Development and characterization of a gelatin‐based coating with unique sealing properties

Abstract

ABSTRACT:The experimental results on the development of thin ($ 1.5 lm) gelatin-based coatings and the investigation on their sealing attribute when applied onto oriented polypropylene (OPP) are reported. The sealing performance, expressed as the strain energy required to separate the sealed joints, was studied as a function of three different influencing factors. pH of the hydrogel solution was varied between 5 and 11. The highest seal strength values were obtained for pH values beyond the isoelectric point (IEP) of the gelatin molecule. The effect of the plasticizer (glycerol) was studied by changing its concentration from 2.5 wt % to 7.5 wt % to the total weight of the hydrogel solution. Glycerol concentration ¼ 7.5 wt % was found to be the best for achieving adequate strain energy values. The influence of a hydrophobic component on the capability of the coating to act as a sealant has also been assessed. The hydrophobic component had a positive effect only up to a certain level (1 wt %, weight percent), whereas beyond this value, it affected the seal strength attribute. According to the best setting conditions, seal strength values for the OPP biocoated films of $ 61 N Â mm were attained, with a corresponding maximum force required to break the joints of 2.4 N. These results are discussed by taking into consideration the modality of seals opening. Interestingly, the heat-seal (temperature: 90 C; dwell time: 1 s; pressure: 4 bar) failed in both peeling and tearing mode failure, as confirmed by microscopy, spectrophotometric, and particle size analyzes.

State of the Art in the Development and Properties of Protein-Based Films and Coatings and Their Applicability to Cellulose Based Products: An Extensive Review

“…As an example in the field of packaging some authors [31] evaluated sealing properties of gelatin based coatings on oriented polypropylene (OPP) surfaces. Up to 1 wt % of a hydrophobic component improved sealing properties.…”

“…In addition, some high molecular weight proteins are insoluble or only weakly soluble in water and may be used to obtain water resistant films [28,29]. Applied as coatings on substrates used in the packaging sector, proteins are aimed to improve a wide range of properties such as gas and water vapor barrier [30] and sealability [31]. Whey protein coatings have been shown as good barriers when applied on paper [32] by increasing oil resistance and reducing water vapor permeability [8,33], on LDPE [34] and on PP [35].…”

Effect of BOPET film surface treatments on adhesion performance of biodegradable coatings for packaging applications

“…Several innovative coatings are proposed in the literature in order to functionalize polymeric substrates and to promote natural and eco-compatible solutions [9][10][11][12]. The adhesive properties of amorphous polymers could be an interesting choice for replacing typically used polyolefins as sealant layers [13]. Furthermore benefits ensuing from the use of a biopolymer as coating layer, concern with both ecological and economic issues: in fact the use of an eco-compatible polymer is nowadays attractive for the industry that pay particular attention to environmental aspect since consumer awareness in ecological issues is now one of the most important factors dictating companies market strategies [2].…”

Emerging coating technologies for food and beverage packaging materials

“…Recently (Farris et al, 2008;Farris et al, 2009c;Farris et al, 2010), a sealing coating (~1.5 µm thick) has been proposed that can be obtained entirely from bio-macromolecules, namely gelatin, acetic acid esters produced from monoglycerides, and glycerol. The special features of this new coating rely on the adhesive properties of gelatin, which allow sealing temperatures ranging from 50°C to 90°C to be achieved, depending on the specifi c formulations.…”

“…14.10 SEM images of the heat-sealed interface of OPP-coated strips after rupture: (1) the substrate (OPP); (2) the coating initially lay on the upper OPP strip, de-bound from the substrate after rupture; (3) the coating initially lay on the lower OPP strip, still bound to the substrate (adapted fromFarris et al, 2010).…”