The Aquaphotomics approach as a tool in studying food coating materials

Food packaging and coatings carry out the well-known and established functions of containment, protection and handling facilitation of the food packaged inside. With the passing of time, new functions have arisen, mostly derived from the needs of the always changing society. Therefore, the packaging has currently an important hedonistic function, basically related on the driving force of marketing. Further, has to be mentioned the communicative function of packaging, often times defined as the ‘silent seller’. New solutions take into account in particular the new concept of eco-friendly food packaging and coating materials. Fast methods able for classifying, sorting, and identifying the quality and the stability characteristics associated to the different materials are requested along the food chain in order to validated their properties. This paper reports latest developing opportunities potentially helpful in suggesting new features in this field. In this context, two innovative products deriving from organics polymers (polyvinyl alcohols = PVA) and recently submitted for Italian patent (#102015000018950), were used as coatings in food industry for both cheese and fruit preservation, and as antimicrobial agents in comparison with the regular coating already used during ripening and/or storage.
This work aimed to study the properties of these coatings, after their application on food and along the ripening period, by using NIR spectroscopy. It was chosen to study differences in coating performances and permeability properties exploiting the Aquaphotomics approach, where information on the absorbance bands can provide a distinctive knowledge of water vibrations and intrinsic interactions between water and other components of the aqueous system.
Three different coatings (control; test 1: SF2; test 2: SF15) were used to coat processed cheese (provola) and winter melon samples for a total of 200 cheese and 58 fruit, and spectra were collected by using a MicroNIR 1700 (Diessechem Srl, Italy) spectrometer; spectral mode (reflectance : 900 to 1600 nm , 50 scans; 128 reading points; pretreatments: MSC and 2nd derivative.
Without attention to quantitative determinations in terms of constituents calibration and relationship between NIR response and day of storage (ripening), the pre-processed spectra were displayed on Aquagrams as function of type of coating used.
This approach allowed the characterization of the different coatings, in fact Aquagrams showed differences ascribable to different coating permeability. Each coating generated a specific fingerprint for the same analyzed product, independently of the time of storage and the chemical composition.