An Application of Image Analysis and Colorimetric Methods on Color Change of Dehydrated Asparagus (Asparagus maritimus L.) (original) (raw)
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2009
Shape and color are key factors in quality evaluation of fresh asparagus (Asparagus maritimus L.). Typical green color of asparagus comes from the chlorophyll, pigment which has been degradated during heat process. The aim of this paper was to compare color changes of asparagus dried at different temperatures for data obtained by chromameter CR-300 (Minolta) and digital image analysis in RGB color model. Basic elements of image analysis system were low voltage halogen lamps with reflector, which provided illumination of sample area of 760± ; ; ; 5 Lux, digital camera (Panasonic Lumix DMC- FZ30) and programs for image preprocessing and analysis IrfanView, Adobe Photoshop, Global Lab Image/2). Samples were placed at 60 cm from camera. Average values of color, color changes and correlation coefficients for asparagus were calculated for both color models. Average color of sample in beginning was in CIE L*a*b* model L = 21.42, a = -2.77, b = 6.28 and in RGB model R = 140, G = 188, B = 10...
Food and Bioprocess Technology, 2024
This research investigates the effects of various drying procedures and intensification technologies on the color profile of dried fruits and vegetables. The primary goal is to identify the most effective techniques for minimizing degradation, which is frequently caused by exposure to heat, oxygen, and longer drying durations, while retaining the original color of these products. Although conventional techniques like sun and hot air drying are often employed, enzymatic and non-enzymatic brownings usually cause a considerable loss of color. New technologies aim to better preserve the original color by cutting down on processing temperature and drying time. The paper also looks at the possibilities of hybrid drying approaches, which combine techniques such as infrared hot air drying and microwave hot air drying. These methods have been demonstrated to be especially successful in preserving color integrity and enhancing drying process effectiveness. The results highlight the vital significance that parameter optimization and drying technique selection play in maintaining the nutritional value and aesthetic appeal of dehydrated fruits and vegetables. This study emphasizes the significance of developing drying technologies to satisfy consumer desires for premium, aesthetically pleasing food goods, because color is a major factor in determining consumer acceptance and perceived product quality. With wider implications for food preservation and the food industry overall, this work helps to develop more effective and efficient drying processes by shedding light on how various drying techniques affect color retention.
Colour Change Kinetics of Plantain During Refractance Window Drying at Different Temperatures
Proceedings of the 22nd International Drying Symposium on Drying Technology - IDS '22, 2022
The kinetics of colour changes of unripe plantain slices dehydrated in a Refractance Window Dryer is investigated. Dehydration of 6 mm thick plantain slices was performed at 75, 85, and 95 o C and colour change history data was recorded. Evaluation of the colour of the plantain slices was carried out in terms of Hunter colour parameters L, a, and b, as well as the total colour difference (ΔE) representing the residual deviations from the undehydrated stage. The Refractance Window drying process changed the Hunter colour parameters of L, a, and b, causing a colour shift toward the darker region. The values of colour parameters L and b decreased, whereas values of the colour parameter, a, and total colour change (ΔE) increased during Refractance Window drying. The essence of this study is to characterise the effect of dehydration temperature of the change in colour of unripe plantain colour. The findings of this work contribute to a better understanding of colour change kinetics of plantain during dehydration, and the established change kinetics models are a good tool for predicting, evaluating, and controlling of colour change of unripe plantain during the Refractance Window drying process.
Journal of Food Science, 2009
The effect of different types of lighting (white, green, red, and blue light) on minimally processed asparagus during storage at 4 • C was studied. The gas concentrations in the packages, pH, mesophilic counts, and weight loss were also determined. Lighting caused an increase in physiological activity. Asparagus stored under lighting achieved atmospheres with higher CO 2 and lower O 2 content than samples kept in the dark. This activity increase explains the greater deterioration experienced by samples stored under lighting, which clearly affected texture and especially color, accelerating the appearance of greenish hues in the tips and reddish-brown hues in the spears. Exposure to light had a negative effect on the quality parameters of the asparagus and it caused a significant reduction in shelf life. Hence, the 11 d shelf life of samples kept in the dark was reduced to only 3 d in samples kept under red and green light, and to 7 d in those kept under white and blue light. However, quality indicators such as the color of the tips and texture showed significantly better behavior under blue light than with white light, which allows us to state that it is better to use this type of light or blue-tinted packaging film for the display of minimally processed asparagus to consumers.
