Natural Biomaterial-Based Edible and pH-Sensitive Films Combined with Electrochemical Writing for Intelligent Food Packaging

Abstract

An edible and pH-sensitive film combined with electrochemical writing was developed using gelatin, gellan gum and red radish anthocyanin extract for intelligent food packaging applications. The composite film displays orange red-to-yellow color change over the pH range 2-12. The tensile strength, ductility, and barrier response of the films to UV light and oxygen improved with the increase of red radish anthocyanin concentration. Multicolor patterns were successfully drawn on the film using an electrochemical writing method. The composite films acted as gas sensors which presented visible color changes in the presence of milk and fish spoilage, while the written patterns were well preserved. Accordingly, this composite film with written patterns could be an easy-to-use indicator with great potential for monitoring food spoilage as part of an intelligent packaging system.

Bio-Based Smart Materials for Food Packaging and Sensors – A Review

“…Many fruits, berries, vegetables and flowers with colors covering practically the entire visible spectrum are dyed by natural compounds such as anthocyanins and curcumin known as natural pH indicators (Yoshida et al, 2009;Silva-Pereira et al, 2015;Choi et al, 2017;Dudnyk et al, 2018;Majdinasab et al, 2018;Saliu and Pergola, 2018;Zhai et al, 2018;Kurek et al, 2019). Upon protonation/deprotonation of these molecules, their delocalized electronic structure rearranges and the change of the total number of resonant electrons as well as their confinement result in a change of their color (Figure 4).…”

“…For instance, Choi et al (2017) demonstrated a pH sensor made of agar and potato starch with anthocyanin extracts from purple sweet potato that showed color variations at pH 2.0-10.0. Zhai et al (2018) used a gelatin-gellan gum matrix with red radish anthocyanin having a slightly broader pH range from 2.0 to 12.0. In Table 4 more examples of biobased sensors developed for food quality monitoring in recent years are listed.…”

Vegetable Additives in Food Packaging Polymeric Materials

“…Food spoilage is associated with pH change, which enables the use of alternative, inexpensive, natural-based colorimetric pH indicators in the form of labels or tags. These pH-sensitive indicators could react with the non-neutral volatile gases that were generated from foods during spoilage and are composed of natural and safe pH sensing pigments, such as anthocyanins and curcumin and a dye carrier/(solid matrix) [208]. Both ingredients have to be non-toxic, meet the food safety requirements, and be stable at the applied pH [209].…”

“…Anthocyanins are natural-based, non-toxic, water soluble pigments, extracted from different plants that provide the purple, blue, and red color of many plants [208]. Anthocyanins possess excellent antioxidant potential [210][211][212], which can be released from packaging films [213] for extending shelf life of food, anti-inflammatory [214], and anticarcinogenic [215] activities.…”

Optimization of betacyanins from agricultural by‐products using pressurized hot water extraction for antioxidant and in vitro oleic acid‐induced steatohepatitis inhibitory activity

“…In recent years, there has been great need for developing new strategies in managing agricultural food processing wastes and residues since productions have increased with over billion tons of food by‐products generated per year. Since agricultural by‐products often contain bioactive compounds with high commercial interest (Huang et al, ; Li et al, ; Liu, Qiao, et al, ; Tahir et al, ; Zhang, Wang, et al, ; Zhao et al, ), the most profitable way could be the recovery of bioactive compounds to decrease the amount of wastes generated as well as to enhance the sustainability of processing units (Xu et al, ; Zhai et al, ).…”