Effects of dietary humate supplementation to broilers on performance,slaughter, carcass and meat colour

BACKGROUND: This experiment was designed to examine the effect of dietary humate supplementation primarily on pH and colour parameters of carcasses, breast fillets and drumsticks and, secondarily on performance and carcass characteristics in broilers. RESULTS: A total of 240 male broiler chicks (Ross‐308) were randomly allocated to four dietary treatments varying in supplemental humate level (0, 0.1, 0.2 and 0.3% for H₀, H₁, H₂ and H₃). Dietary humate supplementation did not affect performance traits and slaughter, hot carcass weights and yields. Carcass‐related variables (pH, L*, a*, b*, H* and C*) were responsive to the dietary treatments. The L*, a*, b*, and C* values for drumstick muscles were higher than those for breast muscles. Except for the L* value, meat colour parameters changed due to packaging. The a* value was higher and b* value was lower for vacuum packaged breast and drumsticks than for those aerobic packaged. Storage period affected colour parameters; while L*, b*, H* and C* values were higher for drumstick skin than for drumstick meat; the a* value was greater in drumstick meat than in skin. CONCLUSION: pH and colour parameters of carcasses, breast fillets and drumsticks of broilers were improved by dietary humate supplementation. However, responses of broiler performance and slaughter and carcass characteristics were minimal. Copyright © 2008 Society of Chemical Industry     

The quality of cold-smoked Atlantic salmon (Salmo salar) as affected by salting method, time and temperature

The effects of temperature (4 and 10–12 °C) and time (6, 12 and 24 h) on colorimetric parameters (Commission International de l'Eclairage (CIE) L*a*b*), carotenoid concentration, salt content and yield were investigated in brine (saturated or 50% saturation) and dry salted fillets of cold‐smoked Atlantic salmon (Salmo salar). Lightness (L*), yellowness (b*), hue (H_ab) and chroma (C*) values were lower at 10 than 4 °C (P < 0.01), whereas redness (a*) was unaffected. L* increased (P < 0.05) and a*, b*, H_ab and C* values dropped when salting time was increased (P < 0.001). Astaxanthin concentration of brine‐salted fillets decreased with increasing salting time (P < 0.05), but was unaffected by salting temperature. Increasing salting time affected colour negatively. The salt content of dry salted fillets increased with temperature and salting time. The process yield was unaffected by temperature and decreased with salting time. In conclusion, the cold smoking process is more important for variation in quality parameters than the salting process.     

Development of a colour scale for colour evaluation of beef carcasses at 60 min post mortem

The pectoralis profundus muscles of 200 selected beef carcasses were measured to develop a standard colour scale for evaluating beef carcasses at the time of classification (approximately 60 min post mortem). Five lightness (L*) values were chosen ranging from 22 to 42 with intervals of five L* units. Corresponding a* and b* values were calculated. Based on regressions between the actual reflection spectra and the L*, a* and b* values, spectra of the five chosen colours for the colour scale were predicted. The L*, a* and b* values accurately predicted the reflection spectra. A paint company imitated the five reflection spectra. Spectra could not be matched exactly, without metamerism occuring. Therefore, the colour scale should be used with specific light sources. The scale is recommended in The Netherlands to classify the colour of beef, as a supplement of SEUROP‐system for conformation and fatness. © 1999 Society of Chemical Industry     

Color of Salmon Fillets By Computer Vision and Sensory Panel

A computer vision method was developed and used to assign color score in salmon fillet according to SalmonFan™ card. The methodology was based on the transformation of RGB to L*a*b* color space. In the algorithm, RGB values assigned directly to each pixel by the camera in the salmon fillet image, were transformed to L*a*b* values, and then matched with other L*a*b* values that represent a SalmonFan score (between 20 and 34). Colors were measured by a computer vision system (CVS) and a sensorial panel (eight panelists) under the same illumination conditions in ten independent sets of experiments. Errors from transformation of RGB to L*a*b* values by the CVS were 2.7%, 1%, and 1.7%, respectively, with a general error range of 1.83%. The coefficient of correlation between the SalmonFan score assigned by computer vision and the sensory panel was 0.95. Statistical analysis using t test was performed and showed that there were no differences in the measurements of the SalmonFan score between both methods (t _c = 1.65 ≤ t = 1.96 at α = 0.05%). The methodology presented in this paper is very versatile and can potentially be used by computer-based vision systems in order to qualify salmon fillets based on color according to the SalmonFan card.     

