Investigating the blanching effect on antioxidants, phytochemicals, and mineral characters of Corchorus olitorius L. cultivars

Abstract

This study aims to provide an in-depth understanding of the effects of blanching pretreatment on the preservation of antioxidants, phytochemicals, and mineral contents in Corchorus olitorius, for optimal retention and utilization. Three distinct varieties of C. olitorius seeds, namely Ewedu_Abeokuta, Ewedu_Yaya, and Ewedu_Eleti_Eku, were sourced from farmers and cultivated. The harvested leaves underwent a 2-minute blanching treatment at 60 °C. Subsequent spectrophotometric-based assays were employed to quantify the biochemical contents. At IC100, Ewedu_Eleti_Eku (blanched) exhibited the highest 2,2-diphenyl-1-picryl hydrazyl (DPPH) activity (81.87 ± 0.10), which was statistically similar (p ≤ 0.05) to that of Ewedu_Yaya (blanched) (76.92 ± 3.62). The Ferric ion Reducing Antioxidant Power (FRAP) revealed Ewedu_Abeokuta (blanched) to have the highest antioxidant activity across tested concentrations (IC25 =17.43 ± 29.83, IC50 =20.53 ± 34.98, IC75 =25.13 ± 42.82, and IC100 =24.93 ± 42.11), when compared to the other varieties. Ewedu_Abeokuta (blanched) showed significantly higher (p ≤ 0.05) Magnesium (Mg) and Selenium (Se) content, with values of 54.60 ± 2.63 and 0.40 ± 0.01, respectively. In contrast, Ewedu_Yaya (blanched) had the highest Zinc (Zn) content (6.17 ± 0.05 Zn), which was statistically similar (p ≤ 0.05) to Ewedu_Eleti_Eku (blanched) (5.69 ± 0.84). The FRAP assays (IC25, IC50, IC75, and IC100) demonstrated perfect positive correlations (r = 1) among themselves, indicating a consistent linear relationship. The treatment further enhanced phenol and tannin content in Ewedu_Yaya and phenol content in Ewedu_Eleti_Eku. These findings suggest that blanching pretreatment can be a valuable technique for improving various quality attributes of C. olitorius varieties.

Keywords

• Corchorus olitorius
• Jute mallow
• Antioxidants
• Blanching
• FRAP

References

1. Abayomi, S. (1993). Medicinal plants and traditional medicine in Africa. Journal of Alternative and Complementary Medicine, 13, 195-238.
2. Agbor, G.A., Vinson, J.A., & Donnelly, P.E. (2014). Folin-Ciocalteau reagent for polyphenolic assay. International Journal of Food Science, Nutrition and Dietetics, 3(8), 147 156. https://www.airitilibrary.com/Article/Detail?DocID=P20151016002-201408-201511190018-201511190018-147-156
3. Al-Rmalli, S.W. (2012). Arsenic and other trace elements in Bangladeshi food and non-food and their relationship to human health [PhD. Thesis]. De Montfort University.
4. Aziz, S., Saha, K., & Sultana, N. (2016). Comparative studies of elemental composition in leaves and flowers of Catharanthus roseus growing in Bangladesh. Asian Pacific Journal of Tropical Biomedicine, 6(1), 50–54. https://doi.org/10.1016/j.apjtb.2015.10.003
5. Baiyeri, S.O., Chimaluka, C.A., & Baiyeri, S. (2022). Evaluation of the minerals, proximate, viscosity and antinutrients of the fruits of Corchorus olitorius accessions. Journal of the Austrian Society of Agricultural Economics, 18(7), 1163-1171.
6. Benzie, I.F.F., & Strain, J.J. (2016). Determination of optimal extraction conditions for phenolic compounds from: Pistacia atlantica leaves using the response surface methodology. Analytical Methods, 8, 6107–6114.
7. Ben Zid, M., Dhuique-Mayer, C., Bellagha, S., Sanier, C., Collignan, A., Servent, A., & Dornier, M. (2015). Effects of blanching on flavanones and microstructure of Citrus aurantium peels. Food and Bioprocess Technology, 8, 2246–2255. https://doi.org/10.1007/s11947-015-1573-1
8. Bhebhe, M., Chipurura, B., & Muchuweti, M. (2015). Determination and comparison of phenolic compound content and antioxidant activity of selected local Zimbabwean herbal teas with exotic Aspalathus linearis, South African Journal of Botany, 100, 213 218. https://doi.org/10.1016/j.sajb.2015.06.006

