Food Chemistry: X最新文献

Accurately identifying grazing (GZ) and supplementary feeding (SF) patterns in yak milk is important for product authentication; however, current methodologies are often expensive and time consuming. In this study, we examined 523 milk samples of lactating yaks at four stages of SF and tested 21 machine learning algorithms to develop a rapid and cost-effective classification method using routine compositional parameters. Ensemble learning techniques performed better than others, with XGBoost having the best accuracy (92%) and AUC (0.94). Multidimensional interpretability analyses, including SHAP, PDP, and ICE, identified fat content (27.8%) and lactose (23.1%) as the most important discriminators, along with biologically meaningful interactions, such as between fat, lactose, and freezing point. This interpretable framework provides a practical, low-cost method for milk authentication of yaks using ordinary dairy analyzers, providing a methodological foundation for the establishment of standardized GZ certification systems in milk production from yaks.

This study investigated the flavor differences among summer pasture-grazed (SM), winter pasture-grazed (WM) and winter stall-fed (HM) yaks using metabolomics, lipidomics and headspace-solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The SM group showed n-3 polyunsaturated fatty acids (n-3 PUFAs) were 225% and 209% higher than those in the WM and HM groups, respectively, with higher thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activities. These changes promoted the formation of (E)-2-decenal and 1-octen-3-ol, which impart green and floral aromas. Conversely, the HM group's high-energy diet increased monounsaturated fatty acids and essential amino acids (EAAs). This promoted the production of Maillard-derived furfural and maintained the oxidative-antioxidant balance, preserving nutty and tallowy flavors. The WM group exhibited off-flavors due to oxidative imbalance, lower PUFAs content, and benzaldehyde accumulation. Overall, feeding regimes shape yak flavor by modulating fatty acid and amino acid compositions and the oxidative-antioxidant balance. This study provides a scientific basis for precision nutrition strategies to optimize flavor in yaks.

In the context of coexisting traditional and intensive yak production systems, clarifying the effects of different fattening strategies is crucial for optimizing meat quality and meeting consumer demands. This study compared three feeding regimes: traditional grazing (TG), low-concentrate (LC), and high-concentrate (HC) stall-feeding, in 18 yaks. The HC regimen enhanced carcass traits, average daily gain, dressing percentage, and marbling score, while also increasing myofiber size and drip loss. Shear force of meat from TG yak was greater than the two stall-fed groups and from LC yaks was greater than the HC yaks. Nutritionally, TG and HC meat had a higher polyunsaturated fatty acid (PUFA) content and PUFA:SFA ratio than LC meat. Importantly, grazing enriched n-3 PUFAs and improved oxidative stability, indicated by higher superoxide dismutase activity and lower malondialdehyde. The HC diet, however, increased n-6 PUFA and intramuscular fat. In conclusion, while feedlot finishing improves production efficiency and tenderness, grazing yields superior nutritional benefits and oxidative stability in yak meat.

The analysis of isomers in Citrus remains challenging due to chemical diversity and structural similarity under conventional 70 eV electron ionisation (EI) conditions. This study investigated electron energies down to 5 eV and evaluated the impact of manual tune on molecular ion (M^+•) repeatability using gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF/MS). Thirty-one representative Citrus isomers were used to optimise EI source parameters: emission current, electron energy, and ion source temperature. Manual tune improved M^+• repeatability, reducing RSD from 15.4-18.5% to 1.8%. The optimised low energy EI method (typically 11-12 eV, 175-195 °C) achieved favourable M^+• intensities with RSD below 5.5%. Comparisons across structurally related compounds revealed that conjugation and trans-configuration enhance M^+• stability, whereas allylic hydroxyl groups reduce it. This low energy EI approach improves M^+• preservation and repeatability, providing a promising option for isomer differentiation in complex Citrus volatile profiles.

To explore variations in the volatile components of milk originating from various species and to explain the material basis of their odor differences, electronic nose analysis coupled with headspace gas chromatography-mass spectrometry (HS-GC-MS) was employed to analyze the characteristics of human, sheep, goat, and cow milk. It was found that human milk exhibited larger response values to the broadrange and sulfur-chlor sensors, while sheep milk exhibited a large response value to the broad-methane sensor. The concentrations of dodecanoic acid, n-decanoic acid, and octanoic acid were significantly higher in human milk than in the sheep, cow, and goat milk. Moreover, it was deduced that a range of the detected volatile organic compounds were involved in the fatty acid biosynthesis pathway. These results allow identification of the different odor components related to human milk and other ruminant milk, providing a scientific basis for development of the dairy industry.

This study comprehensively evaluated the phytochemical and organoleptic evolution of Aronia melanocarpa wines aged for 12 months in glass bottles and oak barrels. Integrated analytical approaches-including CIELab color space, phenolic profiling, antioxidant capacity assays, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), electronic tongue, and Check-All-That-Apply (CATA) consumer testing-revealed distinct aging dynamics. Barrel aging caused 96.2% anthocyanin loss, shifting wine color to reddish-brown, while bottle aging preserved greater color stability (retaining 42.6% of anthocyanins). HS-GC-IMS identified 65 volatile compounds; barrel aging increased oxidative markers (e.g., 3-penten-2-one and 4-hydroxy-4-methyl-2-pentanone) and oak-derived notes (e.g., cocoa and coconut), whereas bottle aging enhanced tertiary aromas characterized by spicy, tobacco, and leather nuances. Electronic tongue and CATA analyses confirmed both aging methods improved taste profiles by reducing sourness and mitigating astringency/bitterness aftertastes. Bottle-aged wine demonstrated superior consumer preference (54.24% first-choice ranking) due to its fruity aroma, deeper color, and balanced taste.

This study aimed to compare the nutritional characteristics, antioxidant activity, and flavor differences of traditional fermented glutinous rice from four regions of China, and to elucidate the underlying metabolic mechanisms using metabolomics. Physicochemical assays, HPLC, GC-MS, and LC-MS analyzed five samples (HB_MPP, SC, JS, GZ_LYM, SWJD). Significant differences in antioxidant capacity and amino acids were found, with lysine as the first limiting amino acid. Dominant organic acids were lactic, malic, and fumaric acids. Forty volatile compounds (mainly esters, alcohols, acids) were detected, with phenylethanol, ethyl hexadecanoate, and ethyl decanoate as key flavor markers (VIP ≥ 1). Metabolomics identified 3027 metabolites, dominated by lipids (27.59%) and organic acids (26.99%). Key pathways included plant secondary metabolite biosynthesis and amino acid metabolism. This first multi-omics comparison highlights regional characteristic bases, aiding traditional fermented food quality evaluation and industrial application.