Effect of extraction methods on the yield and gel strength of gelatin extracted from jellyfish Acromitus flagellatus

Abstract

This study assessed the effects of different extraction methods and conditions on the yield and the gel strength of gelatin extracted from jellyfish Acromitus flagellatus, which were collected from the Southern and Western coasts of Sri Lanka. Gelatin was extracted using three methods; hot water extraction (HWE) (at 55, 60, and 65 ℃ for 4 and 8 hours), microwave-assisted extraction (MAE) (900W microwave power at 10, 30 and 50 % power levels for 3 and 5 minutes) and ultrasound-assisted extraction (UAE) (at 55, 60 and 65 ℃ for 1 and 2 hours), and their gel strength was tested. In the preliminary studies, no gel formation was observed in gelatin extracted from fresh dried jellyfish. Gelatin extracted from salted jellyfish exhibited gel-forming ability. Pretreatment of salted jellyfish at pH 2 resulted in gelatin with better gel properties. The yield and gel strength of jellyfish gelatin varied in different extraction methods and depending on the extraction conditions of the same method. Of all extraction methods and conditions, the highest and the lowest yields were reported in MAE at 30% power level for 3 minutes (34.75 ± 0.02%) and UAE at 55 ℃ for 1 hour (6.19 ± 0.02%), respectively. No gel formation was observed in the UAE. When considering all extraction methods and conditions, the highest gel strength was reported for HWE at 60 ℃ for 8 hours (565.0 ± 7.1 g). Of the MAE conditions, a 50 % power level for 3 minutes rendered gelatin with the highest gel strength (362 ± 24.75 g), which was significantly lower than that of the highest value of HWE (p < 0.05). The results indicate the yield and the gel strength of jellyfish Acromitus flagellatus-based gelatin may vary depending on the extraction methods and the conditions.
KEYWORDS: Gel strength, Gelatin, Jellyfish, Microwave extraction, Ultrasound extraction, Yield