Loss of Aroma Volatile Compounds In Fresh-Cut Carrots

Flavor loss during marketing is a major quality concern for fresh-cut fruits and vegetables.  To identify factors contributing to flavor loss, changes in nine volatile terpene compounds that contribute to carrot flavor, including the two most abundant terpinolene and caryophylene, were monitored during the storage of fresh-cut carrots.  Freshly harvested carrot roots were washed and cooled.  Roots were then cut into 2.5, 10 or 30 mm wide slices and 40 g samples were placed into 4 L glass jars.  Jars were sealed with Teflon lids and vented with a single hypodermic needle (static) or flushed continuously with 140 mL/min humidified air.  Following 0, 3, 7 or 14 days at 5 C, carrot slices were frozen in liquid nitrogen and held at -25 C.  The volatile content of carrot slices were analyzed using heated headspace GC-MS.  Slice thickness, flushing, and storage time all affected the content of volatile terpenes.  The 2.5 mm wide sliced carrots tended to have the greatest loss of terpenes.  Concentrations of β-pinene, β-cymene, limonene, γ-terpinene, terpinolene and bornyl acetate in 2.5 mm carrot slices were 30%, 25%, 37%, 42%, 49% and 89% less, respectively, than that of the 10 mm slices..  Slicing had no significant effect on the loss of caryophyllene or humulene.  Carrot slices held in the continuous flow of air had a higher loss of the more volatile compounds than slices held in the static jars.  Concentrations of α-pinene, β-pinene, β-cymene, limonene and γ-terpinene in carrot slices from the flushed jars averaged 36%, 60%, 45%, 26%, and 36% less, respectively, than slices from static jars.  Flushing had no significant effect on the loss of terpinolene, bornyl acetate, caryophyllene, or humulene.  During storage, volatile concentrations changed and were lowest after 7 days of storage.  Interestingly, there was little loss of volatiles between 7 and 14 days, but rather a slight increase was observed for most compounds.  Results suggest that a portion of the loss of flavor volatiles during storage of fresh-cut carrots is a result of diffusion and compound volatility.