33rd Indian Engineering Congress, The Institution of Engineers (India) Udaipur, 2018
Theme : Integration of Technologies: Emerging Engineering Paradigm
Development of economical colour measuring instrument for solid food
S. R. Kumbhar . A.K. Sahoo1.G.V. Mote1 . I. S. Udachan1
Colour is an crucial feature property in the food industries and it impacts buyer’s decision and inclinations. The perception of color thus results in the detection of certain defects that food items may present. The instrument was developed with camera, computer, and illumination system for colour measurement of solid foods. The determination of color can be carried out by visual (human) inspection or by using a color measuring instrument. With the advances in computer technology, signal processing techniques were applied to food colour measurement and food safety applications. It is often necessary to analyze the surface color of
food samples both qualitatively and quantitatively. The developed low cost instrument for colour measurement, measures colour in L*, a*, b* and RGB values with graphs of each pixel results. Jaggery sample were taken for the experimental purpose to get L*,a*,b* and RGB values. The results obtained were in comparable with high costing colour measuring instrument. Proximate analysis and colour analysis of jaggery samples were carried out to find out the relation between colour and nutritional composition. Jaggery colour changed due to change in moisture content, reducing sugars and ash content.
Keywords Colour measuring instrument.Jaggery .Camera. Computer. illumination
Dr. Iranna S. Udachan
Corresponding author: [email protected]
1Food Technology Programme ,
Department of Technology,
Shivaji University, Kolhapur-416004, Maharashtra Stae, India
Color is the primary feature for the acknowledgement and selection of food product, even befor the consumption by the consumer. A shade of the surface is the primary vibe that purchaser perceives and utilizes as a device to acknowledge or dismiss thefood product. The perception of clour in this way permits the revealing of specific imperfections that may exhibit in the food product. By means visual (human) inspection or color measuring instrument colour analysis can be carried out (M. Abdullahetal 2004).But there is great degree variable from eyewitness to spectator during visual (human) inspection of colour. With the end goal to do a more target color estimation, shading guidelines are regularly utilized as reference material, but regrettably, it implies a slower assessment and needs more exercise of the observers (K. Leónet al 2006).
With the advances in computer technology, signal processing techniques are applied to many food colour measurement and food safety applications. It is often necessary to analyze the surface color of food samples both qualitatively and quantitatively. The qualitative measurement may involve visual inspection and comparison of the food samples. The quantitative measurement may involve obtaining color distribution and
averages. It may also be made to correlate color distribution with other data such as temperature, moisture, shelf life and spoilage content distributions.
Human eye recognizes hues as indicated by the fluctuating affectability of various cone cells in the retina to light of various wavelengths. There are three types of colour photoreceptor cells (cones) for the human with sensitivity peaks in short (bluish, 420-440 nm), middle (greenish, 530-540 nm), and long (reddish, 60-580 nm) wavelengths (Hunt, 1995). Color can be rapidly analyzed by computerized image analysis techniques, also known as computer vision systems (CVS),(F. Mendozaet al 2006).These systems not only offer a methodology for measurement of uneven coloration but it can also be applied to the measurement of other things of total appearance like moisture chemical constituents etc. Dedicated commercial vision systems are currently available for a variety of industrial applications, and they are especially recommended for color assessments in samples with curved and irregular shapes. The knowledge of these effects, such as the variations of L*, a*, b* for a particular shape of the sample, Red Green Blue (RGB) values could be useful for developing image processing. It will helpful in a measurement of the colour of agricultural produce like fruits , vegetables, cereal grains etc also in processed food products like dairy products, bakery products, meat and meat products industry etc.
There are some instruments for solid food colour measurement like Colour Meter, Hunterlab solutions, CIE lab Solutions. Colour meters are used for the colour measurement of solid food, liquid food. This colour meter can read the difference in colour in L *a*b*, L*C*H* and Delta E*ab. Hunterlab solutions, CIE lab Solutions works on a measurement of L*a*b* values and comparison with another products L*a*b* values, (H. Good,2011). These instruments are well designed can be operated easily but some instruments do not store data and results. By using computer vision,store data can be resulted batch wise which will be helpful for traceability also. Main objectives of present work were to develop low-cost colour measurement instrument with a camera, illumination system and computer system and colour measurement of food products (jaggery) in L*a*b*, RGB values.
