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1.
Fermentation of cottonseed and other feedstuffs in cattle rumen fluid   总被引：2，自引：0，他引：2  
Bovine rumen fluid was fermented anaerobically over 48 h with cottonseed, corn, alfalfa, or a mixture of these substrates in anaerobic mineral buffer. Samples taken at different incubation times were derivatized with n-butanol and subjected to gas chromatography and mass spectroscopy. No unusual fermentation end-products from the cottonseed substrate were detected. Cottonseed supported rumen fermentation at levels comparable to those of the other substrates. Major components were usually found in the decreasing order of acetate, propionate, butyrate, and valerate, although acetate and propionate concentrations decreased late in the alfalfa and mixed-feed fermentations, eventually allowing butyrate concentrations to exceed those of propionate. As expected, lactate was produced in high concentrations when corn was fermented. The minor components 2-methylpropionate, 2- and 3-methylbutyrate, phenylacetate, phenylpropionate, and caproate also accumulated, with their relative concentrations varying with the substrate. Succinate was produced in substantial amounts only when corn and alfalfa were fermented; it did not accumulate when cottonseed was the substrate. Samples containing cottonseed were derivatized and subjected to reversed-phase high-performance liquid chromatography, revealing that gossypol concentrations did not change during fermentation.  相似文献   

2.
Two Florida strawberry cultivars, 'Strawberry Festival' and 'Florida Radiance', were harvested at five fruit developmental stages (white, half red, three-quarter red, full ripe, and overripe) at four harvest dates. A static headspace solid-phase microextraction (SPME) sampling technique coupled with gas chromatography (GC) using pulsed flame photometric detection (PFPD) was employed to measure 16 sulfur volatiles in these strawberries. A total of 7 sulfur volatiles have been previously reported, and 9 are reported for the first time in strawberries. Newly identified sulfur volatiles include methyl thiopropionate, ethyl thiobutanoate, methyl thiohexanoate, methyl (methylthio)acetate, ethyl (methylthio)acetate, methyl 2-(methylthio)butyrate, methyl 3-(methylthio)propionate, ethyl 3-(methylthio)propionate, and methyl thiooctanoate. Identifications were based on matching sulfur peak linear retention indexes (LRIs) of unknowns with authentic standards and gas chromatography-mass spectrometry (GC-MS) data. Concentrations were determined using both internal and external standards. Most sulfur volatiles increased with increasing maturity, with only concentrations of hydrogen sulfide and methanethiol remaining relatively consistent at all five stages. At the white and half red stages, most sulfur volatiles consisted of various alkyl sulfides. At three-quarter red (commercial ripe), full ripe, and overripe stages, the majority of sulfur volatiles consisted of sulfur esters. Most sulfur volatiles increased dramatically between the commercial ripe, full ripe, and overripe stages, increasing as much as 100% between full ripe and overripe. Principal component analysis indicated that sulfur volatiles could be used to distinguish overripe from full ripe and commercial ripe berries.  相似文献   

3.
Butyrate is a byproduct of microbial carbohydrate fermentation that occurs primarily in the large intestine. When added to feed, butyrate quickly disappears in the upper digestive tract. Because butyrate is important for epithelial cell development, mucosal integrity, and animal growth, an encapsulation technique has been developed that allows for the slow release of butyrate into the small and large intestines. The purpose of this study was to describe the in vitro release of calcium [1-(14)C]butyrate, formulated into a slow-release (protected) bead, into water and simulated intestinal fluids and to compare the in vivo absorption and disposition of unprotected versus protected calcium [1-(14)C]butyrate in broiler chicks. Formulation of calcium [1-(14)C]butyrate into protected beads allowed release of 5.8 ± 0.2 and 3.4 ± 0.2% of the formulated radiocarbon into water and gastric fluid, respectively, after 2 h of incubation. Beads incubated in gastric fluid for 2 h and subsequently incubated in simulated intestinal fluid released a total of 17.4 ± 0.8% of the formulated radioactivity. Release of respiratory [(14)C]CO(2) after oral dosing of aqueous calcium [1-(14)C]butyrate in broiler chicks peaked at 15.2 ± 5.2% per hour 1.5 h after dosing; in contrast, maximal rates of release in chicks dosed with protected calcium [1-(14)C]butyrate occurred 4 h after dosing at 9.0 ± 3.1% per hour. The data suggested an improved efficacy of protected butyrate delivery to intestinal tissues over nonprotected butyrate. This study confirmed that encapsulation strategies designed to enhance delivery of ingredients to improve intestinal health are effective at prolonging intestinal exposure to butyrate. Encapsulation of such ingredients might benefit the food and feed industries.  相似文献   

