Influence of innovative coatings on salami ripening assessed by near infrared spectroscopy and aquaphotomics

Abstract

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 R2CVof 0.95, 0.90, 0.83 and RMECV of 1.31, 5.28 and 3.88, respectively.