Tuna skin gelatin production: optimization of extraction steps and process scale-up

Abstract

Advantages of fish gelatin production include reduction of environmental impacts from waste, improved functionality, and fewer socio-cultural constraints. The extraction of gelatin from Yellowfin tuna (Thunnus albacares) skin was optimized using response surface methodology. Conditions for acid pretreatment (acetic acid concentration and treatment time) had a significant effect (p < 0.05) on the response variables skin hydration, gelatin extract, gel strength, and gel pH. Conditions for the extraction step (treatment temperature and treatment time) had a significant effect (p < 0.05) on the response variables gelling temperature, melting temperature, and gel strength. Process conditions affected the gel properties, and some effects were confirmed by evaluating the molecular weight profile of extracted proteins obtained through SDS-PAGE. The feasibility of the general extraction process scale-up was evaluated by comparing process yields and characteristics of gelatins, obtained at laboratory and pilot plant scales (scale-up ratio 80:1).Producción de gelatina de piel de atún: optimización de las etapas de extracción y escalamiento del proceso RESUMEN

Cyprinus carpio Skeleton Byproduct as a Source of Collagen for Gelatin Preparation

“…Very low yields of gelatins were achieved in the treatment of Nile tilapia skins (3.8%) and Nile perch skins (8.7%) after their treatment in weak solutions of NaOH and HCl [ 45 ]. Another study looked at the extraction of gelatin from tuna skin after different conditioning methods (CH 3 COOH concentration and treatment time) [ 29 ]; yields of 11.7–14.5% are relatively low, and lower than the lowest yield from our study (18.7%). Slightly higher yields were obtained with gelatins extracted from catfish skin; the authors focused on the study of the influence of different raw material conditioning methods and on different extraction parameters (temperatures of 60, 70 and 80 °C and times of 1, 2 and 3 h).…”

“…Compared to other studies on the preparation of fish gelatins, the M P of gelatins prepared according to our technological procedure is comparable. For gelatins prepared from surimi processing waste, the M P was only 16.2–18.9 °C [ 30 ], from cuttlefish 19.2–25.4 °C [ 44 ], from Nile perch skin 21.4–26.3 °C, from Nile perch bones 25.5–26.5 °C [ 49 ], from tuna skin 25.6 °C [ 29 ], from Nile perch skin 21.4 °C, and from Nile tilapia skin 28.5 °C [ 45 ].…”

“…As far as G P is concerned, the situation is the opposite; all our prepared gelatins from any gelatin fraction have a lower G P (4.2–15.7 °C), in many cases even more pronounced than with standard bovine and porcine gelatins, for which the G P is usually about 5 °C lower than the M P . Compared to other fish gelatins, the gelatins we prepared have a comparable or slightly lower G P ; gelatins prepared from cuttlefish had G P 12.9–21.8 °C [ 44 ], from Nile perch skin 13.8–19.5 °C, from Nile perch bones 18.5–19.0 °C [ 49 ], from Nile perch bones 19.9 °C, from tuna skin 19.0 °C [ 29 ], and from Nile tilapia 17.1 °C [ 45 ]. Exceptions are gelatins prepared from surimi processing waste, for which the authors found a very low G P , 5.1–5.7 °C [ 30 ].…”

“…Such gelatins are rejected by some consumers for dietary, religious, or cultural reasons. Fish or poultry gelatins can be a suitable alternative [ 27 , 28 , 29 ]. Compared to standard porcine and bovine gelatins, most fish gelatins have a lower gel strength, viscosity, and melting and gelling point, which limits their industrial use.…”

Cosmetic, Biomedical and Pharmaceutical Applications of Fish Gelatin/Hydrolysates

“…This leads to different gelatin types, such as Gelatin A and Gelatin B, which have different features, and different applications [ 2 ]. The second step involves heating through water which comprises the actual extraction of gelatin, and the last step includes filtration and drying of gelatin, grinding into solid powder which can be used to prepare sheets [ 2 , 7 , 9 , 11 , 12 , 13 , 14 , 15 , 16 ]. These different steps are summarized in Figure 1 .…”