Analysis of Volatile Components of Jasmine and Jasmine Tea during Scenting Process

Jasmine tea is widely loved by the public because of its unique and pleasant aroma and taste. The new scenting process is different from the traditional scenting process, because the new scenting process has a thin pile height to reduce the high temperature and prolong the scenting time. We qualified and quantified volatiles in jasmine and jasmine tea during the scenting process by gas chromatography-mass spectrometry (GC-MS) with a headspace solid-phase microextraction (HS-SPME). There were 71 and 78 effective volatiles in jasmine and jasmine tea, respectively, including 24 terpenes, 9 alcohols, 24 esters, 6 hydrocarbons, 1 ketone, 3 aldehydes, 2 nitrogen compounds, and 2 oxygen-containing compounds in jasmine; 29 terpenes, 6 alcohols, 28 esters, 8 nitrogen compounds, 1 aldehyde, and 6 other compounds in jasmine tea. The amounts of terpenes, esters, alcohols, nitrogen compounds, and hydrocarbons in jasmine and tea rose and then fell. The amount of oxygenated compounds of tea in the new scenting process first rose and then fell, while it showed a continuous upward trend during the traditional process. The amount of volatiles in jasmine and tea produced by the new scenting process were higher than that of the traditional scenting process at the same time. This study indicated that jasmine tea produced by the new scenting process had better volatile quality, which can provide proof for the new scenting process.

Effects of Pretreatment and Drying on the Volatile Compounds of Sliced Solar-Dried Ginger (Zingiber officinale Roscoe) Rhizome

Ginger (Zingiber officinale Roscoe) rhizomes are mostly used as spice and medicine due to their high aroma intensity and medicinal bioactive compounds. However, the volatile compounds of ginger, partly responsible for its aroma and medicinal properties, can be affected by the pretreatment, drying method, and extraction processes employed. The objective of this study was to assess the effects of pretreatment and drying on the volatile compounds of yellow ginger variety at nine months of maturation. The effect of potassium metabisulfite (KMBS) and blanching pretreatment and drying on the volatile compounds of ginger using head space solid-phase microextraction with GCMS/MS identification (HS-SPME/GCMS/MS) was investigated. KMBS of concentrations 0.0 (control), 0.1, 0.15, 0.2, and 1.0% and blanching at 50°C and 100°C were used for pretreatment and dried in a tent-like concrete solar (CSD) dryer and open-sun drying (OSD). The different concentrations of KMBS-treated fresh ginger rhizomes did not result in any particular pattern for volatile compound composition identification. However, the top five compounds were mostly sesquiterpenes. The 0.15% KMBS-treated CSD emerged as the best pretreatment for retaining α-zingiberene, β-cubebene, α-farnesene, and geranial. The presence of β-cedrene, β-carene, and dihydro-α-curcumene makes this study unique. The 0.15% KMBS pretreatment and CSD drying can be adopted as an affordable alternative to preserve ginger.

Improvement of Robusta Coffee Aroma with L-leucine Powder

L-leucine powder (LP) were added to improve the aroma of Robusta coffee beans. Treatment was a short soaking (M1) or spraying procedure (M2), then LP was added at varying levels up to 3% (w/w). All samples were roasted (240 °C/15 min) and extracted using an espresso machine. Volatile compounds were analysed by solid-phase microextraction−gas chromatography−mass selective detection. Thirty volatile compounds (6 pyrroles, 8 pyrazines, 3 phenols, 9 furans, 2 ketones, 2 aldehydes) were analysed. In 15 coffee samples, the levels of total volatile compounds (based on peak area ratios) ranged from 8.9 (M1-1) to 15.5 (non-treated Robusta: NTR). Robusta coffee has lower levels of bitter aroma compounds when pre-treated with LP. The sum of bitter volatiles (phenols, pyrroles, pyrazines) was lowest in M1-5 (3% LP), M2-1 (1% LP; both dried at 50 °C/15 min) and M2-7 (3% LP, dried at 70 °C/15 min) compared with NTR (p < 0.05).