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The objective of the present study was to apply the polysaccharides from different nontraditional sources for cheese coatings. Chitosan, galactomannan from Gleditsia triacanthos, and agar from Glacilaria birdiae were tested, with different formulations and with the addition of plasticizer and corn oil. The surface properties of the cheese and the wetting capacity of the coatings on the cheese were determined. The three best solutions for each polysaccharide were chosen, further films were cast, and permeability to water vapor, oxygen, and carbon dioxide was determined, along with opacity. The solutions of G. triacanthos (formulation: 1.5% of galactomannan, 2.0% of glycerol, and 0.5% of oil) presented the best properties to coat the cheese: -38.76 mN x m(-1) for wettability; 3.24 x 10(-11) (g x (m x s x Pa)(-1)) for water vapor permeability; 0.94 x 10(-15) and 15.35 x 10(-15) (g x m(Pa x s x m(2))(-1)) for oxygen and carbon dioxide permeabilities, respectively; and opacity values of 5.27%. The O(2) consumption and CO(2) production rates of the cheese with and without coating were evaluated, showing a decrease of the respiration rates when the coating was applied. The uncoated cheese had an extensive mold growth at the surface when compared with the coated cheese. The results show that these coatings can be applied as an alternative to synthetic coatings.

The objective of this work was to evaluate the effect of the concentrations of Gleditsia triacanthos galactomannan and glycerol and the presence of corn oil in the physical properties of edible films. The influence of interactions between those constituents on films' permeability to gases (water vapour, CO and O), solubility in water, mechanical properties and colour was evaluated. The effects of those variables were analysed according to a 2 factorial design; regression coefficients were used to understand the influence of each variable (factor) on the studied properties, and a multifactor model was developed. Results show that galactomannan concentration is the most significant factor affecting the studied properties; moreover, the increase of plasticizer concentration and the presence of oil showed to be the most influent in the particular cases of solubility and transport properties (water vapour permeability and O permeability), respectively. These results show that galactomannan films' properties can be tailored to allow their use as alternative to non-biodegradable, non-edible packaging materials. [ABSTRACT FROM AUTHOR]

The main objective of this work was to evaluate the effect of chitosan and plasticizer concentrations and oil presence on the physical and mechanical properties of edible films. The effect of the film constituents and their in-between interactions were studied through the evaluation of permeability, opacity and mechanical properties. The effects of the studied variables (concentrations of chitosan, plasticizer and oil) were analysed according to a 2 factorial design. Pareto charts were used to identify the most significant factors in the studied properties (water vapour, oxygen and carbon dioxide permeability; opacity; tensile strength; elongation at break and Young's modulus). When addressing the influence of the interactions between the films' constituents on the properties above, results show that chitosan and plasticizer concentrations are the most significant factors affecting most of the studied properties, while oil incorporation has shown to be of a great importance in the particular case of transport properties (gas permeability), essentially due to its hydrophobicity. Water vapour permeability values (ranging from 1.62 × 10 to 4.24 × 10 g m s Pa) were half of those reported for cellophane films. Also the mechanical properties (tensile strength values from 0.43 to 13.72 MPa and elongation-at-break values from 58.62% to 166.70%) were in the range of those reported for LDPE and HDPE. Based on these results, we recommend the use of 1.5% ( w/ w) chitosan concentration to produce films, where the oil and plasticizer proportions will have to be adjusted in a case-by-case basis according to the use intended for the material. This work provides a useful guide to the formulation of chitosan-based film-forming solutions for food packaging applications. [ABSTRACT FROM AUTHOR]

Abstract: Hydrocolloids from seaweeds have interesting functional properties, such as antioxidant activity and gelling ability. A polysaccharide was isolated by aqueous extraction at 90°C from the red seaweed Gracilaria birdiae (Gb), with a yield of 27.2% of the seaweed dry weight. The sulfate content of the polysaccharide was 8.4% and the main sugars present were galactose (65.4mol%), 3,6-anhydrogalactose (25.1mol%) and 6-O-methylgalactose (9.2mol%). Gel permeation chromatography showed that Gb polysaccharide is a heterogeneous system, with molar mass at the main peak of 3.7×105 gmol−1 and a shoulder of 2.6×106 gmol−1. The sulfated polysaccharide of Gb characterized by FTIR exhibits the characteristic bands of agarocolloids (at 1375 and 770cm−1). The rheological behavior of Gb sulfated polysaccharide exhibits a gel-like behavior close to the one observed in commercial agar. The antioxidant properties of Gb sulfated polysaccharide were evaluated by measuring DPPH free-radical scavenging effect, showing that this polysaccharide has a moderate effect in inhibiting the formation of those radicals. [Copyright &y& Elsevier]

