Solid State Fermentation of Turmeric Rhizomes with Aspergillus SP. To Improve Yield and Composition of Extracted Turmeric Oil

Abstract

This research aimed to determine the role of Aspergillus awamori, Aspergillus niger, and Aspergillus oryzae in degrading starch on turmeric rhizome substrate to increase the yield of turmeric oil. The substrate in the form of turmeric rhizome was given additional yeast extract of 10% weight per volume to meet the nutritional needs of fungal growth. The fungal concentration used in inoculation was 5x10⁷ cells/ml. The solid-state fermentation process was carried out in dark conditions (~0 W), temperatures of 25–28 ºC, 99% humidity, and aeration (3.5 L/min). Turmeric oil was isolated using a steam distillation method for three hours, with the substrate moisture content of 68–71% and a substrate–water ratio of 1:5. The biodegradation process was conducted for 11 days. The starch content and turmeric oil yield was determined during the fermentation particularly on days 7, 9, and 11. The results showed that the biodegradation process of starch in solid-state fermentation succeeded in increasing the yield of turmeric oil. Aspergillus awamori showed the most desirable starch degradation activity by 62.5% to 2.9% wet weight on the 11^th day of fermentation. Aspergillus oryzae had the most positive effect, nearly doubling the turmeric oil yield to 3.17% dry weight after 11^th day of fermentation. The main constituents of turmeric oil are ?-turmerone, ?-turmerone, and ar-turmerone.

ABSTRAK: Penelitian ini bertujuan bagi mengkaji peranan Aspergillus awamori, Aspergillus niger, dan Aspergillus oryzae dalam mendegradasikan kanji pada substrat rizom kunyit bagi meningkatkan hasil minyak kunyit. Substrat dalam bentuk rizom kunyit telah diberi tambahan ekstrak yis 10% mengikut berat setiap isipadu bagi memenuhi keperluan nutrisi pertumbuhan kulat. Kepekatan kulat yang digunakan dalam inokulasi adalah 5x107 sel/ml. Proses penapaian berkeadaan pepejal telah dijalankan dalam keadaan gelap (~0 W), suhu 25–28 ºC, kelembapan 99%, dan pengudaraan (3.5 L/min). Minyak kunyit diasingkan menggunakan kaedah penyulingan wap selama tiga jam, dengan kandungan lembapan substrat 68-71% dan nisbah substrat-air 1:5. Proses biodegradasi dijalankan selama 11 hari. Kandungan kanji dan hasil minyak kunyit ditentukan semasa penapaian terutamanya pada hari ke-7, 9, dan 11. Hasil kajian menunjukkan bahawa proses biodegradasi kanji dalam penapaian berkeadaan pepejal berjaya meningkatkan hasil minyak kunyit. Aspergillus awamori menunjukkan aktiviti degradasi kanji yang paling diingini iaitu sebanyak 62.5% hingga 2.9% berat basah pada hari ke-11 penapaian. Aspergillus oryzae mempunyai kesan yang paling positif, iaitu hampir dua kali ganda hasil minyak kunyit kepada 3.17% berat kering selepas hari ke-11 penapaian. Konstituen utama minyak kunyit ialah ?-turmerone, ?-turmerone, dan ar-turmerone.