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     

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.     

Comparison of Minolta colorimeter and machine vision system in measuring colour of irradiated Atlantic salmon

BACKGROUND: Minolta and machine vision are two different instrumental techniques used for measuring the colour of muscle food products. Between these two techniques, machine vision has many advantages, such as its ability to determine L*, a*, b* values for each pixel of a sample's image and to analyse the entire surface of a food regardless of surface uniformity and colour variation. The objective of this study was to measure the colour of irradiated Atlantic salmon fillets using a hand‐held Minolta colorimeter and a machine vision system and to compare their performance. RESULTS: The L*, a*, b* values of Atlantic salmon fillets subjected to different electron beam doses (0, 1, 1.5, 2 and 3 kGy) were measured using a Minolta CR‐200 Chroma Meter and a machine vision system. For both Minolta and machine vision the L* value increased and the a* and b* values decreased with increasing irradiation dose. However, the machine vision system showed significantly higher readings for L*, a*, b* values than the Minolta colorimeter. Because of this difference, colours that were actually measured by the two instruments were illustrated for visual comparison. Minolta readings resulted in a purplish colour based on average L*, a*, b* values, while machine vision readings resulted in an orange colour, which was expected for Atlantic salmon fillets. CONCLUSION: The Minolta colorimeter and the machine vision system were very close in reading the standard red plate with known L*, a*, b* values. Hence some caution is recommended in reporting colour values measured by Minolta, even when the ‘reference’ tiles are measured correctly. The reason for this discrepancy in colour readings for salmon is not known and needs further investigation. Copyright © 2009 Society of Chemical Industry     

High pressure effect on the color of minced cured restructured ham at different levels of drying, pH, and NaCl

Color changes of minced cured restructured ham was studied considering the effects of high pressure (HP) treatment (600 MPa, 13 °C, 5 min), raw meat pH₂₄ (low, normal, high), salt content (15, 30 g/kg), and drying (20%, 50% weight loss). Raw hams were selected based on pH₂₄ in Semimembranosus, mixed with additives, frozen, sliced, and dried using the Quick-Dry-Slice® process. Meat color (CIE 1976 L*a*b*) and reflectance spectra were measured before and after HP treatment. HP significantly increased L*, decreased a*, and decreased b* for restructured ham dried to 20% weight loss, regardless of salt content and pH₂₄. L* and a* were best preserved in high pH/high salt restructured ham. HP had no effect on the color of restructured ham dried to 50% weight loss. HP had no effect on the shape of reflectance curves, indicating that the pigment responsible for minced cured restructured ham color did not change due to HP.     

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     

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     

Colour values of cooked top-round beef juices as affected by endpoint temperatures,frozen storage of cooked samples and storage of expressed juices

Juices from beef semimembranosus/adductor tissue, cooked to endpoint temperatures (EPTs) of 76, 78, 80, 82 and 84°C in a model heat-treating system, were evaluated for changes in CIELAB L*a*b*, chroma (C) and hue angle (H) values before and after storage of the cooked meat at -20°C for 3 weeks and after storage of the expressed juices under N₂ at 3°C for 72 h. Increases in EPTs altered all colour values of the juices. Lightness (L*) increased while yellowness (b*) decreased; redness (a*) and C decreased progressively while H increased toward the vertical axis. Storage of the expressed juices at 3°C under N₂ did not inhibit changes in a*, b*, C and H values. Regression coefficients of changes in relation to EPTs and time of storage of the expressed juices under N₂ were established. Storage of the cooked meats for 3 weeks at -20°C did not change any of the colour values of the juices. These data indicate that evaluations of cooked beef for doneness by colour of expressed juices must be performed immediately after expression of the juices before oxidation of the myoglobin pigments occurs. Storage of cooked meat at -20°C does not alter the colour of the juices, therefore, valid assays for doneness of meat in relation to juice colour can be made after frozen storage. © 1997 This article is a US Government work and, as such, is in the public domain in the United States of America     

