The effect of ionising radiation on the CIELAB colour co-ordinates of chicken breast meat as measured by different instruments

The colour of irradiated and unirradiated chicken breasts was measured at two laboratories (A & B). The effect of instrumental differences on the CIELAB colour co-ordinates and reflex attenuance spectra of the chicken breasts was examined. Each laboratory used two spectrophotometers, one of which was common to both. Laboratory B operated their other spectrophotometer in two different measuring geometries. Irradiated chicken breasts were found to exhibit increased a* values (greater redness) when compared with the unirradiated controls. Although differences in absolute CIELAB co-ordinates were found between instruments, all the instruments evaluated indicated increased redness and chroma values for the irradiated samples. Examination of reflex attenuance spectra indicated that the increases in a* observed were due to lesser absorption of light in the 600–700 nm region, although evidence of a change in pigment form was limited.     

CHEMICAL AND COLOR CHARACTERISTICS OF "LOMO EMBUCHADO" DURING SALTING SEASONING

"Lomo embuchado" is a traditional Spanish dry-cured meat product with two principal stages (salting-seasoning and dry-maturation) in its process. The evolution of chemical (moisture, nitrite, pH and lactic acid) and physical parameters: (CIELAB color space, chroma and hue, a*/b*, ΔE* and reflectance ratios R560/R500, R650/R570 and R630/RS80), during the salting-seasoning stage were measured. Three zones in the salted-seasoned loins were identified, and all parameters in each zone were analyzed. ANOVA and regression analyses were conducted. Moisture, pH and residual nitrite decreased with time (P<0.01), and lactic acid increased (P<0.05). Only moisture showed differences between zones (P<0.05). Color parameters changed during the salting-seasoning stage. Lightness (P<0.01), redness (only during the first 24 h (P<0.05)), and a*/b* ratio (P<0.01) increased. Yellowness (P<0.01), hue (P<0.01) and chroma (P<0.05) decreased during the process. The only parameter that was not affected by time and zone was reflectance ratio R630/R580 (P>0.05). Moisture and reflectance ratio R560/R500 were affected by zones (PCO.05). An excellent cured color was obtained during salting and seasoning.     

Prediction of technological and organoleptic properties of beef Longissimus thoracis from near-infrared reflectance and transmission spectra

Technological and organoleptic properties of beef cuts were predicted by near-infrared (NIR) spectroscopy. Spectra were collected on 189 beef Longissimus thoracis muscle samples using, transmission (NIRT) and reflectance with a probe. Quality assessment and NIR recordings were performed on sliced loin after 2 and 8 days ageing. Partial least squares regression yielded determination coefficients of cross-validation (R(2)(cv)) of 0.12-0.25 for the prediction of Warner-Bratzler Peak Shear Force in reflectance and 0.15-0.41 in transmission. Higher R(2)(cv) were obtained for L* parameter (0.83-0.85), a* (0.39-0.49) and b* (0.73-0.75) with reflectance. Predictions of drip loss and cooking loss were less accurate with a R(2)(cv) range of 0.38 to 0.54 and 0.25 to 0.47, respectively. The NIR spectra collected on fresh meat show good potential to predict CIE L* and b* parameters in reflectance mode.     

Colour characterisation of thyme and avocado honeys by diffuse reflectance spectrophotometry and spectroradiometry

The colour of 23 thyme and 13 avocado honeys was assessed by tristimulus colorimetry based on their spectra, using diffuse reflectance spectrophotometry and spectroradiometry, with the application of the equations for the uniform colour space CIELAB proposed by the Commission Internationale de lEclairage. The best results for distinguishing between the two types of honey have been obtained from spectroradiometry rather than from spectrophotometry. With the discriminant analysis it has been revealed that the two honey types studied are better characterised when considering lightness, chroma ( ) and hue angle as variables (94% correct), with and the hue being the parameters with the highest discriminating power.     

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.     

