Sous-vide packaging: Sensory characteristics of potato slices treated with rosemary essential oil

Fresh-cut potatoes, already peeled, cut and packed, meet a growing favour of consumers, thanks to their high added value simplifying their use and consumption, both at home and in the food service industry. Sous vide is a combined technique used for raw or partially cooked food sources, packaged under vacuum. The request from consumers to reduce or eliminate the synthetic chemical additives, suggested to try natural alternatives such as essential oils (EOs), nowadays these compounds are frequently used, often through dipping techniques. On the basis of studies carried out, it was considered that the rosemary essential oil (EO) was the most appropriate and kindred with the preparation of fresh-cut sliced potatoes. The objective of this study was to evaluate the preserving effect of 0.5 % (w/v) rosemary (Rosmarinus officinalis) EO on physical, sensory and microbiological properties in fresh-cut sliced potatoes packaged in sous vide bags and stored for 12 days at +4 ± 2°C. A sample treated equally, but without EO, was packed in sous vide and stored at the same conditions and kept as control. Color change was measured through Image-Pro® Plus 7.0 software; sensory and microbiological analysis was carried out during the shelf life test. EO addition significantly reduced mesophilic bacteria and Enterobacteriaceae counts over the considered period. The sensory profile method UNI 10957 (2003) was used to measure any change in the sensory characters of samples, as a result of rosemary EO treatment. The best sensory results were for samples treated with EO, statistically significant results were observed on the descriptors sour and floury. HSI (hue, saturation, intensity) describes colors as like as they are perceived by human eyes, suggesting changes in color as browning index. The Hue value did not change during the 12 days of storage, for control slices as for slices treated with EO. Joint use of dipping in EO, sous-vide technology and refrigerated condition allowed to obtain a value-added product, safe, ready to cook, with appreciable characteristics for consumers.