

Comparison of Composite Resin (Duo-Shade) Shade Guide with Vita Ceramic Shades Before and After Chemical and Autoclave Sterilization.

BACKGROUND This study aimed to compare a composite resin (Duo-Shade) shade guide with Vita ceramic shades before/after chemical and autoclave sterilization. MATERIAL AND METHODS Color values (L*a*b*) were recorded directly from shade tabs of prefabricated composite resin (Brilliant NG Universal Duo-Shade) and ceramic (Vita classic) shade guide with a calibrated spectrophotometer (Vita Easy Shade Advance 4.0). Seventy-two composite resin disk samples with 6 different shades (A1/B1, A2/B2, A3/D3, A3.5/B3, A4/C4, and C2/C3) (n=12 each) were divided into 2 groups (Gp) - Gp A (Autoclave) and Gp C (Chemical) (15 cycles) - to assess their influence on respective shades. Mean values calculated the color differences (ΔE) while differences in color values (L*a*b*) were graded on the National Bureau of Standards (NBS) 6-grade scale and assessed for Clinical Acceptance/Perceptible Threshold (CAT), (CPT). All differences were considered significant if the color difference ΔE was ≥3.3. RESULTS Only 2 out of 12 Shade tabs (C2C3, A4C4) of composite resin matched to Vita shade tab C2 and C4 (ΔE ≤3.3). Both groups showed notable color differences after respective sterilization protocols, with color differences in Gp A significantly higher than Gp C (DE ³3.3). Within groups, all shades in Gp A showed remarkably different color changes, with shade C2C3 and A1B1 being denoted as clinically unacceptable. CONCLUSIONS Manufacturer-provided shade guides do not match ceramic shades as claimed and chemical sterilization using 10% Deconex was associated with less color changes than with autoclave sterilization.

English

The present study was conducted to check nutritional characterization i.e., proximate analysis, physicochemical properties (total soluble solid content, titratable acidity, texture, and color), phytochemicals (total phenolic, flavonoids and anthocyanin) and antioxidant capacity (DPPH-2,20-diphenyl-1-picrylhydrazyl radical scavenging capacity) of strawberry varieties (festival, chandler and korona) produced in Pakistan along with shelf life extension using modified atmosphere packaging (MAP) technology. Accordingly, samples were collected from farms and local market for analysis. Results showed statistically differences (p< 0.05) for proximate composition expect ash and crude fat. Higher moisture content documented in variety chandler as 91.12±7.28%, highest ash in variety korona as 1.4±0.17%, lowest protein in variety Chandler as 0.95±0.13% and highest fat in variety festival as 1.13±0.31. Physicochemical analysis showed highest titratable acidity as 0.70±0.04 g citric acid/100g in variety chandler, highest ○Brix as 8.41±0.11in variety festival whereas, phytochemicals analysis revealed highest total phenolic and flavonoids found in variety chandler as 926.17±53.08 mg GAE/100 g and 180.63±15.72 mg/100g respectively, and lowest 864.44±44.16 mg GAE/100 g, 144.84 ± 12.11 mg/100g in variety korona, respectively. The variety chandler displayed highest antioxidant activity (82.09±6.34%) and anthocyanin (2.74 ± 0.09 mg/100g however, non-significant differences in color values. Further, the shelf life of strawberries was extended by 09 days by modified atmospheric packaging under cold storage for 12 days. For this strawberry was categorized into 5 groups with the different gas combination i.e., MAP0 (control group having 0.05% CO2, 20.95% O2 and 79% N2), and 4 treatment groups MAP1 (3% CO2, 15% O2 and 82% N2), MAP2 (5% CO2, 10% O2 and 85% N2), MAP3 (10% CO2, 5% O2 and 85% N2), MAP4 (15% CO2, 3% O2 and 82% N2). Statistical differences (p< 0.05) were found between groups on different storage days (3rd, 6th, 9th, and 12th) in physiochemical, phytochemical, sensory evaluation, and caloric parameters. In nutshell, the results provide valuable information on the nutritional composition, phytochemical characteristics, and quality aspects of strawberries produced in Pakistan. This information is helpful for food processors in value addition, and modified atmosphere packaging technology for the reduction of post-harvest losses.