Rapid Colorimetric Determination of Yellow Seed Content in Red Pepper (Capsicum annuum L.) Powder

When the color reflectance of red pepper powders and their yellow seeds were measured using a colorimeter, the mean lightness (L*), redness (a*), and yellowness (b*) values differed considerably between the pepper powders and seeds. On the basis of this difference, we determined the seed content in the red pepper powders by using the correlated reflectance values. As the seed content of the powders increased, both L* and b* increased, while a* decreased. The polynomial regression curve equation, Y( seed content, % ) = 3.51 ×L * - 1.10 ×a * - 1.34 ×b * - 72.74 Y\left( {{\hbox{seed content}},{ }\% } \right) = 3.51 \times L * - 1.10 \times a * - 1.34 \times b * - 72.74 , was obtained from the tristimulus data (L*, a*, and b*) of all the samples used. This is an easy method for the determination of the seed content in red pepper powders and it can be applied to a similar system.     

Influence of pH on colour and iron content of peptide fractions obtained from bovine Hb concentrate hydrolysates

The effect of pH on colour and iron content (Fe) of peptide fractions obtained from bovine haemoglobin concentrate (BHC) hydrolysates was studied. Four hydrolysates were obtained using three enzymes: Protex‐6‐L (P), Fungal–Protease–Concetrate (FC) and Flavourzyme (F). BHC and its hydrolysates (P, FC, P + F, FC + F) were fractioned at pH 4.5, 7.0 and 9.5. Solubility and Fe from different fractions were measured. Correlations between CIELAB colour parameters and Fe from different fractions were analysed. The colour from different fractions varied from red to yellow (a* and b* positives). Lightness values (L*) ranged from twenty‐four to seventy. FC4.5 and FC + F4.5 fractions were the clearest and yellow (higher L*, b*, h), while BHC9.5 and P + F9.5 fractions had the lowest values of L*, b* and h. There was an inverse linear relationship between b* and L* parameters and Fe from fractions. This relationship could be associated with the pH of extraction. As pH increases Fe significantly increases and lower b* and L* values were obtained.     

Estimation of skin phototypes with optical parameters: an experimental study using newly developed fibre optic detection device

In an experimental study (October 2010 Mannheim Germany) with 99 Caucasian volunteers, the skin colour (L*, a*, b*) and the reflectance spectra of human skin were compared to the Fitzpatrick's sun‐reactive skin photo types (SPT). For this purpose, the skin colour and the reflectance spectra of human skin were determined using non‐invasive method with a newly developed fibre optic detection device. The device, based on reflectance spectroscopy, was designed and optimized using a commercial optical analysis Software. By means of the measured spectra of scattered light, the colour values and the absorption spectra of the skin were calculated. Neither any of the L*, a*, b* colour values nor any of the parameters of the absorbance spectra can be used alone to assess the skin type properly. Therefore, an ordinal logistic regression analysis was performed, using the statistical computing software r , to correlate the skin types with the measured optical parameters. It turned out that the detection device combined with the extended statistical analysis gives a better estimate of skin type in respect of the measured optical parameters than a procedure with only L*, a*, b* colour values. Even with the extended methodology, the procedure gives only a rough estimation of the skin type.     

Comparative effect of red yeast rice (Monascus purpureus), red beet root (Beta vulgaris) and betanin (E‐162) on colour and consumer acceptability of fresh pork sausages packaged in a modified atmosphere

Fresh pork sausages containing natural colorants, red yeast rice powder (Monascus purpureus; Frame^®) or a crude red beet root (Beta vulgaris) juice or commercial betanin (E‐162), at different concentrations, were packaged in an atmosphere containing 80% O₂ and 20% CO₂ and stored in the dark for 20 days. The following parameters were measured at 4 day intervals: instrumental colour (CIE L*, a*, b*, a*/b*, C* and h*), reflectance spectra, sensory discoloration (trained panel) and acceptability and willingness to purchase (habitual and non‐habitual consumer panels) under two different lighting displays (standard fluorescent and Promolux^® lamp). The use of colorants improved the colour properties of fresh pork sausages. Sausages with red yeast rice, red beet root juice and betanin had lower L* and h* and higher a* and a*/b* values than control samples. The colour properties of sausages with red beet root were the closest to control sausages, while sausages with red yeast rice had significantly lower b* values. Both natural colorants and betanin protected sausages from discoloration and extended acceptability and willingness to purchase by about 4 days, according to evaluation by habitual consumers under two different types of lighting display. Therefore, red beet root juice may be envisaged as the most suitable natural colorant for use in fresh pork sausages. Copyright © 2005 Society of Chemical Industry     

