European Journal of Academic Essays 2(7): 23-27, 2015
ISSN (online): 2183-1904
ISSN (print): 2183-3818
Changes in Colour attributes of Kithul (Caryota urens) flour stored in Refrigerated (4°c) Condition
J A A C Wijesinghe1*, I. Wicramasinghe2 and K.H Saranandha3
1,2Department of Food Science and Technology, Faculty of Applied Sciences,
University of Sri Jayewardenapura, Gangodawila, Nugegoda,Sri Lanka.
3Food Research Unit
Abstract: Colour of the food is the first consideration for quality evaluated by consumers. This paper is aimed to evaluate the colour as to define criteria for differentiation of fresh and one year old flour samples. Kithul flour (Caryota urens) colour were evaluated in terms of lightness (L*) value , redness(a*) value ,yellowness (b*) values as well as the total colour difference(ΔE). Kithul flour samples which were collected from five main growing areas presented significant difference (p< 0.05) among their colour attributes during shelf life which was stored in refrigerated condition (4°C). According to the instrumental measurements, lightness value has significantly changed (P<0.05) by improving after one year time period. Nevertheless redness and yellowness value has not significantly changed after one year time period. However redness has improved while yellowness has decreased with the time .According to the colour attributes of flour samples Matale (ΔE=34.77) and Kegalle (ΔE=34.65) had a greater deviation from the standard colour value than the other samples. Kandy area presented the least deviation from standard as ΔE=30.24 at the initial stage. With the time colour difference has decreased for all samples. In the case of Kurunegala (ΔE=29.50) and Kandy (ΔE=29.37) flour are shown least colour deviation than other three areas. However time could be directly influence on reduction of colour difference (ΔE) of flour although it was stored in refrigerated and air–tightened condition. However this can be a focal point for food applications in future to choose better storage condition to keep original colour of the flour.
Keywords: Kithul flour, Refrigerated condition ,Colour variation, storage condition, shelf life, L* a* b* values
Palms are aconstructive source of food products and medicine , and starch is a major renewable resource beside cellulose which forms the chief source of carbohydrate in the human diet . Kithul (Caryota urens) palm ,which is indigenous to India, Malaysia, Myanmar, Nepal, and Sri Lanka,is identified as a multipurpose tree.It provides both edible and non-edible products. Edible products from Kithul tree include sweet toddy, Kithul treacle, Kithul toddy and Kithul jaggery as well as Kithul flour  which still remains as an unexploited resource in food industry.This flour which is equal in quality to industrial sago obtained from Metroxylan Sagu Rottb, plays a very important role as a food source .
For the industrial applications quality attributes are very critical, especially when Kithul flour is used to replace existing ingredients.Colour is a cause of perception and depends on interpretation as well as background differences (contrast effect), directional differences or observer differences or Size differences (area effect).To eliminate these errors ,and create a universal language for colour reading ,numerical system is the best method. By creating scales for hue, lightness, and saturation, colour could be transferred to a numerical value.
. Colour is one of the most influential characteristics of a final food, especially in the case of flour as raw material,modern consumer mainly considers the overall appearance of the flour including the colour . Colour of flour is a noiselesspointer for its novelty while it affects the overall point of view on food from both a tasteful and safety point of view . In this way colour determination is one of the beneficialpoints which could be used for the improvement of flour quality.
The International Commission on Illumination (CIE) serves to define the location of any colour in uniform space by correlating the colour attributes of L*,a* and b* (1976)  which can be measured using a Chroma meter. This instrument enables users to directly determine the colour on the flour  by generating L*, a* and b* values. This readings subjective for the sensorial are brightness, lightness, hue, saturation, Chroma and colourfulness  . L* is a function of measure of the brightness from black (0) to white (100) while a* presents a function of the red-green difference. It varies between -60 to +60 while -a* goes from green and +a* goes towards red. b* is functioning for the green-blue difference. Positive b* indicates yellowness and varies from -60 to +60, with -b* and +b* go towards blue and yellow, respectively. This measurements of the L*,a*,b* system presents the same perception of colour difference  by excluding human errors.
- Materials And Method
- Sample Collection:Five districts, namely Kurunegala (North-western province), Matale and Kandy (Central province), and Kegalle and Rathnapura (Sabaragamuwa province), were selected for the study as the five main growing areas in Sri Lanka. Six Kithul flour samples were collected from each district from both household and commercial markets.
- Sample preparation and Storage:Samples were sifted through a 355μm sieve, packed in air-tight containers, and then stored in refrigerator (4 ºC) until further analysis.
- Chroma meter Minolta (CR 400) colourimeter: The instrumental measurement of Kithul flour colour was carried out with a Chroma meter Minolta CR-400 (Konica Minolta colourimeter, sensing, Japan) and the results were expressed in accordance with the CIELAB system. The meter was calibrated with a white tile (L* = 93.30, a* = 0.32 and b* 0.33). The samples were poured into glass dishes(6.4 mm diameter diaphragm with an optical glass), and the surface of each sample was manually made flat. The measuring head of the meter was carefully placed on three different locations on the petri dish. The measurements were taken in triplicates and mean and standard deviation values were determined. The colour attributes were determined by colour coordinates of L* (L* = 0 [black] and L* = 100 [white]), a* (−a* = greenness and +a* = redness), and b* (−b* = blueness and +b* = yellowness).
