Physical,functional and pasting properties of different maize (Zea mays) cultivars as modified by an increase in γ‐irradiation doses

Physical, functional and pasting properties of six maize (Zea mays) cultivars as modified by an increase in γ‐irradiation doses were investigated. From the L*, a* and b* measured, deltachroma, colour intensity and hue angle were calculated. Functional and physicochemical properties of maize flours were determined using standard methods and Rapid Visco Analyser, respectively. Often, the effect of γ‐irradiation on L*, a* and b* values within each cultivar was almost never significant but pronounced between the yellow and white cultivars. Generally, deltachroma, colour intensity and hue angle decreased with increased γ‐irradiation dose. Mean seed bulk density and 100 kernel weight varied from 0.73–0.77 g cm^?3 and 23.13–35.42 g, respectively. Loose and packed bulk densities, and water (WAC) and oil absorption capacities of the maize flours were not significantly affected by γ‐irradiation. WAC of nonirradiated and γ‐irradiated maize flours ranged from 1.54–1.62 and 1.09–1.70 g g^?1, respectively. Peak, trough, breakdown, final and setback viscosities decreased significantly (P < 0.05) with increased γ‐irradiation dose.     

Colour changes of Scots pine and Norway spruce

Surface of boards, dried with wet bulb temperature above 60 °C are often called discoloured caused by severe resinflow. Discolourisation was evaluated using a tristimulus colour analyser, for measuring the colour changes during drying at three different drying schedules; 50 °C, 60 °C and 70 °C wet bulb temperature. The colour properties were pictured by lightness (L^*), chroma (C^*) and hue (h°). Results showed that lightness decreased and chroma increased during drying. When comparing the three differnt drying schedules the lightness decreased and chroma increased with higher drying temperature. No significant change of hue during drying was noticed, but when comparing the three schedules, hue decreased with higher drying temperature. Drying time and drying temperature level effect the value of lightness more than any other colour properties Values of lightness and chroma returned to its original value after 3 mm planing, while the value of hue for sapwood of Scots pine decreased after 1 mm planing, but increased again after 3 mm, even more for series C (70 °C) than for series A (50 °C). For sapwood of Scots pine, lightness decresed and chroma increased more than for sapwood of Norway spruce, both during drying and with higher drying temperature. A hypothesis is that red-making (or blue) substance such as nutrients and extractives are transported toward the surface during drying and making the surface look more red. That leaves the yellow-making substance in the inner parts of the board and when planing the board, the surface will be more yellow than before.     

Colour changes of fillets of rainbow trout (Oncorhynchus mykiss W.) fed astaxanthin or canthaxanthin during storage under controlled or modified atmosphere

Rainbow trout were fed diets containing two levels of lipids (9 g/100 g and 24 g/100 g) associated with two keto-carotenoid pigments (80 mg of astaxanthin or of canthaxanthin/kg of diet) for 4 months. After slaughter colour stability of fillets was studied during a 4-week storage at +4 °C under controlled (CA) and modified (MA) atmospheres under 100% air, 60:40 N₂-CO₂ mix and 60:40 air-CO₂ mix. Fillets from fish fed high fat level diets showed higher chroma and higher a^* and b^* colour parameters than those from fish fed low fat level diets. Storage time increased lightness and hue angle in CA but only lightness under MA. After storage at +4 °C lightness of fish fillets stored under MA were lower (P<0.05) than those stored under CA. Carotenoid source resulted in differences in chroma and hue angle of fish fillet stored under CA and MA. Dietary lipid levels resulted in differences in chroma under CA. Under CA the lower (P<0.05) differences between stored-initial values was for N₂-CO₂ and the higher (P<0.05) for air. Under MA, air-CO₂ and N₂-CO₂ gave similar results for L^*, C^* and H(°)_ab. Our experiment demonstrated that colour parameters of fish fillets reacted differently according to gas mixture and storage time.     

