The accumulation of synthetic plastics, mainly from food packaging, is causing a serious environmental problem. It is driving research efforts to the development of biodegradable films and coatings. ...The biopolymers used as raw material to prepare biodegradable films should be renewable, abundant and low-cost. In some cases, they can be obtained from wastes. This review summarizes the advances in polysaccharide-based films and coatings for food packaging. Among the materials studied to develop biodegradable packaging films and coatings are polysaccharides such as cellulose, chitosan, starch, pectin and alginate. These polysaccharides are able to form films and coatings with good barrier properties against the transport of gases such as oxygen and carbon dioxide. On the other hand, tensile strength and percentage of elongation are important mechanical properties. Desirable values of them are required to maintain the integrity of the packed food. The tensile strength values showed by polysaccharide-based films vary from each other, but some of them exhibit similar values to those observed in synthetic polymers values. For example, tensile strength values of films based on high amylose starch or chitosan are comparable to those values found in high-density polyethylene films. The values of percentage of elongation are the main concern, which are far from the desirable values found for synthetic polymers. Researchers are studying combinations of polysaccharides with other materials to improve the barrier and mechanical properties in order to obtain biopolymers that could replace synthetic polymers. Functional polymers with antimicrobial properties, as that the case of chitosan, are also being studied.
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•Edible and biodegradable films could be an alternative to synthetic packaging films.•Polysaccharide-based films allow enhancing the shelf-life of ready-to-eat foods.•Polysaccharide-based films are an effective barrier to gas transference.•Polysaccharide-based films have poor water vapour permeability.•Tensile strength is similar to that of synthetic polymers.
Biodegradable films based on bacterial cellulose, glycerol and polyvinyl alcohol are a new alternative to develop food packaging with the capacity to retard or inhibit the effect of UV radiation. ...However, these compounds are sensitive to moisture. Therefore, the purpose of this study was to evaluate the modifications of the mechanical, water vapor permeability and optical properties of these composite films depending on their water activity. Results showed that water molecules acted as a plasticizer agent, modifying the mechanical, water vapor permeability and optical properties of the developed films. However, an overplastification process took place at higher activity water, resulting in a weakness of film structure and decreasing drastically the elongation. The transmittance in the UV–VIS light region decreased when the activity water increased. No significant variations were observed in color, transparency or opacity properties.
Graphic abstract
This study aimed to produce and characterize biosurfactants using the
Thermoanaerobacter
sp. CM-CNRG TB177 strain isolated from an oil field in Mexico, as well as assessing the influence of different ...carbon and nitrogen sources on the capacity of the produced surfactant to reduce the surface tension of water. The thin-layer chromatography (TLC) revealed that the obtained extract corresponds to a mono-rhamnolipid; the results of the ultra-performance-liquid chromatography/mass spectrometry (UPLC/MS) analysis revealed that the
Thermoanaerobacter
sp. CM-CNRG TB177 strain produces a mixture of three rhamnolipids, whose masses correspond to mono-rhamnolipid. The rhamnolipids mixture obtained using 2.5% molasses as carbon source diminished the surface tension of water to 29.67 mNm
−1
, indicating that the concentration of molasses influenced the capacity of the produced surfactant to reduce the surface tension of water. Also, the microorganism was not capable of growing in the absence of yeast extract as nitrogen source. To the best of our knowledge, the presented results describe for the first time the nature of the biosurfactant produced by a bacterium of the
Thermoanaerobacter
genus.
Key points
• Thermoanaerobacter sp. CM-CNRG TB177 produces biosurfactants, and its glycolipid nature is described for the first time.
• The HPLC analysis revealed a mixture of three rhamnolipid congeners, and UPLC/MS analysis determined that two of the congeners are the rhamnolipids Rha-C8-C10 and Rha-C12-C10.
• The lowest surface tension of 29.67 mNm
−1
was obtained with molasses as source of carbon at a 2.5% concentration.
Graphical abstract
High pressure processing (HPP) at refrigeration, ambient or moderate heating temperature can inactivate pathogenic and spoilage microorganisms with fewer changes to product “freshness” as compared to ...conventional food preservation processes. The essential equipment components are here described to help define low and higher cost applications. Specific opportunities are discussed that a food processor can consider to profit from the significant equipment investment required to implement this new processing technology. Although, HPP is the only alternative processing technology that has reached consumers with a variety of new products, there are many pending research questions to be answered to make it a reliable alternative and to have a fundamental understanding of the inactivation of microorganisms and enzymes by pressure. Approaches to generate the knowledge required and the information that is being generated is critically reviewed.
The restructuring process offers to fish processors the opportunity to obtain new products, taking advantage of both low-value fish species and remains from filleting and other processing operations. ...However, mechanical and functional properties of restructured products depend on the biochemical and physicochemical properties of muscle proteins, mainly myosin and actomyosin. In this regard, the biochemistry of fish muscle is different from that of mammals and birds. Therefore, fish products must be processed in a different way from red meat or poultry. The main fish products are surimi and restructured products. Fish products can be improved or modified by using hydrocolloids (carbohydrates and protein) as additives. In this review, the modern technology to obtain these products, the applications of hydrocolloids in fish products, and the implications of the increasing demand for healthy, low-salt fish products are discussed.