Influence of particle characteristics and E/Z‐isomer ratio on the colour of concentrated β‐carotene dispersions

The influence of particle concentrations (0.02–0.40%), mean particle sizes (0.45–1.5 μm) and all‐E‐isomer ratios (95–30%) on the CIELAB colour coordinates (L*, a*, b*) of concentrated β‐carotene dispersions was investigated. Particle concentration between 0.06% and 0.40% had a slight impact on the colour parameters. However, with decreasing the mean particle size from 1.50 to 0.45 μm, there were increases in ΔL* = 8.0, in Δa* = 2.26 and in Δb* = 13.1. And with decreasing the all‐E‐isomers ratio from 95% to 30%, there were increases in ΔL* = 8.66, in Δb* = 17.51 but decrease in Δa* = 7.42. The experimental results were explained in terms of the scattering and absorption of light by dispersions. These findings have important implications for food industry as they offer a means to control and optimise the colour of food dispersions.     

Effect of location in the canopy on the colour development of three apple cultivars during growth

BACKGROUND: Homogeneity in appearance is one of the quality aspects asked for in the supply chain. Decreasing the biological variation in batches of harvested apples (cultivars Braeburn, Fuji and Gala) becomes increasingly important. Skin colour is one of the aspects that determine both optimal harvest and stage of development. Skin colour is affected by location in the canopy. The rules of development of biological variation are now established and will be used on skin colour data. RESULTS: The Minolta colour aspects a*, b* and L* measured before commercial harvest change in a sigmoidal fashion and can be analysed including the biological variation, with a logistic model in indexed nonlinear regression, obtaining explained parts of above 90%. The mechanism of colour change is not affected by state of development or location in the canopy. The location in the canopy affects the intensity of both red and green colouring compounds. The variation in colouration is not affected by the location in the canopy. CONCLUSION: The red‐coloured apple cultivar (Gala) depends more on the location in the canopy than the less‐coloured cultivars (Fuji and Braeburn). The colour development in Fuji apples is considerably slower, with a much larger variation in stage of development. The location in the canopy affects all aspects of biological variation (biological shift factor and asymptotic starting level of colouration) for all three colour aspects L*, a* and b*, but only the mean value, not the standard deviation. The biological shift factors per colour aspects are linearly related. Once induced, variation remains constant during development. Copyright © 2012 Society of Chemical Industry     

Possibilities of enhancing the colour of egg yolk

BACKGROUND: This study attempts to compare two possibilities of enhancing the colour of egg yolk. One of them is based on the ecological rearing of laying hens on natural green grass whereas the other uses a feeding dose supplemented with natural pigments in laying hens reared in individual cages. Is it possible to distinguish these two technologies using yolk colour determination in the CIELAB system? RESULTS: Yolk colour parameters such as L*, a*, and b* in the group of grazed hens are significantly different (α = 0.001) from those observed in hens reared in cages. The yolk colour shows a darker, redder and more yellow colour. The greatest difference was seen in the red colour parameter, a*, that increased more than twice. Visually, this means a shift towards a more orange colour. Compared to grazing in the meadow (ΔE* = 13.257), the addition of artificial pigments in the feed resulted in a more significant increase in the parameter ΔE* (CIE total colour difference), with the greatest value of ΔE* being observed with the use of both pigments (ΔE* = 24.265). CONCLUSION: Grazing increases the parameter a* whereas the values of the parameter C*_ab remain relatively low. The parameter ΔE* is significantly lower in the case of grazing as compared to the supplementation of the feed with pigments. However, colourity parameters cannot be used as a specific standard to identify a particular grazing technology as their values vary during the laying period. Copyright © 2011 Society of Chemical Industry     

Colour of post-harvest ripened and vine ripened tomatoes (Lycopersicon esculentum Mill.) as related to total antioxidant capacity and chemical composition

Greenhouse grown tomatoes (cvs ‘Durinta’, ‘Favorita’ and ‘Liberto’) were harvested green and vine ripe. Colour measurements and chemical analyses were performed on green, post‐harvest red and vine‐ripe fruits. Partial least square (PLS) regression was applied to predict the ferric reducing ability of plasma (FRAP) by means of colour measurements (L*, a* and b*). The PLS showed that 78% of the variation in colour were able to predict 74% of the variation in FRAP value. Chemical variables and colour variables together were able to predict 88% of the variation in FRAP by means of PLS regression. Linear regression showed a high negative correlation between high values of L*, b* and FRAP, and a high positive correlation between titratable acidity, a*, hue, a*/b*, soluble solids, vitamin C, dry matter and FRAP values. Thus, colour measurements of intact tomatoes can be used as a non‐destructive method to assess total antioxidant capacity of tomatoes.     