Influence of ageing time on the quality of yearling calf meat under vacuum

The objective of this study is to determine the effect of the ageing time on the quality characteristics of yearling calf meat under vacuum. Ninety-six Rubia Gallega yearling calves were used. Samples of the Longissimus thoracis at 1 day post slaughter as a control, and vacuum-packaged for 7, 14 and 21 days were analysed. Colour (lightness, L*, redness, a*, yellowness, b*, hue, H^o, chroma, C*, and pigment concentration), water-holding capacity (expressible juice and cooking losses), pH and toughness were measured. The statistical analysis showed an increase in a*, b*, H^o and C* and a decrease in expressible juice, cooking losses and toughness as the ageing time increased. Discriminant analysis divided the samples into two groups; i.e., 1-day post-slaughter samples and vacuum-packaged samples. Considering vacuum-packaged samples only, canonical discriminant analysis separated the long-ageing samples (21 days) from the short-ageing samples (7 days).     

Colour implications of self-association processes of wine anthocyanins

Copigmentation processes have been indicated to be crucial to stabilise coloured forms of the anthocyanins and explain colour expression in young red wines. Several studies exist about copigmentation between anthocyanins and different phenolics in model solutions, but little information is available about interactions among anthocyanins themselves. In this work, the process of self-association has been investigated in wine-like model solutions containing different grape anthocyanins (the 3-glucosides of malvidin, delphinidin and peonidin). The results obtained confirmed the existence of anthocyanin self-association and its influence on the apparent hydration constant of the anthocyanins with subsequent modification in the colour of the solutions. It was observed that the greater the degree of methoxylation of the anthocyanin B-ring the greater was the magnitude of the self-association. Colour analyses in the CIELAB space showed that self-association produces changes, which are more important in quantitative parameters (chroma, C _ab^* and lightness, L ^*) than in qualitative ones (hue, h _ab). Self-association leads to an increase in C _ab^*, indicating a more intense colour of the solutions, and to a decrease in the psychometric index L ^*, meaning that a darkening is produced. The effects on the colour were more pronounced with the passage of time of storage of the solutions.     

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     

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.     

Effect of temperature on the drying characteristics,colour, antioxidant and beta‐carotene contents of two apricot varieties

In this study, the drying characteristics, colour, oxygen reactive antioxidant capacity (ORAC) and beta‐carotene contents of two apricot varieties dried at different temperatures were compared. The hot air drying of apricot slices for both varieties consisted of a constant rate period (CRP) and two of falling rate periods (FRP). The CRP drying rate and the first and second FRP drying coefficients increased with drying temperature for both apricot varieties. The first and second FRP of both apricot varieties gave activation energies of 23.5–28.7 and 25.6–29.3 kJ mole^?1, respectively. The colour values (L*, a* and b*) of both dried apricot varieties decreased with increasing temperature, while the total colour change of both dried apricot varieties increased with temperature. The chroma, hue angle and browning index values of both dried apricot varieties decreased with increasing temperature, and the hydrophilic ORAC and beta‐carotene contents increased with drying temperature.     

Kinetics of colour change of bamboo shoot slices during microwave drying

The effect of microwave power on colour change kinetics of bamboo shoot slices was investigated during microwave drying. Colour changes were quantified by tri‐stimulus Hunter L (whiteness/darkness), a (redness/greenness), and b (yellowness/blueness) system. These values were also used for calculation of total colour change (ΔE), chroma, hue angle, and browning index (BI). Microwave drying as expected changed colour parameters because of browning. The values of L and b decreased, while values of a and ΔE increased during drying. Mathematical modelling of colour change kinetics indicated that L, b, chroma and BI could be defined using a first‐order kinetic model, while a, ΔE and hue angle could be defined using a zero‐order kinetic model. Considering together colour deterioration and quality of dried bamboo shoot slices at higher power reveals the need of process standardisation for getting good quality product.     

Identification of color optima of commercial tomato catsup

Color is an important quality feature of foods which, in many cases, determines consumer choice and selection. This is particularly true in case of products which are used only as additives to various foods and dishes such as tomato catsup. A screening of commercially available catsup showed a large variation in color properties expressed in terms of CIE-Lab parameters (L* = 30.7–35.8, C* = 18.7–30.1, and h _ab = 32.0–39.0). Sensory preference tests revealed that mainly lightness and hue are responsible for consumer preference of catsup. Generally, catsup with a hue angle > 35, corresponding to a more orange appearance, was less preferred. It was also observed that within the preferred samples some consumers significantly preferred brighter catsup (L* ∼ 34), whereas another group of consumers showed an attitude towards darker catsup samples (L* ∼ 32). Color difference scores between the two groups of catsups ranged between 3.7 and 7.2. These samples differed only slightly in hue underlining the importance of lightness and chroma. Several one-dimensional color parameters were related to preference data and judged with respect to applicability.     

