Colorimeter Values Research Articles

Use of Colorimetric Analysis to Estimate Salmonid Flesh Carotenoid Content

Abstract Farm-raised rainbow trout Oncorhynchus mykiss were evaluated by sensory and instrumental analysis to determine differences in flesh color. A wide range of pigment levels matched a single color tile. On the other hand, colorimeter values produced unique concentration values for each sample. A predictive model based on colorimeter readings was created as a rapid, easy-to-use field test for determining flesh color pigmentation levels for selective breeding programs.

Accumulation of the Components of Total Solids in Ripening Fruits of Tomato

To identify qualitative and quantitative chemical variation in tomato fruit dry matter, crosses were made between the high soluble solids concentration (SSC) line LA 1501 (6.3% SSC when red-ripe) and the nearly isogenic commercial tomato cultivar VF 145B-7879 with a lower SSC (4.4% when red-ripe). Fruit samples from the parents and the reciprocal F1 hybrids were collected at 3-day intervals, from 25 to 52 days after anthesis, to evaluate the accumulation of various quality components throughout the development of the fruit from immature-green to red-ripe stage. Fructose and glucose concentrations, titratable acidity, pH, and percent dry weight (pulp and serum) were determined for each sample on a fresh basis. Fruit maturity was evaluated by puree color using Hunter `a' colorimeter values. Changes in most of the chemical constituents of the fruit were found to regress linearly with changes in fruit color. Regression of puree color against fruit SSC, and fructose, glucose, and total sugar concentrations described more of the observed variability in these components than days after anthesis, indicating that Hunter `a' colorimetric values provide a more precise measurement of fruit physiological age. The variation between the parents in fruit dry matter was found to be primarily due to differences in SSC. The ratio of fruit soluble to total solids concentration increased 23.7% in LA 1501 (from 61.6% to 85.3%) throughout ripening compared to-an increase of only 8.9% (from 66.3% to 75.2%) in `VF 145B-7879'. At the red ripe stage, LA 1501 possessed a 44% higher SSC than `VF 145B-7879'. Differences in fructose and glucose accounted for 41% of the variation in SSC between the two lines. An unidentified component(s) was responsible for the residual variation. Application of the genetic and physiological information generated from this study can be used to isolate and select for genes controlling accumulation of tomato fruit dry matter.

Retail Display Lighting Type and Fresh Pork Color

ABSTRACTThe effects of lighting type on fresh pork color were studied by displaying chops under delux cool white (DCW), cool white, Surlyn® coated (CWSC), or warm white (WW) fluorescent or cool flood (CF) incandescent lights. Initial color desirability was assessed. Hunter colorimeter values and percentage myoglobin (Mb), oxymyoglobin (OMb) aand metmyoglobin (MMb) were determined over 5 days of display. Light types CF and DCW provided the most desirable color rendition. Chops displayed under CF lights became darker, had less percentage OMb and greater Mb, and likely had greater microbial growth than other chops due to an increase in chop temperature. It appears that CF and DCW lights provide the most desirable color and that precautions against temperature elevation are needed.

Life Cycle of Canned Tomato Paste: Correlation Between Sensory and Instrumental Testing Methods

ABSTRACTCanned tomato paste was examined to determine its life cycle. Life cycle information can be used to predict the shelf‐life of the product. The product was stored at 45, 37.8, 29.4, 22.2, and 3.3°C for up to 3 yr. The product was analyzed by two sensory testing methods (hedonic evaluations and descriptive profile analysis) and three instrumental testing methods (serum color, hydroxymethylfurfural content and colorimeter values). Two separate studies were conducted to check the repeatability of the data. Correlations were established between the sensory and instrumental methods. The product had a Q10 of 3.8 with a shelf‐life of 38 months at 25°C and an Ea (activation energy) of 23 Kcal/mole, as determined by the descriptive profile analysis.

Relation of Cotton Fiber Properties to Sliver Cohesion

A statistical evaluation was made of the relationship of certain fiber properties to cohesive force and coefficient of variation of cohesive force. Significant positive correlations were found between the cohesive force and fiber length, tenacity, and fiber yellowness (+b); negative correlations were found with fiber perimeter and reflectance (Rd). When length, colorimeter values, and Micronaire readings were used as independent variables in a stepwise regression program, 53% of the variation in the cohesive force could be explained by upper half mean length and Rd. The addition of other fiber properties whose measurement was influenced by fiber surface properties increased the explainable variation in the cohesive force to 71%.