Abstract: The aim of this work was to evaluate the influence of glycerol and corn oil on physicochemical properties of polysaccharide-based films. The polysaccharides used were galactomannan from Gleditsia triacanthos and chitosan. Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis were performed, together with determinations of moisture content, solubility, water vapor permeability and mechanical properties. Structure–properties relationships were established, relating the two polysaccharides’ structures with the way they interact with water, other film’s constituents (glycerol and oil) and the resulting properties. The presence of glycerol and corn oil originated a more hydrophilic structure and a decreased affinity of the film matrix to water, respectively, in both polysaccharides. However, the two polysaccharides presented different behaviors in terms of glass transition temperature, water vapor permeability and elongation-at-break that have been related with the particularities of their structure: while for the galactomannan the specific sorption sites for water are the O–H groups, for chitosan those are O–H and/or NH2 groups. The present work provides insight regarding the physicochemical properties of polysaccharide-based films and established relationships with polymers’ structure, showing that the two polysaccharides studied here have adequate properties to be used as packaging materials for specific food applications. [Copyright &y& Elsevier]

Abstract: Galactomannans of Gleditsia triacanthos, Caesalpinia pulcherrima and Adenanthera pavonina were structurally and thermally characterized. Methylation analyses confirmed that these three galactomannans are composed by a 4-linked mannose polymer with galactose side chains attached at the C6 position. G. triacanthos galactomannan had an estimated average degree of polymerization of 224 mannose residues, with a degree of branching of 0.24, C. pulcherrima galactomannan had a degree of polymerization of 252 and a degree of branching of 0.30, and A. pavonina galactomannan had a degree of polymerization of 475 and a degree of branching of 0.60. Enzymatic hydrolysis with endo-β-mannanase and the subsequent analyses of the low molecular weight fraction by ESI-MS/MS indicated the presence of characteristic structural features of galactomannans. Furthermore, acetyl and pentosyl residues were detected in the galactomannan of G. triacanthos and analyses of higher molecular weight fractions from G. triacanthos were performed, confirming that presence. Differential scanning calorimetry (DSC) showed the presence of two peaks related with water loss, confirmed by thermogravimetric analysis (TGA). The different compositions of galactomannans with different mannose content and different molecular weights influence their thermal behaviour. A higher content of mannose lead to higher values of the enthalpy change (first thermal transition) and glass transition temperature (T g ), while the enthalpy change of the second thermal transition was influenced by the viscosity average molecular weight (Mv) of the samples. This work provides understanding of structural and thermal properties of three galactomannans from non-conventional sources, thus contributing to a better insight on their possible food, pharmaceutical or biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract: In this work, three different extraction procedures were performed in Gleditsia triacanthos seeds in order to obtain extracts that were characterized in terms of the yield of extraction, total phenolic content and antioxidant properties. The extracts have been shown to contain considerable amounts of phenolic compounds (between 4.93 and 12.34mggalicacid gextract − 1) and antioxidant activity between 18.77 and 71.59%. Different concentrations of one of the extracts (extract presenting simultaneously the best values of total phenolic content, radical scavenging activity and the concentration of the compounds that caused a 50% inhibition of the radical scavenging activity) were incorporated into G. triacanthos galactomannan solutions and films were cast from these. A 22 full factorial design was done to evaluate the effect of the galactomannan and extract concentrations in film properties. Galactomannan concentrations ranging from 0.5 to 1.5% and extract concentrations ranging from 0 to 1.0%, were used and the evaluated film properties as: water vapour permeability, colour, total phenolic compounds content and antioxidant activity. This work has shown that G. triacanthos can be used not only as a source of galactomannan films suitable to incorporate antioxidant compounds for further application in the food industry but also as a source of the active compounds to be incorporated. [ABSTRACT FROM AUTHOR]

Abstract: Polysaccharide multinanolayers are becoming a new and general means of modifying and functionalizing surfaces of several materials. This is achieved through changing the interfacial properties of those surfaces followed by sequential adsorption of e.g., polysaccharides. Knowledge of properties of polysaccharide solutions such as zeta potential (Zp) and mean hydrodynamic diameter (Z-average) is crucial to obtain stable, functional nanostructures. In this work sodium alginate, carragennan, chitosan, and two galactomannans were characterized in terms of Zp and Z-average, as a function of polysaccharides and NaCl concentrations and pH. The most relevant effects of these factors on Zp and on Z-average were analysed using a 23 full factorial design. With a few exceptions, the effect of independent variables on Zp and Z-average values is statistically significant. In general (except for k-carragennan solutions) higher polysaccharide concentrations lead to higher Z-average values; and higher pH values lead to higher Z-average values (except for solutions of chitosan and galactomannan of Gleditsia triacanthos). NaCl addition decreases Z-average. For the galactomannans solutions Zp values were found to be neutral (ranging from −13.7 to −2.1mV) independently of the combinations of variables used. This work establishes a relationship between important polysaccharides properties and the values of pH, polysaccharide and salt concentrations, thus providing insight on how to control the structure and texture of multinanolayered films in view of their potential application e.g., in the food, pharmaceutical, and cosmetic industries. [Copyright &y& Elsevier]

