RESUMEN
Mature honeys that brew naturally in the hive develop distinct bioactive components, and thus carry a higher premium due to their superior quality. However, how to identify mature honeys remains difficult. Trace oligosaccharides are a likely source of biomarkers to indicate maturity. Here, we profiled trace oligosaccharides in acacia honey by GC-MS and used a metabolomics strategy to screen oligosaccharides that distinguish honeys with different maturities. Turanose content increased gradually in acacia honey samples and was closely related to the days stored in the hive (p < 0.05). To accurately quantify turanose, a UPLC-ELSD method was developed. Using the established method, honeys with ≥1.20 g/100 g of turanose could be classified as mature acacia honey. Based on the preliminary study, 500 commercial acacia honeys were analyzed, and only 77.2 % of these samples had a satisfactory level of turanose. This work offers a potential method to evaluate the quality of honeys.
Asunto(s)
Acacia , Miel , Cromatografía de Gases y Espectrometría de Masas , Miel/análisis , Metabolómica , OligosacáridosRESUMEN
The Giant Willow Aphid (Tuberolachnus salignus, GWA) is an invasive pest insect in New Zealand, which excretes honeydew. European honeybees collect this honeydew and make it into a type of honey that crystallizes in the comb, representing a significant loss to apiarists. This crystallization has been ascribed to high concentrations of oligosaccharides, particularly melezitose. In this research, the first carbohydrate profile of GWA honeydew honey, a sample of GWA honeydew honey was found to contain 37.8% total oligosaccharides of which 27.4% was melezitose, and 2.5% gluconic acid (higher than typical honeydew honeys); 41.2% monosaccharides (lower than typical honeydew honeys); and 0.054% salicylic acid (higher than previous estimates). Melezitose extracted from GWA honeydew honey was not significantly hydrolyzed in crude human-stomach and human-small-intestine simulations and may therefore meet the prebiotic criterion of human indigestibility.
Asunto(s)
Áfidos/metabolismo , Alimentos Funcionales/análisis , Miel/análisis , Prebióticos/análisis , Animales , Humanos , Nueva Zelanda , Oligosacáridos/análisis , Trisacáridos/análisisRESUMEN
3-Deoxyglucosone (3-DG) is a metabolite from sugar degradation obtained by the Maillard reaction. It is an important precursor compound in Strecker reactionism that directly leads to known beer aging indicators and can influence the final sensory beer quality. However, the conditions of 3-DG formation in the malting process have not yet been described. To investigate the reaction pathways of 3-DG formation, we varied the composition of reactants (sugars, amino acids) by using different malting modification levels (germination time 5-7â¯d; steeping degree 42-45%; germination temperature 12-14⯰C); final kilning temperature (60⯰C to 100⯰C). After its derivatization with ortho-phenylenediamine, we analyzed 3-DG with HPLC-UV. 3-DG concentration was between 5 and 120⯵mol/100â¯g dry weight. The formation of 3-DG increased for high malt modification levels and high final kilning temperature. The abundant formation of 3-DG in the malting process is already comparable to the occurred brewing process concentration.
Asunto(s)
Desoxiglucosa/análogos & derivados , Manipulación de Alimentos/métodos , Aminoácidos/análisis , Cerveza/análisis , Cromatografía Líquida de Alta Presión , Desoxiglucosa/química , Reacción de Maillard , Monosacáridos/análisis , Fenilendiaminas/análisis , Espectrofotometría Ultravioleta , TemperaturaRESUMEN
Power ultrasound as an emerging processing technology has been investigated for stimulating seeds to enhance germination and accumulation of health-promoting metabolites, such as γ-aminobutyric acid (GABA) and phenolic compounds. This work was undertaken to evaluate the effects of power ultrasound (25â¯kHz) on the nutritional properties of germinated oats, and the microstructure of oat groats after treatment. The changes in the external and internal microstructures of the ultrasound-treated oats kernel were investigated using Environmental Scanning Electron Microscopy (ESEM) and 3D X-ray Micro Computed Tomography (Micro-CT). Physicochemical properties of oats including GABA, free sugars, avenanthramides, total phenolic content, and antioxidant capacities were enhanced after germination. Furthermore, the power ultrasound treatment for 5â¯min after soaking significantly enhanced the GABA (48-96â¯h), alanine (24-96â¯h), succinic acid (48-72â¯h), total phenolic content (24â¯h), and total avenanthramides (24â¯h) in the germinated oats.
