Influence of drying technologies on the aroma of Sicilian red garlic

The effects of hot air drying (HAD) and microwave drying (MD) techniques on the aroma quality of Sicilian red garlic, the most appreciated and widespread among the Sicilian garlic varieties, were investigated. Different combinations of temperature/time and power/time were tested for the HAD and MD technologies, respectively; a Ranking Sensory Test allowed to set the drying conditions that were 70 °C/1 h and 400 W/3 min for HAD and MD technologies, respectively. Raw and dried garlic samples, obtained under the HAD and MD previously set conditions, were analyzed by Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (SPME-GCMS) and a large number of aroma compounds were identified. Statistically significant differences resulted among the raw and dried samples, also in relation to the drying technology. The raw samples provided a higher amount of disulfides, mainly diallyl disulfide and allyl (E)-1-propenyl disulfide; the dried samples were characterized by the increase of trisulfides and cyclic sulfur compounds, such as thianes and thiolanes, especially when MD technology was applied. Comparing the drying technologies, MD resulted time saving and led to a processed product rich in bioactive compounds; otherwise, when subjected to the Paired Sensory Preference Test, MD samples were liked more than HAD ones by the consumers.