Application of Gelatin Composite Coating in Pork Quality Preservation during Storage and Mechanism of Gelatin Composite Coating on Pork Flavor

Gelatin coating is an effective way to prolong the shelf life of meat products. Aiming at solving the problem of flavor deterioration during the storage of pork at room temperature, pork coating technology was developed to preserve the pork at 25 °C, and the comprehensive sensory analysis of vision, touch, smell, and taste was used to study the effect of coating on preservation of pork flavor. Herein, uncoated (control) and coated pork samples (including gelatin coating and gelatin coating incorporated with ginger essential oil) were analyzed to investigate the integrity of pork periodically during storage at 25 °C for weight loss, color, texture (springiness, chewiness, cohesiveness, gumminess, and hardness), microstructure, odor (electronic nose), taste (electronic tongue), volatile flavor substance, and taste ingredients. The results suggested that ginger essential oil (GEO) gelatin coating and gelatin coating can effectively inhibit the loss of water dispersion and slow down the oxidation reaction, coating treatments could significantly (p < 0.05) retarded the weight loss of pork slices, with values of 20.19%, 15.95%, 13.12% for uncoated, gelatin coated, and GEO-gelatin coated samples during 24 h of storage, respectively. Compared with control group, the color, texture, smell, and taste evaluations demonstrated that coating treatments had improved sensory and texture attributes during the storage period. Furthermore, the comprehensive results from the physical property assays (especially the texture), morphological assay and volatile odor assays showed that the GEO-fish gelatin composite coating had better preservation effect on pork flavor than the fish gelatin coating. The study suggests that the gelatin composite coating could be developed as a prospective active packaging to preserve pork meat at room temperature.

Interaction between Negatively Charged Fish Gelatin and Cyclodextrin in Aqueous Solution: Characteristics and Formation Mechanism

The effect that ratios of fish gelatin (FG) to α/β/γ cyclodextrins (α, β, γCDs) had on the phase behavior of a concentrated biopolymer mixture were comparatively investigated. This showed that the formed biopolymer mixture had the highest gel strength at ratios of FG–CD = 90:10. FG could interact with CDs to form stable soluble complexes with lower values of turbidity, particle size and ζ-potential. All of the FG–CD mixture solutions exhibited pseudo-plastic behaviors, and FG–αCD samples had the highest viscosity values than others. The addition of CDs could unfold FG molecules and make conformation transitions of FG from a random coil to β-turn, leading to the environmental change of hydrophobic residues and presenting higher fluorescence intensity, especially for βCDs. FTIR results revealed that the formation of intermolecular hydrogen bonds between FG and CD could change the secondary structure of FG. These findings might help further apply FG–CD complexes in designing new food matrixes.

Release of Cinnamaldehyde and Thymol from PLA/Tilapia Fish Gelatin-Sodium Alginate Bilayer Films to Liquid and Solid Food Simulants, and Japanese Sea Bass: A Comparative Study

This study aimed to develop an active biodegradable bilayer film and to investigate the release behaviors of active compounds into different food matrices. Cinnamaldehyde (CI) or thymol (Ty) was encapsulated in β-cyclodextrin (β-CD) to prepare the active β-CD inclusion complex (β-CD-CI/β-CD-Ty). The tilapia fish gelatin-sodium alginate composite (FGSA) containing β-CD-CI or β-CD-Ty was coated on the surface of PLA film to obtain the active bilayer film. Different food simulants including liquid food simulants (water, 3% acetic acid, 10% ethanol, and 95% ethanol), solid dry food simulant (modified polyphenylene oxide (Tenax TA)), and the real food (Japanese sea bass) were selected to investigate the release behaviors of bilayer films into different food matrixes. The results showed that the prepared β-CD inclusion complexes distributed evenly in the cross-linking structure of FGSA and improved the thickness and water contact angle of the bilayer films. Active compounds possessed the lowest release rates in Tenax TA, compared to the release to liquid simulants and sea bass. CI and Ty sustained the release to the sea bass matrix with a similar behavior to the release to 95% ethanol. The bilayer film containing β-CD-Ty exhibited stronger active antibacterial and antioxidant activities, probably due to the higher release efficiency of Ty in test mediums.

Quality of gelatin from tilapia (Oreochromis niloticus) by-products and its effects as edible coating on fish sausage during chilled storage

Gelatin is a hydrolysed collagen that can be used as raw material for edible coatings to protect perishable foods such as fish sausage. This study aims to examine the quality of gelatin from tilapia by products (skin, scale, bone) and determine the best source of fish gelatin as edible coating on quality of tilapia sausage during chilled storage. The process of made skin gelatin was demineralized with acetic acid while scale and bone were demineralized by hydrochloric acid. Gelatin was examined for yield, gel strength, and viscosity. After edible coatings were applied to the sausages by dipping method, the sausages were stored in the refrigerator at ±5°C for 21 days. Quality deterioration of sausages during storage were measured by sensory value, moisture content, TPC, gel strength and color. The results showed that the highest gelatin yield was obtained from tilapia scales, which was 6.87% while the yield of skin and bone were 4.33% and 1.47% respectively. The best material for edible coating was bone gelatin with gel strength and viscosity which were 325 bloom and 7.10 cP respectively. The application of sausage, where the appearance and texture of sensory value were still acceptable until 21st days of storage. Sausages with edible coating from tilapia bone also showed the highest gel strength about 2514,99-3716,05 g.cm.

Effect of Pectin on the Characteristics of Edible Film from Pink Ear Emperor (Lethrinus lentjan) Gelatin

Edible film is a thin layer used to coat food. One of the biopolymers that can be used as a base for the edible film is fish gelatin. Gelatin can be obtained from the skin of Lethrinus lentjan. However, edible film is usually brittle if only gelatin is used, so other materials, such as pectin, are needed to form an elastic film. This study aims to determine the effect of pectin addition on the characteristics of the edible film. The method used in this research was the experimental method with five treatments of pectin concentration (0%, 0.2%, 0.25%, 0.3%, 0.35%). Physical and chemical characteristics (thickness, tensile strength, elongation, water vapor transmission, and moisture content) of edible films were analyzed. The results showed that different concentrations of pectin significantly affected the characteristics of edible film. The best characteristics of edible film (0.12 mm thickness, 15.40 MPa tensile strength, 26.50% elongation, 6.99 gram/m2 24 h water vapor transmission rate, and 8.745% moisture content) were obtained as 0.2% pectin added in making the gelatin-based edible film.