Most films used to preserve foodstuffs are made from synthetic plastic materials.However, for environmental reasons, attention has recently turned to biodegradable films. Gelatin has been extensively studied for its film forming capacity and applicability as an outer covering to protect food against drying, light, and oxygen. Moreover, it is 5 one of the first materials proposed as a carrier of bioactive components. Gelatins from alternatives to mammalian species are gaining prominence, especially gelatins from marine fish species. Because of their good film-forming abilities, fish gelatins may be a good alternative to synthetic plastics for making films to preserve foodstuffs. The mechanical and barrier properties of these films depend largely on the physical and 10 chemical characteristics of the gelatin, especially the amino acid composition, which is highly species specific, and the molecular weight distribution, which depends mainly on processing conditions. Different film formulations can be developed to extend the films' physical and chemical properties and to add new functional attributes. This paper reviews the most recent scientific literature dealing with films based on gelatins from 15 different fish species and considers various strategies intended to improve the physical properties of such films by combining fish gelatins with such other biopolymers as soy protein isolate, oils and fatty acids, and certain polysaccharides. The use of plasticizers and cross-linking agents is also discussed. Specific attributes, such as antimicrobial and antioxidant activities, may be also conferred by blending the gelatin 20 with chitosan, lysozyme, essential oils, plant extracts, or vitamin C to produce an active packaging biomaterial.

The structure-function relationship of composite films obtained from soy protein isolate (SPI) and cod gelatin was studied. Films with different ratios of SPI:gelatin (0, 25, 50, 75, 100% w/w) plasticized by a mixture of glycerol and sorbitol, were prepared by casting. Regardless of the soy protein concentration, the thickness and water vapor permeability of the composite films diminished significantly as compared to pure gelatin films. The formulation containing 25% SPI: 75% cod skin gelatin had the maximum force at the breaking point which was 1.8-fold and 2.8-fold of those of 100% gelatin and 100% SPI films, respectively. Moreover, this formulation offered high percent deformation values as the 100% gelatin film and relatively low water vapor permeability as the 100% SPI film. While all the films exhibited high water solubility, a slight reduction of the protein released in water was observed with increasing soy contents. DSC analyses revealed that gelatin was completely denatured in all the films, while the soy proteins maintained most of their native conformation. The FTIR analysis revealed the presence of 25% SPI to produce gelatin conformational changes, self aggregation of gelatin α-chains as well as intermolecular associations through C=O bonds between gelatin and SPI proteins.. Regarding appearance, all the films were translucent, but the yellowish color (b*) increased with increasing proportions of soy proteins.

The purpose of this study was to analyze the effect of 10-min continuous pressure and pulsed pressure in two 5-min steps (400 MPa at 7 degrees C) on the microbial flora, total volatile bases, pH, and texture of purified and unpurified oysters. High-pressure treatment reduced the number of all the target microorganisms (total viable count, H2S-producing microorganisms, lactic acid bacteria, Brochothrix thermosphacta, and coliforms), in some cases by around 5-log units. The difference between the counts in the control and the pressurized oysters remained stable throughout 41 days of storage at 2 degrees C. No Salmonella spp. were detected in either the control batch or the pressurized batches during this storage period. Deterioration of the oyster was accompanied by increased total volatile bases, mainly in the nonpressurized samples. The pH was practically constant in the pressurized oysters and fell slightly in unpressurized samples. As for mechanical properties, shear strength values were higher in pressurized than in unpressurized oysters. Step-pulse pressurizing (400 MPa at 7 degrees C in two 5-min pulses) produced no apparent advantages over continuous pressurizing based on any of the indices used.

A coating made in cold from a blend of a chitosan and a gelatin solution was applied to patties made of chilled cod, and its preservative effect was assessed by colour measurements, rheological measurements (hardness, elasticity, cohesiveness, chewiness, gumminess, and adhesiveness), biochemical determinations (total volatile bases and thiobarbituric acid as measures of rancidity) and microbiological assays (total bacterial counts, luminiscent bacteria, enterobacteria, pseudomonas, lactic acid bacteria, and Staphylococcus aureus). The effect of dry powdered chitosan mixed into the patties was tested as well. The use of chitosan either as a coating or as a powdered ingredient did not affect lightness at the end of the storage period considered but did result in an increase in the value of yellowness. The coating increased patty elasticity, whereas adding powdered chitosan to the patty mixture increased the other rheological parameter values. The findings on the effect of the chitosan on rancidity were not conclusive due to the low values recorded in the cod. However, the coating did prevent spoilage of the cod patties as reflected by a decrease in total volatile basic nitrogen and in the microorganism counts, in particular counts of gram-negative bacteria. In contrast, none of these effects on spoilage were observed when the chitosan was added to the patty mixture in powdered form. Coatings prepared in cold from a blend of gelatin and chitosan offer a promising alternative for preserving fish patties.

Seafoods possess high nutritional value and moreover offer functional properties. However, fish products do not contain fibre. Fibre is an essential compound in the diet, which has health benefit effects in certain disorders. At the same time, dietary fibres can be an effective tool in seafood processing for improving functional properties such as water binding, gelling, etc. This paper offers a general view of the role of dietary fibres in a food system and discusses the technological and functional roles of different types of fibres of vegetable origin (cereal, fruits) and animal origin (chitosan), with different characteristics, when they are used as ingredients in the development of restructured fish products. WHAT IS DIETARY FIBRE? The way food is perceived in developed countries has changed in the last twenty years, bringing new life to the Hippocratic principle "Let food be thy medicine and medicine be thy food" and following the tradition in oriental cultures of attributing curative and "therapeutic" properties to foods. The upshot has been awareness of the need to use diet as a means of staying healthy. This tendency has brought with it the concept of functional

Sunflower oil was added to cod gelatin in proportions of 0, 0.3, 0.6, and 1% to improve the hydrophobic properties of the resulting films and decrease water vapor permeability and the soluble matter content. Mechanical and optical properties were evaluated to determine the influence of the added oil and the stability of the films during storage for one month. Adding oil increased film thickness, whiteness, and optical absorbance and decreased transparency; all these properties held stable over the storage period. Fourier transform infrared (FTIR) spectra revealed some lipid-protein interactions (hydrogen bonds, ester formation) and early oil oxidation. By the end of storage oxidation was well advanced and secondary oxidation products were present. Adding oil in any quantity decreased the puncture force but not the puncture deformation. Stability of these two mechanical properties decreased during storage in the films that contained ≥0.6 % added oil. Water vapor permeability did not decrease when oil was added and even increased with storage time, though adding oil yielded more insoluble films due to lipid-protein interactions.

Heat-and high-pressure-induced gels were prepared from blue whiting muscle (Micromesistius poutassou R.). Minced muscle was homogenized with salt (1% NaCl), and response surface methodology was used to determine the influence of pressure, time, and temperature on the work of penetration. Two combinations of pressure−time−temperature were chosen to give the highest work of penetration, and samples were compared with a heat-induced gel. The following lots were subjected to chemical and rheological analysis: 200 MPa, 3 °C, 10 min (lot L); 375 MPa, 38 °C, 20 min (lot H); and atmospheric pressure, 37 °C, 30 min/90 °C 50 min (lot T). Breaking force, deformation, and cohesiveness were greater in gels of lot L. Hardness and water holding capacity were greatest in gels of lot T. Elasticity was greater in high-pressureinduced gels. The percentage of hydrophobic interactions, essentially linking actin molecules, was greater in gels of lot H than in gels of lots T and L. There were more cross-linkages in the heat-induced gels (lot T).

No abstract