Apple Pomace as Source of Bioactive Compounds for Meat Enrichment

Apple pomace, the press cake resulting from apple juice production, contains plenty of compounds with nutritional and health properties, among which dietary fibre, minerals and phenolic compounds. The present research aimed at investigating the composition of this by-product, with particular interest for the phenolic fraction, and developing functional products based on beef meat added with dried apple pomace. Ultrasound-assisted extraction was used to isolate the phenolic compounds, then the extract fractionation was performed and the free and bound phenols, together with the hydrolysed fractions in acid and alkaline conditions, were investigated. Ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometer detector and ultraviolet spectrophotometric detector was used to obtain the qualitative and quantitative profile of phenols. Phloridzin and different glycosylated forms of quercetin were the most represented among the phenolic compounds. The antioxidant properties of apple pomace extract were measured by in vitro tests, able to evaluate both the antiradical and the reducing capacity. The second part of the study was relative to the addition of dried apple pomace to minced beef meat, with two addition levels, 4 and 8%. Then apple pomace added burgers were prepared together with non-added burgers as control. The prepared burgers were evaluated for quality attributes including physical characteristics and shelf-life test. Moreover, the samples were cooked in a domestic microwave and then subjected to sensory evaluation. The sensory properties and overall acceptability were higher for burgers added with 4% apple pomace, but satisfactory results have been obtained also for 8% added burgers. The results of this investigation are promising as the addition of vegetable by-products, rich in fibre and phenolic compounds, improves the nutritional and health properties of the meat. In fact, low-fat, fibre rich and antioxidant/antimicrobial rich products can be prepared, avoiding or reducing the addition of additives as nitrites and nitrates.