- Shelf life studies: Keep the samples in air-tight containers, at 5 ºC in refrigerator for one year. Then readings were taken as per the section 2.3.
- Statistical Analysis: Results were analyzed using one-way analysis of variance (ANOVA) and paired T-test at 0.05 probability level with MINITAB software package (version 17 for Windows).
- Results and Discussion
The colour attributes of the Kithul flour treatments from five different growing areas in Sri Lanka is shown in Table 1. According to the results, there were significant differences among flour samples from five different growing areas for both L*(lightness) in initial and after one year values.But these two readings follows same pattern according to the superscripts except for samples from Kegalle area. Kandy (71.56) and Kurunegala (70.18) flours presented higher L* values than other flour treatments. Kithul flour samples from Matale (65.58) district has the lowest L* value at the initial stage. After one year, the lightness (L*) of all Kithul flour samples were increased and this could be attributed relationship of colour of flour vs the time of storage. Both stages (Initial flour samples and after one year flour samples) represent the mostly same significant difference pattern among areas .
The lowest a* value (4.54) was observed in Kandy flour samples while the highest values were reported from Kegalle (5.34) at the initial stage .But after one year redness has developed more in Ratnapura samples (6.02) while other samples ( Matale,Kandy and Kegalle) also showed considerable redness .But in the case of Kithul flour samples from Kurunegala area showed reduction of redness when compare with the initial a* value.At the initial stage redness (a*) of Kithul flour presented significant differences as three groups based on superscripts as, Kurunegala, Matale in one group, while Kegalle and Ratnapura in another group and Kandy as third group.However at the final stage this pattern has changed in to four significantly different groups.
|Table 1:Variations in Colour properties(L* ,a*,b*) of Kithul flour collected from five districts in Sri Lanka vs Shelf life|
|Sample||L*(Initial)||L*(after1 year)||a*(Initial)||a*(after1 year)||b*(Initial)||b*(after 1 year)|
|Kandy||71.56± 3.07 a||72.44±2.72a||4.54±0.64b||5.13±0.77bc||16.5±0.82ab||16.12±0.66ab|
|a,b,cDissimilar letters indicate differences in treatment means within the same column (p < 0.05)|
At the initial and final stage yellowness (b*) has presented significant difference among all areas (Table 01).The Kithul flour samples from Kegalle area recorded higher b* value (deeper yellow) of +17.90 and +14.29 was recorded by Matale area as lower b* value at the initial stage. However after one year yellowness has decrease from deeper to lighter in Kegalle as +17.28 and Matale as +14.19 .These could be attributed to the age of the Kithul flour (24 months) which made it very fibrous and resulted in the conversion of starch granules to sugars .
|Table 2:Variations in Colour difference(ΔE) of Kithul flour collected from five districts in Sri Lanka vs Shelf life|
|Sample||ΔE(Initial)||ΔE(after 1 year)|
|a,b,cDissimilar letters indicate differences in treatment means within the same column (p < 0.05)|
The differences in colour could be attributed to the variety, age and also different processing procedures for flour.The larger the ΔE value represents, the larger the colour difference .The estimation of ∆E, indicate the extent of deviation of colour of samples from the standard tile colour used (L*=97.63, a*=- 0.48, and b*=+2.12). From the results the flour samples from Matale (ΔE=34.77) and Kegalle (ΔE=34.65) had a greater deviation from the standard colour value than the other samples (Table 2). Kandy area presented the lowest deviation from standard as ΔE=30.24 at the initial stage. With time colour difference has decreased for all samples. Floor samples from Kurunegala (ΔE=29.50) and Kandy (ΔE=29.37) has shown the least colour deviation compared to flours from other three areas.
Figure 1: Figure 1. L* variations of Five districs Kithul Flour samples vs Time
Figure 2: Figure 2. a* variations of Five districs Kithul Flour samples vs Time
Above area wise comparison which has analyzed by ANOVA one–way variance showed differences from results which were test. L* value has significantly changed (P<0.05) after a one year storage period according to the results of paired T-test. Lightness (L*) has improved. It can clearly identify by Figure 01,which is graphed with mean L* value of Kithul flour from different areas.
Although based on paired T-test a* value (P>0.05) and b* value ( P>0.05) has not significantly changed after one year time period, while graphs of mean value of redness (a*) and yellowness (b*) in area wise comparison shows more reddish (Fig.02) and low yellowness( Fig.03) tones (higher a* and lower b* values) as compared to initial stage of Kithul flour.
Variations in ΔE of mean values among different growing areas behave as per the Figure 4. ΔE value has decreased after one year time period in all Kithul flour samples from five different growing areas. Again it was proved by paired T-test. ΔE value has significantly changed (P<0.05) after a one year storage period .It showed clear cut observation as time could directly affect colour differences of flour although refrigerated in air –tighten conditions.