Effect of moisture content on engineering characteristics of apricot (Prunus armeniacaL.) kernel

AbstractApricot (Prunus armeniaca L.) kernels, the innermost part of the economical stone fruit, are utilized for edible purposes, extraction of oil, and many pharmaceutical products. Biological materials are complex in structure and get affected by their moisture content. This study investigates the effect of different moisture content from 5.66% to 26.47% wet basis apricot kernels on its various engineering characteristics and develops their correlations. The engineering characteristics such as linear dimension length (13.26–14.47 mm), breadth (8.69–9.97 mm), thickness (5.36–6.50 mm), arithmetic mean diameter (9.11–10.32 mm), geometric mean diameter (8.48–9.77 mm), surface area (227.91–302.68 mm2), projected area (91.99–114.95 mm2), 1000 kernel mass (0.317–0.403 kg), true density (881.23–973.55 kg m−3), and porosity (33.74%–43.68%) increased linearly with moisture content. On the other hand, bulk density (548.23–583.89 kg m−3) and elongation ratio (2.25–2.51) showed a decreasing trend with an increase in moisture content. The frictional properties such as angle of repose (22.81–28.92°) and coefficient of static friction value for glass, stainless steel, galvanized iron, and wood were found to increase with increased moisture content and ranged from 0.179–0.283, 0.272–0.347, 0.416–0.512, and 0.488–0.595, respectively. The highest static coefficient of friction was observed for wood surfaces. A significant difference in color values L*, a*, b*, hue angle (H), chroma (C), and ∆E values were observed at different moisture content. Terminal velocities and hardness of AK increased linearly with moisture content and the values were found between 4.26 and 5.91 m s−1 and 21.59 to 35.25 N mm−1, respectively.Practical applicationsApricot kernels have nutritional and pharmaceutical value due to the abundance of bioactive components in them but are still underutilized due to a lack of handling knowledge and processing mechanization. Apricot kernels are delicate and sensitive for mechanical damage during every stage of their processing. This study investigates engineering characteristics in view to understand their relationship with moisture content, as many instruments and equipment are yet to be designed. Knowledge of its engineering characteristics at different moisture content would help handlers for quality evaluation, and manufacturers in optimally designing processing machinery and quality analytical instruments.

Radiofrequency heating: A novel thermal treatment on the quality of peanut during disinfestation of Caryedon serratus and its potential in reducing aflatoxin

This study investigated the effect of radiofrequency (RF) treatment on the quality of peanuts and peanut oil. After treating at the least electrode height and conveyor speed of 180 mm and 5 m/h, respectively, it resulted in a temperature rise of up to 89.96°C showing a maximum effect on the quality of peanuts and peanut oil. It significantly reduced moisture content (7.45%–2.11%) and protein content (22.17%–20.94%) and increased oil extraction yield (51.34%–70.31%) with no significant difference in color values. During storage of up to 2 months, the quality of the oil decreased as it was stored in closed plastic containers at room temperature (35.30 ± 2°C), however, all the parameters were within the specified range allowed by CAC. The RF treatment showed complete mortality of Caryedon serratus. It also proved in the reduction of aflatoxin B1 and B2 contents (92.64% and 90.51%, respectively). Hence, it was deduced that RF treatment is a viable technique which can be deployed in peanut processing industries. Novelty impact statement RF treatment effectively disinfested Caryedon serratus. Aflatoxin detoxifying property of RF has proven as a potential alternative to safeguard the product. Quality of peanut and peanut oil after RF treatment were acceptable as per CAC.

Meta analysis on color, total flavonoids, antioxidants, frictional, mechanical, and cutting force of moringa pods

