Polymers are extensively used in food and beverage packaging to shield against contaminants and external damage due to their barrier properties, protecting the goods inside and reducing waste. However, current trends in polymers for food, water, and beverage applications are moving forward into the design and preparation of advanced polymers, which can act as active packaging, bearing active ingredients in their formulation, or controlling the head-space composition to extend the shelf-life of the goods inside. In addition, polymers can serve as sensory polymers to detect and indicate the presence of target species, including contaminants of food quality indicators, or even to remove or separate target species for later quantification. Polymers are nowadays essential materials for both food safety and the extension of food shelf-life, which are key goals of the food industry, and the irruption of smart materials is opening new opportunities for going even further in these goals. This review describes the state of the art following the last 10 years of research within the field of food and beverage polymer’s applications, covering present applications, perspectives, and concerns related to waste generation and the circular economy.

Colorimetric cation responsive water soluble polymers and manageable films or membranes have beendesigned. The sensory materials respond with a colour change to the presence in water of Fe(III), Co(II),Cu(II), and Sn(II). The colour change is specific of each metal cation, and enables its identification (purplefor iron, orange for cobalt, green for copper, and yellow for tin). The design of the materials relies onan addition monomer having a terpyridine moiety, which behaves as a dye in presence of transitionmetal cations due to its proven chelating capability towards these species and the colour developmentthat always accompany the metallic complex formation. Water solutions of the sensory linear polymersallow for the UV/vis titration of Fe(III), Co(II), Cu(II), and Sn(II) with a limit of detection of 1.3 × 10−7,6.4 × 10−8, 1.3 × 10−5and 1.4 × 10−5M, respectively. On the other hand, sensory kits, cut from sensorymembranes, permitted the visual quantification of the cations in a dynamic range of five decades (1 × 10−7to 5 × 10−3M) for Fe(III) and Co(II) and of two decades (9 × 10−5to 9 × 10−3M) for Cu(II) and Sn(II).Titration curves can also be drawn from a picture taken to the sensory kits with a smartphone, by usingthe digital colour definition of the materials as analytical signal. Also, after entering into contact withhands, shapes of metallic objects (iron and cobalt containing tools) can be colour revealed by pressingthe hands on paper or cotton fabrics wetted with water solutions of the linear sensory polymer.Spanish Ministerio deEconomía y Competitividad-Feder (MAT2014-54137-R

Iron in blood serum, wine and water has been visually detected and quantified quickly by processing photographs of an iron colorimetric sensory polymer substrate. The photographs may be taken with a conventional digital camera or Smartphone. The sensory materials were designed following a straightforward strategy. A proven iron organic chelator was easily transformed into an acrylic monomer and further copolymerized with hydrophilic co-monomers to render a membrane comprised of a hydrophilic, gel-like, polymer network. The film-like membrane generated was cut into small-diameter sensory discs. Thus, upon immersion of the sensory disks in blood serum, wine, and water, a colour development was rapidly observed which could be easily correlated with the iron concentration of the samples. RGB digital parameters obtained from photographs of the sensors were processed statistically using principal component analysis (PCA) and used to elaborate titration curves and quantify iron concentrations. The response time of the sensory films was short, 15 min, and the concentrations measured in water ranged from 56 ppb to 56 ppm. This broad range covers the U.S. Environmental Protection Agency (EPA) and European Union (EU) drinking water standards for iron in drinking water (<300 and 200 ppm, respectively), the typical iron content in wines (1 to 10 ppm) and the normal range of iron in the blood serum in men (0.8–1.8 ppm). This methodology for detecting and quantifying chemical species avoids the time-consuming sample preparation, expensive laboratory techniques, and specialized personnel needed to carry out conventional analytical methods.