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Bacterial cellulose films were combined with glycerol and chitosan to improve the UV-barrier and mechanical properties. In part 1, the moisture content and mechanical properties (tensile and puncture ...properties) were analysed by response surface methodology. The calculated values of the mechanical properties were in the range of 1.23-39.28 MPa for tensile strength, 2.28-25.34% for percentage of elongation, 11.72-1579.59 MPa for Young's modulus, 0.22-1.92 MJ/m
3
for toughness, 43.74-1067.35 g for burst strength and 0.39-3.12 mm for distance to burst. In general, a plasticizing and a reinforcing effect on the bacterial cellulose films was observed by glycerol and chitosan addition. Glycerol provided adhesive properties, which can be an advantage for application on foods, such as fruit or vegetables, as a wrapping material.
Bacterial cellulose films synthesized by Komagataeibacter xylinus were combined with glycerol and chitosan to obtain composite films with improved UV-barrier. In part 2, the interaction among the ...compounds was analyzed by scanning electron microscopy, UV-Vis and FT-IR spectra, thermogravimetry, and differential scanning calorimetry. The water permeability, water solubility and water retention capacity were analyzed by response surface methodology. The optical properties indicated that glycerol and chitosan improved the UV-barrier properties, obtaining average transmittance values in the UV regions below 5.15%. This fact opens multiple possibilities for applications in foods and products sensitive to sunlight radiation. Hence, these properties would facilitate the application of BC-glycerol-chitosan films on fresh food, with high moisture content and susceptible to oxidation by the sunlight radiation. In addition, the thermal properties of the films showed that they could be applied in heat-treated foods at temperatures until 135°C.
Beef is a fundamental part of the human diet, but it is highly susceptible to microbiological and physicochemical deterioration which decrease its shelf life. This work aimed to formulate an active ...edible film (AEF) incorporated with amino-functionalized mesoporous silica nanoparticles (A-MSN) loaded with Mexican oregano (
Kunth) essential oil (OEO) and to evaluate its effect as a coating on fresh beef quality during refrigerated storage. The AEF was based on amaranth protein isolate (API) and chitosan (CH) (4:1,
/
), to which OEO emulsified or encapsulated in A-MSN was added. The tensile strength (36.91 ± 1.37 MPa), Young's modulus (1354.80 ± 64.6 MPa), and elongation (4.71%) parameters of AEF made it comparable with synthetic films. The antimicrobial activity of AEF against
O157:H7 was improved by adding 9% (
/
) encapsulated OEO, and interactions of glycerol and A-MSN with the polymeric matrix were observed by FT-IR spectroscopy. In fresh beef, after 42 days, AEF reduced the population growth (Log CFU/cm
, relative to uncoated fresh beef) of
(5.5),
(3.5),
spp. (2.8), and aerobic mesophilic bacteria (6.8). After 21 days, odor acceptability of coated fresh beef was improved, thus, enlarging the shelf life of the beef and demonstrating the preservation capacity of this film.
In this study, biodegradable active films were prepared from potato starch and polyvinyl alcohol at different proportions, mixed with acetone extract of
Hibiscus sabdariffa
L. (HS) and using glycerol ...as a plasticizer. Functional properties, antimicrobial, and antioxidant capacity were evaluated. Potato starch films with a proportion of polyvinyl alcohol up to 50% and HS extract had significant antioxidant capacity and antibacterial effect against most of the analyzed strains. Adding polyvinyl alcohol (PVOH) and HS extract improved the mechanical performance and reduced water vapor permeability of the materials. The active biobased films with HS extract presented good physicochemical, antimicrobial, and antioxidant properties. These materials are considered as suitable for food packaging, and the active compounds in the roselle extract are a natural antibacterial option for the food area. The materials based entirely on biodegradable products are an excellent alternative when developing and marketing biobased materials, minimizing the environmental impact of food packaging.
Chitosan and polyvinyl alcohol films were prepared by the casting method. Moisture adsorption isotherms were obtained at 15 °C, 20 °C, 25 °C and 30 °C. Experimental isotherms were well fitted using ...the GAB model (
E
< 10%). The thermodynamic analysis showed a minimum integral entropy (∆
S
int
) at the 0.3–0.6 range of water activity (
a
w
) in all films. Pore radius values of the films ranged from 1.005 nm to 20.766 nm, which correspond to the micropores and mesopores classification. Compensation enthalpy-entropy in films showed that the water vapor adsorption process was driven by enthalpy at low
a
w
values (0.3–0.5 for CS and 0.2–0.3 for PVA). Most of the mechanical properties showed constant values at the zone of minimum ∆
S
int
, confirming that thermodynamic properties could be used to predict the stability of films. The study of thermodynamic water adsorption and the mechanical properties allows understanding the preparation process of stable films with adequate parameters intended for food packaging materials.
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