AbstractThe color, total flavonoids, antioxidants, frictional and mechanical properties (bending stress, hardness, puncture force, peak cutting force) and cutting power requirement of moringa pod was studied and reported. Drying curves exhibited the falling rate drying characteristics with drying rate constant (k) (−1.18 × 107–.00571 m−1) and effective moisture diffusivities (1.500 × 10−6–2.817× 10−8 m2 s−1). The Page model with high R2 (.997–.8282) and low value (.00119–.000927) shows the best fit on drying curves. The L*, a*, b* and total difference in color values varied from 47.05 to 32.5; −9.89 to 6.41; 35.76–21.07; and .07–21.07, respectively. The chlorophyll content (.353–.264 mg/g dm) and the total flavonoids (1.3023–.1050 mg QE/g dm) were recorded. The total phenolics (5.4–21.739 mg GAE/g dm) showed an increasing trend whereas the antioxidant activity (31.5102–20.922%) decreased with increasing drying temperature. The bending stress, hardness, and puncture force ranged from 6514.38 to 1189.33 N/mm2; from 14.707 to 225.16 N; from 267.625 to 25.364 N. The peak cutting forces; and power requirement for cutting on the horizontal and longitudinal direction of moringa pods were 94.67–27.27 N and 179.95–73 N; and .249–.704 W and .434–1.124 W; respectively. The SEM analysis of moringa pods substantiated the variations in mechanical properties through microstructural changes. The results indicated that aspect ratio significantly affected the drying characteristics, frictional, and mechanical properties of moringa pods. Therefore, the aspect ratio can be considered while designing cutting tools, conveying, and processing equipment.Practical ApplicationsMoringa pods are used as a vegetable in curries, soups, and cuisines in significant parts of Asia and Africa. It has good nutritional characteristics and a very tempting flavor and aroma. However, the processing and value addition of moringa lack owing to primary processing tools and value addition machines because of the non‐existence of frictional, mechanical properties, and cutting force data concerning size, that is, aspect ratio and moisture content. The study's findings can help design and develop the cutters, tools, machines, and conveyors used for the primary processing and value addition of moringa pods.

Effect of partial replacement of NaCl with KCl on physical and sensory traits of dry-cured loin

The aim of this study was to investigate the effect of partial replacement of NaCl with KCl on the physical and sensory properties of dry-cured loin. The dry-cured loins were prepared after three treatments, where treatment C served as a control without NaCl replacement, while in treatments F1 and F2, 25 and 37.5 % NaCl was replaced by KCl, respectively. A significant difference (P<0.05) was found in the water activity of the dry-cured loins at all stages between treatments C and F2 and at most stages between treatments C and F1. The study revealed a significantly higher (P<0.05) pH after salting in treatment F2 (5.79) compared to control treatment C (5.58), but no significant differences were found between treatments during the rest of production until the end of storage in vacuum. It was found that there were no significant differences in color values between treatments at all stages of production and storage in vacuum. Among the 17 descriptive sensory traits, significant differences were found only for color uniformity, salty taste and aromatic plant aroma intensity. In contrast, likeability sensory traits like texture and taste likeability, maturity impression, aroma richness and overall likeability were significantly better rated in the control treatment. Considering the adverse effects on likeability sensory traits, replacing NaCl with KCl does not seem to be sufficiently justified. Therefore, further studies are needed as taste improvement could also be achieved by mixing substitutes with a more favourable effect on flavor and other technological indicators, still resulting in lower sodium content.

Ultrasound treatment combined with fumaric acid for inactivating food-borne pathogens in apple juice and its mechanisms

The purpose of this study was to evaluate the synergistic bactericidal efficacy of combining ultrasound (US) and fumaric acid (FA) treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in apple juice and to identify the synergistic bactericidal mechanisms. Additionally, the effect of combination treatment on juice quality was determined by measuring the changes in color, pH, non-enzymatic browning index, and total phenolic content. A mixed cocktail of the three pathogens was inoculated into apple juice, followed by treatment with US (40 kHz) alone, FA (0.05, 0.1, and 0.15%) alone, and a combination of US and FA for 1, 2, 3, 4, and 5 min. Combined US and 0.15% FA treatment for 5 min achieved 5.67, 6.35, and 3.47 log reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, with the 1.55, 2.37, and 0.57 log CFU reductions attributed to the synergistic effect. Although the pH value slightly decreased as FA increased, there were no significant (P > 0.05) differences in color values, browning indices, and phenolic content between untreated and treated samples. To identify the mechanism of this synergistic bactericidal action, membrane integrity, malfunctions in the membrane efflux pump, and intracellular enzyme activity were measured. The analyses confirmed that damage to the cell envelope (membrane integrity and efflux pump) was strongly related to the synergistic microbial inactivation. These results suggest that simultaneous application of US treatment and FA is a novel method for ensuring the microbial safety of apple juice.

