Quality changes of shrimp cracker covered with fish gelatin film without and with palm oil incorporated during storage

Impact of fish gelatin film incorporated without and with palm oil on the quality changes of fried shrimp cracker stored for 15 days at room temperature was investigated, in comparison with nylon/linear low-density polyethylene (nylon/LLDPE) film. The moisture content and water activity of shrimp cracker packaged with all films increased during storage (p < 0.05). The lowest moisture content and water activity were found in the sample packaged with nylon/LLDPE film throughout the storage (p < 0.05). Sample packaged with fish gelatin films incorporated with palm oil generally had lower moisture content than those without oil added during the first 12 days of storage (p < 0.05). During 15 days of storage, shrimp cracker packaged with nylon/LLDPE film generally had the lower PV and TBARS value as well as volatile compounds, except for n-nonanal, than those stored in fish gelatin films, regardless of oil incorporation. The decrease in crispiness and increase in toughness occurred in all samples during the 15 days of storage. Nevertheless, the lower changes were observed in the sample packaged with nylon/LLDPE film. Overall, gelatin film showed excellent oxygen barrier property, which was associated with the retardation of lipid oxidation. The incorporation of oil into gelatin film could lower WVP, but negatively increased oxygen permeability of the resulting film. Thus, the improvement of gelatin film is still required.     

Characteristics of Gelatin Extracted from the Swim Bladder of Yellowfin Tuna (Thunnus albacores) as Affected by Alkaline Pretreatments

ABSTRACT

Gelatins extracted from the swim bladder of yellowfin tuna (Thunnus albacores) using various alkaline pretreatments were characterized. Alkaline mixtures (Na₂CO₃:NaOH) at different ratios (9:1, 8:2, 7:3, and 6:4) with a concentration of 4% (w/v) were used. The corresponding gelatins termed “G1,” “G2,” “G3,” and “G4” had yields of 9.78, 14.91, 35.96, and 13.60% (dry weight basis), respectively. All gelatins had α-chains as the major components. Fourier transform infrared spectra of obtained gelatins revealed the significant loss of molecular order of the triple-helix. G3 having the highest imino acid content and exhibited the highest gel strength (p < 0.05), compared with others. The microstructure of G3 gel was finer with smaller voids, compared with others. With increasing proportion of NaOH, the L*-value of gelatin gel increased with coincidental decrease in ΔE*-value. Gelling and melting temperatures of swim bladder gelatin were 12.3–15.1 and 21.3–22.3°C, respectively.