Effect of Transglutaminase Cross-Linking in Protein Isolates from a Mixture of Two Quinoa Varieties with Chitosan on the Physicochemical Properties of Edible Films

Abstract

The growing demand for minimally processed foods with a long shelf life and environmentally friendly materials has forced industry to develop new technologies for food preservation and handling. The use of edible films has emerged as an alternative solution to this problem, and mixtures of carbohydrates and proteins, may be formulated to improve their properties. The objective of this work was to evaluate the effect of protein cross-linking with transglutaminase (TG) of two varieties of quinoa protein isolate (Chenopodium quinoa) [Willd (QW), and Pasankalla (QP)] on the physicochemical and barrier properties of edible films based on chitosan (CT)-quinoa protein. The evaluated properties were water vapor permeability (WVP), solubility, adsorption, roughness determined by atomic force microscopy, and the interactions among the main film components determined by Raman spectroscopy. The results indicated that TG interacted with lysine of QW and QP. CT:QW (1:5, w/w) showed the lowest solubility (14.02 ± 2.17% w/w). WVP varied with the composition of the mixture. The WVP of CT:quinoa protein ranged from 2.85 to 9.95 × 10−11 g cm Pa−1 cm−2 s−1 without TG, whereas adding TG reduced this range to 2.42–4.69 × 10−11 g cm Pa−1 cm−2 s−1. The addition of TG to CT:QP (1:10, w/w) reduced the film surface roughness from 8.0 ± 0.5 nm to 4.4 ± 0.3 nm. According to the sorption isotherm, the addition of TG to CT-QW films improved their stability [monolayer (Xm) = 0.13 ± 0.02 %]. Films with a higher amount of cross-linking showed the highest improvement in the evaluated physical properties, but interactions among proteins that were catalyzed by TG depended on the protein source and profile.

Protein-Based Films and Coatings for Food Industry Applications

“…Consequently, the enumerated physical properties showed a much higher improvement when the edible films had a higher quantity of cross-linking. The interactions between the proteins that were caused by the amount of transglutaminase depended on profile and the protein source [ 69 ].…”

Black Edible Films from Protein-Containing Defatted Cake of Nigella sativa Seeds

“…In fact, as far as both mechanical and barrier properties are concerned, sometimes increases and other times decreases in the values of the individual measured parameters (TS, EB, and YM) were reported. The same variability was observed when permeabilities to gases or water vapor were analyzed in films containing different proteins able to act as TGase substrates [11,26,27,30,[33][34][35][36][37][38].…”

Rheological and Antimicrobial Properties of Chitosan and Quinoa Protein Filmogenic Suspensions with Thyme and Rosemary Essential Oils

“…The protein isolates were ground for 2 min using the coffee grinder and passed through a No. 9 mesh (Tyler standard) of 200 µm pore opening [12].…”

“…The quinoa protein (QP) FS (2% w/v) was adjusted to pH 11, with constant stirring for 1 h. On the other hand, a 2% (w/v) chitosan solution was prepared in 0.5 M HCl, according to Escamilla [12]. The solutions were then mixed in 1:10 ratio (C:QP), sorbitol was added in a 1:1 weight ratio (C:sorbitol), and adjusted to pH 11.…”

“…FD is directly related to the extent of surface roughness (Rq) (Equation 4), which was obtained following the protocol of Escamilla-García [12]. Rq is the standard deviation of Zi values indicating roughness (nm); Zi is the difference in the height of i relative to the average height, and N is the number of points in the image.…”