Preparation, optimization and characterization of foam from white-flesh and yellow-flesh cassava (Manihot esculenta) for powder production

Cassava foam, another form in which cassava may potentially be used as food, was produced from the pulp of yellow-flesh and white-flesh cassava varieties by whipping with foaming agent (20 %w/w glycerol monostearate colloid, GMS) and stabilizer (sodium carboxymethyl cellulose, NaCMC). Cassava foaming was optimized for concentration of foaming agent, stabilizer and whipping time. Using Box-Behnken experimental design, two responses were measured: foam expansion (FE, %) and foam density (FD, g/mL). White-flesh cassava pulp required 14.97% GMS, 0.51% NaCMC and 2.07 min to give a foam of 52.63% expansion and density of 0.75 g/mL. Yellow-flesh cassava pulp required 14.29% GMS, 0.6% NaCMC and 2 min to yield a foam of 48.25% expansion and density of 0.76 g/mL. Predicted optimal FE and FD were 54.9% and 0.73 g/mL for white-flesh cassava foam, and 49.86% and 0.73 g/mL for yellow-flesh cassava foam, respectively, and are close to validated values. The optimal foams were quite stable after 4 h at 25 ± 2 °C, with low volume collapse of 1.79% and 1.26% for white and yellow cassava foams, respectively. The optimal cassava foams were dried into foam powder. There was significant difference in color values (L*, a*, b*, C*, E*, H*, % W, ΔEyellow−white∗) and total carotenoids content of pulp, optimal foam, and powder of both varieties. Microstructure analysis of the optimal foams revealed round air bubbles and positive skewed distribution of bubble sizes. Foaming and drying significantly reduced total cyanogenic potential in cassava, and may be considered as processing operations capable of reducing cyanogenic potential in cassava considerably.

양파분말을 첨가한 국수의 품질과 저장성

The quality and shelf life of noodles containing onion powder (0, 3, 5, and 10%) were investigated. The pH ofraw noodles decreased by increasing the concentration of onion power. The weight, volume, and water absorption of the cooked noodles were comparable, irrespective of onion powder concentrations. Color L and a values of raw noodles decreased, while b value increased by addition of onion powder. However, no considerable differences in color values were observed among the control and onion noodle groups after cooking (p<0.05). The total polyphenol contents and DPPH radical scavenging activities of raw and cooked noodles increased with increasing onion powder concentrations, although the latter had lower values. In the aspect of texture, the control group showed higher hardness and chewness than those of noodle containing onion powder, except for springiness. The results of raw noodle storage at 10℃ for 12 days indicated that raw onion noodles, especially those with 5% onion powder added, could be preserved for at least 6 days longer than the control noodle. In the sensory evaluation of cooked noodles, no significant differences in appearance, taste, flavor, texture and overall acceptability were observed between the control and onion noodle groups. This study indicates that the addition of 5% onion powder could improve the functionality and shelf life of noodles

Detecting Concentration of Analytes with DETECHIP: A Molecular Sensing Array

DETECHIP® is a detection system made of various sensors that has been shown to detect and discriminate between small molecules of interest, including various illicit and over-the-counter drugs. Previously, detection was normalized to a single concentration of analyte. Now this detection assay can detect concentration differences in analytes via red, green, and blue color value changes and shifts in the UV-Vis spectra of the assay. To determine the concentrations differences, the exposed assays were scanned on a flatbed scanner and the images were analyzed for individual RGB values with a custom macro in ImageJ, an image analysis program. Increasing concentrations of the analyte resulted in greater differences in color values between control and analyte wells. These differences showed a linear relationship to concentration change, some with correlation coefficients greater than 98%. This work expands the capability of DETECHIP to give information about the concentration of analyte when the analyte identity is known.