Browning Inhibition in Fresh-cut'Fuji'Apple Slices by Natural Antibrowning Agents

ABSTRACT Response surface methodology was used to study the effect of antibrowning agents (4‐hexylresorci‐nol, glutathione, N‐acetylcysteine, and ascorbic acid) and storage time (14 d) on the color of minimally processed Fuji apples. The selected color parameters were L*,a*, b*, hue angle (h*), and color difference (ΔE*). Storage time had a significant effect on all the studied color parameters (P± 0.05). 4‐hexylresorcinol showed the most effective individual effect on keeping constant a*values (P± 0.0001). Besides, the interaction of N‐acetylcysteine/ glutathione was found to have a significant effect (P± 0.05) on maintaining a* values over time. On the other hand, individual treatment with N‐acetylcysteine in concentrations higher than 0.75% w/v may be used to preserve a*and h*.According to the F‐test, 4‐hexylresorcinol and N‐acetylcysteine (P± 0.05) displayed a significant individual effect on ΔE*, indicating that ΔE* decreased when increasing the concentration of these antibrowning agents. Nevertheless, color difference went down when 4‐hexylresorcinol concentration increased up to 0.5%, but higher concentrations of this agent led to an increase in ΔE* that indicates browning.     

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.     

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.     

EFFECTS OF DIFFERENT SALT CONTENTS ON SOME QUALITY CHARACTERISTICS DURING PROCESSING OF DRY‐CURED TURKISH PASTIRMA

ABSTRACT

This study examined the effects of different salt contents (3, 6 and 9%) during process stages on physicochemical, lipid oxidation and microbial quality of a dry‐cured meat product, past?rma, throughout 21 days of processing. Significant changes in moisture content, NaCl content, pH and water activity (a_w) were observed in past?rma after the third drying and pasting stages. There were significant decreases (P < 0.05) in objective color characteristics (L*, a* and b*) between raw material and final product for all past?rma samples. However, no significant effect of salt level (P > 0.05) was detected on L* and a*. Salt level significantly (P < 0.05) affected thiobarbituric acid‐reactive substances (TBARS) formation, which was lower in low‐salt past?rma samples, while the combination of salting, drying and pressing stages increased TBARS values in high‐salt past?rma samples. Higher salt content (6% and 9%) and last drying resulted in reduction of microbial count.

PRACTICAL APPLICATIONS

Salt (NaCl) is an important agent in inhibiting microbial growth, reducing water activity and imparting a salty taste to dry‐cured meat products such as ham and past?rma. Salt content in past?rma varies from 5% to 10% in the final product and has an impact on product quality parameters. The effects of different NaCl contents (3, 6 and 9%) and processing stages on pH, water activity (a_w), color parameters, lipid oxidation and microbial count were studied during processing of past?rma. Low‐salt concentration had some negative impacts on past?rma characteristics, giving high a_w, pH and microbial count, but low Thiobarbituric acid‐reactive substances value and NaCl content. Drying, pressing and pasting with çemen mixture during past?rma processing had a positive impact on reduction of moisture, a_w and microbial count.

     

The effects of pre-salting methods on water distribution and protein denaturation of dry salted and rehydrated cod - A low-field NMR study

Low field Nuclear Magnetic Resonance (LF-NMR) relaxation time measurements were used to evaluate the effect of different pre-salting methods (brine injection of salt and/or phosphates followed by brining, solely brining, pickling and kench salting) on the protein denaturation and change in muscle properties during the production steps of dry salted cod fillets followed by rehydration. The NMR relaxation curves were affected by the salting method and represented well the structural differences between the salting methods at each processing step. Significant correlations were observed between the NMR relaxation parameters and all physicochemical quality properties measured, except the cooking yield, when samples from all processing stages were analyzed together. The longitudinal relaxation time T₁, and the faster relaxing transverse relaxation time T₂₁ were shown to be especially sensitive to protein denaturation in the fillets. The water distribution indicated that the salting and rehydration processes changed the cells irreversibly. The study indicated that pre-brining by brine injection followed by brining, with low salt concentrations, led to the least protein denaturation during the dry salting and rehydration process.     

