Wettability of gelatin coating formulations containing cellulose nanofibers on banana and eggplant epicarps

Physical Properties of Cellulose Derivative-Based Edible Films Elaborated with Liposomes Encapsulating Grape Seed Tannins

Combined use of edible films (EF) with nanoencapsulation systems could be an effective alternative for improving the films' physical properties and maintaining bioactive compounds' stability. This research work focuses on the combined use of EF of cellulose-derived biopolymers enriched with liposomes that encapsulate grape seed tannins and on the subsequent evaluation of the physical properties and wettability. Tannin-containing liposomal suspensions (TLS) showed 570.8 ± 6.0 nm particle size and 99% encapsulation efficiency. In vitro studies showed that the release of tannins from liposomes was slower than that of free tannins, reaching a maximum release of catechin of 0.13 ± 0.01%, epicatechin of 0.57 ± 0.01%, and gallic acid of 3.90 ± 0.001% over a 144 h period. Adding liposomes to biopolymer matrices resulted in significant decrease (p < 0.05) of density, surface tension, tensile strength, elongation percentage, and elastic modulus in comparison to the control, obtaining films with greater flexibility and lower breaking strength. Incorporating TLS into EF formulations resulted in partially wetting the hydrophobic surface, reducing adhesion and cohesion compared to EF without liposomes. Results indicate that the presence of liposomes improves films' physical and wettability properties, causing them to extend and not contract when applied to hydrophobic food surfaces.

Optimization of the Formulation of Sago Starch Edible Coatings Incorporated with Nano Cellulose Fiber (CNF)

This study aimed to produce new edible coatings based on the mixture of sago starch, cellulose nanofiber (CNF), glycerol, and tween-80.The effect of sago starch (5–10 g of starch/100 ml of distilled water), CNF (0.5–20% w/w), glycerol (10–30% w/w), and tween-80 (0.5–10% w/w) based on sago starch concentration on contact angle (CA), water vapor permeability (WVP), oxygen permeability (PO2) and tensile strength (TS) properties of the edible coatings were optimized using factorial experimental design (2k).The result showed that the linear model for all independent variables was significant (<i>P</i><0.05) on all responses (dependent variable).The sago starch concentration depicted a significant (p < 0.001) positive effect on contact angle; CNF showed a statistically significant effect on WVP, PO2, and TS; tween-80 showed a significant effect on all dependent variables, whereas glycerol only affected WVP. The optimum concentrations of sago starch, CNF, glycerol, and tween-80 were predicted to be 5 g/100 ml distilled water, 20% w/w, 10% w/w, and 0.5% w/w based on sago starch, respectively to obtain the minimum contact angle, WVP, PO2, and the maximum TS. The predicted data for the optimized coating formulation were in good agreement with the experimental value. This work revealed that the potential of sago starch/CNF based coating formulation could be effectively produced and successfully applied for coating of food.

Cellulose and cellulose derivatives: Different colloidal states and food-related applications

Development of new sources and isolation processes has recently enhanced the production of cellulose in many different colloidal states. Even though cellulose is widely used as a functional ingredient in the food industry, the relationship between the colloidal states of cellulose and its applications is mostly unknown. This review covers the recent progress on illustrating various colloidal states of cellulose and the influencing factors with special emphasis on the correlation between the colloidal states of cellulose and its applications in food industry. The associated unique colloidal states of cellulose like high aspect ratio, crystalline structure, surface charge, and wettability not only promote the stability of colloidal systems, but also help improve the nutritional aspects of cellulose by facilitating its interactions with digestive system. Further studies are required for the rational control and improvement of the colloidal states of cellulose and producing food systems with enhanced functional and nutritional properties.