쌀의 품종, 쌀의 도정도, 누룩에 따른 막걸리의 품질 특성

본 연구에서는 전분원료의 종류, 쌀의 도정도, 누룩의 종류를 달리하여 담근 막걸리의 품질 특성을 조사하였다. 밀가루는 쌀보다 조지방과 조단백 함량이 높았으며 수분함량은 낮았고, pH 및 총산함량은 쌀과 밀가루로 담근 막걸리 간에 차이가 없었다. 쌀과 밀가루로 담근 막걸리의 주된 유기산은 각각 lactic acid와 succinic acid였으며, 총 유기산 함량은 각각 4.0∼5.6 mg/mL와 3.5 mg/mL로 쌀로 담근 막걸리의 유기산 함량이 더 많았다. 쌀과 밀가루로 담근 막걸리의 주된 유리당은 glucose였으며, 쌀과 밀가루로 담근 막걸리의 총 유리당 함량은 각각 76.41∼54.53 mg/mL와 67.75 mg/mL로 쌀로 담근 막걸리의 유리당 함량이 더 많았다. 색도는 쌀 품종별로는 차이가 없었으며, 밀가루로 담근 막걸리의 b 값은 양의 값으로 황색이 진했다. 관능평가 결과, 쌀로 담근 막걸리가 밀가루로 담근 막걸리보다 기호도 점수가 더 높았다. 쌀의 도정도가 증가함에 따라 수분, 조지방, 조단백질, acetic acid의 함량은 감소하나, pH, 총산, 유리당, 색도에 있어서는 유의적인 차이가 없었다. 쌀의 도정도는 과실향을 제외한 기호도 점수에 유의적인 차이를 나타내지 않았다. 전통누룩과 개량누룩으로 담근 막걸리의 pH는 각각 4.29∼4.65와 4.20∼4.23으로 전통누룩으로 만든 막걸리의 pH가 더 높았으며, 총 유기산 함량도 전통누룩으로 담근 막걸리(3.5∼6.3 mg/mL)가 개량누룩으로 담근 막걸리(2.3∼4.3 mg/mL)보다 높았다. 총 유리당 함량은 개량누룩으로 담근 막걸리(59.44∼73.34 mg/mL)가 전통누룩으로 담근 막걸리(56.45∼59.75 mg/mL)보다 많았다. 색도는 전통누룩으로 담근 막걸리가 개량누룩으로 담근 막걸리보다 L, a, b 값이 높았으며, 관능적 기호도 점수는 개량누룩으로 담근 막걸리가 더 높았다. 본 연구 결과, 쌀로 담근 막걸리가 밀가루로 만든 막걸리에 비해 품질이 우수한 것으로 보이나, 쌀의 품종에 의한 품질 차이는 없었다. 쌀의 도정도에 따른 막걸리의 품질은 향미의 관능적 특성 외에는 영향을 미치지 않았으며, 도정을 많이 할수록 막걸리의 향미가 좋아졌다. 누룩 종류에 따른 막걸리의 품질 특성 분석 결과, 전통 누룩에 비해 개량누룩으로 담근 막걸리의 관능적 특성이 더 좋았다. 위 결과를 종합해 볼 때, 도정도가 높은 쌀을 전분질 원료로 하고 개량누룩을 사용하여 막걸리를 담근다면 품질이 우수한 막걸리를 제조할 수 있을 것이다.

Facial spectrum and color characteristics of five viscera reflecting on the face in sub-health status

To observe the facial spectrum and color of different points, the positions of heart, liver, spleen, lung and kidney of traditional Chinese medicine reflecting on the face, in healthy participants and those with a sub-health status, so as to provide an objective basis for health evaluation. The health condition of 470 subjects without acute and chronic conditions was assessed using the Health Evaluating Questionnaire H20 V2009. The subjects were diagnosed with health (more than 80 score) or sub-health (score between 60 and 80) status according to the questionnaire score. The subjects with a subhealth status were also analyzed using the five-viscera syndrome differentiation of traditional Chinese medicine using the form for collecting information according to the four examinations. Then for gathering the facial color information, CIE L*a*b and C values and reflections of wavelengths ranged from 400 to 700 nm were measured using a CM-2600D spectrophotometer on 8 points of the face, including the frontal part, glabella, nose, mandible, two cheeks and eyelids. L value of the sub-health group was higher than that of the health group (P<0.05), and a, b and C values were lower than those of the health group (P<0.05), suggesting that the facial complexion of the sub-health group was pale/whiter than the health group. The reflectance rates of wavelengths (from 400 to 550 nm) of the sub-health group were higher than those of the health group (P<0.05), which suggested that the facial complexion of the sub-health group was partially green. The a, b and C values of the forehead, glabella and nose of subjects in the sub-health group were apparently different from the health subjects. L values of five-viscera types were significantly different from people of a health status (P<0.05). There were some differences in color values among the five-viscera groups: lung group's color values were significantly different from the others in terms of a, b and C values. The spectral reflectance of different viscera groups of the sub-health group also showed certain differences: reflectance of wavelengths at 400 to 490 nm in the lung group and at 520 to 580 nm in the spleen group showed significant difference from the other groups, and the lung group was lower and the spleen group was higher than the others. There are some differences in facial spectrum and color in different sites of the face in sub-health status of different viscera syndrome types, which can provide an objective basis for health evaluation.