Relating raw rice colour and composition to cooked rice colour

BACKGROUND: The whiter the rice, the more it is preferred by consumers and the more value it has in the market place. The first objective of this study was to determine the interrelationships of raw colour, cooked colour, amylose content and protein content in rice. The second objective was to assess whether or not the colour of cooked rice can be predicted from raw rice colour in conjunction with amylose and protein contents. RESULTS: Protein and amylose contents were not significantly correlated with the colour measurements for raw rice. Protein and amylose showed moderate, significant associations with L* and a* and a*, b* and C* respectively for cooked rice. Only the colour variable a* of cooked rice could be predicted using protein, amylose and raw rice colour with high enough precision to be useful, and this was only for modelling using samples cooked in the same manner (rice cooker). Cooking method (rice cooker versus excess water) affected the colour of cooked rice. CONCLUSION: Being able to predict a* in cooked rice is likely of limited value. Only the model that used samples where postharvest handling conditions were controlled (US‐grown rice) was able to predict C*, a more useful measure, and then with only moderate ability. L*, a measure of brightness/whiteness, was not predicted well by any of the models. Copyright © 2011 Society of Chemical Industry     

Correlation between astaxanthin amount and a* value in fresh Atlantic salmon (Salmo salar) muscle during different irradiation doses

The amount of astaxanthin and a* value changes in fresh Atlantic salmon light and dark muscle during cold storage was studied for different e-beam doses (0, 1, 1.5, 2 and 3 kGy). Astaxanthin (mg/kg muscle) and a* value decreased with increasing irradiation dose for both fresh light and dark muscle. The level of irradiation dose gave high correlation between a* value and amount of astaxanthin. The reason for the change in colour or decrease in a* value of Atlantic salmon during irradiation could be due to the destruction of astaxanthin. The amount of astaxanthin and a* value of 1 kGy treated salmon fillets were not significantly different (p > 0.05) from that of the control but significantly different (p < 0.05) from other irradiation treatments. The colour (a* value) of salmon muscle was related to the content of astaxanthin, which decreased as irradiation increased. The amount of astaxanthin in light muscle was three to five times greater than dark muscle. This study demonstrated that irradiating salmon fillets at 1 kGy, can be successfully used and leads to no significant change in colour and amount of astaxanthin.     

CIELAB coordinates in response to berry skin anthocyanins and their composition in Vitis

Abstract: Berry skin color OIV index, anthocyanin composition, and content of 78 grape cultivars were surveyed using a CIELAB system and high‐performance liquid chromatography (HPLC)‐mass spectrometry (MS) coupled with photodiode array detection. There were high correlations between L*, b*, and color, while a* was not a representative parameter. L* and b* values declined as berry skin color OIV became darker, and a* increased as berry skin color OIV became darker in pink and red grape cultivars only. The composition and content of anthocyanins varied widely among the cultivars. Total anthocyanins and types of anthocyanins were significantly correlated with color OIV parameters. Through multiple linear regression analysis, cyanidin derivatives had a positive effect on values of L* and b*. Delphinidin derivatives had positive effects on the value of a*. The CIELAB system gave good results for differentiation of grape berry skin color OIV.     

Changes of colour and pH in fish musculature after ionizing radiation exposure

Irradiation of meat causes sensory changes as do other technological methods. The most significant sensory and quality indicator of meat is colour; therefore, the effect of irradiated pieces of fish was studied in relation to colour changes. Colour was measured at the musculature of Oncorhynchus mykiss. The parameters of colour, L*, a* and b*, were determined with the portable Superchroma S-Spex (Braive) spectrophotometer in the CIELAB system before irradiation (3 h post mortem) and after irradiation (⁶⁰Co source, a dose of 3 kGy and a dose rate of 3.33 kGy h^–1) (5 h post mortem). The change of L* was identical for both irradiated and nonirradiated samples. This change may be caused by maturation of fish flesh. a* was identical and b* decreased. This effect differs from that of irradiated pork. The decrease of the pH was identical for both irradiated and nonirradiated samples. This change may be caused by maturation of fish flesh.     

