Combined effects of high hydrostatic pressure and chemical pre-treatment on physico-chemical properties of beef, using FTIR and diffuse reflectance spectroscopy

Abstract

High pressure processing (HPP) was combined with a previous short chemical treatment to stabilize the color of beef tissue. Beef samples were treated with a solution containing ascorbic acid, sodium chloride, and a very low concentration of sodium nitrite. The effects of pressure levels (0.1–600 MPa) and preservative solution on: (i) color properties based on diffuse reflectance spectroscopy (DRS), which determines the relative concentrations of muscle pigments, (ii) protein denaturation and changes in the secondary structures by DSC and FTIR-ATR, were determined. At high pressures, the disappearance of DSC peaks due to protein denaturation, a decrease in the proportion of α-helix and an increase in the percentage of disordered structures, were evidenced. DRS spectra and Kublelka-Munk theory equations demonstrated that nitrosilmyoglobin was a more stable chromophore, decreasing discoloration of the tissue. These techniques contribute to the knowledge of the physico-chemical properties of the tissue submitted to combined preservation processes. Practical Applications: There is an increasing demand from consumers for high-quality beef products, with significant emphasis placed on color and safety attributes. Extending the shelf life by applying high hydrostatic pressure treatment (HHP) improves food safety and will produce a positive impact on both the industry and consumers. HHP is a non-thermal preservation technology with generally minimal effects on sensory qualities and nutritional content; however, the direct application of this technology on beef leads to the production of a product with an unacceptable pale coloration. Therefore, it must be remarked that a pre-treatment stage by immersing the pieces in a preservative solution is essential to improve the color of beef products treated by HHP. In this regard, from a technological point of view, it is very important to know the combined effects of both stages (short chemical treatment and high-pressure) on the quality of beef products.