共查询到19条相似文献,搜索用时 62 毫秒
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研究300~600 MPa超高压条件下处理四川泡萝卜5~25 min,对其细菌总数的影响、对霉菌、酵母菌及大肠菌群的杀灭效果的影响。并采用3 种模型对不同压力条件下杀菌动力学过程进行分析比较。结果表明:随处理压力和时间的增加,超高压对泡萝卜的杀菌效果增强;霉菌和酵母菌对压力较为敏感,500 MPa处理5 min可被全部杀死;Weibull模型能很好地拟合泡萝卜超高压杀菌的动力学过程(决定系数R2>0.99),且相较Log-logistic模型更简洁、灵活实用。尺度参数b随处理压力的增加而增大,形状参数n则随压力的增加而减小。 相似文献
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超高压杀菌及其反应动力学 总被引:14,自引:7,他引:14
大多数非芽孢微生物的耐压性较低,室温450MPa以下压力的杀菌效果良好,微生物的死亡遵循一级反应动力学。低温(0℃以下)或高于室温的温度有利于对这些微生物的超高压杀菌。芽孢菌孢子耐压,杀菌时需要更高的压力,而且往往要结合加热等其它处理才更有效。常中温时,超高压下孢子的死亡一般不遵循一级反应动力学。温度、介质等对微生物超高压杀菌的模式和效果影响很大。间歇性重复高压处理是杀死耐压性芽孢的良好方法。 相似文献
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本文研究了高压二氧化碳(HPCD)对梨汁中细菌菌落总数的影响,并分析其杀菌动力学。结果表明:随着温度、压强升高以及处理时间延长,梨汁中细菌菌落总数显著降低(p<0.05);在相同温度和处理时间条件下,HPCD处理显著高于热处理的杀菌效果,处理温度对HPCD杀菌具有协同效应;当HPCD处理条件为30MPa、40℃、60min时,灭菌效果最佳,梨汁中细菌菌落总数的残存率降低了2.66个对数;Weibull模型能较好地拟合HPCD处理后梨汁中细菌菌落总数的失活曲线,模型动力学参数比例因子a和形状因子b随压力增加和温度升高呈现逐渐变小的规律性变化。 相似文献
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目的 为实现炼乳的减糖,研究不同低聚糖类益生元替代蔗糖对炼乳品质的影响。方法 选用低聚果糖、低聚异麦芽糖、低聚木糖、低聚半乳糖四种低聚糖类益生元分别作为蔗糖替代物,研究不同替代比的益生元炼乳体系质构、流变、感官、色泽、晶体大小的变化,得到最佳糖替代益生元及替代比例。结果 综合考虑质构、色泽、晶体大小、喜好度排序感官四种指标表明,低聚果糖炼乳和低聚异麦芽糖炼乳品质较为优良,其中低聚果糖炼乳可接受的替代比为15%以内、低聚异麦芽糖炼乳可接受的替代比为25%以内。进一步通过静态流变学试验表明低聚异麦芽糖是最佳糖替代物质,在炼乳体系中其最佳替代比为15%。结论 糖替代比15%的低聚异麦芽糖炼乳既满足了甜感需求,又实现了减糖的目标,此外益生元的加入赋予了炼乳更多的功能性。该研究可为炼乳产品的减糖开发提供一定的理论依据和技术支持。 相似文献
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Effects of supplementing condensed tannin extract on intake, digestion, ruminal fermentation, and milk production of lactating dairy cows 总被引:1,自引:0,他引:1
Dschaak CM Williams CM Holt MS Eun JS Young AJ Min BR 《Journal of dairy science》2011,94(5):2508-2519
A lactation experiment was conducted to determine the influence of quebracho condensed tannin extract (CTE) on ruminal fermentation and lactational performance of dairy cows. The cows were fed a high forage (HF) or a low forage (LF) diet with a forage-to-concentrate ratio of 59:41 or 41:59 on a dry matter (DM) basis, respectively. Eight multiparous lactating Holstein cows (62 ± 8.8 d in milk) were used. The design of the experiment was a double 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments, and each period lasted 21 d (14 d of treatment adaptation and 7 d of data collection and sampling). Four dietary treatments were tested: HF without CTE, HF with CTE (HF+CTE), LF without CTE, and LF with CTE (LF+CTE). Commercial quebracho CTE was added to the HF+CTE and the LF+CTE at a rate of 3% of dietary DM. Intake of DM averaged 26.7 kg/d across treatments, and supplementing CTE decreased intakes of DM and nutrients regardless of forage level. Digestibilities of DM and nutrients were not affected by CTE supplementation. Milk yield averaged 35.3 kg/d across treatments, and yields of milk and milk component were not influenced by CTE supplementation. Negative effects of CTE supplementation on feed intake resulted in increased feed efficiency (milk yield/DM intake). Although concentration of milk urea N (MUN) decreased by supplementing CTE in the diets, efficiency of N use for milk N was not affected by CTE supplementation. Feeding the LF diet decreased ruminal pH (mean of 6.47 and 6.33 in HF and LF, respectively). However, supplementation of CTE in the diets did not influence ruminal pH. Supplementing CTE decreased total volatile fatty acid concentration regardless of level of forage. With CTE supplementation, molar proportions of acetate, propionate, and butyrate increased in the HF diet, but not in the LF diet, resulting in interactions between forage level and CTE supplementation. Concentration of ammonia-N tended to decrease with supplementation of CTE. The most remarkable finding in this study was that cows fed CTE-supplemented diets had decreased ruminal ammonia-N and MUN concentrations, indicating that less ruminal N was lost as ammonia because of decreased degradation of crude protein by rumen microorganisms in response to CTE supplementation. Therefore, supplementation of CTE in lactation dairy diets may change the route of N excretion, having less excretion into urine but more into feces, as it had no effect on N utilization efficiency for milk production. 相似文献
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紫外分光光度法鉴别复原奶和保鲜奶 总被引:2,自引:2,他引:2
对保鲜奶和复原奶中未变性乳清蛋白质量浓度的差别进行研究,初步探索了以紫外分光光度法对二者进行快速鉴别的方法。通过对未变性乳清蛋白的吸光度的研究确定了它的最大吸收波长为292nm,可在此波长下测出它的吸光度值并由标准曲线的线性回归方程算得其质量浓度。结果表明,复原奶中的未变性乳清蛋白质量浓度与保鲜奶中未变性乳清蛋白质量浓度差异较大。测量结果与凯氏定氯法的测量结果进行比较,这种方法与凯氏定氯法无显著差异,但此法较为简易,实用性较强。 相似文献
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本文简介乳汁EPO的结构、功能及其测定方法,重点关注母乳EPO影响新生幼仔生理功能的研究进展,这些研究显示:母乳EPO在新生幼仔体内红血球生成、肠道发育、神经营养以及免疫调节等方面均有重要作用。 相似文献
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浓缩大豆磷脂是由大豆油精炼过程中毛油水化脱胶时的副产物在真空下干燥脱水、纯化处理而得。介绍了浓缩大豆磷脂的制取工艺、功能特性及在饲料行业中的应用价值。 相似文献