Effect of the addition of water extract from guelder rose (Viburnum opulus) flowers on physicochemical and sensory properties of veal burgers

The use of plant extracts is gaining increasing popularity among both food producers and consumers. Extracts can impart health-promoting properties and improve the antioxidant properties of food products, while stabilising sensitive compounds can positively extend the shelf life of food. The objective of the study was to assess the effect of the addition of water extract from guelder rose flowers (GRE) at concentrations of 0.05%, 0.1% and 0.4% on the physicochemical properties (pH, water activity, texture, colour, lipid oxidation - TBARS, α-tocopherol content), sensory properties (beef aroma, off-odours, juiciness, tenderness, beef flavour, off-flavours) and overall quality of veal burgers stored refrigerated for 15 days. Burgers containing 0.1% and 0.4% GRE showed a significantly lower pH (on average, 5.56 in both GRE treatments vs. 5.61 in control samples) and higher purge loss after 10 days (2.39% and 2.90%, respectively, vs. 1.00% in control samples) and 15 days of storage (3.04% and 3.80%, respectively, vs. 1.22% in control samples; P < 0.05). The addition of the extract, irrespective of its concentration, slowed down lipid oxidation and significantly increased α-tocopherol retention (2.15–2.21 μg/g in GRE treatments vs. 1.83 μg/g in control samples; P < 0.05). However, at concentrations of 0.1% and 0.4%, it worsened the sensory properties while increasing the intensity of off-odours and off-tastes, thus lowering the overall quality rating (on average, 6.75 and 5.75, respectively, vs. 7.37 in control samples; P < 0.05). Among the tested GRE levels, a concentration of 0.05% was associated with the most favourable overall outcomes, without significant negative effects on water-holding capacity or sensory characteristics ( P > 0.05), while improving α-tocopherol retention and reducing TBARS values. The use of water extract from guelder rose flowers at an appropriate concentration can improve the shelf life and oxidative stability of burgers without adversely affecting their water-holding capacity and sensory quality.