4.
本研究采用体外法在油酸（Oleic acid,OA）、亚油酸（Linoleic acid,LA）、亚麻酸（Linolenic acid,LNA）的基础上添加不同水平苹果酸(Malic acid, MA),研究苹果酸和不饱和脂肪酸对瘤胃发酵模式与瘤胃主要功能菌群的影响。结果表明添加不饱和脂肪酸和苹果酸后,丙酸浓度随着脂肪酸不饱和度的增加显著升高（P<0.01）,总产气量和CH4产量显著降低（P<0.01）,其它挥发性脂肪酸均随着脂肪酸不饱和度的增加显著降低（P<0.01）。添加不饱和脂肪酸LA与LNA的甲酸甲烷杆菌数量显著增加（P<0.01）;白色瘤胃细菌与黄色瘤胃细菌数量比CK组显著增加（P<0.05）;而脂解厌氧弧杆菌和溶纤维丁酸弧菌数量比CK组却显著下降（P<0.05）。联合添加苹果酸和不饱和脂肪酸组中,只有在添加10 mmol/L苹果酸的OA组的甲酸甲烷杆菌,数量明显减少（P<0.05）。结论是不饱和脂肪酸和苹果酸能够改善瘤胃发酵模式,但二者对体外CH4抑制作用之间没有直接的联系。并且联合添加二者对于瘤胃主要功能菌群没有显著影响。  相似文献   

5.
A method is described for determining major constituents in the smoke of a cigarette that heats, but does not burn, tobacco. Dual, simultaneous separations are performed in a single gas chromatographic oven to determine water, glycerol, nicotine, and propylene glycol in a rapid and cost-effective manner. A materials balance of new cigarette smoke total particulate matter was attempted from both Cambridge filter and electrostatic precipitation smoke collection data. Serious deficiencies were found when Cambridge filter smoke collection was applied for this purpose. Electrostatic precipitation smoke collection eliminated these problems. The data obtained by electrostatic precipitation smoke collection indicate that water, glycerol, nicotine, and propylene glycol make up about 94% of new cigarette smoke total particulate matter.  相似文献   

6.
Aroma-active compounds from a beeflike process flavor, produced by extrusion of enzyme-hydrolyzed vegetable protein (E-HVP), were analyzed using aroma extract dilution analysis. The number of aroma-active compounds and the aroma intensity were increased by the addition of aroma precursors prior to extrusion. The most intense compound was 2-methyl-3-furanthiol having a cooked rice/vitamin-like/meaty aroma note. Several sulfur-containing furans, such as 2-methyl-3-(methylthio)furan, 2-methyl-3-(methyldithio)furan, and bis(2-methylfuryl)disulfide, were detected with high flavor dilution (FD) factors. Some pyrazines, such as 2-ethyl-3,5-dimethylpyrazine, 2,6-diethylpyrazine, and 3,5-diethyl-2-methylpyrazine, also had high FD factors. It is hypothesized that sulfur-containing amino acids and thiamin were important precursors in aroma formation in process flavor from E-HVP.  相似文献   

