Effect of Preservation on Two Different Varieties of Vernonia amygdalina Del. (Bitter) Leaves

Nyerhovwo J. Tonukari^1,2*, Oghenetega J. Avwioroko^1,2, Theresa Ezedom¹, Akpovwehwee A. Anigboro¹

¹Department of Biochemistry, Faculty of Science, Delta State University, Abraka, Nigeria.
²African Research Laboratories, Otorho-Agbon, Ethiope-East LGA, Delta State, Nigeria.

DOI: 10.4236/fns.2015.67067                

Abstract

Vernonia amygdalina Del. is one of the leafy vegetables that can be used in an attempt to alleviate the problem of micronutrient malnutrition, prominent in tropical Africa. In order to ensure availability in non-growing areas or seasons, the vegetable needs to be preserved. Processing and preservation methods influence the nutrient content of vegetables. The present study was aimed at determining the effects of preservation on two different varieties of V. amygdalina (bitter) leaves (broad and small leaves). To this effect, evaluations were made on the chlorophyll content, phytochemicals, and antioxidant capacity of the two varieties of bitter leaf (V. amygdalina Del.) stored at 4℃ and –20℃ over a period of two weeks. Results showed a significant decrease in all parameters studied for both varieties at –20℃ except for the free radical reducing power (FRAP), DPPH radical scavenging activity (%RSA) and nitric oxide radical scavenging activity (%RSA) of V. amygdalina broad leaves where increase in scavenging activity was observed. Thus, it was concluded that to preserve the chlorophyll, phenol, total soluble proteins and reducing sugar levels, preservation at 4℃ is recommended. The present study finding would be useful during short-term preservation of bitter leaves for soup preparation and/or its aqueous extract for ethnomedicinal purposes, especially the small leaf variety.

Keywords

Vernonia amygdalina, Preservation, Refrigeration, Phytonutrients, Chlorophyll, Phenolic Compounds, Antioxidant Capacities