9. Biswas, A., Susmita, D., Defang, L., Yi L., Jiangjiang, Z., Siqi, H., Gen, P., & Yong, D. (2020). Comparison of phytochemical profile, mineral content, and in vitro antioxidant activities of Corchorus capsularis and Corchorus olitorius leaf extracts from different populations. Journal of Food Quality, 1, 2931097. https://doi.org/10.1155/2020/2931097
10. Chang, C.C., Yang, M.H., Wen, H.M., & Chern, J.C. (2002). Estimation of total flavonoid content in propolis by two complementary colometric methods. Journal of Food and Drug Analysis, 10(3), 3. https://doi.org/10.38212/2224-6614.2748
11. Deng, Q., Yu, X., Ma, F., Xu, J., Huang, F., & Huang, Q. (2018). Comparative analysis of the in-vitro antioxidant activity and bioactive compounds of flaxseed in China according to variety and geographical origin, International Journal of Food Properties, 20(3), 2708 2722. https://doi.org/10.1080/10942912.2017.1402029
12. Deylami, M.Z., Rahman, R.A., Tan, C.P., Bakar, J., & Olusegun, L. (2016). Effect of blanching on enzyme activity, color changes, anthocyanin stability and extractability of mangosteen pericarp: A kinetic study. Journal of Food Engineering, 178, 12 19. https://doi.org/10.1016/j.jfoodeng.2016.01.001
13. Doraswamey, N., Vorirod, D., & Nisha, S. (2010). Herbal rapid release tablets manufactured from Corchorus olitorious leaves. International journal of pharmacy and Bio sciences, 1(2), 56.
14. Farvin, K.H.S., & Jacobsen, C. (2013). Phenolic compounds and antioxidant activities of selected species of seaweeds from Danish coast. Food Chemistry, 138, 1670 1681. https://doi.org/10.1016/j.foodchem.2012.10.078
15. Islam, M.M. (2013). Biochemistry, medicinal and food values of jute (Corchorus capsularis L. and C. olitorius L.) leaf: a review. International Journal of Enhanced Research in Science Technology and Engineering, 2(11), 35-44.
16. Kamga, R.T., Kouam´e, C., Atangana, A.R., Chagomoka, T., & Ndango, R. (2013). Nutritional evaluation of five African indigenous vegetables. Journal of Horticultural Research, 21(1), 99–106. https://doi.org/10.2478/johr-2013-0014
17. Kartika, H., Shido, J., Nakamoto, S.T., Li, Q.X., & Iwaoka, W.T. (2011). Nutrient and mineral composition of dried mamaki leaves (Pipturus albidus) and infusions. Journal of Food Composition and Analysis, 24(1), 44–48. https://doi.org/10.1016/j.jfca.2010.03.027
18. Kaseke, T., Opara, U.L., & Fawole, O.A. (2021). Quality and Antioxidant Properties of Cold- Pressed Oil from Blanched and Microwave Pretreated Pomegranate Seed. Foods, 10(4), 712. https://doi.org/10.3390/foods10040712
19. Kirk, H., & Sawyer, R. (1998). Frait Pearson Chemical Analysis of Food. 8th edition. Longman Scientific and Technical. Edinburgh, (8), 211-212.
20. Kumar, S., Li, G., Huang, X., Ji, Q., Zhou, K., Hou, H., Ke, W., & Yang, J. (2021). Phenotypic, nutritional, and antioxidant characterization of blanched Oenanthe javanica for preferable cultivar. Frontiers in Plant Science, 12, 639639. https://doi.org/10.3389/fpls.2021.639639
21. Magangana, T.P., Makunga, N.P., Fawole, O.A., & Opara, U.L. (2020). Processing factors affecting the phytochemical and nutritional properties of pomegranate (Punica granatum L.) peel waste: A rview. Molecules, 25 (20), 4690. https://doi.org/10.3390/molecules25204690
22. Magangana, T.P., Makunga, N.P., Fawole, O.A., & Opara, U.L. (2021). Effect of solvent extraction and blanching pre-treatment on peel extracts. Processes, 9(6), 1012. https://doi.org/10.3390/pr9061012
23. Magangana, T.P., Makunga, N.P., Fawole, O.A., Stander, M.A., & Opara, U.L (2022). Antioxidant, antimicrobial, and metabolomic characterization of blanched pomegranate peel extracts: Effect of cultivar. Molecules, 27(9), 2979. https://doi.org/10.3390/molecules27092979
24. Nefertiti, A.S.G., Batista, M.M., Da Silva, P.B., Batista, D.G.J., Da Silva, C.F., Peres, R.B., & Soeiro, M.N.C. (2018). In vitro and in vivo studies of the trypanocidal effect of novel quinolines. Antimicrobial Agents and Chemotherapy, 62(2), 10-1128. https://doi.org/10.1128/aac.01936-17