7.
Metabolite production and antioxidant released during colonic fermentation of naturally occurring dietary fiber (DF) from two European diets (Mediterranean and Scandinavian) were determined. With this aim, DF and associated components were isolated from both whole diets, as well as from cereals and fruits and vegetables comprising the diets. DF was used as substrate for colonic fermentation in a dynamic in vitro model of the colon, samples were collected, and fermentation metabolites were analyzed. Statistical differences between samples were observed in the concentrations of short-chain fatty acids and ammonia and in the ratio acetate/propionate/butyrate. Whole grain cereal DF generated a larger amount of propionate than refined flour cereal DF. Fruit and vegetable DF generated higher amounts of butyrate than cereal DF. Most antioxidant compounds were released from DF during in vitro colonic fermentation. It is concluded that different sources of DF may play a specific role in health maintenance mediated by metabolites produced during colonic fermentation.  相似文献   

8.
Three commonly used flavor industry solvents (propylene glycol, triacetin, and triethyl citrate) were tested for their capacity to interfere with the ability of alpha-, beta-, and gamma-cyclodextrin to form molecular inclusion complexes with flavors. Six flavor compounds (ethyl butyrate, ethyl heptanoate, l-menthol, methyl anthranilate, neral, and geranial) were measured by headspace gas chromatography above 2:1 water/ethanol containing appropriate additions of cyclodextrin and flavor solvent. The smallest and most polar solvent molecule represented by propylene glycol had the least effect on cyclodextrin/flavorant complex formation. In contrast, triacetin, intermediate in size among the three flavor diluents studied, had the greatest effect, even though, based on at least some computed molecular parameters, it appears to be more polar than triethyl citrate. The explanation for this apparent anomaly may lie in differences in the extent to which triacetin and triethyl citrate are able to interact with cyclodextrins by means of partial interaction with the hydrophobic cavities of the latter.  相似文献   

9.
甜高粱是一种重要的能源作物,为实现长时间贮存并提升糖化效率,该研究分析了瘤胃液不同添加量对全株甜高粱青贮品质和酶解糖化效果的影响。设置R1、R3、R5和R7共4个瘤胃液处理组(添加量依序分别为1、3、5和7 mL/100 g原料)和1个对照组(CK,等量蒸馏水),考察了瘤胃液不同添加量对全株甜高粱青贮过程中有机组分、发酵品质和酶解性能等质量指标的动态影响,并跟踪解析青贮期间微生物菌群的动态演绎。结果表明,添加瘤胃液能明显减少青贮甜高粱中的干物质、水溶性碳水化合物、粗蛋白以及木质纤维组分含量,使青贮pH和氨氮含量显著下降(P0.05),并与瘤胃液添加量呈负相关。青贮中的乳酸、乙酸含量随瘤胃液添加量和青贮发酵时间延长而明显增加(P0.05),瘤胃液强化了青贮发酵并有助于减少干物质损失,尤其在较高添加量时,青贮60d时的甜高粱综纤维素含量反而有所增加。4种瘤胃液处理组的门水平优势细菌主要为厚壁菌和变形菌,厚壁菌相对丰度随时间延长和瘤胃液添加量的增加而逐渐增加,变形菌门丰度则逐渐下降;属水平主要以乳酸杆菌、泛菌和醋酸杆菌为主,乳酸杆菌丰度与时间、瘤胃液添加量呈正相关,而泛菌则呈减少趋势。瘤胃液强化青贮后的甜高粱还原糖得率显著提升,尤其瘤胃液添加量为7 mL/100 g的R7处理组的糖得率较原料分别提高了11.06%(30 d)和19.28%(60 d)。添加瘤胃液能有效改善青贮甜高粱的发酵质量和生物降解性能,起到生物强化的预处理作用,为甜高粱的乙醇化利用奠定了基础。  相似文献   

10.
In vitro fermentabilities of the oat flour digestion residues (ODR) from two commercial oat lines with 4.7 and 5.3% beta-glucan and from two high-beta-glucan experimental lines with 7.6 and 8.1% beta-glucan were evaluated and compared with fermentations of lactulose, purified oat beta-glucan (POBG), and purified oat starch (POS). Substrates were fermented by using an in vitro batch fermentation system under anaerobic conditions for 24 h. The progress of the fermentation was studied by following the change in pH of the fermentation medium, production of short-chain fatty acids (SCFA) and gases, and consumption of carbohydrates. The substrate from the flour with the greatest amount of beta-glucan tended to have the greatest pH decline and the greatest total SCFA production. A significant correlation occurred between gas production and SCFA formation (R 2 = 0.89-0.99). Acetate was produced in the greatest amounts by all of the substrates except POBG, by which butyrate was produced in the greatest amount. More propionate and butyrate, but less acetate, were produced from high-beta-glucan ODR. With the given fermentation conditions, >80% of the total carbohydrate was depleted by the bacteria after 24 h. Glucose was the most rapidly consumed carbohydrate among other available monosaccharides in the fermentation medium. Overall, the high-beta-glucan experimental lines provided the best conditions for optimal in vitro gut fermentations.  相似文献   