LWT - Food Science and Technology, 2013
The changes of chromatic attributes due to different hydration degree, anthocyanins degradation and browning development were studied in dehydrated strawberries. Strawberry slices were freeze-dried, equilibrated at different relative humidities and stored at 45 C. The changes of several functions of the CIELAB color space were analyzed using a computer vision system, employing segmented image analysis. Darkening promoted by browning reactions could be evaluated through the decrease of luminosity and increase of hue angle and yellow coordinate in the whitish sections of the samples. During humidification the anthocyanin degradation increased as increasing water content. Of the several color functions, only the red coordinate values of the reddish sections of the samples correlated with anthocyanin degradation, but at relative humidities values higher than 43%. Light diffusion in the dried material caused a lighter appearance up to 75% relative humidity, while browning reaction and pigment degradation were accelerated at this relative humidity. These effects were related with the appearance of mobile water populations in the material, as detected by 1 H NMR.
Color Analysis of Carrots and Lemons by Using Spectrophotometer
This research was carried out to assess the distribution of color in carrots, green lemons and yellow lemons for quality estimation. The color measurements of these fruits and vegetable were taken from a coordinate system of points on the surface. A Minolta Spectrophotometer (CM-508i) was used to measure a* and b* in the CIE L *a*b* color model with the standard illuminant (D 65 ) and spectral wave of reflectance in visible range (400-700) nm. For color analysis using the Coefficient of Variation (CV) as an indicator of color homogeneity, carrots and yellow lemons were found to have lower CV values of a* and b* than the green lemons. From the result of CV analysis of the spectral wave of reflectance in visible range, the carrots and yellow lemons only had primary color that a single measurement point of color may be possible. On the other hand, green lemons having a secondary color required more measurement points to accurately describe the color of the fruits.
Food Quality and Safety
Colour and moisture content are two most important attributes of the commercial food product. Estimation of moisture content is very important to know the storability of the food product. It also relates to the process of drying in a fruit or vegetable. Extra drying and shrinkage deteriorates the quality of food product. The goal of the experiment was to examine the changes in RGB values of an apple during drying at different temperatures. In this study, emphasis was given on how the colour changes when there is a significant change in the moisture content of the apple. Three randomly chosen varieties of apples were sliced to 8 mm thickness and dried in vacuum oven at 60°C, 70°C, and 80°C. The loss of moisture was recorded for every 30 min interval and corresponding digital images were taken to determine the change in RGB value. The images that were captured during the study was analysed in MATLAB image analysis computer software. The analysis of moisture content and average colour share with respect to time showed that average colour share value decreases with time at all three temperatures. More than 50 per cent of variation in moisture content was explained by average colour share. There is a significant linear relationship between moisture content and colour changes in RGB and can be used to predict the moisture content of apple during drying process.
Colour as a Primary Indicator of Fruit Quality in Convective Drying
Fresh fruits are extremely sensitive to temperature, oxygen and enzymatic activity. Real-time quality evaluation in the process of drying could mitigate risks of food quality damage. This study evaluated the potential of real-time colour imaging for quality evaluation in fruit drying. The objective was to investigate colour changes of blueberries during air convective drying in the range of temperatures from 40 to 80 o C. Pilot-scale air convective tray dryer was equipped with multiple cameras for threedimensional fruit imaging and computerized real-time measurement system. Two varieties of blueberries were used in this study: highbush (Vaccinium corymbosum L.) and wild blueberries (Vaccinium angustifolium). Both varieties were purchased fresh from a local supermarket in Truro, Nova Scotia. The effect of temperature on blueberry colour was evaluated from drying experiments at 40, 50, 60, 70 and 80 o C for two blueberry varieties in three replications. To more precisely identify the critical temperature, which affected colour, additional experiments at temperatures 45 and 50 o C were carried out. In each experiment approximately 50g of blueberries were distributed in one layer on the tray. Colour changes were measured in CIE L * , a * , b * colour space, using real-time imaging.
Color Change Kinetics of Mango at Different Maturity Stages during Air Drying
Journal of Food Processing and Preservation, 2014
The objective of the present study was to evaluate color changes for the purpose of gathering data of kinetic parameters (rate constant [k] and activation energy [Ea]) of color change in mango slices at different maturity stages during air drying using Hunter color parameter values. Samples of green, half-ripe and ripe stages were dried at air velocities of 1.76, 1.80 and 1.91 m/s and temperatures of 50, 60, 70 and 80C. Colors (total color difference [DE], chroma [C] and hue [h]) in slices were monitored at 20 min intervals for 240 min. The changes in DE value followed the zero-order kinetics, while C and h values followed the first-order kinetics. Analysis of variance showed that the rate constants (k) for DE, C and h differ significantly (P < 0.05) with maturity stage, air temperature, air velocity and their interactions. Dependence of k on temperature followed an Arrhenius relationship, regardless of maturity stage and air velocity. Rate constant as a function of air temperature and velocity was found. PRACTICAL APPLICATIONS To obtain a better understanding of the industrial process applications, it is important to model and quantify the kinetics and process yield. This work was intended to provide models that allow describing the effects of air temperature and velocity on color change kinetics of mango slices at different maturity stages during air drying.