Starch films loaded with tannin: the study of rheological and physical properties.

Recently, the research on innovative food packaging has been oriented toward biodegradable materials to lower the environmental impact generated by conventional plastics. The films often carry functional additives interacting with the matrix and modifying its physical properties. In this work tannin, a scarcely exploited active additive, was used to obtain potato starch-based films, and its content was optimized on the basis of mechanical and microscopic tests. Rheological measurements were adopted to evaluate the tannin-starch interaction and the microstructure of the film forming solutions (FFSs). Their thickness, color, thermal conductivity, elastic modulus (Eel), elongation at break (EAB), surface wettability and water solubility were evaluated. Furthermore, microstructure was investigated through Fourier-transform infrared spectroscopy (FTIR), polarized light (POM) and scanning electron microscopy (SEM). It was observed that all FFSs behave as weak gels and tannin addition weakens the gel structure and decreases the gelatinization temperature from about 60 °C to 57 °C. Plastic and deformable films (Eel = 1.96 MPa and EAB = 189 %) were obtained at low tannin fractions, whereas, at a higher concentration, stiffer films (Eel = 12 MPa and EAB = 10 %), with hydrophobic behavior were produced. Among the tested tannin fractions, an intermediate value of 1.7 % (w/w) was found to be promising for industrial purposes.

Interfacial behavior of vegetable protein isolates at sunflower oil/water interface.

Proteins are widely used in the formation and stabilization of multiphase systems, thanks to their ability to adsorb at the interface reducing the interfacial tension and promoting the formation of viscoelastic layers. Owing to the growing consumer demand, the food industry is moving toward the growing use of plant-based proteins, suitable for consumers who do not eat products of animal origin, for either ethical or health reasons. Nevertheless, the scientific literature lacks information on the surface activity and emulsifying ability of these proteins. In this work, the interfacial properties of soy, hemp and brown rice isolate proteins were investigated at the interface with commercial sunflower oil (O/W) to evaluate their characteristics in view of potential uses in food applications such as emulsions, sauces, dressing, topping and soft foods. Dilatational and shear kinematic, with pendant drop and magnetic rod techniques, respectively, were used. The dilatational analysis was performed in static and dynamic conditions, to obtain the equilibrium adsorption isotherms and the rheological parameters of the interfacial layers under both oscillation and stress relaxation. The interfaces were studied in shear conditions with small amplitude oscillations and creep tests. The obtained results evidenced that all tested proteins are able to build a strong viscoelastic layer with properties comparable to those of animal proteins. Brown rice protein seems particularly effective in reducing the interfacial tension even if shear tests evidence that the interface is weaker than that obtained using hemp or soy protein. Hemp protein seems very promising for potential practical uses yielding intermediate interfacial tensions and strong viscoelastic layers.

Emulgels Structured with Dietary Fiber for Food Uses: A Rheological Model.

Emulgels are biphasic emulsified systems in which the continuous phase is structured with a specific gelling agent. In this work, a rheological and microscopic investigation of O/W emulgels prepared by structuring the aqueous (continuous) phase with citrus fiber was carried out with the aim of designing their macroscopic properties for food uses and predicting their characteristics with a rheological model. According to previous investigations, fiber suspensions behave as "particle gels" and, consequently, the derived emulgels' properties are strongly dependent on the fiber concentration and on process conditions adopted to produce them. Therefore, a rotor-stator system was used to prepare emulgels with increasing fiber content and with different levels of energy and power used for mixing delivered to the materials. An investigation of particle gels was then carried out, fixing the operating process conditions according to emulgel results. Furthermore, the effect of the dispersed (oil) phase volume fraction was varied and a modified semi-empirical Palierne model was proposed with the aim of optimizing a correlation between rheological properties and formulation parameters, fixing the process conditions.

Cardiac and Metabolic Impact of Functional Foods with Antioxidant Properties Based on Whey Derived Proteins Enriched with Hemp Seed Oil.

The impaired ability to feed properly, evident in oncologic, elderly, and dysphagic patients, may result in malnutrition and sarcopenia. Increasing the consumption of dietary proteins by functional foods and enriching their composition by adding beneficial nutrients may represent an adjuvant therapy. We aimed to evaluate the safety and the positive effects of a standard diet (SD) supplemented with whey-derived protein puddings (WDPP), with appropriate rheological properties, and hemp seed oil (HSO), rich in polyphenols. Rats were assigned to SD, WDPP, WDPP plus hemp seed oil (HSOP), and HSO supplemented diets for eight weeks. "Anthropometric", metabolic, and biochemical variables, oxidative stress, tissue injury, liver histology, and cardiac susceptibility to ischemia/reperfusion were analyzed. All the supplementations did not induce significant changes in biochemical and metabolic variables, also in relation to glucose tolerance, and livers did not undergo morphological alteration and injury. An improvement of cardiac post-ischemic function in the Langendorff perfused heart model and a reduction of infarct size were observed in WDPP and HSOP groups, thanks to their antioxidant effects and the activation of Akt- and AMPK-dependent protective pathways. Data suggest that (i) functional foods enriched with WDPP and HSOP may be used to approach malnutrition and sarcopenia successfully under disabling conditions, also conferring cardioprotection, and that (ii) adequate rheological properties could positively impact dysphagia-related problems.