11.
Flavor quality is of major importance to the consumer, but the flavor characteristics of beer appear to deteriorate greatly with time, at a rate depending on the composition of the beer and its storage conditions (notably pH). Prior to identifying the influence of pH on the development of the most intense staling flavors found in aged lager beers, the corresponding key flavor compounds were determined by aroma extract dilution analysis. In addition to trans-2-nonenal, beta-damascenone seems at least as important in the flavor of aged beer. Ethyl butyrate, dimethyl trisulfide, 2-acetylpyrazine, 3-(methylthio)propionaldehyde, 2-methoxypyrazine, maltol, gamma-nonalactone, and ethyl cinnamate are also relevant to the sensory profile of aged beer. Upon aging, a beer having a higher pH produces less beta-damascenone, because acid-catalyzed glycoside hydrolysis is decreased. On the other hand, it produces more 3-(methylthio)propionaldehyde, owing to Strecker degradation of methionine. Raising the beer pH additionally causes the release of 3-(methylthio)propionaldehyde from sulfitic adducts. These adducts, more stable at a lower pH, protect the aldehyde against premature oxidation to 3-(methylthio)propionic acid, thus making it available for dimethyl trisulfide formation during aging.  相似文献   

12.
互花米草与土豆混合厌氧发酵产酸和产沼气特性（英）   总被引：1，自引：1，他引：1  
研究了中温（35℃）批量发酵条件下互花米草与土豆VS配比分别为6∶1、7∶1和9∶1时混合厌氧发酵的产酸发酵和产沼气特性。试验结果表明：1）与互花米草单独发酵时的丙酸型产酸发酵不同,混合发酵的产酸发酵表现为丁酸型发酵;混合发酵时发酵液中总挥发性有机酸（TVFAs）的浓度比互花米草单独发酵时提高了1倍多;混合发酵时发酵液中各单一有机酸浓度依次为乙酸>丙酸>丁酸,而互花米草单独发酵时为丙酸>乙酸>丁酸;2）6∶1、7∶1和9∶1三种配比下的沼气产量分别为460、431和415 mL/g VS,比互花米草单独发酵时的361 mL/gVS分别提高了27.4%、19.3%和15.0%;3）6∶1、7∶1和9∶1三种配比下的沼气中的甲烷含量分别为60.3%、62.4%和62.7%,比互花米草单独发酵条件下57.4%的平均甲烷含量提高了大约3%～5%。总之,混合发酵显著改变了互花米草的产酸发酵特性,这些改变对促进互花米草的厌氧发酵和提高所产沼气的质量均具有积极的意义。  相似文献   

13.
RS4‐type resistant wheat starch (RWS) and resistant potato starch (RPS) were subjected successively to in vitro digestion with pepsin and pancreatin‐bile, and the indigestible residues (82.1% db and 74.1% db, respectively) were recovered and subsequently fermented by in vitro techniques using fresh human fecal microbiota as inoculum. Scanning electron microscopy of the indigestible residues showed surface erosion on the residual granules. Total gas production during the in vitro fermentation increased almost linearly over time with the two resistant starches exhibiting similar gas production rates, as well as a similar rate of production of total short‐chain fatty acids (SCFA). The indigestible fractions from both starches produced acetate as the major SCFA and relatively higher levels of butyrate than propionate, but wheat starch tended to produce more butyrate over time than potato starch. Fractional molar ratios of acetate, propionate, and butyrate from the RWS and RPS were 0.586:0.186:0.228 and 0.577:0.200:0.223, respectively. The calculated caloric contributions of the RWS and RPS are ≈33% lower than for unmodified starch and are comparable to those reported in the literature for RS2 and RS3 high‐amylose maize starches.  相似文献   

