Dynamic Head Space Analyses of Orange Juice Flavor Compounds and Their Absorption into Packaging Materials

Release of glycosidically-bound volatiles in orange juice under natural conditions

Glycosidically-bound volatiles (GBV) can be released by exogenous acid and enzymatic hydrolysis. However, the liberation of GBV in natural juice is not reported. It was found that part of the GBV in orange juice (OJ) under natural conditions can be released and the types of volatiles were considerably fewer than the ones under exogenous acid, or enzymatic hydrolysis. Seven types of aroma substances were released under endogenous enzyme, among which ethyl 3-hydroxyhexanoate and eugenol are characteristic aroma substances of OJ. Six kinds of aroma substances can be released under natural acidic conditions, none are characteristic aroma substances of OJ. Ten kinds of substances were released under endogenous enzymes in combination with the acidic condition, among which benzyl alcohol, ethyl 3-hydroxyhexanoate, citral, and eugenol are characteristic aroma substances of OJ. The results indicated that GBV may play an important role in resisting the decrease of free aroma in OJ during storage.

Optimization of a Dynamic Headspace-Thermal Desorption-Gas Chromatography/Mass Spectrometry procedure for the determination of furfurals in vinegars

The use of a Dynamic Headspace System (DHS) device combined with a Thermal Desorption Unit (TDU) interfaced to a Gas Chromatography/Mass Spectrometry (GC/MS) system is proposed for the determination of furfurals in oenological products. An experimental design protocol has been employed for the optimization of the instrumental settings concerning DHS and TDU extraction and desorption steps. It has been possible to individuate the following optimized conditions: incubation temperature 40°C, purge volume 800 mL, dry volume 1500 mL, TDU hold time 5 min and incubation time 10 min. The performance of two different SPE sorbents, namely Tenax TA and Tenax GR used for the furfurals trapping, was investigated too. The developed DHS sampling procedure showed good reproducibility values with a RSD% lower than 10% for all the monitored species. The optimized experimental settings have been used to determine furfurals in several vinegar samples obtained by traditional procedure starting from cooked grape musts, i.e. in Aceto Balsamico Tradizionale di Modena (ABTM). In fact, the control of these species is extremely important for quality and safety issues.