Jaggery is sugarcane based natural sweetener made by the concentration of sugarcane juice without any use of chemicals, (Dilip Kumaret al 2013). It is available in the form of solid blocks and in semi-liquid form. It contains the natural sources of minerals and vitamins inherently present in sugarcane juice and it is one of the most wholesome and healthy sugars in the world. Of the total world production, more than 70% of the jaggery is produced in India but most of the jaggery business suffers from losses. The development of different value added products from jaggery and their commercial availability becomes needs of the hour to sustain future profitability in the jaggery trade. Due high moisture content, humidity jaggery colourmay changes that’s why there is need of colour analysis of jaggery. Jaggery colour also changes due to change in nutrients, structure, atmosphere. Sometimes jaggery cubes become rubbery which leads to change in colour indirectly which also effects on cost . Jaggery colour also depends on varieties of raw cane used for manufacturing of jaggery.
Development of colour measurement instrument
The colour measurement instrument was developed by 2 ft. (Breadth) × 2.5 ft. (Length) × 1.75 ft. (Height) steel frame covered with 8mm plywood. The illuminating bulbs and the camera were placed in a box, the interior walls of which were painted black to eliminate background light. Below the camera jaggery sample was placed.
Table1 Material required for development of instrument
Material Description Quantity
Steel pipe 1.5 inch 35 ft
Illumination 3 watt syska LED bulbs 4
Holders Pipe holders 4
Plywood 8mm 1.5 piece
Colour Asian paints mat finishing black colour 200 ml
Camera Web cam 25 megapixel 1
Computer Photoshop cs 4 1
Camera captures photo of sample placed, send signals to computer. While capturing photo illumination light helps to maintain proper lighting condition. Photo was taken in Adobe Photoshop CS4 which displays RGB, L*a*b* values and graphs . Quantum color digital camera with 25 Mega Pixels of resolution,was placed vertically at a distance of 30 cm from the samples. The angle between the axis of the lens and the sources of illumination was approximately 45º. Illumination was achieved with 4 Syska LED, Natural Daylight 3W fluorescent lights, with a color temperature of 6500 K. Material required for instrument is presented in Table 1.
Various samples were collected from local market Kolhapur for color measurement and proximate analysis. Sample codes are presented in following table II.
Table 2 Codes of samples
Sr. no Sample code Sample name
1 JI Fresh jaggery
2 JII Organic jaggery fresh
3 JIII Chemically processed jaggery
4 JIV Organic jaggery old
5 JV Kesari jaggery
(JI) (JII) (JIII) (JIV) (JV)
Fig 1 Samples used in experiment
Proximate analysis of jaggery
Determination of moisture content
About 5.0 g of sample was weighed and transferred into a previously weighed crucible. The crucible was then placed in the drying oven at 105°C for 5 h. After this, the sample removed and placed in a desiccator to cool. The cooled crucibles were reweighed. This was done in triplicate. The loss in weight after drying was then calculated as the percentage moisture (W. Horwitz, 2000).
Determination of ash content
About 5.0 g of sample was weighed into a previously weighed crucible and placed in the muffle furnace (600°C) for 4 h. The crucibles were cooled and reweighed. The loss in weight was then calculated as the percentage as or ash content of the sample (W. Horwitz, 2000).
Determination of fat content
The dry sample was transferred to a paper thimble. Sample was added to a previously dried 250 ml round bottom flask and weighed. 150 ml of petroleum ether was added to the flask and the apparatus was assembled. Condenser was connected to the Soxhlet extractor and kept for six hours on low heat. The flask was removed and evaporated on a steam bath. The flask with the fat was heated for 30 min in an oven at 103°C. The flask and its contents were cooled to room temperature in a desiccator after which it was weighed and percentage fat calculated (W. Horwitz, 2000).
