Determination of mechanical properties of whey protein films during accelerated aging: Application of FTIR profiles and chemometric tools

Abstract

Nowadays, the application of non‐destructive techniques in food engineering is arising. Fourier transform infrared spectroscopy (FTIR) combined with chemometric tools show potential in evaluation of food materials. The aim of this work was to determine the applicability of FTIR profiles and chemometric tools to predict the mechanical properties of whey protein‐based film (WPF). A WPF solution was prepared using whey protein concentrate/distilled‐water/glycerol in (10/85/5% wt/wt) respectively. Then, the films were aged at 30°C/5 days and 60% RH. Each day, 10 pieces were evaluated, obtaining their FTIR profiles (4000–650 cm−1), tensile strength (TS), elongation at break (EB), and elastic modulus (EM). Principal component analysis‐multilinear regression (PCA‐MLR) and partial least square regression (PLSR) were developed using the K‐fold cross‐validation technique. For EB and EM, the coefficient of correlation (R2) and root means squared error (RMSE) were above 0.8990 and under 0.5250 (Full PLSR) and 0.8730 and 0.1378 (Optimized PLSR), unlike to TS presented R2 and RMSE values lower than 0.2160 and 2.5247, similar to PCA‐MLR models with values lower than 0.2050 and 0.1889, respectively (for all variables). In this sense, the use of FTIR profiles coupled to chemometric tools could be adequate to predict some properties in WPFs during aging. Practical applications This research presents a practical way for mechanical properties evaluation in films by means of Fourier Transform Infrared Spectroscopy (FTIR) coupled to chemometric tools. This new method could be useful for rapid monitoring of textural properties and characterization of films for food packaging.

Whey Protein Concentrate/Isolate Biofunctional Films Modified with Melanin from Watermelon (Citrullus lanatus) Seeds

“…Absorbance spectra of WPC-based and WPI-based films are presented in Figure 3 . As can be seen the films have characteristic peaks at 3280 cm −1 attributed to C–H, N–H and/or O–H of WPC/WPI and melanin [ 10 , 27 ]. Characteristic CH 3 and CH 2 stretching peaks at approximately 2940 cm −1 and 2880 cm −1 were also observed.…”

“…The peak centered at 1630 cm −1 can be attributed to Amide-I associated with C=O stretch and C–N vibrations; however, in the case of melanin-modified films, it also corresponds to the vibration of aromatic C=C of melanin [ 10 ]. Peaks in the region 1400–1550 cm −1 and 1200–1350 cm −1 can be assigned to Amide-II (groups N-H) and to Amide III (with N–H bonds and C–N stretching), respectively [ 27 ]. The region from 750 to 1200 cm −1 was assigned to the absorption of glycerol (plasticizer), vibrations C–O and C–C bonds [ 27 ].…”

“…Peaks in the region 1400–1550 cm −1 and 1200–1350 cm −1 can be assigned to Amide-II (groups N-H) and to Amide III (with N–H bonds and C–N stretching), respectively [ 27 ]. The region from 750 to 1200 cm −1 was assigned to the absorption of glycerol (plasticizer), vibrations C–O and C–C bonds [ 27 ]. In the case of WPC and WPI films modified with melanin, slight variations in peak intensities and positions were observed, particularly at 3280 cm −1 , 2940 cm −1 , 2880 cm −1 and 1630 cm −1 .…”

“…be assigned to Amide-II (groups N-H) and to Amide III (with N-H bonds and C-N stretching), respectively [27]. The region from 750 to 1200 cm −1 was assigned to the absorption of glycerol (plasticizer), vibrations C-O and C-C bonds [27].…”

“…Heat-denatured whey proteins, with the addition of a plasticizer, yield transparent, bland, and flexible films with very good resistance to oxygen, aroma, and lipid transfer at low humidity [ 15 , 23 ]. However, the hydrophilic nature of the proteins enables interactions with water, which leads to a reduction in the moisture barrier properties [ 25 , 27 ]. In addition to applications in edible films, whey protein concentrates and isolates (WPC, WPI) also have the potential to be used in the biomedical field, for example forming hydrogels as bioactive carriers or by leveraging their antioxidative properties [ 28 , 29 , 30 , 31 ].…”