The changing of gelatin properties from tra catfish skin (Pangasianodon hypophthalmus) by alkaline replacement to enzyme in pretreated process

Abstract

The effect of pretreated method to remove the non-collagenous protein by using alkaline and enzyme Alcalase, as well as the temperature and time for extracting on the properties of gelatin from tra catfish skin were investigated. Yields of gelatin extracted at 70 °C for 1h from pretreated skin by enzyme method (16.2%) was significantly higher than that of the sample by alkaline method (12.14%). However, the gel strength of gelatin from skin treated via enzyme Alcalase was lower than gelatin sample pretreated by alkaline while the turbidity values was higher than gelatin from skin pretreated via alkaline. From SDS-PAGE profile, gelatin from skin pretreated by alkaline consisted of two different α- chains in protein pattern while enzymatic gelatin had low molecular weight peptides. The FT-IR spectra showed the lower wavenumber in amide I and III of enzymatic gelatin in compare to alkaline gelatin by the loss of triple helical structure during enzyme treatment. From the results, the using enzyme for pretreated material has potential to replace the alkaline method for gelatin production with purpose to reduce chemical waste caused serious ecological issues.

Properties of gelatin extracted from snakehead fish (Chitala striata) by-products at various temperatures and times

“…The gel strength of gelatin reached its highest value at 248 g and 245 g when the same extraction at 80 °C for 1 h was observed in the snakehead scale and skin and scale mixture, respectively. These data were consistent with that of the studies by Zuraida & Pamungkas (2020) for gelatin extracted from snakehead scales (229 g) and Thuy et al (2022) for tra catfish skin gelatin (208 g).…”

“…However, degradation of protein patterns was observed in fish-scale gelatin when compared to gelatin from skin and scale mixtures, indicating an association between the transition of α-helix by uncoupling of intermolecular cross-links and interruption of intramolecular bonding (Kittiphattanabawon et al, 2012). The relationship between protein degradation and the increase in amide I and amide III bands in FTIR spectra has been described in studies by Kittiphattanabawon et al (2012) and Thuy et al (2022), who reported that gelatin from shark skin and tra catfish skin with a lower wavenumber in amide I and amide III showed a high degree of protein denaturation.…”

“…Protein patterns of gelatin extracted from snakehead fish by-products were determined as described by Thuy et al (2022), with minor modifications. Gelatin in the supernatant extracted at 80 °C for 1 h was mixed with buffer (Tris-HCl 0.5 M at pH 6.8, with 20% (v/v) glycerol and 10% (w/v) SDS in the presence of 10% (v/v) mercaptoethanol) at a gelatin/buffer ratio of 1:2 (v/v).…”

“…The results showed that there was a significant increase in ΔE* of gelatin with an increase in temperature and time during extraction. The temperature rise facilitated extremely high extent of non-enzymatic browning reaction, contributing to the increased yellowness (b*) and concomitantly the darker lightness by retaining the minimal fragments via damage of gelatin molecules (Thuy et al, 2022). The gelatin samples of the fish scale and the skin and scale mixture extracted at 80 °C for 1 h in showed a low total difference in color value (ΔE*) with high lightness (L*-values) when the extraction temperature was lower than 90 °C and time was not longer than 2 h.…”

“…Indeed, the social demand for gelatin has increased over the last few decades because of its unique surface-active properties, allowing its wide application in the food, pharmaceutical, cosmetic, and other industries (Zhou & Regenstein, 2007). For these reasons, gelatin production from processing fish by-products has been a concern of broad interest to related-scientist groups, such as the skin of tra catfish (Thuy et al, 2022); wami tilapia skin (Alfaro et al, 2013); seabass skin (Tekle et al, 2022); and snakehead skin and bone (Rosmawati et al, 2021). However, there is no public consideration for gelatin extracted from snakehead fish by-products.…”