The influence of myoglobin on the colour of minced pork loin

The influence of the total and chromatic absorbance at wavelengths of 525 nm (A₅₂₅ and A_525p) and 700 nm (A₇₀₀), and the relative content of oxymyoglobin (MbO₂), metmyoglobin (MetMb) and deoxymyoglobin (Mb), on the value of the colour parameters (L*, a*, b*, C* and h°) of minced pork loin, were evaluated. Lightness (L*) depended almost entirely on variation in total absorbance at a wavelength of 525 nm. Redness (a*) depended on the forms of myoglobin and A_525p, while yellowness (b*) depended mainly on the proportions of the reduced form (Mb), the oxygenated form (MbO₂) and the oxidised form (MetMb). Yellowness (b*) significantly increased with a decrease in the relative amount of Mb and an increase in relative amounts of MbO₂ and MetMb, although a greater impact was exerted by fluctuations in MbO₂ than MetMb. Variability of chroma (C*) depended mainly on proportions of the forms of myoglobin. Hue angle (h°) depended primarily on chromatic absorbance at 525 nm (A_525p).     

Physicochemical,sensorial and textural characteristics of liquid‐smoked salmon (Salmo salar) as affected by salting treatment and sugar addition

The effect of salting method, dry salting (DS), brine salting (BS), brine salting with sucrose addition (BSS) or dry salting with sucrose addition (DSS) on the quality of Atlantic salmon treated with a liquid smoke flavouring was investigated over a 45‐day storage period. Sugar‐added samples were the ones with the significantly lowest values for TBARS (β₀, DS = 0.09^b; BS = 0.18^a; DSS = 0.07^c; BSS = 0.07^c). BSS and DSS fillets showed faster production rates of trimethylamine (TMA), 0.57 and 1.46, than the DS and BS fillets, 0.81 and 1.19, respectively. The DS and DSS fillets showed long delay periods before the TMA concentration started to increase (16.18; 20.60), and 90% of the panellists preferred these to BS or BSS fillets. In fact, only the BSS fillets were rejected during the storage, after 34 days; and the fillets with the most overall desirable characteristics at the end of the storage period were those of the DSS group.     

A colorimetric study of oenin copigmented by procyanidins

A colorimetric method was used to analyse the influence of procyanidin structure on colour changes of malvidin 3‐O‐glucoside (oenin) solution resulting from copigmentation. The study was performed in hydroalcoholic citrate/phosphate buffer solution (120 g L^?1) at pH 3.6 and ionic strength 0.2 mol L^?1. Chromatic L*, a* and b* coordinates (CIELAB, D65/10° illuminant/observer condition) obtained from spectral curves recorded between 360 and 830 nm allowed the calculation of lightness L*, chroma C* and hue angle h_ab. In general, addition of copigment induced colour enhancement (loss of lightness and increased chroma). The prevailing parameters affecting colour changes were lightness and chroma for monomers and lightness and hue for procyanidins B5 and B8 (C4–C6 dimers). A small blueing effect was observed only for catechin monomer‐copigmented solutions. For procyanidin copigments, as the structural complexity of the copigment increased, the hue angle moved to yellower values. The ester gallate of dimer B2 produced the strongest modification of colour attributes of oenin solution. Copyright © 2006 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     