Prospects and application of nanobiotechnology in food preservation: molecular perspectives

Applications of biotechnological tools in food preservation have shown promising results in minimizing food spoilage. Design and development of highly efficient food preservatives are one of the key success factors in this application field. However, due to the inherent shortcomings of the bulk forms of such preservatives, research was in progress to find suitable alternatives to replace conventional modalities. The intervention of nanotechnology has made this approach feasible in almost every aspect of food preservation. This interface domain of nanobiotechnology has been very well explored in the last few decades and vast literature has been reported. Researchers have developed efficient nanopreservatives (NPRs) for diverse applications. However, the literature available on nano-based food preservation is not inclusive of molecular perspectives involved in food preservation. There is a large knowledge gap in the interface domain concerning the physics of intermolecular and interfacial forces and nanotechnology which play decisive roles in designing edible coatings (ECs). There is an urgent need for identifying the nano and molecular level contributing factors for developing efficient NPRs. Moreover, it is imperative to understand the possible health impact of NPRs in public interest and concern. This review revisits the fundamental aspects of food preservation and navigates through the applicability, safety, molecular aspects and future direction of NPRs.

The Effect of an Edible Coating with Tomato Oily Extract on the Physicochemical and Antioxidant Properties of Garambullo (Myrtillocactus geometrizans) Fruits

The Myrtillocactus geometrizans (Mart. ex. Pfeiff.) fruit, locally called garambullo, is an important source of bioactive compounds, mainly betalains, polyphenols, and ascorbic acid. However, information on the application of post-harvest technologies that prolong the shelf life of the fruits is still insufficient. The objective of the present research was to evaluate the effect of a gelatin coating incorporating 0%, 1%, or 3% tomato oily extract (TOE), compared to a control (without coating), on the physicochemical and antioxidant properties of garambullo fruits stored for 15 days at 5 °C. The gelatin coatings with TOE significantly (p ≤ 0.05) delayed changes in weight loss, brix degrees, titratable acidity and pH, compared to the control during storage. Fruits coated with TOE-gelatin had a higher content of betalains, ascorbic acid, total phenols, and flavonoids. The results showed that a higher concentration of phytochemicals increased antioxidant activity in vitro; the maximum values found for Trolox equivalents per kg of fresh weight were 10.46 and 17.65 mM for the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and Trolox Equivalent Antioxidant Capacity Method (TEAC) tests, respectively. The gelatin coating with TOE-3% (COTE-3%) reduced water loss by 1.66 times, compared to the control. In addition, the fruits covered with COTE-3% showed the highest concentration of bioactive compounds during storage.

Surface Free Energy Utilization to Evaluate Wettability of Hydrocolloid Suspension on Different Vegetable Epicarps

Surface free energy is an essential physicochemical property of a solid and it greatly influences the interactions between vegetable epicarps and coating suspensions. Wettability is the property of a solid surface to reduce the surface tension of a liquid in contact with it such that it spreads over the surface and wets it, resulting from intermolecular interactions when the two are brought together. The degree of wetting (wettability) is determined by an energy balance between adhesive and cohesive work. The spreading coefficient (Scf/food) is the difference between the work of adhesion and the work of cohesion. Surface wettability is measured by the contact angle, which is formed when a droplet of a liquid is placed on a surface. The objective of this work was to determine the effect of hydroxypropyl methylcellulose (HPMC), κ-carrageenan, glycerol, and cellulose nanofiber (CNF) concentrations on the wettability of edible coatings on banana and eggplant epicarps. Coating suspension wettability on both epicarps were evaluated by contact angle measurements. For the (Scf/food) values obtained, it can be concluded that the surfaces were partially wet by the suspensions. Scf/food on banana surface was influenced mainly by κ-carrageenan concentration, HPMC-glycerol, κ-carrageenan-CNF, and glycerol-CNF interactions. Thus, increasing κ-carrageenan concentrations within the working range led to a 17.7% decrease in Scf/banana values. Furthermore, a HPMC concentration of 3 g/100 g produced a 10.4% increase of the Scf/banana values. Finally, Scf/fruit values for banana epicarps were higher (~10%) than those obtained for eggplant epicarp, indicating that suspensions wetted more the banana than the eggplant surface.