Effects of gas composition in modified atmosphere packaging on the meat quality of Spanish Manchega lamb

The effects of four types of packaging atmosphere, each with a different gas composition (20–80% CO₂), on the meat quality of Spanish Manchega lamb were examined in order to suggest a gas composition for optimal preservation. Meat quality was assessed by pH, colour (L*,a* and b* values), water‐holding capacity (WHC), cooking loss (CL) and shear force (SF). Gas composition affected all parameters except L* and SF. The pH values decreased significantly in samples packed with 80% CO₂ but remained constant in the other groups. The b* values were lower in samples packed without O₂ than in the other groups and increased with time. However, the a* values decreased in all groups with time. Samples packed in low‐CO₂ atmosphere tended to lose more water (ie to have less WHC and show more CL). The SF values decreased with time, and similar values of this parameter were observed for all treatments. © 2001 Society of Chemical Industry     

Characterisation of peach juices obtained from cultivars Redhaven,Suncrest and Maria Marta grown in Italy

The compositions of three peach juices obtained from the cultivars Redhaven, Suncrest and Maria Marta, respectively, were studied. The fruits were grown in the Emilia-Romagna region (Italy). The juices were characterised by pH, CIE L*, a*, b* colour values, soluble solids, individual carbohydrates, organic acids, and phenolic compounds. Univariate analysis disclosed some significant differences among the compositions of the varietal peach juices. Principal component revealed clear group structures in the data matrix, the most relevant variables being glucose, fructose, sorbitol, malic acid, L* and b*-values. Suncrest peach juice was clearly distinguished from Redhaven and Maria Marta juices.     

Image analysis of changes in surface color of chocolate

Blooming or the migration of fat to the surface of chocolate results in color changes and development of non-uniform color patterns. These phenomena were assessed during storage of milk chocolate tablets (cycling temp. between 16 and 28 °C for 52 days) by a computer vision system and image analysis. Eight features were extracted from images (L*, a* and b* values, whiteness index, chroma, hue, % bloom and energy of Fourier). Major changes occurred after day 36 of storage, coincidental with visual perception. Initially, white specks emerged on the brown background but were superseded by the development of a whitish color extending over most of the surface. L*, whiteness index, a* and chroma correlated well with values taken with a commercial colorimeter (R² > 0.70). Changes in image texture (energy of Fourier) followed a similar trend as color changes. The sequential forward selection strategy allowed correct classification of 97.8% of samples into four classes with only five features. The computer vision system has the capability to quantify overall changes as well as particular features over the whole chocolate surface thus enabling customization and standardization for quality assessment.     

Modelling the biological variance of the yellow aspect of Granny Smith apple colour

BACKGROUND: The yellow aspect of colour is usually not considered for produce with a green‐to‐red or a green‐to‐yellow transition upon ripening. The magnitude of change is simply too small and, additionally, masked by a large variation. The colour of ‘Granny Smith’ apples, harvested from three orchards at two stages of maturity, was measured individually using the CIE L*a*b* system during storage in a regular atmosphere at three temperatures: 1, 4 and 10 °C. A model was developed based on a simplified mechanism, consisting of two consecutive reactions, to describe the development of the apple colour expressed as b* and L* values during storage. RESULTS: Monitoring individual apples made it possible to include and describe the biological variance of colour in batches of apples and to extract information on chilling injury, as a process active at 1 °C. All variations could be attributed to a single source related to the amount of yellowing compounds at the moment of harvest, indicating differences in state of maturity between individual apples. The obtained explained part (R²_adj), using nonlinear mixed effects regression analysis was well over 90% for all data combined over more than 3000 observations. CONCLUSION: Orchard location had a slight effect on the mean initial colour value, indicating differences in development stage, most probably due to differences in assessing the harvest date. The magnitude of the variation in these colour values was, however, the same for all three orchards. The behaviour of the green colour aspect (a* value) has been reported separately, as this represents the major change in perceived colour. The changes in b* and L* values are rather small, while the biological variation between the individual fruit is at least of the same magnitude. The model presented here is, as far as known, the first model on b* and L* values for green‐coloured products. Analysing b* and L* data using this model provides additional information with respect to the stage of maturity at harvest in a batch or for an orchard of Granny Smith apples. All the variation in the yellow colour aspects could be attributed exclusively to the initial level of yellow compounds. Copyright © 2010 Society of Chemical Industry