14.
Xylo-oligosaccharides (XOS) with various substituents were fermented in vitro by fecal inocula (FI) from four human volunteers to study the influence of substitution on the ability and rate of fermentation and on the production of short-chain fatty acids (SCFA) and lactate. By all FI used nonsubstituted XOS (nXOS) and arabino-XOS (AXOS) were fermented more quickly than the more complex structures of acetylated XOS (AcXOS) and XOS containing a 4-O-methylglucuronic acid group (GlcA(me)XOS). In the first stage (0-40 h) of the fermentations of nXOS and AXOS mainly acetate and lactate were formed. The fermentations of AcXOS and GlcA(me)XOS resulted in a lower lactate production, whereas the concentration of propionate and butyrate increased. These results put emphasis on the detailed elucidation of the structural features of nondigestible oligosaccharides in general to understand their fermentation mechanisms more precisely.  相似文献   

15.
Volatile compounds of 15 Charentais melon cultivars, known to exhibit differences in their ripening behaviors and in their storage lives (wild, mid, and long shelf life), were investigated. Twenty-eight volatiles (11 esters, 8 sulfur compounds, 6 alcohols, and 3 carbonyl compounds) were isolated by direct dichloromethane extraction and analyzed by means of GC-MS and GC-FID. A considerable reduction in the aroma profile was observed for the long shelf life cultivars, in which total volatiles were 49-87% lower than in the wild or mid shelf life melons. Most of the esters such as ethyl 2-methylbutyrate, ethyl butyrate, ethyl hexanoate, hexyl acetate, and butyl acetate and sulfur compounds such as ethyl 2-(methylthio)acetate, 2-methylthioethanol, ethyl 3-(methylthio)propanoate, 3-(methylthio)propyl acetate, and 3-(methylthio)propanol with low odor values were 2-30-fold lower in long shelf life cultivars than in the others. Discrimination of long shelf life cultivars from wild and mid shelf life melons was achieved by statistical treatment of the data by principal component and variance analysis.  相似文献   

16.
The irreversible binding of selected sulfur-containing flavor compounds to proteins was investigated in aqueous solutions containing ovalbumin and a mixture of disulfides (diethyl, dipropyl, dibutyl, diallyl, and 2-furfuryl methyl) using solid-phase micro-extraction (SPME). In systems which had not been heated, the recovery of disulfides from the headspace above the protein at the native pH (6.7) was similar to that from an aqueous blank. However, significant losses were observed when the pH of the solution was increased to 8.0. When the protein was denatured by heating, much greater losses were observed and some free thiols were produced. In similar heat-denatured systems at pH 2.0, no losses of disulfides were observed. Disulfides containing allyl or furfuryl groups were more reactive than saturated alkyl disulfides. Interchange reactions between protein sulfhydryl groups and the disulfides are believed to be responsible for the loss of the disulfides.  相似文献   

17.
Patulin, a toxic fungal metabolite, negatively affects rumen fermentation. This mycotoxin has also been associated with intoxication cases in cattle. This study investigates the use of SH-containing reducing compounds to prevent patulin's negative effects on the rumen microbial ecosystem. The effect of 50 microg/mL patulin on the fermentation of alfalfa hay was measured in batch cultures with and without reducing agents. Sulfhydryl-containing cysteine and glutathione prevented the negative effects of the toxin on dry matter degradation, gas, and volatile fatty acid production (P < 0.01). However, non-sulfhydryl-containing ascorbic and ferulic acids did not protect against patulin's toxicity (P > 0.01). Patulin was unstable in buffered rumen fluid as the concentration decreased by half after 4 h of incubation. In the presence of sulfhydryl groups, the toxin disappeared rapidly and was not detected after 1 h of incubation. The utilization of sulfhydryl-containing compounds such as cysteine to avert patulin toxicity could have practical implications in ruminant nutrition.  相似文献   

