Effect of hydrochloric acid extraction on yield and gel properties of gelatine from salted jellyfish by-products

Abstract

Salted jellyfish by-products have collagen protein that is mainly sold for animal feed at a low price. The change of jellyfish by-products into a food ingredient like gelatine could benefit food applications and reduce food waste. Indeed, jellyfish gelatine production is a time-consuming process that includes alkaline pre-treatment, acid pre-treatment, hot water extraction, and drying. Reduced times of acid pre-treatment and water extraction might deliver different gel properties. Therefore, this research aimed to investigate the effect of hydrochloric acid (HCl) pre-treatment on the gel quality of resultant gelatine. Desalted jellyfish by-products were immersed in 0.5 M sodium hydroxide at 4oC for 1 h and then were acidtreated by varying HCl concentrations (0.1, 0.2, and 0.3 M) at 25oC for 2 h. After that, samples were extracted at 60oC for 3 h and dried at 60oC for 3 days. Results showed that gelatine yield significantly increased with increasing HCl concentration. Gelatine yield were 2.97±0.97%, 5.60±1.01%, and 6.34±1.08%, after extraction with 0.1, 0.2, and 0.3 M HCl, respectively. Gel strength generally decreased as HCl concentration increased. Gel strength values were in the range of 118.89-223.60 g. The colour of jellyfish gelatine showed light to dark brown with no differences in Hue values. Thus, the short duration of HCl pre-treatment for 2 h and hot water extraction for 3 h was insufficient for the jellyfish gelatine process.

Influence of extraction times on physical and functional properties of gelatin from salted jellyfish by-products

“…For gelatin extraction, jellyfish by-products gelatin was prepared according to Lueyot et al [11] and Charoenchokpanich et al [12] with a slight modification. Firstly, the desalted by-products (1 kg) were agitated at 150 rpm and 4 o C for 2 h with 0.5 M sodium hydroxide (NaOH) solution (1:3, w/v) in a shaking incubator (WIS-20R, WiseCube, Korea).…”

“…The salt content of the gelatin solution was measured using a conductivity meter (TDS Meter 308, Systronics, India), and the calculated value was extrapolated from the standard sodium chloride 0-1,000 ppm graph [12].…”

“…Marine gelatin is mainly produced from by-products to decrease food waste and the functional qualities of marine gelatin. Several researchers have reported gelatin extracted from marine by-products such as cold-water fish (chum salmon [6]), warm-water fish (cobia [7], pangasius catfish [8], and tilapia [9][10]), and jellyfish [11][12].…”

“…The low price of salted jellyfish by-products but rich in collagen protein with minimal fat content [14][15][16][17][18] have potentially been a source for gelatin extraction. The attempts to improve jellyfish gelatin by varying hydrochloric acid (HCl) pretreatment conditions (concentration and time), extraction temperature, and extraction time [11][12][15][16] have been reported. Charoenchokpanich et al [12] reported that the condition of 2 h HCl pretreatment at 25 o C and 3 h water extraction at 60 o C was insufficient for the jellyfish gelatin process and delivered the low gel strength of 214.47 g. Research on the functional properties of jellyfish gelatin produced from salted jellyfish byproducts has been limited.…”

“…The attempts to improve jellyfish gelatin by varying hydrochloric acid (HCl) pretreatment conditions (concentration and time), extraction temperature, and extraction time [11][12][15][16] have been reported. Charoenchokpanich et al [12] reported that the condition of 2 h HCl pretreatment at 25 o C and 3 h water extraction at 60 o C was insufficient for the jellyfish gelatin process and delivered the low gel strength of 214.47 g. Research on the functional properties of jellyfish gelatin produced from salted jellyfish byproducts has been limited. Therefore, this research aimed to investigate the duration of hot water extraction (at 60 o C) varying from 12, 24, and 48 h on jellyfish gelatin's yield, gel properties, and functional properties.…”