Determination of reducing sugar content by DNSA method
About 5.0 g of sample dissolved in 50ml water, filtered by Whitman paper no 42. 5.0ml of the sample taken in conical flask 2.0ml DNSA reagent added. Solution kept in boiling water for 5 minutes then cooled under tap water. Measured optical density at 530nm by making 150 times dilution. Plotted the standard curve and calculated the amount in the sample from the standard curve (W. Horwitz, 2000).
The jaggery sensory attributes were evaluated using a 9-point hedonic scale, where a score of 1 is “dislike extremely” and a score of 9 is ‘like extremely”. A panel of judges comprising ten participants randomly selected from the students of the Department of Technology. Taste, aroma, colour, flavor, texture and general acceptability of the jaggery were determined.
Results were expressed as mean ± SD. values were the average of triplicate experiments. Significant differences between the results were calculated by analysis of variance (ANOVA) with the help of Microsoft excel 2010, (Mohammad Daneshi1,2013).
Results and Discussion
In this study for comparisons colour measurement was done at MPKV Rahuri (Department of Agricultural Process Engineering) on a standard colour measurement instrument(Premier colour scanning machine, Thane).
Table 3 Comparison between developed colour measurement instrument and Premier colour scanning instrument
Parameter Standard colourmeasurement instrument Developed colour measurement instrument
Tile Jaggery Tile Jaggery
R – – 224 152
G – – 225 134
B – – 225 52
L* 87.95 45.327 89 57
a* 0.017 3.08 -1 6
b* 8.02 27.63 5.33 30
Two samples viz. fresh jaggery, organic jaggery were taken in experiment.For standardization piece of tile used. Developed instrument was calibrated on the basis of standard colour measurement instrument values. L*, a*, b* and RGB values obtained in developed colour measurement instrument of each pixel of image. Comparison between developed colour measurement instrument and Premier colour scanning instrument is presented in Table 3.
Measurement of jaggery colour in developed colour measurement instrument
Sample wereplaced in image acquisition zone where camera captured the image of sample.
Table 4 L*, a*, b* and RGB values from developed colour measurement instrument
Images were analysed by using Adobe Photoshop CS4.L*, a*, b* and RGB values were obtained by taking mean of three values.RGB values stands for percentage of Red, Green, Blue, colour present in sample. Colour values were used to finding the relation between chemical components in jaggery. Basically JIII was lighter and JIV was dark.Values shown in Table 4 were obtained in measurement of colour of various jaggery samples in developed color measurement instrument.The low value of L* (lightness) denoted darkness. JIII sample had higher L* value than JII and JIV samples. JI sample had average L*, a*, b* and RGB values. R and G value of JIII and JV samples were same but slightly changed in L* value.
Proximate analysis of jaggery and relation between colour and nutrients.
Analysis of proximate composition provides information on the basic chemical composition of jaggery. Sample JII had L* value 37.66 which resulted in dark in colour and moisture content 15.23%, where as sample JIII had L* value 70 which resulted in lighter in color and moisture content 6.23%. Due to high moisture content colour changed from lighter to darker (Brown)(Dilip Kumaret al 2013).As presented in Table 5,L* values increased with decrease in moisture content and ash content respectively in samples JII, JIV, JI, JV, JIII. There was the slighter change in fat content and protein content of both the samples. There was small difference in reducing sugars in chemically treated jaggery and organic jaggery. Values of proximate are presented in Table 5.
Table 5 Values of proximate analysis of jaggery in percentage
Compone-nts JI JII JIII JIV JV
Reducing sugar 17.05
Developed colour measurement instrument was able to measure colour in L*a*b* and RGB units and simultaneously measure the colour of each pixel on the target surface. Colour change occured due to variation in nutrients of jaggery. With the help of this colour measurement instrument, the relation between colour and nutritional composition can be determined.. This instrument can be used for colour analysis other solid food products.
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