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Egedigwe, C.A. (2010) Effect of Dietary Incorporation of Vernonia amygdalina and Vernonia colorata on Blood Lipid Profile and Relative Organ Weights in Albino Rats. M.Sc. Dissertation, Michael Okpara University of Agriculture, Umudike.
[2]	Igile, G.O., Oleszk, W., Burda, S. and Juryzsta, M. (1995) Nutritional Assessment of V. amygdalina Leaves in Growing Mice. Journal of Agricultural and Food Chemistry, 93, 2162-2166. http://dx.doi.org/10.1021/jf00056a038
[3]	Owen, O.J., Amakiri, A.O., David, E.U., Nyeche, V.N. and Ndor, L. (2009) Proximate Composition, Energy Content and Mineral Profile of Vernonia amygdalina (Bitter Leaf) Meal. Proceedings of 14th Annual Conference Animal Scence Association of Nigeria, Ogbomoso, 14-17 September 2009, 173-176.
[4]	Sobukola, O.P. and Dairo, O.U. (2007) Modeling Drying Kinetics of Fever Leaves (Ocimum viride) in a Convective Hot Air Dryer. Nigerian Food Journal, 25, 145-153. http://dx.doi.org/10.4314/nifoj.v25i1.33663
[5]	Akah, P.A. and Okafor, C.I. (1992) Blood Sugar Lowering Effect of V. amaygdalina Del. in Experimental Rabbit Model. Phytotherapy Research, 6, 171-173. http://dx.doi.org/10.1002/ptr.2650060318
[6]	Uhegbu, F.O. and Ogbuehi, K.J. (2004) Effect of the Aqueous Extract (Crude) of Leaves of Vernonia amygdalina on Blood Glucose, Serum Cholesterol and Serum Albumin Levels in Alloxan Induced Diabetic Albino Rats. Global Journal of Pure and Applied Sciences, 10, 189-194. http://dx.doi.org/10.4314/gjpas.v10i1.16380
[7]	Nwajo, H.U. (2005) Efficacy of Aqueous Leaf Extract of Vernonia amygdalina on Plasma Lipoproteins and Oxidative Status in Diabetic Rat Model. Nigerian Journal of Physiological Sciences, 20, 39-42.
[8]	Akah, P.A., Okoli, C.O. and Nwafor, S.V. (2002) Phytotherapy in the Management of Diabetes Mellitus. Journal of Natural Remedies, 2, 59-65.
[9]	Oboh, G. (2003) Hemolytic Effect of Saponin Extract from Vernonia amygdalina (Bitter Leaf) on Human Erythrocyte. Applied Natural Science Research, 1, 25-29.
[10]	Masaba, S.C. (2000) The Antimalarial Activity of Some Traditional Medicinal Plants. Ethiopian Journal of Health Development, 13, 211-216.
[11]	Akinpelu, D.A. (1999) Antimicrobial Activity of Vernonia amygdalina Leaves. Fitoterapia, 70, 432-434. http://dx.doi.org/10.1016/S0367-326X(99)00061-1
[12]	Kafaru, E. (1994) Immense Help for Natures Workshop Public. Elkaf Health Services Ltd, Benin-City, 54-58.
[13]	Erasto, P., Grierson, D.S. and Afolayan, A.J. (2007) Evaluation of Antioxidant Activity and the Fatty Acid Profile of the Leaves of Vernonia amygdalina Growing in South Africa. Food Chemistry, 104, 636-642. http://dx.doi.org/10.1016/j.foodchem.2006.12.013
[14]	Nwanjo, H.U. (2005) Efficacy of Aqueous Leaf Extract of Vernonia amygdalina on Plasma Lipoprotein and Oxidative Status in Diabetic Rat Models. Nigerian Journal of Physiological Sciences, 20, 39-42.
[15]	Adaramoye, O.A., Akintayo, O., Achem, J. and Fatunso, M.A. (2008) Lipid Lowering Effects of Methanolic Extracts of Vernonia amygdalina Leaves in Rats Fed on High Cholesterol Diet. Vascular Health and Risk Management, 4, 235-241. http://dx.doi.org/10.2147/vhrm.2008.04.01.235
[16]	Fafunso, A. and Bassir, O.O. (1977) Nigerian Medicinal Plants. University of Ibadan Press, Ibadan, 121.
[17]	Delcour, J.A. and Piet, V.L. (1988) Hydrolysable Tannins for Chillproofing Beers. The New Brewer, 5.
[18]	Arnon, D. (1949) Copper Enzymes in Isolated Chloroplasts. Phenoloxidase in Beta vulgaris. Plant Physiology, 24, 1-15. http://dx.doi.org/10.1104/pp.24.1.1
[19]	Reezi, S., Babalar, M. and Kalantari, S. (2009) Silicon Alleviates Salt Stress, Decreases Malondialdehyde Content and Affects Petal Color of Salt-Stressed Cut Rose (Rosa xhybrida L.) “Hot Lady”. African Journal of Biotechnology, 8, 1502-1508.
[20]	Jia, Z., Tang, M. and Wu, J. (1999) The Determination of Flavonoid Contents of Murlberry and Their Scavenging Effects on Superoxide Radicals. Food Chemistry, 64, 555-559. http://dx.doi.org/10.1016/S0308-8146(98)00102-2
[21]	Singleton, V.L. and Rossi, J.A. (1965) Colorimetry of Total Phenolics with Phosphomolybdic-Phosphotungstic Acid Reagents. American Journal of Enology and Viticulture, 16, 144-158.
[22]	Oyaizu, M. (1986) Studies on Products of Browning Reactions: Antioxidative Activities of Products of Browning Reaction Prepared from Glucosamine. The Japanese Journal of Nutrition and Dietetics, 44, 307-315. http://dx.doi.org/10.5264/eiyogakuzashi.44.307
[23]	Hatano, T., Kagawa, H., Yasuhara, T. and Okuda, T. (1988) Two New Flavonoids and Other Constituents in Licore Root: Their Relative Astringency and Radical Scavenging Affects. Chemical & Pharmaceutical Bulletin, 36, 2090-2097. http://dx.doi.org/10.1248/cpb.36.2090
[24]	Marcocci, L., Packer, L., Droy-Lefai, M.T., Sekaki, A. and Gardes-Albert, M. (1994) Antioxidant Action of Ginkgo biloba Extracts EGb 761. Methods in Enzymology, 234, 462-475. http://dx.doi.org/10.1016/0076-6879(94)34117-6