25. Noha, M., Hussien, S.E., Labib, R.A., El-Massry, H.T.M., Hefnawy, P., & Zagazig, J. (2017). Phytochemical studies and antioxidant activity of leaves extracts of Corchorus olitorius L. (molokhia). Agricultural Research, 44(6), 2231-2239. https://doi.org/10.21608/ZJAR.2017.51291
26. Nurhuda, H.H., Maskat, M.Y., Mamot, S., Afiq, J., & Aminah, A. (2013). Effect of blanching on enzyme and antioxidant activities of rambutan (Nephelium lappaceum) peel. International Food Research Journal, 20(4), 1725–1730.
27. Ojha, S., Raj, A., Roy, A., & Roy, S. (2018). Extraction of total phenolics, flavonoids and tannins from Paederia foetida L. leaves and their relation with antioxidant activity. Pharmacognosy Journal, 10(3), 541–547. https://doi.org/10.5530/pj.2018.3.88
28. Olagunju, O.F., Ezekiel, O.O., Ogunsh, A.O., Oyeyinka, S.A., & Ijabadeniyi, O.A. (2018). Effects of fermentation on proximate composition, mineral profile and anti-nutrients of tamarind (Tamarindus indica L) seed in the production of daddawa-type condiment. Journal of food science and technology, 90, 455–459. https://doi.org/10.1016/j.lwt.2017.12.064
29. Osundinakin, M., Sharaibi, O., & Adekoya, I. (2025). Phytochemical profile and scavenging capacity of blanched Cnidoscolus aconitifolius (Mill.) IM Johnst and Telfairia occidentalis Hook. Fil. leaves. Haceteppe Journal of Biology and Chemistry, 53(2), 71 81. https://doi.org/10.15671/hjbc.1572632
30. Panche, A.N., Diwan, A.D., & Chandra, S.R. (2016). Flavonoids: an overview. Journal of Nutritional Science, 5, e47. https://doi.org/10.1017/jns.2016.41
31. Sofowora, A. (1993). Recent trends in research into African medicinal plants. Journal of Ethnopharmacology, 38(2-3), 197-208.
32. Taiwo, B.J., Taiwo, G.O., Olubiyi, O.O., & Fatokun, A.A. (2016). Polyphenolic compounds with anti-tumour potential from Corchorus olitorius (L.) tiliaceae, a Nigerian leaf vegetable. Bioorganic & Medicinal Chemistry Letters, 26(15), 3404-3410. https://doi.org/10.1016/j.bmcl.2016.06.058
33. Upadhyay, P., Mishra, S.K., Purohit, S., Dubey, G.P., Singh Chauhan, B., & Srikrishna, S. (2019). Antioxidant, antimicrobial and cytotoxic potential of silver nanoparticles synthesized using flavonoid rich alcoholic leaves extract of Reinwardtia indica. Drug and Chemical Toxicology, 42(1), 65-75. https://doi.org/10.1080/01480545.2018.1488859 Wagdy, R., Abdelkader, R.M., El-Khatib, A.H., Linscheid, M.W., Hamdi, N., & Handoussa, H. (2019). Neuromodulatory activity of dietary phenolics derived from Corchorus olitorius L. Journal of Food Science, 84(5), 1012–1022. https://doi.org/10.1111/1750-3841.14587
34. Wang, Z., Pan, Z., Ma, H., & Atungulu, G.G. (2011). Extract of phenolics from pomegranate peels. The Open Food Science Journal, 5, 17–25. https://doi.org/10.2174/1874256401105010017
35. Xiao, H.W., Pan, Z., Deng, L.Z., El Mashad, H., Yang, X.H., Mujumdar, A.S., Gao, Z.J., & Zhang, Q. (2017). Recent developments and trends in thermal blanching—A comprehensive review. Information Processing in Agriculture Journal, 4(2), 101 127. https://doi.org/10.1016/j.inpa.2017.02.001
36. Yan, D., Chen, D., Shen, J., Xiao, G., Van Wijnen, A.J., & Im, H.J. (2013). Bovine lactoferricin is anti‐inflammatory and anti‐catabolic in human articular cartilage and synovium. Journal of cellular physiology, 228(2), 447-456. https://doi.org/10.1002/jcp.24151
37. Zammouri, C., Chokri, M., Mohamed, B., & Yosr, Z. (2013). Antioxidant activity, total phenolic and flavonoid content variation among Tunisian natural populations of Rhus tripartite (Ucria) Grande and Rhus pentaphylla Desf. Industrial Crops and Products, 51, 171 177. https://doi.org/10.1016/j.indcrop.2013.09.002
38. Zheng, J., Tian, W., & Yang, C. (2019). Identification of flavonoids in Plumula nelumbinis and evaluation of their antioxidant properties from different habitats. Industrial Crops and Products, 127, 36–45. https://doi.org/10.1016/j.indcrop.2018.08.020