Gelatin from fish skin is known to be an alternative source for mammalian gelatin. However, it has weaker properties compared to bovine and porcine gelatin, which limits its use in the industry. The conventional method for fish gelatin extraction requires long production time and could cause serious water pollution and chemical treatments are often being used to enhance the yield of fish gelatin and its properties but it may affect the amino acid content of the gelatin. In this regard, High-Pressure Processing (HPP) is a novel method suggested for fish gelatin extraction. The HPP method is classified as green technology as it requires low electricity throughout the process. This study will discuss the impact of HPP the technique gelatin extracted from fish skin. Skins from four types of fish, namely red tilapia (Oreochromis niloticus), black tilapia (Oreochromis mossambicus), grouper (Epinephelus areolatus) and threadfin bream (Nemipterus tambuloides), were used. High pressure was applied at either pretreatment in citric acid solution or during thermal extraction; and the pressure was maintained at 250 MPa with pressure holding time of 10 minutes and 18 hours of water extraction. Gelatin extract from traditional acid-base method was prepared as a standard for comparison. The study found that there was an increment in the yield of gelatin and the concentration of gelatin extract, and the pre-treatment time was also reduced.
Extraction of gelatin using traditional acid-base pretreatment method has several limitations
such as time consuming and causes serious water pollution. Chemical treatment often being used
as an alternative process to overcome the weaknesses of the conventional method. However,
excessive chemical elements would damage the structure of the gelatin due to its high sensitivity
to the acid content. High Pressure Processing (HPP) is a novel and environmental friendly
method that has been suggested to assist gelatin extraction. Pressurization during pretreatment
could reduce the extraction time and amount of acid used. It also has a potential in enhancing the
properties of the gelatin extract and increasing the gelatin yield. In this research, One-Factor-
at-Time (OFAT) and optimization study were done to determine the optimum parameters for
extraction of gelatin assisted by HPP from red tilapia skin. Four parameters; applied pressure,
pressure holding time, ratio of acid to skin and extraction time have been selected for the OFAT
design and concentration of the gelatin extract and percentage of yield gelatin were evaluated.
From OFAT, optimum technical parameters for response surface optimization design were 250
MPa pressure, 7.5 ml of acid to 1 g of skin and 12 hours extraction time. Pressure holding
time was fixed for 10 min. FCCCD has been used for optimization study. Results from the
data shows that the optimum conditions for gelatin extraction from red tilapia skin were 250
MPa for pressure, 10 min of pressure holding time, 7.5 ml of acid for 1 g of skin and 12 hours
of extraction time while the maximum concentration and yield were 19.51 mg/ml and 32.04%
(320.4 mg/g), respectively. These findings proved that HPP could increase the concentration
and the yield of the gelatin while reducing the chemical waste and shortening the extraction
process.