Figure 3: Figure 3. b* variations of Five districs Kithul Flour samples vs Time
Figure 4: Figure 4. Variation of Colour difference vs Time
- Conclusion and Further Work
Kithul flour samples collected from five main growing areas presented significant differences(p< 0.05) with respect to colour attributes such as L* (lightness) value, a* (redness) value, and b* (yellowness) values. Further colour attributes of flour sample significantly changed during shelf life. According to the instrumental measurements, L* value has significantly changed (P<0.05) after one year time period. Lightness has improved. Nevertheless a*and b* value has not significantly changed after one year time period. However +a* (redness) has improved while +b* (yellowness) has decreased with the time.According to the colour attributes of flour samples Matale (ΔE=34.77) and Kegalle (ΔE=34.65) had a greater deviation from the standard colour value than the other samples. Kandy area presented the least deviation from standard as ΔE=30.24 at the initial stage. With time colour difference (ΔE) has decreased significantly (P<0.05). Kurunegala (ΔE=29.50) and Kandy (ΔE=29.37) flour have shown least colour deviation than other three areas.
Acknowledgement: The authors thank the University of Sri Jayewardenepura, Sri Lanka for providing the financial assistance for this study. Grant No: ASP/06/RE/SCI/2012/04. And also authors are grateful to
Dr.B.M.K.S. Tilakaratne ,Director of Institute of Post-Harvest Technology Research and Development Centre, Anuradhapura, Sri Lanka for providing Chroma meter Minolta CR-400 (Konica Minolta colorimeter ,sensing, Japan) to carry out this study and Dr. M.A.P.K Seneviratne, Department of Export Agriculture, District office, Peradeniya for assisting in classification of Kithul growing areas.
- RajyalakshmiP ., Caryotapalm sago O A potential get underutilized natural resource for modern starch industry. Natural product radiance , (May-June 2004) ,vol 3(3) , pp144 -149.
- RajyalakshmiP ., (2005); Processing Of Unconventional Foods. Report On Training Programme Of “Emerging Trends In Food Processing Technology – Prospects & Opportunities” 14-09-2005 to 4-10-2005, pp-24-29.
- Orwa C., Mutua A.,Kindt R.,Jamnadass R., Simons A. (2009) ; Arecaceae L; Agroforestree Database: a tree reference and selection guide version 4.0. (2009). (http://www.worldagroforestry.org/af/treedb/) visited on 2013.10.02.
- Evelyn S. A.,(2013);Development and Quality Characteristics of Yam Bean (PachyrhizusErosus) Flour and Its Performance In Bread; Published MSc.,thesis, Kwame Nkrumah University of Science and Technology, KUMASI .(32-52)
- Clydesdale, F. M. (1984). The influence of colour on the sensory perception and food, feed and industry. CRC Press, Inc. Boca, Florida, USA. pp 113-127.
- CIE 15:2004. The Executive Director Office Of The Federal Register, Washington,.CIE 15: Technical Report: Colorimetry, 2004,3rd edition.17, 16-27.
- Konica Minolta Chroma Meter CR-400/410 instruction manual.2002-2013.9222-1878-20. http://www.konicaminolta.com/instruments/download/instruction_manual/color/pdf/cr-400-410_instruction_eng.pdf
- Macdougall D. B.,(2002), Colours in food, Improving quality, Chapter 3: Colour measurement of food, Principles and practice, D. MacDougall, Woodhead Publishing in Food Science and Technology, Cambridge, England. 2002,44, 33-60. ISBN 0-8493-1542-5.
- Oliver J.R., Bkakeney A.B., Allen H.M.,(1992); Measurement of flour in colour space parameters. cereal chem.,69(5).546-551
- ISCC (Inter-Society Color Council) and NBS (the United States Department of Commerce’s National Bureau of Standards) .2013.Universal Color Language, Level 3 Color Names. http://www.december.com/html/spec/colorucl.html).Cited on 2014/07/15.
- Oduro-Yeboah, C., Johnson, P-N.T., Sakyi-Dawson, E. and Budu, A..(2010); Effect of processing procedures on the colorimetry and viscoelastic properties of cassava starch, flour and cassava-plantain fufu flour; International Food Research Journal 17: 699-709
- Morrison, W.R and Laignelet, B. 1983. An improved colorimetric procedure for determining apparent and total amylose in cereal and other starches. Journal of Cereal Science 1: 9-20.d, 2002,pp. 352–366. ISBN 0-8493-1542-5.
Mrs. J A A C Wijesinghe received the BSc.(Hons) in Food Science and Technology from University of Sri Jayewardenapura, Sri Lanka in 2006 to 2010y. During 2010-2013, she stayed in Food industry as Assistant production Manager and ISO Auditor for ISO 22000 and ISO 9001 international schemes. She now with University of Sri Jayewardenapura,Sri Lanka as Ph,D Candidate.