Effects of powdered activated carbon, diatomaceous earth and β-cyclodextrin treatments on the clarity and volatile compounds of tilapia (Oreochromis niloticus) skin gelatin

Abstract

Fish gelatin may have unpleasant odor that adversely affects its applications. Powdered activated carbon (PAC, 0.5–2.0% w/v), diatomaceous earth (DE, 0.1–0.5% w/v) and β-cyclodextrin (CD, 1.0–3.0% w/v) were used to purify tilapia (Oreochromis niloticus) skin gelatin at various absorption temperature and time (30–50 °C; 10–60 min). The use of all three materials at optimized conditions could lead to a significant improvement in the clarity of 6.67% (w/w) gelatin solutions: the transmittance was increased from 85 to 92–93% at 640 nm, and the color was changed from light yellow to colorless. There were 18 volatile compounds (11 aldehydes, 4 alcohols, and 3 other compounds) identified from the tilapia gelatin solution, and the number was reduced to 12 after the DE treatment (0.5%, 50 °C, 30 min) and to 9 after the PAC treatment (1.5%, 40 °C, 30 min). The amounts of all detectable compounds were greatly decreased after the PAC (decreased 12–89%) and β-CD treatments (decreased 35–96%), but less satisfied results were obtained with the DE treatments.