Comparison of odor compounds of brown sugar, muscovado sugar, and brown granulated sugar using GC-O-MS

Potential of ultraviolet laser pulse-induced current for characterizing the grain size of table sugar

In this work, we proposed a laser-induced current (LIC) method to investigate the grain-size dependence of the plasma of table sugar induced by a nanosecond (ns) pulsed ultraviolet laser in the size range of <180 μm->550 μm and achieve the lower power consumption in measurement. Under multiple laser irradiations and an external electric field (Vb) of 200 V, the LIC variation's (ΔIp) standard deviation and variance were 0.53 nA and 0.05 nA, respectively, indicating the relatively small systematic error during the testing process. The Vb causes a decrease in the possibility of electron-ion complexation and accelerates the separation, resulting in an increase in ΔIp with Vb. With increasing grain size (diameter D) of table sugar, ΔI demonstrate a valley-like behaviour and 250-380 μm is the critical range Dc where ΔI is very weak and considerably depends on the Vb with the slope of 0.031 nA/V. At D > 550 μm and Vb = 5 V, ΔI intensities monotonically rise by 30 % when D surpasses Dc. In this instance, the energy was the main contributor to the LIC signal during plasma generation and expansion. While D is less than Dc, ΔIp increases by 27 % at D ≤ 180 μm and Vb = 5 V. The yield stress is the main reason for the formation of plasma with high temperature and density in this situation because the sugar behaves like an elastic solid. The reason for such a LIC variation trend was discussed, which can be explained by considering the morphological, thermal and mechanical properties competing with each other. The present result suggests that the LIC method enables non-contact characterisation of sugar particle size at low-power consumption.

A comparative study on flavor trapping techniques from the viewpoint of odorants of hot-pressed rapeseed oil

Rapeseed oil, as one of the three major vegetable oils in the world, its matrix effect makes the decoding flavor a challenge. Solid-phase microextraction (SPME), SPME-Arrow, headspace stir bar sorptive extraction (HSSE), direct thermal desorption (DTD), and solvent-assisted flavor evaporation (SAFE) were compared based on the odorants in hot-pressed rapeseed oil. Besides, methodological validation for 31 aroma standards was conducted to compare reliability and robustness of these approaches. DTD showed the largest proportion of acids, while the other techniques extracted a majority of nitriles. The highest number of odorants was detected by SAFE (31), followed by HSSE (30), SPME-Arrow (30), SPME (24), and DTD (14). SPME-Arrow showed the best performance in linearity, recovery, and reproducibility followed by SPME, HSSE, DTD, and SAFE. Results reveal the advantages and limitations of diverse methodologies and provide valuable insights for the selection of extraction methods in an oil matrix and flavor decoding.

Analysis and Comparison of Aroma Compounds of Brown Sugar in Guangdong, Guangxi and Yunnan Using GC-O-MS

Guangdong, Guangxi and Yunnan are the three provinces in China that yield the most brown sugar, a brown-red colored solid or powdered sugar product made from sugar cane. In the present study, the differences between odor compounds of brown sugar from Guangdong, Guangxi, and Yunnan provinces in China were compared and analyzed by gas chromatography-olfactometry-mass spectrometry (GC-O-MS). A total of 80 odor compounds, including 5 alcohols, 9 aldehydes, 8 phenols, 21 acids, 14 ketones, 5 esters, 12 pyrazines, and 6 other compounds, were detected. The fingerprint analysis of the brown sugar odor compounds showed 90% similarity, indicating a close relationship among the odor properties of brown sugar in each province. Moreover, the orthogonal partial least squares discriminant analysis (OPLS-DA) was performed to identify the compounds contributing to the volatile classification of the brown sugar from three provinces, which confirmed that OPLS-DA could be a potential tool to distinguish the brown sugar of three origins.

Discrimination and characterization of the volatile organic compounds in eight kinds of huajiao with geographical indication of China using electronic nose, HS-GC-IMS and HS-SPME-GC-MS

Huajiao (Zanthoxylum bungeanum maxim. and Zanthoxylum armatum DC.) is a highly prized spice in China due to its distinctive aroma and taste. The volatile organic compounds (VOCs) of eight kinds of red and green huajiao which varied according to geographical indication of P.R. China were evaluated by electronic nose (E-nose), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). Results showed that red huajiao emitted more terpenes, esters, and fewer alcohols than green huajiao. Partial least squares-discriminant analysis based on GC-MS and GC-IMS data was revealed a good classifying tool for huajiao from different original habitats. Four and eight aroma substances were selected as the potential markers by the variable importance in projection (VIP) variable selection method, respectively. The results of the current study provide a useful basis in the huajiao aroma difference study. Additionally, a rapid huajiao aroma analysis method using GC-IMS was developed.