Mechanical and barrier properties of maize starch-gelatin composite films: effects of amylose content.

BACKGROUND: In order to obtain new reinforcing bio-fillers to improve the physicochemical properties of gelatin-based films, three types of maize starch, waxy maize starch (Ap), normal starch (Ns) and high-amylose starch (Al), were incorporated into gelatin film and the resulting film properties were investigated, focusing on the impact of amylose content. RESULTS: The thickness, opacity and roughness of gelatin film increased depending on the amylose content along with the starch concentration. The effects of the three starches on the mechanical properties of gelatin film were governed by amylose content, starch concentration as well as environmental relative humidity (RH). At 75% RH, the presence of Al and Ns in the gelatin matrix increased the film strength but decreased its elongation, while Ap exhibited an inverse effect. Starch addition decreased the oxygen permeability of the film, with the lowest value at 20% Al and Ns. All starches, notably at 30% content, led to a decrease in the water vapor permeability of the film at 90% RH, especially Ns starch. Furthermore, the starches improved the thermal stability of the film to some extent. Fourier transform infrared spectra indicated that some weak intermolecular interactions such as hydrogen bonding occurred between gelatin and starch. Moreover, a high degree of B-type crystallinity of starch was characterized in Gel-Al film by X-ray diffraction. CONCLUSION: Tailoring the properties of gelatin film by the incorporation of different types of maize starch provides the potential to extend its applications in edible food packaging. © 2017 Society of Chemical Industry.

An Attempt of Using ß-Sitosterol-Corn Oil Oleogels to Improve Water Barrier Properties of Gelatin Film.

Oleogel with tailored viscoelasticity is a great interest for food structuring, while its potential benefits for edible film performance are not clear. In this study, ß-sitosterol (0, 5, 10, 15, and 20 wt%)-corn oil oleogel was developed and used in the formation of gelatin-based films. Importantly, adding oleogel significantly decreased water vapor permeability of the gelatin films, however, it had little negative influence on film strength. In addition, the results of this study demonstrated that increasing the sitosterol in oleogels led to an increasing number of ordered crystals formed in the oleogel, which contributed to compact and smooth surface of the film. Moreover, the incorporation of oleogel also caused some changes in molecule conformation and film barrier property. Therefore, the superior mechanical performance and moisture resistance properties of the film were obtained when 15% ß-sitosterol was used to prepare oleogel. PRACTICAL APPLICATION: Corn oil oleogels ß-sitosterol was incorporated with gelatin to prepare the gelatin film aiming to improve the water resistance of the films for its variety of practical production. The enhanced vapor permeability and accepted strength of the emulsion film indicated the potential application of it with a variety of edible packaging forms, such as films, pouch and sachet in medium and high humid condition.

Performance of high amylose starch-composited gelatin films influenced by gelatinization and concentration.

In order to study the impact of starch in film performance, high amylose corn starch was composited in gelatin films under different gelatinization conditions and, in high and low concentrations (10 and 50wt.%). It was found that hot water gelatinized starch (Gel-Shw) increased film mechanical strength and was dependent upon the starch concentration. The addition of an alkali component to the starch significantly enhanced the swelling of the starch granules and expedited the gelatinization process. Incorporation of starch, especially the alkalized starch (Sha), into the gelatin films decreased film solubility which improved its water resistance and water vapor permeability (WVP). Multiple techniques (DSC, TGA, FT-IR, and XRD) were used to characterize the process and results, including the crosslinking of the dissolved starch molecules and the particles formed from gelatinized starch during retrogradation process, which played an important role in improving the thermal stability of the composited gelatin films. Overall, the starch-gelatin composition provides a potential approach to improve gelatin film performance and benefit its applications in the food industry.

Mechanical properties and solubility in water of corn starch-collagen composite films: Effect of starch type and concentrations.

This study investigated the possibility of enhancing the properties of collagen with three different maize starches: waxy maize starch, normal starch, and high amylose starch. Scanning electron microscopy images revealed that starch-collagen films had a rougher surface compared to pure collagen films which became smoother upon heating. Amylose starch and normal starch increased the tensile strength of unheated collagen films in both dry and wet states, while all starches increased tensile strength of collagen film by heating. Depending upon the amylose content and starch concentrations, film solubility in water decreased with the addition of starch. DSC thermograms demonstrated that addition of all starches improved the thermal stability of the collagen film. Moreover, X-ray diffraction results indicated that except for high amylose starch, the crystallinity of both starch and collagen was significantly decreased when subject to heating. FTIR spectra indicated that intermolecular interactions between starch and collagen were enhanced upon heating.

Up-regulated biglycan expression correlates with the malignancy in human colorectal cancers.

Biglycan, an extracellular matrix protein, has been implicated in the oncogenesis and cancer development in various types of human cancer. The clinical significance of biglycan in colorectal cancer, however, remains unclear. In the present study, biglycan mRNA expression was analyzed in 110 samples (primary colorectal tumor and matched adjacent normal tissue) derived from 55 patients with colorectal cancer using quantitative real-time RT-PCR. The correlations between biglycan up-regulation and the clinicopathological data were also evaluated. We found that the up-regulation of biglycan occurred in 61.8% (34/55) of colorectal cancer tissues, and biglycan expression in colorectal cancer tissues was markedly higher than that in corresponding normal tissues (P = 0.0264). Moreover, statistical analysis displayed a significant correlation in biglycan up-regulation with poor tumor differentiation (P = 0.009), lymph node metastasis (P = 0.041), and distant metastasis (P = 0.036). However, there was no significant correlation between biglycan up-regulation and other clinicopathological factors (all P > 0.05). In conclusion, biglycan may be a potential marker for the malignancy of colorectal cancer.