Asunto(s)
Avena/metabolismo , ortoaminobenzoatos/metabolismo , Antioxidantes/química , Avena/química , Cromatografía Líquida de Alta Presión , Germinación , Espectrometría de Masas , Fenoles/análisis , Fenoles/química , Fenoles/metabolismo , Semillas/química , Semillas/metabolismo , Sonicación , Factores de Tiempo , Microtomografía por Rayos X , Ácido gamma-Aminobutírico/análisis , Ácido gamma-Aminobutírico/metabolismo , ortoaminobenzoatos/análisisRESUMEN
Lactobacillus buchneri is a Gram-positive, obligate heterofermentative, facultative anaerobe commonly affiliated with spoilage of food products. Notably, L. buchneri is able to metabolize lactic acid into acetic acid and 1,2-propanediol. Although beneficial to the silage industry, this metabolic capability is detrimental to preservation of cucumbers by fermentation. The objective of this study was to characterize isolates of L. buchneri purified from both industrial and experimental fermented cucumber after the onset of secondary fermentation. Genotypic and phenotypic characterization included 16S rRNA sequencing, DiversiLab® rep-PCR, colony morphology, API 50 CH carbohydrate analysis, and ability to degrade lactic acid in modified MRS and fermented cucumber media. Distinct groups of isolates were identified with differing colony morphologies that varied in color (translucent white to opaque yellow), diameter (1â¯mm-11â¯mm), and shape (umbonate, flat, circular or irregular). Growth rates in MRS revealed strain differences, and a wide spectrum of carbon source utilization was observed. Some strains were able to ferment as many as 21 of 49 tested carbon sources, including inulin, fucose, gentiobiose, lactose, mannitol, potassium ketogluconate, saccharose, raffinose, galactose, and xylose, while others metabolized as few as eight carbohydrates as the sole source of carbon. All isolates degraded lactic acid in both fermented cucumber medium and modified MRS, but exhibited differences in the rate and extent of lactate degradation. Isolates clustered into eight distinct groups based on rep-PCR fingerprints with 20 of 36 of the isolates exhibiting >97% similarity. Although isolated from similar environmental niches, significant phenotypic and genotypic diversity was found among the L. buchneri cultures. A collection of unique L. buchneri strains was identified and characterized, providing the basis for further analysis of metabolic and genomic capabilities of this species to enable control of lactic acid degradation in fermented plant materials.
Asunto(s)
Ácido Acético/metabolismo , Cucumis sativus/microbiología , Ácido Láctico/metabolismo , Lactobacillus/genética , Lactobacillus/metabolismo , Propilenglicol/metabolismo , Reactores Biológicos , Fermentación , Genotipo , Lactobacillus/clasificación , Lactobacillus/aislamiento & purificación , ARN Ribosómico 16S/genéticaRESUMEN
This study dealt with the influence of a crucial pH value of 4.0 on the microbiota of spontaneously fermented backslopped liquid wheat sourdoughs. Two spontaneously fermented wheat sourdough fermentation experiments were carried out, one without control of the pH and one with the pH kept constant at pH4.0, both during nine backslopping steps. In each case, two additional backslopping steps were carried out, with the pH kept constant at 4.0 and with free pH, respectively. Keeping the pH constant at 4.0 changed the microbial community dynamics and metabolite kinetics of the sourdough fermentations. A slower prevalence of sourdough-specific Kazachstania yeasts occurred. Nevertheless, in both experiments, Lactobacillus fermentum, Lb. plantarum/pentosus/paraplantarum, and Kazachstania exigua/bulderi/barnettii prevailed ultimately. The lactic acid and ethanol concentration profiles were affected positively by keeping the pH constant at a minimum of 4.0 as well as the l- and d-lactic acid ratio profile, a potential biological marker for sourdough stability and maturity. Also, the concentration and diversity of acetate esters and their precursors, in particular isoamyl acetate and isoamyl alcohol, were affected negatively by the pH control, indicating the role of pH stress in the sourdough aroma formation.
