Kulit pomelo menyumbang 30% daripada berat buah tetapi ia telah dibuang tanpa mengiktiraf nilai pemakanan buah itu. Kajian telah dijalankan untuk mengenal pasti kesan pelbagai jenis pelarut dan saiz zarah yang berbeza terhadap pengekstrakan nootkatone dan valencene dengan menggunakan kulit kering Citrus grandis. Pengkajian pengekstrakan nootkatone dan valencene dilakukan dalam alat Soxhlet menggunakan pelarut berair (methanol, aseton dan n-heksana), ukuran partikel kulit kering (125 μm, 250 μm dan 500 μm), waktu pengekstrakan (2 jam) dan suhu pengekstrakan (50°C-80°C) melalui air. Jumlah kandungan nootkatone dan valencene ditentukan secara kuantitatif dengan menggunakan kromatografi gas dan didapati bahawa pengekstrakan nootkatone dan valencene yang maksimum berlaku pada suhu 60ºC selama 2 jam dalam metanol iaitu 1.1172 x 10-5 g/L dan 9.01587 x 10-5 g/L masing-masing. Selain itu, didapati bahawa pengekstrakan nootkatone dan valencene menggunakan kulit kering dengan saiz zarah 250 μm adalah saiz yang dptimum yang menghasilkan kepekatan 4.36802 x 10-6 g/L dan 4.42184 x 10-5 g/L masing-masing. Spektrometri massa kromatografi gas kemudian digunakan untuk mengenal pasti dan mengira komponen aktif yang diperoleh daripada pengekstrakan Soxhlet. Hasilnya setakat ini menunjukkan bahawa kulit Citrus grandis yang memiliki aroma seperti anggur yang kuat mengandungi limonene sebagai unsur utama dan sebatian meruap yang lain.
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The peels of pomelo contribute 30% of the fruit weight and yet it has been dump without recognizing the possible nutritional value of the peels. Study has been carried out to identify the effect of different types of solvents and different particle sizes of Citrus grandis dry peel extraction. Extraction was conducted using Soxhlet apparatus with various types of aqueous solvents (methanol, acetone and n-hexane), particle size of dry peel (125 μm, 250 μm and 500 μm), extraction time (2 hours) and extraction temperature (50°C-80°) via heating mantel. The total content of extract was quantitatively determined using gas chromatography and it was found that the extraction at 60ºC for 2 h in aqueous methanol was the optimal solvent for maximum nootkatone and valencene which were 1.12 x 10-5 g/L and 9.02 x 10-5 g/L respectively. Besides, it was also found that extraction of nootkatone and valencene using dry peel with a particle size of 250 μm was the optimal size which yield a concentration of 4.37 x 10-6 g/L and 4.42 x 10-5 g/L respectively. Gas chromatograph mass spectrometry was then used to identify and quantify the active components obtained from the Soxhlet extraction. The results thus far showed that the peel of Citrus grandis which possesses a strong grape-like aroma contain limonene as the major constituent and other volatile compounds.
Extraction and quantification of (+) –valencene and (+) – onootkatone from citrus grandis / Muthu Kumar Ganeson