Evaluation of the oxidative stability of blends of ‘Arbequina’ olive oils with other monovarietal olive oils

Like elsewhere in the Mediterranean, the olive oil sector is one of the strategic branches of the Moroccan economy owing to its social and economic significance. This research entailed evaluation of the oxidative stability of olive oils made up of a blend of ‘Arbequina’ olive oil with ‘Arbosana’ and ‘Koroneiki’ monovarietal oils known for their high content of natural antioxidants (phenols and tocopherols) and their superior oxidative stability compared with ‘Arbequina’ oil. The monovarietal oils produced from the ‘Arbequina’, ‘Arbosana’ and ‘Koroneiki’ varieties, which have recently been introduced under intensive cultivation in the eastern region of Morocco, underwent physico–chemical characterisation to determine quality criteria, natural antioxidant content, fatty acid composition and triacylglycerol profile. The Rancimat test* was performed to assess the oxidative stability of these monovarietal oils and their three-variety blends. The oxidation tests were performed on five freshly prepared blends (A) of the three varieties – ‘Arbequina’/’Arbosana’/‘Koroneiki’ – according to the following volume ratios: A1: 60/30/10; A2: 60/20/20; A3: 60:10:30; A4: 50:25:25 and A5: 40:30:30. The test results show that blends A4 and A5 displayed the best oxidative stability, recording respective values of 72.67 h and 75.42 h. These results are comparable to those obtained for ‘Arbosana’ monovarietal oil (75.42 h), which is considered to be relatively stable. Hence, blending is an excellent tool for enhancing oils produced from varieties which, despite their excellent initial quality and their organoleptic attributes, are handicapped by their poor stability, as is the case of ‘Arbequina’ oil.