Asunto(s)
Pan/microbiología , Etanol/metabolismo , Concentración de Iones de Hidrógeno , Ácido Láctico/metabolismo , Microbiota/fisiología , Triticum/metabolismo , Acetatos/metabolismo , Acetoína/metabolismo , Fermentación , Harina/microbiología , Cromatografía de Gases y Espectrometría de Masas , Cinética , Limosilactobacillus fermentum/metabolismo , Manitol/metabolismo , Triticum/microbiología , Levaduras/metabolismoRESUMEN
The effect of processing conditions on heat damage, starch digestibility, release of advanced glycation end products (AGEs) and antioxidant capacity of puffed cereals was studied. The determination of several markers arising from Maillard reaction proved pyrraline (PYR) and hydroxymethylfurfural (HMF) as the most reliable indices of heat load applied during puffing. The considerable heat load was evidenced by the high levels of both PYR (57.6-153.4 mg kg(-1) dry matter) and HMF (13-51.2 mg kg(-1) dry matter). For cost and simplicity, HMF looked like the most appropriate index in puffed cereals. Puffing influenced starch in vitro digestibility, being most of the starch (81-93%) hydrolyzed to maltotriose, maltose and glucose whereas only limited amounts of AGEs were released. The relevant antioxidant capacity revealed by digested puffed kernels can be ascribed to both the new formed Maillard reaction products and the conditions adopted during in vitro digestion.
Asunto(s)
Manipulación de Alimentos/métodos , Calor , Almidón/química , Triticum/química , Antioxidantes/análisis , Fenómenos Químicos , Grano Comestible/química , Furaldehído/análogos & derivados , Furaldehído/análisis , Glucosa/química , Hidrólisis , Reacción de Maillard , Maltosa/química , Modelos Biológicos , Norleucina/análogos & derivados , Norleucina/análisis , Pirroles/análisis , Trisacáridos/químicaRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: The cortex and leaves of Eucommia ulmoides Oliv. from the family Eucommiaceae are traditional Chinese medicines (TCM). Roasted Eucommiae cortex is utilized to reinforce the muscles and lungs, lower blood pressure and improve the tone of the liver and kidneys, while Eucommia ulmoides leaves (EUL) are traditionally used as folk remedies to treat diabetes. MATERIALS AND METHODS: EUL extract, obtained by ethanol (40%) was loaded onto an AB-8 macroporous resin column, and washed thoroughly with 0, 20, 40, 60, and 80% (v/v) ethanol for purification. The ethanol eluents of EUL were first determined to inhibit α-glucosidase in vitro, and then the inhibition of the most potent eluent, i.e., 20% ethanol eluent of EUL (EEUL), against carbohydrate-degrading enzymes and glucose transport in Caco-2 cells was demonstrated. And computational modeling was also employed to evaluate the binding modes of compounds identified in EEUL by GC-MS analysis. RESULTS: EEUL significantly inhibited α-glucosidase (43.08±0.55%) competitively in vitro and concentration-dependently suppressed sucrase (IC50, 0.07mg/mL) and maltase (IC50, 0.53mg/mL) in Caco-2 cells. The inhibitory activity of EEUL (0.02mg/mL) on sucrase and maltase was identical to that of acarbose (0.02mg/mL). Moreover, 1.0mg/mL EEUL decreased glucose transport in cells by 26.25±0.86%. GC-MS revealed that EEUL was rich in monosaccharides, polyphenols and esters, which comprised 47.16% of the total extract. Computational modeling showed that catechin, α-d-glucopyranose and d-mannono-1,4-lactone docked tightly into the sucrase active site with low binding energies. CONCLUSION: These results indicated that EEUL exerted marked anti-hyperglycemic effects by suppressing disaccharidases and glucose transporters. Therefore, EUL is a beneficial source of inhibitors of carbohydrate-utilizing enzymes, glucose transporters, and potentially hyperglycemia.