Mitochondrial oxygen consumption in permeabilized fibers and its link to colour changes in bovine M. semimembranosus muscle

Animal and muscle characteristics were recorded for 41 cattle. The oxygen consumption rate (OCR) of M. semimembranosus was measured between 3.0–6.4 h post mortem (PM3-6) and after 3 weeks in a vacuum pack at 4 °C. Colour change measurements were performed following the 3 weeks using reflectance spectra (400–1100 nm) and the colour coordinates L*, a* and b*, with the samples being packaged in oxygen permeable film and stored at 4 °C for 167 h.     

Ascorbic Acid Effects on Bovine Muscle Pigments in the Presence of Radiant Energy

Untreated and treated (dipped in ascorbic acid solutions of 0, 0.5, 1.0, or 5.0%) raw psoas major muscle samples were exposed to radiant energy in a model system (500W Hg lamp, 577 nm, 2°± 1°C, 20% 02) with spectral reflectance measured every 30 min. Results varied with reflectance ratios or differences at 572/525, 630-582, 630/582, or 630-614 nm. Differences between 0 and 4 hr exposure indicated that ascorbic acid retarded pigment oxidation. The K/S ratio at 572/525 nm indicated that 5% ascorbic acid solution retarded pigment oxidation and protected muscle color most. Ascorbic acid retarded lipid oxidation (TBA values) in muscle stored at ?26°C from 3–10 wk; a 5% solution gave the least protection of the solutions tested.     

Colour effects of co-pigmentation of anthocyanins revisited—2.A colorimetric look at the solutions of cyanin co-pigmented byrutin using the CIELAB scale

Spectral measurements (380–780 nm) were performed on 224 model solutions of cyanin co-pigmented by the flavonol rutin at pH between 2.5 and 5.5. The colour of the solutions was expressed as colorimetric co-ordinates in the CIELAB scale using the L^* (lightness) C^* (chroma) and h (hue angle) notation (for the D65/10° CIE Illuminant/Observer condition). Contrary to previous reports, all the most intensely co-pigmented solutions, although exhibiting the strongest bathochromic of their λ_max, did not displayed the bluest hues; an inverse, i.e. yellowing, effect was observed in the co-pigmented solutions at the lowest cyanin concentrations. The hyperchromic effect of co-pigmentation always caused a decreasing lightness of the solutions coupled with either an increasing or a decreasing chroma for those at low or high pigment concentrations respectively. Based on the amplitude of total colour CIELAB differences (ΔE*) at each co-pigment to pigment ratio, the most intense effects of co-pigmentation were observed at pH 3.5, except for the solutions at the highest pigment content (pH 4.5); the evolution of colour differences at increasing co-pigment to pigment ratios at pH between 2.5 and 5.5 are discussed. Colour differences calculations also showed that the maximum colour steps at successive increasing co-pigment to pigment ratios were observed at low values (0.5 or 1:1) in the most coloured solutions and at the highest values (up to 8–16:1) in the less coloured ones. In describing the colour effect of co-pigmentation on anthocyanins, the discrepancies found between the results of the present colorimetric approach and those previously reported based on spectral data at the λ_max only are discussed. Only the first one—by considering the spectral variations over the complete range of visible wavelengths and using the psychometric correlates of the three attributes of colour specified in the CIELAB system—correctly describes the colour variations as these are perceived by the human eye.     

PROPERTIES OF DRY-CURED HAM: TEMPERATURE AND pH INFLUENCE DURING SALTING STAGE

The influence of pH and temperature upon color properties, during the salting stage of 11 days for the dry-cured ham process was studied. Semimembranosus, Semitendinosus and Biceps femoris muscles were studied and each muscle was divided in three sections (outer, middle and inner). The parameters under study were: moisture, salt concentration, residual nitrite level, CIELAB and reflectance ratio (R650/R570). Neither temperature nor pH affected any parameter analyzed (P>0.05). Only Semimembranosus (and its outer zone) showed differences (P < 0.05) for moisture and salt concentration. A concentration gradient between muscles and Semimembranosus zones was found for residual nitrite level. Lightness, yellowness and chroma showed differences (P<0.01) for Semimembranosus muscle and its outer zone. Redness and reflectance ratio R650/R570 were not different (P>0.05) between muscles and zones. Only the Semimembranosus muscle was different (P<0.01) for hue. Semimembranosus and Biceps femoris zones were different (P<0.01 and P<0.05 respectively) for this parameter.     

