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优化酶碱法制备麦糟不溶性膳食纤维的过程中,蛋白质酶解和碱溶的工艺条件。通过单因子和正交试验,考察加酶量、酶解温度、酶解时间、NaOH浓度、碱溶温度和碱溶时间对不溶性膳食纤维的得率和蛋白质质量分数的影响,分析因素的主次顺序,优化工艺条件并验证。结果表明在酶解温度45℃,酶解时间3.5 h,加酶量为0.09 g,碱溶温度50℃,碱溶时间45 min,NaOH浓度1 mol/L的条件下,制备得到麦糟不溶性膳食纤维的得率为29.2%,蛋白质质量分数3.1%。结果为制备优质不溶性膳食纤维提供一定参考。 相似文献
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Dried distillers grains with solubles (DDGS) has been commonly used as a dietary protein source for lactating dairy cows. However, there is a paucity of data evaluating the use of DDGS as a partial replacement of forage or grain. The objective of this study was to determine the effects of partially replacing barley silage or barley grain with corn/wheat-based DDGS on dry matter intake (DMI), chewing activity, rumen fermentation, and milk production. Six ruminally cannulated lactating Holstein cows were used in a replicated 3 × 3 Latin square design with 21-d periods. Cows were fed the control diet (CON: 45% barley silage, 5% alfalfa hay, and 50% concentrate mix), a low forage (LF) diet or a low grain (LG) diet, in which barley silage or barley grain was replaced by DDGS at 20% of dietary dry matter, respectively. All diets were formulated to contain 18% crude protein and fed as total mixed rations. Compared with CON, cows fed the LF diet had greater DMI (26.0 vs. 22.4 kg/d), yields of milk (36.4 vs. 33.0 kg/d), milk protein (1.18 vs. 1.05 kg/d), and milk lactose (1.63 vs. 1.46 kg/d), but milk fat yield was not affected. The LF diet decreased chewing time compared with the CON diet (29.7 vs. 39.1 min/kg of DMI), but did not affect rumen pH and duration of rumen pH below 5.8. Compared with CON, feeding the LG diet tended to increase minimum and maximum rumen pH, but did not affect DMI, milk yield, and milk composition in this study. These results indicate that a partial replacement of barley silage with DDGS can improve the productivity of lactating dairy cows without negatively affecting rumen fermentation and milk fat production. Barley grain can also be partially replaced by DDGS in diets for lactating dairy cows without causing negative effects on productivity. 相似文献
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S.E. Boucher S. Calsamiglia C.M. Parsons H.H. Stein M.D. Stern P.S. Erickson P.L. Utterback C.G. Schwab 《Journal of dairy science》2009,92(12):6056-6067
The objectives of this experiment were to measure intestinal digestibility of AA in the rumen-undegraded protein fraction (RUP-AA) of distillers dried grains with solubles (DDGS) and fish meal (FM) samples and to determine whether these feeds contain a constant protein fraction that is undegradable in the rumen and indigestible in the small intestine, as assumed in the French Institut National de la Recherche Agronomique (Paris, France) and Scandinavian AAT-PBV (AAT = AA absorbed from small intestine; PBV = protein balance in the rumen) models. Five sources of DDGS and 5 sources of FM were obtained from Feed Analysis Consortium, Inc. (Champaign, IL). To obtain the rumen-undegradable protein fraction, samples were ruminally incubated in situ for 16 h in 4 lactating cows, and the collected rumen-undegraded residues (RUR) were pooled by sample. Subsamples of the intact feeds and RUR were crop-intubated to 4 cecectomized roosters, and total excreta were collected for 48 h. Intact feeds, RUR, and excreta were analyzed for AA. Basal endogenous AA loss estimates were obtained from fasted birds and were used to calculate standardized digestibility of RUP-AA and AA in the intact feeds. Indigestibility coefficients of the intact feeds were calculated as (100 − % standardized AA digestibility), and indigestibility of the RUR was calculated as [(100 − % ruminal degradation of AA) × (100 − % standardized RUP-AA digestibility)/100]. Results indicate that standardized digestibility of feed-AA differs from RUP-AA for DDGS samples but not for FM samples, and that standardized digestibility of individual AA differs within samples. For the DDGS samples, standardized feed-AA and RUP-AA digestibility values were most often lowest for His and Lys and highest for Met and Trp. For FM samples, standardized feed-AA and RUP-AA digestibility values were most often lowest for His and highest for Trp. Results also indicate that DDGS and most FM samples do not contain a constant protein fraction that is both undegradable in the rumen and indigestible in the small intestine. Indigestibility values of RUR were lower than in intact feeds, suggesting that the feed ingredients used in this experiment contain a protein fraction that is indigestible in the intestine but partly degradable in the rumen or digestible in the intestine after rumen incubation, or both. 相似文献
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Coda R Di Cagno R Rizzello CG Nionelli L Edema MO Gobbetti M 《Journal of food science》2011,76(6):M329-M335
Abstract: Acha and Iburu flours were singly subjected to sourdough fermentation with previously selected autochthonous starters. Sourdoughs were used (30%, wt/wt) as aroma carriers and acidifiers during short time fermentation with the addition of baker's yeast. Acha and Iburu sourdough breads were compared to wheat sourdough bread started with the same strains and to breads made with the same formula but using baker's yeast alone. During Acha and Iburu sourdough fermentations, starter lactic acid bacteria reached almost the same cell density found in wheat sourdoughs. Acidification was more intense. Iburu sourdough bread had the highest total titratable acidity, the lowest pH, and contained the highest levels of free amino acids and phytase activity. The values of in vitro protein digestibility did not differ between Acha sourdough and wheat sourdough breads, while Iburu sourdough bread showed a slightly lower value. Acha and Iburu sourdough breads showed lower specific volume and higher density with respect to wheat sourdough breads. Nevertheless, Acha and Iburu sourdough breads were preferred for hardness and resilience. As shown by sensory analysis, Acha and especially Iburu sourdough breads were appreciated for color, acid taste and flavor, and overall acceptability. Practical Application: This study was aimed at evaluating the technological and nutritional properties of the African cereals Acha and Iburu. Sourdough fermentation and the use of selected starters increased the nutritional and sensory qualities and the potential application for bakery industry. 相似文献
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From a total of four thousand presumed lactic acid bacteria, obtained from raw, unmalted sorghum and barley, 308 isolates were shown to exhibit inhibitory activity against the indicator strain Listeria innocua 4202. Six of these inhibitor‐producing isolates were selected for further study on the basis of their relatively wide antimicrobial spectrum, which showed that these producers inhibited several Gram‐positive bacteria, including a range of beer spoiling bacteria. The proteinaceous nature, anti‐microbial activity against closely related species, heat resistance and pH stability of the inhibitory substances produced by these six bacteria identified these compounds as bacteriocins. All six isolates were shown to secrete the inhibitory compounds into the cell free supernatants. Bacteriocins produced by five of the six producers were purified to homogeneity. Further analytic data was obtained for three of the inhibitory compounds by means of mass spectroscopy and/or N‐terminal amino acid sequencing. 相似文献