BIODELIGNIFICATION OF LEMON PEELS USING Aspergillus sp. TO IMPROVE YIELD AND COMPOSITION OF EXTXRACTED LEMON OIL

Abstract

 Lemon oil obtained from lemon peels has a high market value. However, the presence of lignocellulose composed of cellulose, hemicellulose, and lignin, can inhibit the extraction process. This study aimed to determine the effect of biodelignification on lemon peels using Aspergillus sp. towards lignin content, yield, chemical composition, and productivity of lemon oil. A solid-state fermentation was carried out under controlled relative humidity of 99% and a light intensity of ~0 W/cm2 for 0, 3, 6, and 9 days. The number of spores used was in the range of 0.3-5 x 105 spores/gram substrate with a ratio of spore solution and substrate of 1:1. Extraction was performed using a steam distillation method at 97-98°C for 6 hours. The results showed that the lignin content decreased with an increased fermentation time: 8.01%, 6.97-7.28%, 5.83-7.28%, and 4.35-5.44% dry weight for day 0, 3, 6, and 9, respectively. Lemon oil yield increased as the period of fermentation increased up to 0.27%, 0.29-0.31%, 0,30-0.46%%, and 0.67-0.79% for day-0, 3, 6, and 9, respectively. A major component of lemon oil is d-limonene. The d-limonene content reached 72,54% for day-0, 73-99% for day-3, 75,09-84.59% for day-6, and 88,03-99% for day-9. ABSTRAK: Minyak lemon yang terhasil dari kupasan lemon mempunyai nilai tinggi dalam pasaran. Walau bagaimanapun, kehadiran lignoselulosa yang terdiri daripada selulosa, hemiselulosa dan lignin, boleh merencatkan proses pengekstrakan. Kajian ini bertujuan memperolehi kesan biodelignifikasi pada kulit lemon menggunakan Aspergillus sp. terhadap kandungan lignin, hasil, komposisi kimia, dan penghasilan minyak lemon. Penapaian keadaan-pepejal dijalankan di bawah 99% kawalan kelembapan relatif dan keamatan cahaya ~0 W/cm2 bagi 0, 3, 6 dan 9 hari. Bilangan spora yang digunakan adalah dalam lingkungan substrat 0.3-5 x 105 spora/gram dengan nisbah larutan spora kepada substrat adalah 1:1. Pengekstrakan dijalankan menggunakan kaedah penyulingan stim pada suhu 97-98°C selama 6 jam. Keputusan menunjukkan kandungan lignin berkurangan dengan pertambahan masa penapaian: 8.01%, 6.97-7.28%, 5.83-7.28%, dan 4.35-5.44% berat kering pada hari 0, 3, 6, dan 9, masing-masing. Hasil minyak lemon bertambah dengan pertambahan masa penapaian sehingga 0.27%, 0.29-0.31%, 0,30-0.46%%, dan 0.67-0.79% pada hari 0, 3, 6, dan 9, masing-masing. Komponen major minyak lemon adalah d-limonina. Kandungan d-limonina mencapai 72,54% pada hari-0, 73-99% pada hari-3, 75,09-84.59% pada hari-6, dan 88,03-99% pada hari-9.