Impregnation Techniques for Aroma Enrichment of Apples: a Preliminary Study

Food industry often needs flavour enriched food products to be employed as ingredients of more complex preparations. At the best of our knowledge there are not applications concerning with the production of minimally processed food items enriched with aromas. This research aims to enrich apples with an artificial green apple aroma, applying different techniques; vacuum impregnation (VI), ultrasound technology (USI) and the combination of these two techniques (VUSI) were tested and compared with atmospheric pressure impregnation (AI). An isotonic solution of fructose, containing ascorbic acid and green apple artificial aroma was used for the impregnation of regular and uniform sticks of apple. Different durations of impregnation (2.5, 5.0 and 7.5 minutes) were tested and the impregnation kinetics of the main components of artificial aroma were recorded. Significant differences between treatments were detected: VI and VUSI gave the highest aroma enrichment at 5 minutes of treatment. Different impregnation kinetics were recorded for alcohols and esters: the first tended to increase even after 7.5 minutes of treatments, the others components instead grown until 5 minutes and then decreased, mainly when ultrasounds were applied (US and VUSI). Some possible causes of such results were hypothesized, but the need of further studies is, also suggested in order to clarify the mechanisms involved.