Effect of storage temperature and time on stability of poly(lactide)–whey protein isolate laminated films

Abstract

The stability of biopolymeric multilayer film fabricated from poly(lactide) (PLA) and glycerol‐plasticized whey protein isolate (WPI), PLA/WPI/PLA, at 4 °C, 25 °C, and 35 °C were examined. The PLA/WPI/PLA film showed small rates of decreasing in transparency and increasing total color difference. Storage at 35 °C caused the film to become stronger and less extendible. The multilayer structures showed lower tensile strength and higher elongation over storage at 4 °C and 25 °C. Oxygen and water vapor barrier abilities of PLA/WPI/PLA gradually improved over time, especially at 35 °C. The changes in properties of laminate structure can be empirically fitted with either zero‐ or first‐order reaction kinetics, with overall R2 ≥ 0.90. The results suggested that PLA/WPI/PLA film could be stored at 4–35 °C, 50–59% RH, for extended period of inventory time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43547.

Storage stability of packaged baby formula in poly(lactide)‐whey protein isolate laminated pouch

“…The color change of PLA/WPI/PLA film was hypothesized to be mainly caused by non‐enzymatic Maillard browning of whey proteins and trace reducing sugars that could slowly change color of the film during storage . By comparing the rates of corresponding ΔE change of the blank films, as well as those of the film from baby formula sachets, packaging with baby formula did not promote the rates of color change of PLA and PLA/WPI/PLA sachets.…”

“…). The slope of decreasing transparency of the baby formula PLA/WPI/PLA sachet was in accordance with the result from a previous film storage experiment by Phupoksakul et al . Packing the baby formula in the sachet did not accelerate the change in film transparency.…”

“…The smaller slopes of the Δ E change of the PLA samples than those of the PLA/WPI/PLA samples indicated that PLA samples had a higher color stability than PLA/WPI/PLA under all storage conditions. The trend of color changes were in accordance with the results from previous film storage tests . The color change of PLA/WPI/PLA film was hypothesized to be mainly caused by non‐enzymatic Maillard browning of whey proteins and trace reducing sugars that could slowly change color of the film during storage .…”

“…The PLA/WPI/PLA film is optically transparent, colorless and glossy. The demonstrated stability of the laminated structure at common commercial storage conditions [4–35 o C, 50–59% relative humidity (RH)] indicated its feasibility as a renewable alternative to existing synthetic oxygen‐barrier polymers for oxygen‐sensitive dry food products . Such film can potentially be fabricated in novel applications for active sachets and pads with specific properties …”

Development of whey protein isolate/polyaniline smart packaging: Morphological, structural, thermal, and electrical properties

“…In this context, WPI-based films have barriers properties effective, but have low mechanical properties, thus requiring the use of plasticizers, such as glycerol, which increase the film extensibility, reducing its fragility. [3][4][5][6][7] PANI is a conducting polymer that exhibits conductive form when protonated. 8,9 PANI is more widely used when compared to other conducting polymers, due to its high environmental stability, low cost of aniline (its monomer), 10 high reactivity, easy synthesis, 8 changes in mechanical and electromagnetic properties, and solubility as a function of the dopant acid, besides the adsorbent properties.…”