Abstract: The objective of this work was to produce new edible coatings, based on a mixture of galactomannans from novel sources (seeds of Adenanthera pavonina and Caesalpinia pulcherrima), collagen and glycerol, and to determine their influence in gas transfer rates when they are applied on mangoes and apples. The first part of the work consisted in obtaining coating solutions with the convenient values of wettability for each fruit; such coating solutions were then characterized in terms of their permeability (to CO2, O2 and water vapour), mechanical properties, colour and opacity. Gas transfer rates from mangoes coated with a solution of A. pavonina galactomannan (0.5%), collagen (1.5%) and glycerol (1.5%) were compared with those of mangoes without coating: 28% less O2 consumption and 11% less CO2 production were observed in coated mangoes. The same procedure was performed in apples (in this case using C. pulcherrima galactomannan (0.5%), collagen (1.5%) and no glycerol); the CO2 production and the O2 consumption was approximately 50% lower in apples with coating than in apples without coating. The results suggest that these coatings can reduce gas transfer rates in these fruits, and can be therefore important tools to extend their shelf life. [Copyright &y& Elsevier]

Abstract: The effect of the concentrations of the polysaccharide from Anacardium occidentale L. (Policaju) and a surfactant (Tween 80) on relevant properties of edible coatings/films, in view of their application on apples (cv. Golden) was evaluated. The influence of the interactions between those two constituents on apples’ surface properties and on the coating/film’s wettability, water vapor permeability, opacity and mechanical properties was evaluated. The effects of the studied variables (polysaccharide and surfactant concentrations) were analyzed according to a 22 factorial design. Pareto bar charts were used to understand the most significant factors on the studied properties. The addition of surfactant reduced the cohesion forces, therefore reducing the surface tension and increasing the wettability; this resulted in an improved compatibility between the solution and the fruit skin surface. The opacity was also reduced. The results of each of the analyzed properties were adjusted to a polynomial, multifactor model, which provided a good fitting accuracy. This model is important once it will reduce the characterization work needed in subsequent applications of these coatings/films on foods. [Copyright &y& Elsevier]

Abstract: This work presents a methodology for the extraction of galactomannans from seeds of four different species of Leguminosae (Adenanthera pavonina, Caesalpinia pulcherrima, Gleditsia triacanthos and Sophora japonica) to be used e.g. in the food and biomedical industries. The galactomannans were obtained by aqueous extraction followed by a precipitation with ethanol. This methodology is simpler and easier to perform than other existing extraction and purification methodologies, and because it avoids the use of organic solvents (other than ethanol), it is able to generate food grade substances and is environmentally friendlier. The yield of extraction in different stages of the process, monosaccharide composition, as well as physical and chemical parameters of the isolated galactomannans were determined and compared with previously published results. The mannose/galactose ratio of the extracted galactomannans ranged from 1.35 (A. pavonina) to 5.75 (S. japonica). The intrinsic viscosity ranged from 11.34dL/g (C. pulcherrima) to 8.74dL/g (S. japonica), while the viscosity average molecular mass ranged between 1.81×106 Da and 1.17×106 Da (A. pavonina > C. pulcherrima > G. triacanthos > S. japonica). The results confirm the suitability of the extraction and purification procedure to obtain galactomannans from non-traditional sources. [Copyright &y& Elsevier]

Protein–polysaccharide conjugates often display improved techno-functional properties when compared to their individual involved biomolecules. α-Lactalbumin:acacia gum (α-la:AG) conjugates were prepared via Maillard reaction by the dry-heating method. Conjugate formation was confirmed using results of absorbance, o -phthalaldehyde test, sodium dodecyl sulfate–polyacrilamide gel electrophoresis (SDS–PAGE) and size exclusion chromatography. Techno-functional properties (emulsifying characteristics, solubility, and thermal stability) were evaluated for α-la, α-la/AG mixtures and α-la:AG conjugates. Conjugate thermal stability was improved compared to pure α-la treated at the same conditions of conjugate formation. Response surface methodology was used to establish models to predict solubility and emulsifying activity as functions of the salt concentration, pH and reaction time. α-la:AG conjugate solubility is affected in a complex manner by the three factors analyzed. Emulsifying activity index (EAI) of α-la is significantly affected by pH, while the α-la:AG EAI is affected by the three analyzed factors. Both solubility and EAI are maximized with pH 8.0, NaCl concentration of 0.3 mol L −1 and two days of Maillard reaction. [ABSTRACT FROM AUTHOR]