Changes in Volatiles and Numbing Compounds of Dried Andaliman (Zanthoxylum acanthopodium) upon Various Drying Techniques
Wijaya, Christofora Hanny
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Andaliman (Zanthoxylum acanthopodium DC) is an endemic plant from North Sumatera, commonly used as spices and folk medicines. Andaliman has a robust citrus aroma and numbing trigeminal sensations. Unfortunately, the research, usage, and popularity of andaliman are much behind its related species, such as Z. piperitum (Japanese pepper) and Z. bungeanum (Sichuan pepper). The main hurdles in fresh andaliman usage are the fast rotting and rapid flavor degradation. Proper processing techniques by farmers and industries will be crucial to expand its usage. Drying could prevent andaliman from degradation by reducing the moisture content; however, its effects on volatiles, numbing compound, and aroma profile have not been fully understood. Unsaturated alkylamides (sanshools) have been reported to be responsible for the unique numbing sensation. Analysis of sanshools is usually conducted using column chromatography or High Pressure Liquid Chromatography; however, these methods tend to be time-consuming and requires a large amount of costly solvent. On the other hand, aroma analysis is conducted using Gas Chromatography-Mass Spectrometry (GC-MS), which requires researchers to use two types of analytical methods to get the complete picture of both the aroma and taste of andaliman. However, three studies managed to analyze sanshools by GC-MS, which will shorten the research timeline and reduce research costs. This research was composed of three main stages: drying of andaliman (sun, sunshade, shade, oven, and freeze drying), confirmation of the GC-MS parameter, analysis of the volatiles, sanshools, sensory and physical characteristics. The volatiles and sanshool analysis were conducted with GC-MS, while the sensory analysis used the Rate All That Apply-Hedonic method. Physical characteristics such as moisture, water activity, yield, bulk density, and color were analyzed. Statistical data analysis using Principal Component Analysis (PCA), one-way ANOVA, Duncan posthoc, Pearson’s correlation, and Partial Least Square regression analysis were conducted to evaluate the impact of drying on volatiles, numbing, and sensory profile as well as to determine the volatiles responsible for andaliman aroma quality. The logarithmic thin-layer drying model best-described andaliman drying kinetics. The drying process significantly altered andaliman appearance, aroma profile and physical properties. No significant difference was found in the yield of each drying method; however, shade drying resulted in the highest moisture and water activity, while sun drying and freeze drying resulted in the lowest moisture content and water activity. Freeze drying resulted in the lowest bulk density. All drying methods managed to produce andaliman with less than 17.90% moisture content and 0.6 water activity, indicating the drying targets have been achieved. Generally, drying increased the a*, indicating green color degradation, however, no significant difference was observed in the a* values of dried samples. GC-MS analysis of all chloroform andaliman extract managed to detect total of 67 peaks while identifying 42 compounds. However, 25 unidentified peaks could comprise of other sanshool isomers. Fresh and dried andaliman generally had similar total relative content of volatiles and chromatogram pattern, differing mostly in the individual compound quantities. The content of limonene, (E)-2-hexenal, geranial, α-pinene, sabinene, and β-myrcene as well as the intensities of citrus and green aroma tended to decrease. In contrast, the content of geranyl acetate, citronellal, neral, α-sanshool as well as the intensities of warm and lime leaf aroma tended to increase upon drying. The more efficient extractions of volatiles with the absence of water and the hydrolyzation of volatiles from its glycosides by the native enzyme or acid and isomerization of citral could explain the increase of specific compounds in dried andaliman. The overall aroma intensities of all samples were not significantly different despite variability in each volatiles content. Oven-dried andaliman had a high liking score, similar to fresh, shade, and freeze-dried andaliman. PCA on volatiles and aroma intensities resulted in a similar separation of samples. Shade-dried and freeze-dried andaliman were clustered while the sun and sunshade-dried andaliman were clustered. Oven-dried and freeze-dried andaliman were separated from the other samples, indicating their unique qualities and that no drying process managed to produce dried andaliman with a similar aroma profile to fresh andaliman. Citrus, orange peel, and acidic aroma were the favorable attributes based on their positive correlation with the overall liking. These favorable attributes were found to be the dominant aroma in oven-dried andaliman. Partial Least Square Regression and Pearson correlation analysis of volatiles and aroma attributes showed that the citrus aroma was correlated with sabinene, limonene, (Z)-β-ocimene, β-citronellol, and geranial. Orange peel aroma was correlated with (E)-β-ocimene and citronellal, while acidic aroma was correlated with (E-)-β-ocimene, (Z-)-β-ocimene, and citronellal. This correlation indicated that these compounds played significant roles in andaliman sensory acceptability and the future screening of andaliman could be based on targeted analysis on that seven volatiles. Even though no drying method could produce dried andaliman with a similar volatile and sensory profile to a fresh one, oven drying could be proposed as the ideal drying method because of its short duration and low water activity as well as high liking score, aroma intensity, and volatiles content.
- MT - Agriculture Technology