The use of bulgur as a meat replacement: bulgur‐sucuk (a vegetarian dry‐fermented sausage)

In this study, bulgur was used to produce a new sucuk (Turkish dry‐fermented sausage) as a vegetarian product. Yellow and black/brown bulgurs were mixed into the sucuk dough as fat and meat imitations respectively. Instead of animal fat, olive oil was used for lubrication. Nitrite and nitrate were not added to the recipe. The bulgur‐sucuk was ripened at 60–95% relative humidity and 18–25 °C over 15 days. During ripening, pH, moisture content and textural (hardness, adhesiveness, springiness, cohesiveness, gumminess, chewiness and resilience), sensory (flavour, colour, cutting and overall scores) and colour (Hunter L, a, b, yellowing index (YI), total colour difference, hue angle, chroma and browning index values) attributes were monitored. The pH and moisture content of the bulgur‐sucuk were 5.81 and 493 g kg^?1 respectively before ripening and decreased to 4.14 and 280 g kg^?1 during ripening. The colour values L, a, b and YI decreased significantly (P < 0.05) to 33.03, 7.67, 11.63 and 80.70 respectively during ripening. Some of these decreases in colour values were expected owing to the lack of nitrite and nitrate. All instrumentally measured textural properties of the bulgur‐sucuk increased significantly (P < 0.05) during ripening. From the results of the parameter measurements and sensory evaluations, bulgur appears to be suitable as a meat replacement when used in a dry‐fermented formulation. Copyright © 2006 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.     

Changes in selected quality characteristics of minimally processed carambola (Averrhoa carambola L.) when treated with ascorbic acid

‘B 10’ carambola of ripening stage (RS) 3 and 4 were minimally processed (MP) and then dipped in 0, 15 and 30 mg L^?1 ascorbic acid (AA). The 1‐cm‐thick slices were then dried, packed into cling‐wrapped‐foam tray and stored at 7 °C for 0, 3 and 5 days. Skin colour (L*, C* and h°), flesh firmness, soluble solids concentration, vitamin C content, titratable acidity, pH, degree of browning, polyphenoloxidase (PPO) activity and sensory attributes of MP carambola treated with AA were determined. AA treatment had significant effect in decreasing cut surface browning degree but no significant effect on all the selected quality characteristics of the MP carambola. In the sensory evaluation, flesh colour, sweetness, flavour and overall taste were significantly affected by AA treatment especially at 15 mg L^?1. The RS of fruit significantly affected skin colour (C* and h°), pH and sensory attributes of colour and flavour of the MP carambola. As storage day (SD) progressed, skin colour (C* and h°), flesh firmness and vitamin C content, cut surface browning, PPO activity and all the sensory attributes of MP carambola decreased significantly. Flesh firmness of the MP carambola was affected by the interaction between AA × SD. Sensory attributes of MP carambola were affected significantly by AA × RS. All the sensory attributes of MP carambola positively correlated to each other but negatively correlated with browning degree. PPO activity positively correlated with browning degree. Copyright © 2007 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 cut‐type on quality of minimally processed papaya

BACKGROUND: This research was undertaken to study the effects of different cut‐types (cube, parallelepiped, cylinder and sphere) on the quality and shelf‐life of papaya cv. Sunrise Solo. Physicochemical analyses were carried out during 10 days of storage at 4 °C to determine colour, firmness, pH, titratable acidity, total soluble solids, weight loss and vitamin C content. Microbiological analysis and sensory evaluation were also performed. RESULTS: Papaya spheres (1.55 cm radius) presented the most favourable physicochemical and microbiological properties (smaller changes in colour parameters L*, a*, b*, chroma and hue angle, firmer texture, lower increase in pH, higher titratable acidity, almost constant total soluble solids, reduced weight loss, high vitamin C content and lower microbial loads) and sensory characteristics on day 10, while papaya cubes (1.4 cm side) proved to be the least acceptable. CONCLUSION: The results of physicochemical, microbiological and sensory analyses performed on different cut‐types of papaya indicated acceptable fresh‐cut produce during 10 days of storage at 4 °C. The potential shelf‐life at 4 °C is therefore 10 days, provided that no contamination occurs in the postharvest period and during minimal processing operations. Copyright © 2008 Society of Chemical Industry     

