Sesame oil is one of the most popular sesame products for consumers. Roasting is a commonly employed heat treatment method in sesame oil processing. This work aims to investigate the effects of roasting temperature and time on sensory profiles, volatile components, fatty acid composition, and oxidative stability of the oil. Quantitative descriptive sensory analysis was employed to reveal changes in aroma characteristics of sesame oils from different roasting conditions. Volatile compounds of the oils were analyzed via headspace solid-phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC-MS), identifying 56 components, including 30 key aroma-active compounds (odor activity value, OAV ≥ 1) across 18 samples. Principal component analysis (PCA) was performed to explore the effect of roasting conditions on volatiles of sesame oils. The oxidative stability of the oils was also determined by RapidOxy reactor. The results demonstrated that the effect of roasting time on the flavor of sesame oil was greater than that of temperature. Moreover, the effect of roasting conditions (temperature/time) on the fatty acid profile of sesame oil was not significant. This provided some theoretical foundation and data support for improving the processing technology of sesame oil and controlling its flavor quality.

In metabolically engineered plants, the target products are usually uniformly distributed in the whole plant or specific tissues. When engineering tobacco to produce astaxanthin, a ketocarotenoid with strong antioxidant activity and multiple bioactivities, a scattered distribution of astaxanthin-producing regions was observed in a small portion of astaxanthin-producing tobacco plants, which caused mosaic-like red and green spots on the leaves (ASTA-mosaic). A physiological assay showed that the non-astaxanthin green region (Mosaic_G) had relatively higher chlorophyll content and better chloroplast structure than the astaxanthin-producing red region (Mosaic_R). Then, metabolomics, proteomics, and small RNA transcriptomics were employed to analyze the uneven distribution of astaxanthin-producing regions in tobacco leaves. The results of metabolomics and proteomics revealed a decrease in carotenoid metabolism, chlorophyll biosynthesis, and chlorophyll degradation in the Mosaic_G region. Pheophorbide a, an intermediate of chlorophyll degradation, was found to be significantly reduced in the Mosaic_G region, which was accompanied by the attenuation of chlorophyllase and pheophytinase, which catalyze the formation of pheophorbide a in chlorophyll degradation. Reductions in photosynthetic antenna proteins and photosystem-associated proteins were observed in the Mosaic_R region, consistent with the better chloroplast structure of the Mosaic_G region. Small RNA transcriptomics showed that several small RNAs could target chlorophyll-degradative genes, but they were more effective in targeting the astaxanthin biosynthetic genes. This finding was supported by the fact that the Mosaic_G region can remain green up to the senescence of tobacco leaves. This work provides insights into the mechanism of the uneven distribution of astaxanthin-producing regions in tobacco leaves and may contribute to the specialized utilization of tobacco plants for metabolic engineering.

Sweetening compounds are commonly incorporated into food products to enhance their texture and flavor, thereby indicating product quality. 4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) is a sweet aromatic compound characterized by its pineapple-like baking scent. While it serves as a taste enhancer in various industries, including wine production and soy sauce manufacturing, HDMF also exhibits DNA-damaging activity in foods. In this study, a fluorescence detection method based on fluorescence resonance energy transfer (FRET) for the sensitive detection of HDMF was developed. Initially, gold nanoparticles were deposited onto the surface of Fe₃O₄ to create fluorescence-quenching materials. Subsequently, thiol-functionalized β-cyclodextrin (SH-β-CD) was modified to provide cavities that allow the fluorescent dye rhodamine 6G (R6G) to enter. The fluorescence of R6G remains quenched until HDMF is present because it will compete with R6G for binding sites within the SH-β-CD cavities through competitive host–guest recognition. Furthermore, the fluorescence intensity of R6G at 553 nm exhibited a strong linear correlation with the logarithmic value of HDMF concentration over a range from 5 × 10⁻⁷ M to 10⁻⁴ M. This rapid and sensitive fluorescence detection strategy rooted in FRET and competitive host–guest recognition demonstrated significant potential for detecting HDMF in food products.

The chemoselectivity origin of boric acid-mediated transformation of d -glucosamine for the synthesis of 2,5-deoxyfructosazine has been investigated using density functional theory (DFT) and the projection of orbital coefficient vector (POCV) method.