Browning Prevention of Flour from Freshly Harvested Porang (Amorphophallus oncophyllus) Tubers through Immersion in Sodium Metabisulfite at Various Times




Porang (Amorphophallus oncophillus) tubers contain multifunctional water-soluble heteropolysaccharides, called glucomannan. Therefore, the quality of porang tuber chips is highly depending on its glucomannan content and physical appearance. The presence of considerable amount of carotene, polyphenoloxidases and tannins in these tubers may cause browning of flour during processing. The purpose of this research was to study the effect of enzymatic anti-browning agent (sodium metabisulfite) concentrations (2, 5 and 7.5%) w/w) and immersion times (30, 60, 90, 120, 150 and 180 minutes) on the degree of whiteness. An increase in the concentration of anti-browning agent solution up to 5% w/w caused significant increase the degree of whiteness of porang flour and quality of porang flour. However, further increase in the concentration of anti-browning agent solution exhibited reduction in the degree of whiteness and quality of porang flour. In addition, a longer immersion time also resulted in a higher degree of whiteness of porang tuber chips. The best browning prevention conditions were through immersion of porang tuber chips in 7.5% w/w sodium metabisulfite solution for 150 minutes, from which a highest degree of whiteness was achieved (81.99).


Abdulla G, El-Shourbagy G A and Sitohy M Z 2014 Effect of Pre-Drying, Blanching, and Citric Acid Treatment of the Quality of Fried Sweet Potato Chips, American Journal of Food Technology pp 39-48.

Chua M, Chan K, Hocking T J, Williams P A, Perry C J and Baldwin,T C 2012 Methodologies for the Extraction and Analysis ff Konjac Glucomannan from Corms of Amorphophallus konjac K. Koch, Carbohydrate Polymers chapter 87 pp 2202– 2210

Dave V and McCarthy S P 1997 Review of Konjac Glucomannan pp 237–241

Friedman M 1996 Food Browning and Its Prevention pp 631-653

Huang Z W 1994 Processing Technique of Dried Konjac Flakes Practical Engineering Technique in Countryside chapter 12 p 32

Kumalaningsih, S., Harijono., Amir, Y. F., 2011, Pencegahan Pencoklatan Umbi Ubi Jalar (Ipomoea batatas (L). Lam) untuk Pembuatan Tepung Pengaruh Kombinasi Konsentrasi Asam Askorbat dan Sodium Acis Pyrophosphate, Universitas Brawijaya, Malang

Koswara S, 2010 Ebook Pangan : Iles-ilesdan Hasil Olahannya (Bogor: Balai Besar Litbang Pascapanen Pertanian Bogor)

Kumoro A C, Budiyati C S and Retnowati D S 2014 Calcium Oxalate Reduction During Soaking of Giant Taro (Alocasia Macrorrhiza (L.) Schott) corm chips in sodium bicarbonate solution pp 1583-1588

Mosneaguta R 2012 The Effect of Chemical Preservatives on Inhibition of Potato Browning, Volatile Organic Compounds Profile, and Microbial Inhibition (Ohio: The Ohio State University)

Mulyono, E 2010 Peningkatan Mutu Iles-Iles (Amorphophallus onchophyllus) Food Grade (glukomanan 80%) Melalui Teknologi Pencucian Bertingkat dan Enzimatis (Bogor: Balai Besar Litbang Pascapanen Pertanian Bogor)

Vamosâ€Vigyazo L and Haard N F 1981 Polyphenol oxidases and peroxidases in fruits and vegetables (C R C Critical Reviews in Food Science and Nutrition 15, 1, pp 49-127)

Wardhani D H, Atmadja A A and Nugraha C R 2016 Pencegahan Pencoklatan Enzimatik pada Porang Kuning (Reaktor vol 17 pp 104-110)

Widjanarko S B, Sutrisno A, and Faridah, A 2011b Effect of Hydrogen Peroxide on Physicochemical Properties of Common Konjac (Amorphophallus oncophyllus) Flour by Maceration and Ultrasonic Methods (Jurnal Teknologi Pertanian) pp 143-152

Wu W X and Zhang Z L 1994 The Report Of Production Engineering Of Konjac Flour (Science and Technology of Food Industry vol 4) pp 25-28

Zarubica A R, Miljković M N, Purenović M M and Tomić V B 2005 Colour Parameters Whiteness Indices and Physical Features of Marking Paints for Horizontal Signalization pp 205-216

Zhang Y Q, Xie B J, and Gan X 2005 Advance in the Applications of Konjac Glucomannan and its Derivatives Carbohydrate Polymers pp 27-31.

Zhao J, Zhang D, Srzednicki G, Kanlayanarat S and Borompichaichartkul C 2010 Development of a low-cost two-stage technique for production of low-sulphur purified konjac flour, International Food Research Journal chapter 17 pp 1113-1124.