Abstract
Simple SummaryUsing polyphenols from olive oil waste as feed supplements in animal diets can be a strategy to reduce adverse environmental effects of this by-product and to enhance the quality of products of animal origin. The aim of the study was to assess the effects of adding a polyphenolic concentrate from olive oil wastewater to a typical sheep diet on the nutraceutical and quality characteristics of cheese. The experiment was carried out on thirty-six Sarda ewes, divided into two homogenous groups fed a standard diet composed of hay and concentrate. In one of the two diets, the concentrate was supplemented (25 g/kg) with polyphenols obtained from olive mill wastewater using a special filtration system. Data showed that the polyphenol supplementation in the ewe’s diet resulted in the presence of tyrosol and hydroxytyrosol sulphate metabolites in milk and cheese. Furthermore, these compounds were able to provide a direct antioxidant effect on cheese with no modification in its chemical composition.The aim of the study was to define the chemical characteristics, antioxidant capacity, oxidative status, sensory properties, and the presence of polyphenols in ovine cheese obtained after dietary administration of spray-dried olive mill wastewater (SDP). SDP is a waste from olive oil production rich in bioactive molecules obtained by further processing the olive mill wastewater through a spray-drying system. Thirty-six sheep were randomly assigned to two experimental groups that received a standard diet based on hay and concentrate. The concentrate fed to the SDP group was supplemented with SDP at a rate 25 g/kg (as fed). The trial lasted 9 weeks. Milk from the two treatment groups was separately collected and used for manufacturing cheese. Cheese quality parameters and proximate composition were not affected by the dietary treatment, whereas the antioxidant status and oxidative stability of cheese were positively affected. Polyphenol analyses in cheese were performed through liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The concentration of hydroxytyrosol and tyrosol, and their sulphate metabolites, were higher in cheese from supplemented sheep. These findings suggest that polyphenol metabolites can play a major role in the beneficial effects observed in food produced from sheep fed SDP.
Highlights
The production of olive oil is widespread around the world but is located in the Mediterranean region
Olive oil extraction generates adverse environmental effects with the production of a variety of by-products, depending on the process used; solid residues and liquid residues are produced with a traditional method through discontinuous press extraction and continuous three-phase extraction, while very wet residues represented by the olive wet cake are produced with the two-phase centrifugation process [2,3,4]
The experimental treatments were represented by: (1) a basal control diet (C) composed of hay and concentrate; (2) a C diet where the concentrate was supplemented with olive mill wastewater (25 g/kg) treated with a filtration system consisting of progressive permeability membranes and dehydrated using a spray-drying system (SDP: spray-dried phenolics) (Table 1)
Summary
The production of olive oil is widespread around the world but is located in the Mediterranean region. According to the International Olive Oil Council (IOOC), 67% of the world’s olive oil production occurs in Europe, and Italy is one of the largest producers in the world [1]. Olive mill wastewater and olive wet cake are environmental pollutants because of their high organic and phenolic content and have phytotoxicity activity [4]. New techniques for the treatment of these by-products have been developed to recover the highly valuable bioactive compounds found in olive oil waste [5]. The most representative bioactive molecules are phenolic compounds: (a) hydroxytyrosol (3,4-DHPEA) and tyrosol (p-HPEA) (class of phenolic alcohols); (b) dialdehydic form of decarboxymethyl elenolic acid linked to 3,4-DHPEA or p-HPEA (3,4-DHPEA-EDA or p-HPEA-EDA) (class of secoiridoids derivatives); (c) verbascoside (a derivative of hydroxycinnamic acid); (d) caffeic acid, p-coumaric acid, and vanillic acid (class of phenolic acids and derivatives); (e) lutein (class of flavones); and (f) (+)-acetoxypinoresinol and (+)-pinoresinol (class of lignans) secoiridoids, especially 3,4-DHPEA-EDA and verbascoside [6]
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