均匀色空间下红葡萄酒颜色量化分级研究

以宁夏贺兰山东麓产区2012年和2013年瓶储陈酿的13个红葡萄酒样品为材料,采用紫外可见分光光度法和国际照明委员会推荐的CIE L*a*b*均匀色空间参数,来量化葡萄酒的颜色指数,初步研究均匀色空间下红葡萄酒颜色的量化分级。数据量化结果表明:在标准光源D65下,所测试的红葡萄酒色相分为3级,紫红、胭脂红、宝石红;彩度分为5级,灰、淡、中、浓、鲜艳;明度分为5级,中等、稍亮、较亮、亮、明亮。建立CIE L*a*b*下的模型:Ry CX(1-5)LX(1-5)、Rz CX(1-5)LX(1-5)、Rb CX(1-5)LX(1-5),试验表明13种酒样分布在Ry C5+L2+、Ry C4+L3+、Rz C4+L2+、Rz C3+L3+、Rz C3+L4+、Rz C2+L4+、Rb C2+L4+、Rb C+L5+以上8级。     

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     

Application of Image Analysis Combined with Computational Expert Approaches for Shrimp Freshness Evaluation

This study was aimed to evaluate the freshness and quality of cultured shrimp (litopenaeus vannamei) during 9 days of storage on ice (i.e., at a temperature of 0°C) using image processing technique. A lighting chamber was used to provide uniform conditions for illumination. The shrimp freshness was evaluated using computer vision technique through color changes of head, legs and tail of the harvested shrimps. Thirty-six color parameters of the images such as mean and variance of red (r), green (g), blue (b), lightness hue (h), saturation (s), value (v), luma information (i and y), the luma component (y), chroma component (cr), lightness (L*), redness (a*), yellowness (b*), chroma (c), and hue (h) were analyzed. Some parameters, such as b*, from side pictures and r mean, b variance, v mean, y mean, b* mean and (L*) mean from top pictures changed with a rather similar trend during the storage period. Different computational expert approaches such as linear discriminant analysis, quadratic discriminant analysis, K nearest neighbors, and discriminant partial least squares regression were examined for shrimp freshness classification. For this, all the variables and the subsets of variables were selected by means of stepwise linear discriminant analysis, stepwise orthogonalization, classification and regression trees. The shrimp freshness was characterized with a high classification accuracy of 90%. Freshness evaluation using image processing is proposed as a potential technique to the food industry.     

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.     

Maintaining quality and bioactive compounds of broccoli by combined treatment with 1‐methylcyclopropene and 6‐benzylaminopurine

BACKGOUND: Broccoli deteriorates very quickly after harvest at ambient temperature due to the loss of green colour and the consequent yellowing of florets. To search for an effective method to control quality deterioration, the effect of 1‐methylcyclopropene (1‐MCP) combined with 6‐benzylaminopurine (6‐BA) treatment on visual quality, antioxidant enzymes and bioactive compounds in broccoli florets were investigated. RESULTS: A combined treatment of 2.5 µL L^?1 1‐MCP and 200 mg L^?1 6‐BA significantly reduced the increase of lightness (L*) value, and retained a high level for the hue value (H) and chlorophyll content. Superoxide dismutase, ascobate peroxidase and catalase activities increased while the activity of peroxidase decreased during storage in treated samples in comparison with the controls. The combined treatment enhanced the biosynthesis of glucosinolate and the formation of the anticarcinogen sulforaphane, which improved the health benefit of broccoli. CONCLUSION: These results indicate that a combined treatment of 1‐MCP and 6‐BA could be a good candidate for maintaining the visual quality and enhancing the nutritional value in broccoli during storage at 15 °C. © 2012 Society of Chemical Industry