Early Postmortem Prediction of Meat Quality Traits of Porcine Semimembranosus Muscles Using a Portable Raman System

Modern abattoirs are lacking objective, fast, and noninvasive methods to measure or predict important meat quality traits such as pH, color, drip loss, or shear force early postmortem. In this work, a mobile Raman system was used to perform measurements under real-life conditions in the cooling room of an abattoir using pig's semimembranosus muscles (N?=?96), 60–120 min after exsanguination. The traits pH₄₅, pH₂₄, CIE L*a*b*, drip loss, and shear force after 24 and 72 h were measured as reference and correlated with the Raman spectra using partial least squares regression. Strong correlations of the Raman spectra were obtained for pH₄₅ (R ² _cv?=?0.65, RMSECV?=?0.17 pH units), pH₂₄ (R ² _cv?=?0.68, RMSECV?=?0.09 pH units), L*-value (R ² _cv?=?0.64, RMSECV?=?1.9), b*-value (R ² _cv?=?0.73, RMSECV?=?0.6), drip loss (R ² _cv?=?0.73, RMSECV?=?1.0 %), and shear force after 72 h (R ² _cv?=?0.7, RMSECV?=?4 N). On the other hand, shear force after 24 h and a*-value showed only weak correlations (R ² _cv?=?0.22, RMSECV?=?7.8 N and R ² _cv?=?0.36, RMSECV?=?1.3). The predictions can be traced back to differences in the early postmortem metabolic conditions as indicated by Raman signals of phosphocreatine, creatine, adenosine triphosphate, inosine monophosphate, glycogen, lactate, phosphorylated metabolites, and inorganic phosphate. This study demonstrates the potential of Raman spectroscopy for the early postmortem prediction of six pork quality traits which can be useful for the discrimination of meat qualities and sorting in the production chain.     

The use of visible and near-infrared reflectance spectroscopy to predict colour on both intact and homogenised pork muscle

Visible and near-infrared reflectance spectroscopy (VIS/NIRS) was used to predict colour on pork muscle samples. Colour values were measured on 44 pork muscles (n=44) using a Minolta digital camera to determine CIE L* (lightness), CIE a* (redness) and CIE b* (yellowness). Samples were scanned in the visible and near-infrared region of the spectra on a monochromator instrument (400–2500 nm) on both intact and homogenised presentation to the instrument. Two mathematical treatments (first and second derivative) and two scatter transformations to the spectra were explored, none and standard normal variate and detrend (SNV-D). Predictive (VIS/NIRS) calibrations were developed using a modified partial least-squares regression (mPLS) with internal cross validation. The highest coefficients of determination in calibration (R²_cal) and lower standard errors in cross validation (SECV) were found for both CIE L* and a*, in homogenised presentation, while poor calibration statistics were found on intact presentation.     

The effects of mixing,transport and duration of lairage on carcass characteristics in commercial bacon weight pigs

On arrival at the factory commercial crossbred pigs were subjected to various treatments: (i) penned in producer lots; (ii) mixed with pigs from another producer and (iii) mixed and subjected to an additional transport of 1-1.5h duration. Groups of pigs were killed on the day of arrival or after overnight lairage. Carcass parameters including pH₁ (pH 45 min post mortem) and pH_u (pH 20 h post mortem) values of the Longissimus dorsi (LD) and adductor muscles were taken post mortem. Mixing and transport had no statistically significant effect on any of the carcass parameters measured, although overnight lairage resulted in significant decreases in hot carcass weight, killing-out percentage and liver weight. The incidence of carcasses classified as pale soft and exudative [PSE (muscles with a pH₁ of 5.9 or less)] or dark firm dry [DFD (muscles with a pH_u of 6.2 or greater)] was high after both normal and overnight lairage. pH₁ and pH_u values of the LD and adductor muscles were not significantly affected by mixing or transport. Statistically significant differences in the incidence of DFD between treatment groups were observed. In general the incidence of DFD increased more after overnight lairage in pigs penned in producer lots, than in pigs penned in mixed producer lots.     

