Sains Malaysiana 43(9)(2014): 1311–1315

Frying Quality of Virgin Coconut Oil as Affected by Zea mays . Extract

(Kualiti Menggoreng Minyak Kelapa Dara Disebabkan oleh Ekstrak Zea mays)

A.M. MARINA*, W.I. WAN ROSLI & S.L. NEOH

School of Health Sciences, Health Campus, Universiti Sains Malaysia

16150 Kubang Kerian, Kelantan, Malaysia

Received: 6 June 2013/Accepted: 7 February 2014

ABSTRACT

The effect of corn silk or Zea mays extract on the physicochemical changes of virgin coconut oil was studied during three consecutive days of deep frying. There were three types of oil blend systems used: virgin coconut oil without antioxidant as control system; virgin coconut oil with butylated hydroxytoluene (BHT) as synthetic antioxidant and virgin coconut oil with Zea mays extract as natural antioxidant. The oil quality was assessed by measuring the colour, viscosity, peroxide, p-anisidine, free fatty acids, totox and iodine value. The results show that Zea mays extract delayed the oil deterioration. The Zea mays extract significantly (p<0.05) lowered the rate of oxidation in virgin coconut oil compared to control oil and was comparable to BHT. Zea mays extract did not change the sensory profiles of French fries which was shown by insignificant difference (p<0.05) between Zea mays and control fries for all sensory attributes (colour, taste, aroma, crispiness, oiliness and overall quality). In general, the Zea may extract was capable of extending the stability and quality of virgin coconut oil and therefore has potential as new source of natural antioxidant for use in deep frying.

Keywords: Fats; frying; oils; virgin coconut oil; Zea mays

ABSTRAK

Kesan ekstrak sutera jagung (Zea mays) ke atas perubahan fizikokimia minyak kelapa dara semasa penggorengan telah dikaji selama tiga hari berturut-turut. Terdapat tiga jenis campuran minyak yang digunakan: minyak kelapa dara tanpa antioksidan sebagai kawalan, minyak kelapa dara bersama butylated hydroxytoluene (BHT) sebagai antioksidan sintetik dan minyak kelapa dara bersama ekstrak Zea mays sebagai antioksidan semula jadi. Kualiti minyak dinilai dengan mengukur warna, kelikatan, nilai peroksida, nilai asid lemak bebas, nilai totox dan nilai iodin. Keputusan kajian menunjukkan bahawa ekstrak Zea mays telah melewatkan kadar kerosakan minyak. Ekstrak Zea mays telah menurunkan kadar pengoksidaan minyak secara signifikan (p<0.05) berbanding dengan minyak kawalan dan setara dengan minyak bercampur BHT. Ekstrak Zea mays tidak mengubah profil sensori kentang jejari sebagaimana ditunjukkan dalam keputusan kajian bahawa tidak ada perbezaan yang signifikan (p<0.05) berbanding kawalan pada semua attribut sensori (warna, rasa, aroma, keranggupan, rasa berminyak dan kualiti keseluruhan). Secara keseluruhan, ekstrak Zea mays mampu memanjangkan kestabilan dan kualiti minyak kelapa dara dan dengan itu mempunyai potensi sebagai sumber baru antioksidan semula jadi untuk digunakan dalam penggorengan.

Kata kunci: Lemak; menggoreng; minyak kelapa dara; Zea mays

REFERENCES

AOCS. 1996. Official Methods and Recommended Practice of the American Oil Chemists’ Society vol 5. AOCS Press, Champaign.

Che Man, Y.B. & Tan, C.P. 1999. Effects of natural and synthetic antioxidants on changes in refined, bleached and deodorized palm olein during deep-fat frying of potato chips. Journal of the American Oil Chemists’ Society 76: 331-339.

Ebrahimzadeh, M.A., Pourmorad, F. & Samira, H. 2008. Antioxidant activities of Iranian corn silk. Turkish Journal of Biology 32: 43-49.

El-Ghorab, A., El-Massry, K.F. & Shibamoto, T. 2007. Chemical composition of the volatile extract and antioxidant activities of the volatile and non-volatile extracts of Egyption corn silk (Zea mays L.). Journal of Agricultural and Food Chemistry 55: 9124-9127.

Ghazali, H.M., Tan, A., AbdulKarim, S.M. & Dzulkifly, M.H. 2009. Oxidative stability of virgin coconut oil compared with RBD palm olein in deep-fat frying of fish crackers. Journal of Food Agricultural and Environment 7: 23-27.

Guo, J., Liu, T., Han, L. & Liu, Y. 2009. The effect of corn silk on glycaemic metabolism. Nutrition and Metabolism 6: 47.

Hemalatha, G. 2007. Sesame lignans enhance the thermal stability of edible vegetable oils. Food Chemistry 105: 1076-1085.

Liu, J., Wang, C., Wang, Z., Zhang, C., Lu, S. & Liu, J. 2011. The antioxidant and free radical scavenging activities of extract and fractions from corn silk (Zea mays L.) and related flavone glycosides. Food Chemistry 126: 261-269.

Maksimovic, Z.A. & Kovacevic, N. 2003. Pleminary assay on antioxidative activity of Maydis stigma extracts. Fitoterapia 74: 144-147.

Marina, A.M., Che Man, Y.B., Nazimah, S.A.H. & Amin, I. 2009. Chemical properties of virgin coconut oil. Journal of the American Oil Chemists’ Society 86: 301-307.

Mcclement, D.J. & Decker, E.A. 2000. Lipid oxidation in oil-in-water emulsions: Impact of molecular environment on chemical reactions in heterogeneous food systems. Journal of Food Science 65: 1270-1282.

Nor, F.M., Mohamed, S., Idris, N.A. & Ismial, R. 2008. Antioxidative properties of Pandanus amaryllifolius leaf extracts in accelerated oxidation and deep frying studies. Food Chemistry 110: 319-327.

Serjouie, A., Tan, C.P., Mirhosseini, H. & Che Man, Y.B. 2010. Effect of vegetable-based oil blends on physicochemical properties of oils during deep-fat frying. American Journal of Food Technology 5: 310-323.

Shahidi, F. & Wanasundara, P.K. 2002. Extraction and analysis of lipids, In Food Lipids: Chemistry, Nutrition and Biotechnology, edited by Akoh, C.C. & Min, D.B. New York, Marcel Dekker Inc. pp. 133-168.

SPSS Inc. 2009. Predictive Analytics Software Statistics (PASW Statistics), version 18, Chicago.

Wang, G-Q, Xu, T., Bu, X-M. & Liu, B-Y. 2012. Anti-inflammation effects of corn silk in a rat model of carrageenin-induced pleurisy. Inflammation 35: 822-827.

Yaghmur, A., Aserin, A., Mizrahi, Y, Nerd, A. & Garti, N. 2001. Evaluation of argan oil for deep fat frying. Lebensm Wiss Technology 34: 124-130.

*Corresponding author; email: mareena@usm.my