Responsive Bio‐Composites from Magnesium Carbonate Filled Polycaprolactone and Curcumin‐Functionalized Cellulose Fibers

Abstract

non-toxicity, low-density, biocompatibility properties, and low cost. [1][2][3][4][5] The main drawback associated with the use of cellulose in specific composites-related applications is its water sensitivity and ability to uptake significant amounts of moisture. [6][7][8] On the other hand, cellulose fibers have very good mechanical properties, and because of this, they have been employed to reinforce many petroleum polyolefins or bio-based resins. [9][10][11] Advances in the development of cellulose nanofibers and bacterial cellulose have led to many new generation cellulose composites with superior mechanical properties and functionality. [12][13][14][15][16] In addition, many different physicochemical methods have also been developed to extract cellulose from agricultural and food wastes including biomass that can potentially reduce deforestation related to cellulose production feedstock. [17][18][19][20] Many sustainable packaging solutions and technologies must guarantee product safety and increase shelf life while decreasing pollution related to nondegrading plastics. It is believed that biobased responsive polymers and composites can address this necessity if accompanying economic and environmental benefits are also demonstrated. This study is motivated by these recent advances. At the same time, recent awareness in reducing environmental plastic pollution has fueled a significant momentum towards using natural polymers Development of responsive bio-based and biodegradable materials is particularly important in food preservation and monitoring technologies. Although replacing conventional plastic products with sustainable alternatives is still a challenge, promising advances have been reported. In this work, the fabrication of responsive bio-composite films from polycaprolactone (PCL) and magnesium carbonate (MgCO 3 ), known as food additive E504 with melt impregnation into cellulose, is reported. Cellulose fibers are stained/coated with ethanoic curcumin solutions, primarily to protect them against oxidative degradation. The films demonstrate a strong antioxidant effect against fatty and aqueous food simulants with improved oxygen gas barrier properties. Interestingly, the natural chelation of curcumin with magnesium within the composites improves the bioavailability and antioxidant potency of curcumin. Moreover, the composites show reversible color change response detectable by the naked eye in basic solutions or vapors. This response is tested by placing the composite film inside a sealed plastic container containing shrimp at room temperature, but not in direct contact. Due to spoilage, a noticeable color change in the bio-composites is recorded. These simple, cost-effective, non-toxic, and paper-like flexible bio-composites can be fabricated on large scale and be used in diverse applications ranging from sustainable packaging to medical applications and freshness indicators.

Natural Fiber-Reinforced Polycaprolactone Green and Hybrid Biocomposites for Various Advanced Applications

“…Recently, Quilez-Molina et al (2021) [ 153 ] developed curcumin-functionalized cellulose–magnesium and carbonate–PCL hybrid biocomposites. Magnesium carbonate (MgCO 3 ) was used as a food additive.…”

Highly Porous Curcumin-Loaded Polymer Mats for Rapid Detection of Volatile Amines

“…The color changes of the porous material can be visually perceived even by inexperienced users, as demonstrated by CIELAB color space analysis. Above all, results showed that the porous fiber mats present an increased sensitivity compared to their non-porous equivalents and, consequently, to the vast majority of the up to date colorimetric indicators, which have mostly the form of films ,− or pore-less fibers. ,, The presented study highlights the importance of the high porosity for an efficient and rapid visual inspection of the alkaline environment, necessary for various applications, such as intelligent food packaging, environmental protection, and biomedicine.…”

“…The presented study reveals the importance of the highly porous structure for an effective and real-time colorimetric indication of alkaline vapors. Compared to the majority of the studies presented so far on colorimetric indicators containing natural molecules ,, such as curcumin, ,,− ,,,− which test the efficiency of the material to change color in the presence of buffer solutions, ,, acidic or alkaline vapors, ,,,, and/or acidic or alkaline semisolid media without proper investigation of different concentrations, or with no precise evaluation of the kinetics of the color change and reusability, , this work offers a comprehensive view of the overall performance of the system in terms of responsivity, sensitivity, and reusability. Compared to the already explored curcumin-based films ,− , and fibrous mats, ,, but also compared to other types of colorimetric indicators, , PCLCU1 mats present faster color change response and higher sensitivity.…”

“…Thanks to this behavior, curcumin has been used to fabricate colorimetric pH indicators for food packaging applications, alone or combined with other pH-sensitive dyes, in order to indicate the presence of amines and therefore the food condition. To do so, polymer-based solid-composite structures in the form of films, ,− hydrogels, fibers, ,,− and other structures that can be applied in the headspace of the package have been developed. However, as in the case of other types of colorimetric indicators developed for food packaging, there are several challenges that still need to be tackled to reach a feasible, well-performing system .…”

“…Moreover, the evaluation of pH-induced color changes of the indicators upon their immersion into buffer solutions, ,, the generic tests with vapors of fixed concentrations without further investigation (i.e., limit of detection, realistic spoilage vapor concentrations, time of response, etc. ), ,,,, the lack of testing with specific off-flavor compounds responsible for microbial food spoilage, the demo tests with food without verification of its spoilage, and the missing color reversibility studies ,, are some of the limitations of the previous studies. These inadequacies may guide to misleading information, as the food may be spoiled way before the color change of the indicator, either because this occurs at amine concentrations higher than the ones of the spoilage limit or due to the indicator’s mismatching response time.…”