The Effects Of Some Machining Processes On Volatiles And Aroma Of Guanxi Pummelo Juice

Aroma was the most important quality of fruit juice, it was susceptible in the process ofmachining. This extraction comditions of volatiles were optimized in this paper, and the volatileswere analyzed by gas chromatography equipped with a mass spectrometer (SPME-GC-MS),explored the effects of pasteurization, resin adsorption and naringinase treatment on the volatilesand aroma of Guanxi pummelo juice. The results showed that the optimum extration conditionsof Guanxi pummelo juice by solid-phase microextration was extracted for30min at40oC, thefresh juice was found to have24volatiles, in which hexanal,(E)-3-hexen-1-ol and1-hexanolexisted in the highest concentrations, while hexanal and linalool exhibited the highest odoractivity values (OAVs).The treatment of pasteurization resulted in the generations of (E)-3-penten-2-one andbenzene acetaldehyde, the increases in the concentration of hexanal,(E)-2-hexenal, heptanal,octanal,1-octanol,(Z)-linalool oxide,(E)-linalool oxide, linalool and nonanal. The calculation ofodor activity value showed that the pasteurized pummelo juice had a much stronger aroma, andthe odor of floral, green and cooked were stronger than fresh pummelo juice.Resin adsorption captured most of the volatiles from the juice. After the naringinasetreatment, the juice showed32volatiles, in which (Z)-linalool oxide and (E)-linalool oxide werethe most dominant volatiles, hexanal and linalool had the highest OAVs, principal componentanalysis (PCA) was used to compare6volatiles that constituted the majority of the OAVs of thepummelo juices. The result demonstrate that the naringinase treated juice had the aroma profilesimilar to the fresh juice, but the cooked odor was stronger than fresh pummelo juice.By simulated the reaction conditions of naringinase hydrolysis pummelo juice, it suggestedthat furfural was the degradation production of ascorbic acid, benzene acetaldehyde was thedegradation production of phenyalanine, α-terpineol was the transformation production oflimonene and linalool.Through extracted and hydrolysised the glycosidic in Guanxi pummelojuice It have been found that Guanxi pummelo juice have rhamnoside bound hexanal, andglycosidic bound (Z)-linalool oxide and (E)-linalool oxide.These results suggested pummelo juice had a much stronger aroma after pasteurization, andthe odor of floral, green and cooked were stronger. The naringinase treatment is more desirablethan the resin adsorption to remove naringin in Guanxi pummelo juice on maintain the aroma.The generation or increase of volatiles were manily caused by the degradation of some nonvolatile nutrient contents and the hydrolysis of some glycoside bound volatiles.