35% 과산화수소에 제2인산칼슘를 함유한 치아미백제가 치아의 색과 경도에 미치는 영향

이 연구는 전문가 미백(in-office bleaching)에 사용하는 35% 과산화수소(hydrogen peroxide, HP)를 제2인산칼슘(dicalcium phosphate dihydrate, DCPD)와 혼합하여 치아의 미백 효과와 미세경도를 평가하고자 하였다. 소구치로부터 30개의 치아시편을 제작하여 3군으로 분류하였다(n=10). 35%과산화수소에 DCPD를 0.1, 1wt% 첨가하여 실험군으로 하고 하루 60분간 치아미백을 실시하였다. 치아 미백제에 pH를 측정하였고, 미백 적용한 치아 표면에는 색과 미세경도를 측정하였다. pH는 DCPD 함유한 군에서 DCPD의 함유량이 증가할수록 함유되지 않은 군에 비해 pH 수치가 증가하였다. 색조변화량 (<TEX>${\Delta}$</TEX>E)을 비교한 결과, 미백 전에 비해 미백 후 색조 변화를 보였고(p<0.05), 결과적으로 색 변화에 있어 DCPD를 함유한 군과 함유되지 않은 군 사이에 통계적으로 유의한 차이는 없었다(p>0.05). 법랑질의 표면미세경도를 분석한 결과, 모든 군에서 미백 후 미세경도의 감소를 보였고(p<0.05), DCPD를 혼합한 군은 함유되지 않은 군에 비해 경도 감소의 폭이 훨씬 적게 나타났다. 이상의 결과로부터 DCPD를 함유한 35%과산화수소의 치아미백제는 치아미백 효과가 있고, pH를 상승시켜서 법랑질의 표면 경도를 덜 감소시키므로 치아미백제의 구성성분으로 실용할 수 있을 것으로 사료된다. The purpose of this study was to evaluate tooth whitening and microhardness after treatments with tooth bleaching agents containing dicalcium phosphate dihydrate (DCPD) and 35% hydrogen peroxide (HP) which were used in-office bleaching. Thirty enamel specimens were obtained from human premolars and randomly divided into 3 groups(n=10). Tooth bleaching agents were prepared with DCPD (0 g for controls, 0.1 g and 1 g for experimental groups) and HP solution (35% HP). All groups were applied to enamel surfaces for 60 min for 1 day. The pH of each tooth bleaching agent was measured. Tooth color, microhardness of enamel surfaces were also measured. The tooth bleaching agents containing DCPD showed a significant increase in pH compared to the ones without DCPD(p<0.05). Paired t-tests showed significant difference in color values of enamel before and after bleaching in all the groups(p<0.05). As a result, changes in color, containing DCPD group does not contain a statistically significant difference between groups was observed.(p>0.05). In all groups, tooth hardness after bleaching showed a significant decrease in microhardness (p<0.05). However, the DCPD concentration increased in the bleaching, microhardness values slightly decreased. Based on the above results, tooth bleaching agents containing DCPD and 35%HP were equally effective. Due to increases in pH and effective reduction of tooth surface decalcification, the surface characteristics are exposed to a reduced degree of negative effects, resulting in fewer constituent enamel alterations. Thus, commercial availability of the constituents of tooth whitening materials can be achieved.

Reaction of Folin's Reagent with Proteins and Biuret Compounds in Presence of Cupric Ion

In an earlier paper1 the writer noted that traces of copper sulfate increased the blue color obtained by treating such proteins as pepsin or gelatin with Folin's phenol reagent.It has now been found that a number of organic substances reduce the Folin's phenol reagent only if a small amount of cupric ion is present. These same substances also show a positive biuret reaction.The copper-phenol values in Table I represent the amount of color per milligram of substance produced as a result of adding m/1300 copper sulfate to the solution under examination with the phenol reagent. One obtains this value from the difference in color values produced with and without copper ion. For many substances no color is produced in the absence of copper but most proteins contain tyrosine and tryptophane and must, therefore, be analyzed with and without cupric ion. No attempt has been made to determine whether each of the substances in Table I produces a blue color exactly in proportion to its concentration. With leucyl-glyc...