Improved oxidative stability of low-nitrite cooked ham formulated with phenolic extracts from olive vegetation water

During olive oil mechanical extraction process, two by-products (vegetation waters and paste) are generated, which are sources of high-added value molecules to produce new foods and/or ingredients with higher functionality. For both food industry and consumer is of great interest to replace synthetic additives (i.e. nitrite/nitrate salts and colorants) with natural compounds (such as biophenols). Moreover, the utilization of natural compounds extracted from agri-food by-products increases the food chain sustainability, promoting the development of healthier food products as well. The phenolic extract from olive vegetation water is of particular interest, as it has a high concentration of secoiridoids’ derivatives and verbascoside, so its addition in cooked meat products can exert an antioxidant action towards lipids and myoglobin, thus contributing to the reduction of the use of nitrites in their formulation. The aim of this study was to evaluate the effect of an extract rich in phenols (PE) obtained from olive vegetation water on the oxidative stability and the sensory characteristics of cooked ham during storage. Cooked ham was prepared using fresh pork meat. The injected brine contained: i) sodium chloride (1.5%), ii) glucose (0.2%), iii) ascorbic acid (0.02%), iv) flavours (0.15%), v) PE + NO2 at different levels (S1, S2 and S3, PE 200 mg/kg + NO2 150/35/0 mg/kg; Control + NO2 150 mg/kg). After the brine injection, meat was kneaded, kept at 4 °C and cooked up to an internal temperature of 69 °C. After slicing and packaging in ATM made of N2 (80%) and CO2 (20%), samples were stored in a refrigerated cabinet where they were exposed to fluorescent light (11 h/day) and sampled at 0, 15 and 30 days. During the 30-day storage, more than 35% of the added phenols were still retained in all formulations (S1, S2 and S3). Regarding secondary lipid oxidation, S1 showed the best oxidative stability, with TBARs below 1.0 mg MDA/kg of meat (reference value for rancidity development in cooked pork meat), while the control sample had significantly higher TBARs values (less than 3.79 mg MDA/kg of meat). S2 and S3 displayed a similar oxidative trend, with TBARs values below 1.4 mg MDA/kg of meat; therefore, it is possible to hypothesize that the antioxidant activity in both S2 and S3 was mainly due to phenols, while nitrites in S1 were more involved in the color development. The volatile organic compounds (VOCs) showed a general raise in C5 and C6 saturated aldehydes, reaching an increase of more than 400% in control sample, 300% in S1, 100% in S2 and 200% in S3 after 30 days of storage. Total cholesterol oxidation products (COPs) and its oxidation ratio (OR%) were particularly low (less than 4 mg/kg of meat and 0.4%, respectively) in all cooked ham samples. Taste and flavor attributes were not negatively affected by PE, whilst the pink color was positively protected by PE in combination with the lowest concentration of NO2. This study confirms that PE obtained from OMWW is able to improve lipid oxidation in low-nitrate cooked ham, being a good strategy to produce healthier meat products with a circular economy approach.