If you order extra-virgin olive oil at the restaurant these days, you better check the label carefully. According to Europol, selling fake olive oil has become a “common practice”. The warning came after authorities seized 260,000 litres of counterfeit product in coordinated raids across Italy and Spain, in November. Less than two months later, around fifty restaurants came under investigation for the same reason, in Rome, sparking new alarms. How do you tell if an olive oil is authentic?Some fraudsters are substituting the precious “liquid gold” with much cheaper seed oil. Seed oil is transpa…