Initial chilling rate of pre-rigor beef muscles as an indicator of colour of thawed meat

The effect of three rigor temperatures and two muscles of different fibre composition on the colour of thawed meat were determined. Within 45 min post-mortem, m. semitendinosus (ST) and m. biceps femoris (BF) from unstimulated heifer sides were held at 0, 10 and 35°C until they entered rigor. The rate of pH fall was higher at 35°C than at 0 and 10°C; and the pH values were lower (first 12 h post mortem) in the ST than the BF. Hunter L*, a* and b* and the hue angle increased with increasing rigor temperature (P<0.001). The ST was lighter and yellower and had greater hue angle than the BF. Colour parameters were plotted against the rate of muscle cooling in the first hour post mortem and linear regression lines were fitted to the data and equations were derived that gave a good indication of the colour and colour stability of the muscles as meat.     

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.     

Colour of Amontillado wines aged in two oak barrel types

The colour of 123 Amontillado wines from “Condado de Huelva” Designation of Origin, made from white grapes of the Zalema variety and slowly aged in different types of wood casks, has been studied. Colour differences due to different materials from which the casks were manufactured (Spanish and American oak wood) have been appreciated. Tristimulus methods have been applied following the recommendations of the International Commission on Illumination (CIE). Colour parameters (, , , , h _ab10) from CIELAB space and saturation () from CIELUV space have been used for calculus. The results indicated differences for lightness and saturation, which allows one to establish the areas of predominant colour for the characterisation of the colour of this type of wines. Multivariate statistical analysis demonstrated that different groups of selected variables give similar results, meaning that the wines aged in American oak barrels and Spanish oak barrels show significant (p<0.05) differences in colour variables. Three supervised learning methods, classification tree, linear discriminant analysis and back-propagation artificial neural network, have been applied for distinguishing between classes.     

Non-enzymatic Browning and Fluorescence Development in a (E)-4,5-Epoxy-(E)-2-heptenal/Lysine Model System

As a model system for studying oxidized lipid/protein browning, the reaction between (E)-4,5-epoxy-(E)-2-heptenal (a secondary oxidation product of ω-3 pentaenoic acids) and lysine was studied. CIELAB L*a*b* and fluorescence followed zero-order kinetics, and were always correlated, as a function of time, pH, temperature and epoxy-aldehyde/lysine ratio, suggesting parallel reactions for producing brown macromolecular pigments and fluorescent products. Activation energy, according to the Arrhenius equation, was 66.5 and SOKJ/mol for color difference and fluorescence intensity, respectively. This model system may help understand the non-enzymatic browning produced by lipids.     

Predictive value of slaughterhouse measurements of ultimate pork quality in seven halothane negative Yorkshire populations

An experiment with 1969 pigs, belonging to Yorkshire sire lines, was set up in cooperation with seven Dutch breeding organizations. The pigs, which were claimed to be halothane negative, were slaughtered in weekly batches. Light reflectance was determined with the Hennessy Grading Probe (HGP) and Fibre Optic Probe (FOP), in addition to pH(1) and rigor mortis at 45 min post mortem (p.m.). Further meat quality determinations were performed either in the slaughterhouse at 20 h p.m., or in the laboratory at 24 h p.m.. At first sight, both the scatter of light (HGP-PSE, FOP) and pH, measured at 45 min p.m., appeared to be indicative of the ultimate meat quality score. More accurate analyses, however, showed that the value of reflectance values is limited and less suitable in comparison to pH(1), especially with reference to the prediction of ultimate quality characteristics of water holding capacity. The correlations for pH(1) with drip loss were rather consistent, ranging from -0·34 to -0·52 per breeding population. In contrast, HGP-reflectance values ranged from -0·27 to 0·34, while those based on FOP(1) had a range from nearly zero (0·02) to 0·20. The proportion of variation (R(2) × 100%) in drip loss, explained by a set of slaughterline measurements, ranged from 13 to about 28% per breeding population. The use of measurements carried out at 20 h p.m. improved the R(2) × 100% for drip loss to a range from 50 to 62%.     