Eco-friendly biorefractory films of gelatin and TEMPO-oxidized cellulose ester for food packaging application

BACKGROUND

In recent years, many types of food-packaging films and composites have been prepared using gelatin because of its good film-forming ability, non-toxic nature and cost-effectiveness. However, the relatively weak thermal stability, poor mechanical properties and easily-degradable quality limit the potential application of gelatin as a practical material. Microcrystalline cellulose (MCC), which comprises one of the most abundant biomass resources, has been regarded as a safe and reliable food additive because it has the same ingredients as the cellulose in people's daily intake. Food-packaging films with the excellent properties provided by gelatin and oxidized-cellulose represent a topic of great interest.

RESULTS

MCC was modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and chosen as the base of the macromolecule cross-linker (TMN). After modification of gelatin film by TMN, the minimum amount of free -NH₂ in solution was 4.8 × 10^-4  mol g^-1 ). The thermal property obviously increased (from 322.31 ^o C to 352.63 ^o C) and was crucial for usage in the food industry. The highest water contact value 123.09° (η = 25%) indicated a better surface hydrophobicity. The higher E_ab (58.88%) and lower E_m (77.16%) demonstrated that a more flexible and shatter-proof material was obtained. Water vapor uptake studies suggested increased moisture absorption and greater swelling ability.

CONCLUSION

The film material obtained in the present study was safe, stable, eco-friendly and biorefractory and could also be decomposed completely by the environment after disposal as a result of the properties of the ingredients gelatin and cellulose. The incorporation of a cellulosic cross-linker to gelatin-based films was an ideal choice with respect to developing a packaging for the food industry. © 2016 Society of Chemical Industry.

Effect of Gelatin-Based Edible Coatings Incorporated with Aloe vera and Black and Green Tea Extracts on the Shelf Life of Fresh-Cut Oranges

The aim of this study was to evaluate the effect of gelatin coating incorporated with Aloe vera gel (50,100%) and green and black tea extracts (5,10%) on physicochemical, microbial, and sensorial properties of fresh-cut oranges at 4°C for 17 days. Significant differences in terms of quality parameters were observed between the control and coated fresh-cut oranges. The highest variation of quality parameters was observed in control, while the least variations were observed in coated slices with 100% Aloe vera and 10% green tea extract. The weight loss was increased with time, but the coating treatment especially with 100% Aloe vera had significant effect on the prevention of weight loss. Also, Aloe vera coated samples obtained the highest score in sensory evaluation. Coating with gelatin incorporated with Aloe vera and green tea extracts successfully retarded the microbial growth and therefore extended the shelf life of fresh-cut oranges during cold storage.

Obtainment and partial characterization of biodegradable gelatin films with tannic acid, bentonite and glycerol

BACKGROUND

Research studies concerning the overall effect of the addition of plasticizers, cross-linking and strengthening agents in gelatin film-forming mixtures are very scarce. Also, there are no studies focused on the interactions among their individual components, or showing what sort of effects they might cause all together. A gelatin film obtained from a composite consisting of tannic acid, bentonite and glycerol was evaluated. Nine gelatin films were manufactured by the casting method, using these materials, following a 2(3) factorial design with five replicates on the central point.

RESULTS

The interactions among gelatin, tannic acid and bentonite caused a decrease in hydrogen bonds, while the polar groups of the gelatin chains were less exposed to interactions with water molecules. There was an increase in temperature and enthalpy of gelatin denaturation, due to increasing tannic acid and bentonite concentration. Tactoids were found in the gelatin films, caused mainly by bentonite polydispersion.

CONCLUSIONS

A synergistic effect among tannic acid, bentonite and glycerol, which overall improved the measured gelatin film properties, was found. The best film formulation was that with 40, 150 and 250 g kg(-1) gelatin of tannic acid, bentonite and glycerol respectively, displaying a tensile strength of 38 MPa, an elongation at break of 136%, water vapor permeability of 1.28 × 10(-12) g (Pa s m)(-1) and solubility of 23.4%. © 2015 Society of Chemical Industry.

Anti-degradation gelatin films crosslinked by active ester based on cellulose

An anti-degradation gelatin film crosslinked by an active ester based on MCC was prepared for applications in the food industry, medical engineering, agriculture, etc.