Effect of trehalose on physical and structural properties of whey protein concentrate glycerol-based edible films

PICCIRILLI, G. N.; DELORENZI, N.; VERDINI, R. A.; PÉREZ, L. M.

Concordia (Entre Ríos)

Congreso; International Conference on Food Innovation (FoodInnova 2014); 2014

Universidad Nacional de Entre Ríos y Universitat Politecnica de Valencia

Trehalose (Tre) is a naturally-occurring non-reducing disaccharide with similar functionality to sucrose. The use of Tre as a functional food ingredient has been approved as a GRAS additive in many countries. It can be used to improve existing products or to create innovative new ones. Its mild sweetness (45% sucrose), moderate glycaemic index with low insulinemic response, low cariogenicity, low hygroscopicity, and protein protection properties are all of immense benefit to food technologists. Considering that whey protein films plasticized with sucrose have beneficial properties, the aim of the present study was to develop and characterize whey protein concentrate (WPC)/glycerol (Gly)-based edible films incorporating Tre at different concentrations (0, 4, 6, or 8 % w/w). Solubility in water (% soluble solids), mechanical properties, changes in colour parameters (L, a* and b*) caused by Maillard reaction, transparency (%T600nm), and scanning electron microscopy (SEM) morphology analysis of films were evaluated. Films obtained were rather flexible and manageable. Control films without Tre were moderately transparent (%T600nm ~57%), but when Tre was included into WPC/Gly formulation films opacity increased. We hypothesized that this phenomenon relies on the crystallization of the sugar at the WPC/Gly film matrix and could be explained by the growth of Tre crystals after conditioning. Accordingly, SEM images confirm that Tre incorporated into WPC/Gly matrix produced films with more heterogeneous surfaces while control films (0% Tre) were more compact and homogeneous. As expected, increasing the proportion of the soluble sugar into film formulations caused solubility in water increased. Tre incorporated into WPC/Gly films decreased elongation at break and increased Young´s modulus as an indicative of an enhanced mechanical resistance of the films, but was not effective to improve tensile strength. Interestingly, Tre proved to be effective in preventing the non-enzymatic Maillard reaction that occurs upon heating and produces browning of WPC-based films. This result is promising since Maillard reaction results in both the production of potentially toxic by-products, as well as in the loss of reacting proteins and sugars with the concomitant loss of the nutritional content of the films. Additionally, adding Tre into WPC/Gly edible film formulations reduced the distinctive odor of WPC which could be related with a major retention of volatile flavor compounds. These results may be used to design new applications of edible films containing Tre in a rational manner toward their eventual application as food packaging.