| Popis: |
The effect of storage conditions on the oxidative stability, phenol content and composition as well as on sensory properties of the virgin olive oil with the rosemary addition was studied. Samples were kept in the dark, at the room temperature during 2 months. Analyses were carried out every 15 days. Rosemary (Rosmarinus officinalis, L.) was added in concentration of 5 g/100g oil as integral leaves which were left in the oil during the whole experiment, and as ground leaves, well mixed and filtrated after 48 hours of extraction procedure. According to the results of Rancimat test, peroxide values and K-values the highest oxidative stability had sample with ground rosemary leaves which also had better extraction of phenol components. The greatest extraction of phenol components from integral rosemary leaves into the oil was within first 15 days. Phenol content in the oils with rosemary decreased afterward, although it was always higher than in control sample. Using HPLC method with available standards, certain phenol compounds (caffeic acid, vanillin, vanillic acid, p-coumaric acid and o-coumaric acid) were identified in oils with rosemary but not in control sample. The intensity of bitterness analyzed by spectroscopic method was in correlation with phenol content. The results of the sensory determined bitterness showed significant impact of the rosemary addition, but not of storage period. Preference tests indicated that all samples with rosemary had specific flavour but after 60 days of storage oils with the integral leaves assimilated too intense and became repulsive. |