基于近红外光谱的冷鲜肉--解冻肉的判别研究

目的 利用近红外光谱对冷鲜肉和解冻肉进行判别研究。方法 利用385～935nm的近红外光谱系统,采集冷鲜肉与解冻肉表面的反射光谱数据,采用Savitzky-Golay(S-G)平滑和标准变量正态变换(SNVT)方法对光谱数据进行预处理。然后利用主成分分析法(PCA)实现数据降维,提取主成分后结合两种状态肉的理化指标(L*值,a*值,pH,蒸煮损失和嫩度),分别利用Fisher判别法、贝叶斯判别法两种判别分析方法对冷鲜肉和解冻肉进行判别研究。结果 两种判别分析方法,均取得较好的分类效果,尤其是Fisher判别法,校正集的回判正确率为96.67%,验证集的正确率为100%。结论 近红外光谱技术应用于冷鲜肉和解冻肉的鉴别是可行的。     

热处理下鲜枣红变与叶绿素酶活性相关性的研究

为研究热处理下鲜枣红变与叶绿素酶活性相关性。将鲜枣在60、65、70、75℃热水处理1min后,在室温下放置0～100min,测定叶绿素酶活性和色泽相关指标L*、a*、b*值,并且采用SPSS软件对鲜枣红变指标(a*)与叶绿素酶活性变化进行相关性分析。结果表明:热水温度为65、70℃,红变指标a*与叶绿素酶活性相关性较显著(相关系数R65℃=-0.923*、R70℃=-0.868);而热水温度为60、75℃时,二者相关性不显著(R60℃=-0.14、R75℃=-0.617)。鲜枣色泽与叶绿素酶活性显著相关,叶绿素酶直接参与鲜枣的红变。     

The measurement of light scattering and electrical conductivity for the prediction of PSE pig meat at various times post mortem

Measurements of light scattering and electrical conductivity were made in the Longissimus dorsi (LD) and Semimembranosus (SM) muscles using the Fibre Optic Probe (FOP) and Quality Meter (QM), respectively, to assess their ability to estimate pig meat quality, particularly the occurrence of PSE meat. One-hundred-and-fifty-three gilt carcasses were measured on three occasions post mortem (pm): 45 min (FOP(45) and QM(45)), 2h (FOP(2) and QM(2) and 24 h (FOP(u) and QM(u)). Measurements of pH were taken in the same anatomical position and at the same times. At 24 h pm muscle reflectance (GOFO value) and subjective colour assessments were made on the cut surface of the LD at the level of the last rib. Water-holding capacity (WHC) was estimated in a sample taken from the exposed surface of the LD by the solubility of sarcoplasmic and myofibrillar proteins. The FOP(45) predicted most accurately the WHC (R(2) = 0·49). Neither of the other quality measurements improved the prediction at 45 min pm. However, at 2h, adding QM(2) as a second independent variable improved prediction of WHC (R(2) = 0.58). At 24 h the combination of FOPu, QMu and GOFO did not improve the prediction of WHC (R(2) = 0.58). The best prediction used measurements of FOP(45), QM(2) and GOFO (R(2) = 0·62). The best relationship between subjective colour scores and the quantitative measurements of meat quality using discriminant analysis was obtained with the FOPu with an error-count estimate of 15·1% followed by FOP(2) (17%), GOFO value (18·7%), pH(2) (19·7%) and QMu (20·2%). With combination measurements of two instruments, pH(2) and FOP(2) had the lowest error-count estimate (10·9%). No further precision was obtained with combinations of three instruments. These results suggest that FOP and QM can be used to predict PSE and normal pig meat at different times pm and can replace traditional pH muscle measurements.