18.
Rye bran and aleurone, wheat bran and aleurone, and oat bran and cell wall concentrate were compared in their in vitro gut fermentation patterns of individual phenolic acids and short-chain fatty acids, preceded by enzymatic in vitro digestion mimicking small intestinal events. The formation of phenolic metabolites was the most pronounced from the wheat aleurone fraction. Phenylpropionic acids, presumably derived from ferulic acid (FA), were the major phenyl metabolites formed from all bran preparations. The processed rye, wheat, and oat bran fractions contained more water-extractable dietary fiber (DF) and had smaller particle sizes and were thus more easily fermentable than the corresponding brans. Rye aleurone and bran had the highest fermentation rate and extent probably due to high fructan and water-extractable arabinoxylan content. Oat samples also had a high content of water-extractable DF, β-glucan, but their fermentation rate was lower. Enzymatic digestion prior to in vitro colon fermentation changed the structure of oat cell walls as visualized by microscopy and increased the particle size, which is suggested to have retarded the fermentability of oat samples. Wheat bran was the most slowly fermentable among the studied samples, presumably due to the high proportion of water-unextractable DF. The in vitro digestion reduced the fructan content of wheat samples, thus also decreasing their fermentability. Among the studied short-chain fatty acids, acetate dominated the profiles. The highest and lowest production of propionate was from the oat and wheat samples, respectively. Interestingly, wheat aleurone generated similar amounts of butyrate as the rye fractions even without rapid gas production.  相似文献   

19.
瘤胃真菌与酿酒酵母仿生共培养提升秸秆发酵产乙醇量   总被引：1，自引：1，他引：0  
玉米秸秆中具有较高的纤维素、半纤维素含量,是一种具有稳定产率、可集中处理、可代替木材作制浆原料的生物质材料。为了研究厌氧微生物与酵母共培养预处理玉米秸秆的产物,该研究模拟反刍动物消化玉米秸秆的过程,从羊瘤胃液中分离出厌氧真菌（Pecoramyces sp.）。以玉米秸秆茎皮碎为底物,与厌氧真菌、酿酒酵母菌S1145在39℃进行共培养72 h,分析发酵对秸秆茎皮降解及其代谢产物的影响。结果表明,在瘤胃真菌作用下,添加不同量的酿酒酵母可对代谢产物中乙醇含量产生影响,其中添加5 mL酿酒酵母时产生的乙醇含量最高,占总代谢产物比例为32.09%,相对于未添加酿酒酵母的对照组,乙醇含量提高了23.04百分点。研究表明,在厌氧真菌与酿酒酵母共培养预处理玉米秸秆茎皮的过程中,添加酿酒酵母可提高乙醇产量,为玉米秸秆高效资源化处理和生物质燃料生产提供了一种可靠的方法。  相似文献   

20.
Providing balanced energy and nutrients for microbiota growth is essential for the maintenance of the colon ecosystem, and dietary fiber (DF) fermentation, particularly butyrogenic fermentation, augments colon health. Cereal DF, which are the complex carbohydrates of cereal grains that escape small intestine digestion and function either as substrate for colonic fermentation or as bulking material, are a dietary measure to mitigate the occurrence of certain colonic diseases, and perhaps to some degree act as therapeutic agents. In developed Western countries, as well as in many developing countries, colon cancer is one of the major causes for premature death and disability, and inflammatory bowel disease and other colonic disorders have become serious health issues. The function of DF in colon health is mediated through its physicochemical properties (e.g., water‐holding for laxative effect) or effect on colon microbiota (e.g., leading to immune regulation), as well as through colonic fermentation products, principally the short chain fatty acids (SCFA) of acetate, propionate, and butyrate. Due to the chemical diversity and complexity of DF and because not all DF materials function equally, new developments in DF fermentation behavior (pattern and end product profile) will be reviewed from a structure‐function viewpoint. The effect of cereal DF, mainly nonstarch cereal polysaccharides and resistant starch on colonic microbiota, fermentation products of SCFA, microbiota modulation, as well as on colon health will be summarized.  相似文献   

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