Owing to the increasing environmental concerns and requirements for high-quality foods, edible films and coatings (based on proteins, polysaccharides, natural phenolic active substances, etc.) are being developed as effective alternatives to traditional plastic packaging. Gelatin is extracted from collagen. It is an ideal material for food packaging due to its versatile advantages such as low price, polymerization, biodegradability, good antibacterial and antioxidant properties, etc. However, gelatin film exists poor waterproof and mechanical properties, which limit its developments and applications in food packaging. Previous studies show that pure gelatin can be modified by adding active ingredients and incorporating them with bio-polymers to improve its mechanical properties, aiming to achieve the desirable effect of preservation. This review mainly shows the preparation and molding ways of gelatin-based edible films and the applications of gelatin modified with other biopolymers. Furthermore, this review provides the latest advances in gelatin-based biodegradable packaging and food applications that exhibit outstanding advantages in food preservation.

The volatile and odor-active compounds in cooked meat of farmed obscure puffer (Takifugu obscurus) were analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). The volatile compounds were extracted by the simultaneous distillation-extraction (SDE) method, then separated and identified by GC-MS. Odor-active compounds in the SDE extract were characterized by GC-MS-O. A total of 68 volatile compounds were found, including 23 aldehydes, 10 alcohols, nine ketones, 17 N- or S-containing compounds and aromatics, three acids, three alkanes, and three esters. Of these, 31 odor-active compounds were detected and identified. Trimethylamine (fishy), octanal (grassy, leafy, green), (E)-2-octenal (roast, fatty), 1-octen-3-ol (fishy, fatty, mushroom, grassy), 2-ethyl-1-hexanethiol (cooked fish), (E,E)-2,4-octadienal (cooked meat, sweet), 2-acetylthiazole (meaty, roast, nutty, sulfur), 2-acetylpyrrole (nutty, walnut, bread) were identified as the key odorants in the cooked meat of farmed obscure puffer based on posterior intensity and time-intensity methods.

The Yangtze Coilia ectenes is a delicious fish known for its distinctive aroma, intense umami taste and high nutritional value. The analysis of Yangtze Coilia ectenes flesh extract using an e-Tongue indicated that saltiness and umami taste were the primary sensory attributes. The relationship between umami-related components and umami taste of this fish was studied by using an electronic tongue (e-Tongue) and sensory perception analysis. As free amino acids, nucleotides and inorganic ions are the main contributors for umami, their contents in Yangtze Coilia ectenes flesh extract were quantified instrumentally and a synthetic sample composed of similar contents of free amino acids, nucleotides and inorganic ions was prepared subsequently. No significant difference in umami taste between that of the synthetic sample and the flesh extract were observed by using the e-Tongue and sensory analysis (p < 0.05). Our further analysis using an omission test indicated nine components including Glu, Gly, AMP, IMP, GMP, K⁺, Na⁺, Cl⁻ and PO₄ ³⁻ are the key umami-related components with a proportion of 1 : 5 : 40 for amino acids, nucleotides and inorganic ions, respectively. Our results indicated that a simplified synthetic extract can replicate the umami taste of Yangtze Coilia ectenes flesh which provides solid evidence for the preparation of new flavor enhancers in the future.

Gelatin–sodium alginate-based edible films cross-linked with pullulan were prepared using the solution casting method. FTIR spectroscopy demonstrated the existence of hydrogen bonding interactions between the components, and scanning electron microscopy observed the component of the films, revealing electrostatic interactions and thus explaining the differences in the properties of the blend films. The best mechanical properties and oxygen barrier occurred at a 1:1 percentage of pullulan to gelatin (GP11) with sodium alginate dosing for modification. Furthermore, GP11 demonstrated the best thermodynamic properties by DSC analysis, the highest UV barrier (94.13%) and the best oxidation resistance in DPPH tests. The results of storage experiments using modified edible films encapsulated in fresh fish liver oil showed that GP11 retarded grease oxidation by inhibiting the rise in peroxide and anisidine values, while inappropriate amounts of pullulan had a pro-oxidative effect on grease. The correlation between oil oxidation and material properties was investigated, and water solubility and apparent color characteristics were also assessed.