[25]	Miller, G.L. (1959) Use of the Dinitrosalicylic Acid Reagent for the Determination of Reducing Sugar. Analytical Chemistry, 31, 426-428. http://dx.doi.org/10.1021/ac60147a030
[26]	Gornall, A., Bardsmill, C.T. and David, M.M. (1949) Determination of Serum Proteins by Means of the Biuret Reaction. The Journal of Biological Chemistry, 177, 751-766.
[27]	Catunescu, G.M., Tofana, M., Muresan, C., Ranga, F., David, A. and Muntean, M. (2012) The Effect of Cold Storage on Some Quality Characteristics of Minimally Processed Parsley (Petroselinum crispum), Dill (Anethum graveolens) and Lovage (Levisticum officinale). Bulletin of the University of Agricultural Sciences and Veterinary Medicine Cluj- Napoca Agriculture, 69.
[28]	Agüero, M.V., Barg, M.V., Yommi, A., Camelo, A. and Roura, S.I. (2008) Postharvest Changes in Water Status and Chlorophyll Content of Lettuce (Lactuca sativa L.) and Their Relationship with Overall Visual Quality. Journal of Food Science, 73, S47-S55.
[29]	Kidmose, U., Edelenbos, M., NØrbæk, R. and Christensen, L.P. (2002) Color Stability in Vegetables. In: MacDougall, D.B., Ed., Color in Food: Improving Quality, CRC Press/Woodhead Publishing Limited, Cambridge, 179-232. http://dx.doi.org/10.1533/9781855736672.2.179
[30]	Abe, K. and Watada, A.E. (1991) Ethylene Absorbent to Maintain Quality of Lightly Processed Fruits and Vegetables. Journal of Food Science, 56, 1589-1592. http://dx.doi.org/10.1111/j.1365-2621.1991.tb08647.x
[31]	Bolin, H.R. and Huxsoll, C.C. (1991) Effect of Preparation Procedures and Storage Parameters on Quality Retention of Salad-Cut Lettuce. Journal of Food Science, 56, 60-62. http://dx.doi.org/10.1111/j.1365-2621.1991.tb07975.x
[32]	Haard, F.N. (1993) Características de los tejidos vegetales comestibles. In: Fennema, O.R., Ed., Química de los Alimentos, 2nd Edition, Acribia, Zaragoza, 961-1024.
[33]	Watada, A.E., Abe, K. and Yamuchi, N. (1990) Physiological Activities of Partially Processed Fruits and Vegetables. Food Technology, 44, 116-122.
[34]	Yamuchi, N. and Watada, A.E. (1991) Regulated Chlorophyll Degradation in Spinach Leaves during Storage. Journal of the American Society for Horticultural Science, 116, 58-62.
[35]	Shioi, Y., Tomita, N., Tsuchiya, T. and Takamiya, K. (1996) Conversion of Chlorophyllide to Pheophorbide by Mg-Dechelating Substance in Extracts of Chenopodium album. Plant Physiology and Biochemistry, 34, 41-47.
[36]	Jacob-Wilk, D., Holland, D., Goldschmidt, E.E., Riov, J. and Eyal, Y. (1999) Chlorophyll Breakdown by Chlorophyllase: Isolation and Functional Expression of the Chlase 1 Gene from Ethylene-Treated Citrus Fruit and Its Regulation during Development. The Plant Journal, 20, 653-661. http://dx.doi.org/10.1046/j.1365-313X.1999.00637.x
[37]	Ferruzzi, M.G. and Schwartz, S. (2001) UNIT F4.1. Overview of Chlorophylls in Foods. Current Protocols in Food Analytical Chemistry, Published Online.
[38]	Fahey, J.W., Stephenson, K.K., Dinkova-Kostova, A.T., Egner, P.A., Kensler, T.W. and Talalay, P. (2005) Chlorophyll, Chlorophyllin and Related Tetrapyrroles Are Significant Inducers of Mammalian Phase 2 Cytoprotective Genes. Carcinogenesis, 26, 1247-1255. http://dx.doi.org/10.1093/carcin/bgi068
[39]	Chaovanalikit, A. and Wrolstad, R.E. (2004) Total Anthocyanins and Total Phenolics of Fresh and Processed Cherries and Their Antioxidant Properties. Journal of Food Science, 69, FCT67-FCT72. http://dx.doi.org/10.1111/j.1365-2621.2004.tb17858.x
[40]	Turkmen, N., Sari, F. and Velioglu, Y.S. (2005) The Effect of Cooking Methods on Total Phenolics and Antioxidant Activity of Selected Green Vegetables. Food Chemistry, 93, 713-718. http://dx.doi.org/10.1016/j.foodchem.2004.12.038
[41]	Majewska, M., Skrzycki, M., Podsiad, M. and Czeczot, H. (2011) Evaluation of Antioxidant Potential of Flavonoids: An in Vitro Study. Acta Poloniae Pharmaceutica, 68, 611-615.
[42]	Murugan, S.B., Reshma, A., Deepika, R., Balamurugan, S. and Sathishkumar, R. (2013) Antioxidant Capacities of Amaranthus tristis and Alternanthera sessilis: A Comparative Study. Journal of Medicinal Plants Research, 7, 2230-2235.
[43]	Stangeland, T., Remberg, S.F. and Lye, K.A. (2009) Total Antioxidant Activity in 35 Ugandan Fruits and Vegetables. Food Chemistry, 113, 85-91. http://dx.doi.org/10.1016/j.foodchem.2008.07.026
[44]	Wills, R., McGlasson, B., Graham, D. and Joyce, D. (1998) Post Harvest: An Introduction to the Physiology and Handling of Fruits, Vegetables and Ornamentals. 4th Edition, University of New South Wales Press Ltd., Sydney.
[45]	Singh, G.D., Siingh, S., Jindal, N., Bawa, A.S. and Saxena, D.C. (2010) Physico-Chemical Characteristics and Sensory Quality of Singhara (Trapa natans L.): An Indian Water Chestnut under Commercial and Industrial Storage Conditions. African Journal of Food Science, 4, 693-702.