Non-enzymatic browning in peach puree during heating

Non-enzymatic browning in peach puree (11° Brix) due to extended thermal treatment was investigated. Absorbance at 420 nm, colorimetric parameters (CIE L*, a*, b* and ΔE*), content in sugars (fructose, glucose and sucrose) and hydroxymethylfurfural were used to estimate the extent of nonenzymatic browning during heating at high temperatures (80, 85, 90, 95 and 98°C) for 480 min. Zero and first order kinetics were applied to describe evolution of relative absorbance at 420 nm. Relative luminosity and sucrose content follow a first order kinetic. Colour difference was successfully adjusted to a model including two stages: the first one includes the colour formation and it follows a kinetic of order zero and the second includes the colour destruction and it follows a first order kinetic model. Both first and autocatalytical models can describe HMF formation. Parameter b* was significantly reduced with heating time, especially at higher temperatures, on the contrary parameter a* increases during heating. The Arrhenius model described well the temperature dependence of the reaction rate constant for all the parameters considered.     

Effects of Brining Conditions on Weight Gain in Herring (Clupea harengus) Fillets

Salted herring is an important product category in many European countries. Reduced need for salt as a preserving agent and the increased emphasis on less salt in the human diet has changed the basis for the traditional processing of these products. This has led to significant changes in the processing conditions and in the characteristics of the salted products. In this perspective, the effects of different brine concentrations (10.0%, 16.5%, and 25.5%), brining temperatures (3.5 °C and 17.5 °C), the presence of skin or not on the fillets, and brining time (1, 2, 3, 4, and 7 d) were investigated on the weight gain (%) and final salt content (%) of herring (Clupea harengus). A significant (P < 0.001) higher weight gain of the fillets were observed at the lowest brining temperature (3.5 °C) compared with at the higher temperature (17.5 °C), independently of brine concentration and brining time. Increased brine concentration and skinning of the fillets caused the weight gain to significantly decrease (P < 0.001) and increase (P < 0.001), respectively. After 1 d of brining, the weight gain was in the range of 10% to 12% for both brining temperatures, and at the lowest temperature, the weight gain increased significantly (P < 0.001) as a function of brining time. At the higher temperature, no further significant increase in weight was observed from 1 to 7 d of brining. It is concluded that the weight gain in herring fillets brined according to the present commercial practice is significantly affected by temperature, brine concentration, brining time, and the presence or not of skin on the fillets and that the weight gain may be of high magnitude.     

Selected Quality Characteristics of Fresh‐Cut Sweet Potatoes Coated with Chitosan during 17‐Day Refrigerated Storage

ABSTRACT: Selected quality characteristics of fresh‐cut sweet potatoes (FCSP) coated with chitosan were evaluated during 17‐d refrigerated storage. The FCSP cubes were coated with a solution (1%, w/v) of chitosan having 470 or 1110 kDa. Color (L*, a*, b*) values of uncoated and chitosan‐coated FCSP during storage were generally affected by storage time as well as coating treatments (P < 0.05). No significant changes in color lightness (L*) of 470 kDa‐coated FCSP were observed during the 17‐d storage. During days 3 to 17, 470 kDa‐coated FCSP had significantly higher redness (a*) and yellowness (b*) values than did uncoated and 1110 kDa‐coated FCSP. Texture firmness of uncoated and chitosan‐coated FCSP exhibited minimal changes during the 17‐d storage. Although actual weight loss values (%) of uncoated and chitosan‐coated FCSP were not significantly different at day 17, the weight loss difference (%) between day 3 and day 17 for uncoated FCSP (3.02%) was slightly higher compared to those (2.24% to 2.26%) of chitosan‐coated FCSP. The initial total aerobic count was 4.7 log₁₀ CFU/g which then gradually increased to 8.54 and 9.67 log₁₀ CFU/g after 17 d of storage for 470 kDa‐coated and uncoated FCSP, respectively. After day 6, the total aerobic counts of uncoated FCSP were higher than those of 470 kDa‐coated FCSP. The yeast and mold count of chitosan‐coated FCSP was about 2.5 log₁₀ CFU/g at day 17. Overall, consumers could not differentiate between 470 kDa‐coated FCSP at day 17 and uncoated FCSP at day 0.     

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.