Ricotta cheese is a dairy product characterised by a short shelf life. The aim of this study was to monitor changes occurring during storage of packed industrial ricotta cheese using a simple and fast method. Several samples of manufactured ricotta cheese were monitored during storage at three different temperatures (3, 10 and 20°C). Spectral data were collected over the range 12000 to 4400 cm⁻¹ using a Fourier transform near infrared (FT-NIR) spectrometer fitted with an optic fibre working in diffuse reflectance. Some chemical and rheological parameters were also measured. Principal component analysis (PCA) was applied as an exploratory chemometric technique to each one of the three sets of data (FT-NIR, chemical and rheological data) and a calibration model between the NIR data set and chemical and rheological indices was developed by means of partial least squares regression. The PCA results showed in all cases the influence of the storage temperature on the shelf life trend and were able to identify a critical day of shelf life for each storage temperature.

Coatings play an important role in preserving the quality of meat products by reducing weight loss, improving appearance and integrity. The aim of this work was to study the effect of an innovative coating on the ripening of “Salame Piacentino”. Sixty samples were collected after 40 days of aging: 30 samples were treated with a water-soluble complex based on a cellulose polymer and 30 samples were used as control. All samples were measured after 8, 21, 36, 63 and 78 days of ripening at 11℃ by NIR spectroscopy and were analyzed for weight loss, mechanical properties, colour of outer casing and of the meat, volatile profile (by electronic nose) and sensory characteristics (firmness, meat colour uniformity, fat color, odor). Treated salami showed lower weight loss, firmness and stiffness, were perceived less firm than control samples and had lower CIELab colour values of casing L* and a* and higher values of meat L*. During ripening, weight loss, mechanical and sensory firmness increased while outer casing a*, meat L* and meat color uniformity decreased. As for sensory analysis, panelists were able to distinguish coated salami from control ones only at 78 days of ripening, when also volatile patterns were significantly different. Partial least squares – discriminant analysis of NIR spectra was able to discriminate coated and control salami and identify high variable importance in the projection (VIP) scores in the region 1398–1518 nm, which is within the wavelength range of the water first overtone, suggesting the suitability of the aquaphotomics approach. Comparing aquagrams, coated salami showed higher absorbance values at 1382, 1398 and 1410 nm and lower values in the 1438–1492 nm range than control ones, indicating a higher presence of free water molecules, while hydrogen-bonded water was predominant in control salami. Weight loss, firmness and stiffness were successfully predicted by PLS regression analysis showing R ² _CV of 0.95, 0.90, 0.83 and RMECV of 1.31, 5.28 and 3.88, respectively.

Near infrared (NIR) and nuclear magnetic resonance (NMR) spectroscopy studies were performed to determine the behaviour of water during an osmotic process of apple spheres in concentrated sugar solutions. The osmotic dehydration is a process of water removal from cellular structures through immersion in a hypertonic solution. Relationships between sugars and water were studied using both two-dimensional correlation, calculated on NIR spectra recorded during the process, and NIR–NMR outer product analysis (OPA). We found that there was a shift of 7nm towards higher wavelengths in the maximum absorbance of the first overtone range of the water O–H stretching, due to the increase of hydrogen bonds implicated in the binding of the sugars progressively increasing in concentration during water removal. The absorptions detected by two-dimensional correlation, using processing time as the dynamic variable, belong to the elements which have more OH free as indicated from the outer product analysis, i.e. free water at 1936 nm followed by bonded water at 1393 nm and 1518 nm and sugars at 2131 nm, respectively.