自制与市售酸奶贮藏过程品质变化对比研究

[目的]对比自制酸奶与市售酸奶在贮藏期间的品质变化。[方法]通过乳酸菌活菌数、酸度、pH值等指标,先探究自制酸奶在发酵过程中的品质变化,后与市售酸奶进行对比研究。[结果]自制酸奶过程中,发酵开始3 h后,随着乳酸菌发酵产物乳酸的累积,酸度上升、pH值下降,乳酸菌活菌数大幅度上升。发酵开始7 h后,乳酸菌总数开始下降,酸度的增加趋势和pH的降低趋势都有所减缓。在贮藏阶段,随着贮藏时间的增长,各种酸奶品质变化基本相同,乳酸菌含量先升后降,pH值下降,酸度上升。在4℃贮藏条件下,品质变化小于25℃。[结论]冷藏处理下酸奶的品质下降更慢,在自制或者购买酸奶时应该尽可能选择冷藏处理,开盖后尽快饮用完。两种酸奶具有不同的特点,消费者可以根据需求进行选择。总之,本研究为酸奶的安全贮藏提供参考依据。     

超滤法对牛初乳中IgG含量和活性的影响

本文研究了超滤分离牛初乳乳清中IgG的方法，测定不同超滤温度和压力条件下IgG含量和活性的变化情况。结果表明：通过超滤可将乳清中IgG含量提高一倍左右；超滤压力增加，IgG含量相应增加．IgG活性基本不变。在压力0．08MPa时，IgG含量为45．98mg／mL，活性未变，仍为1024；超滤温度增加，初乳中的IgG含量先有较小增加然后减少，IgG活性则下降。在超滤温度40℃时，IgG含量最高，达到46、85mg／mL，IgG活性未有变化。     

降胆固醇双歧杆菌B菌在零脂酸奶生产中的应用

研究降胆固醇益生菌在酸奶中的应用。筛选一株具有降低人体胆固醇水平的双歧杆菌B菌,采用此双歧杆菌B菌(Bifidobacterium animalis)和常规酸奶菌种A菌(L.bulgaricus和S.thermophilus)在43℃混合发酵,发酵5.5～6h可达到发酵终点,该酸奶产品在4℃、28d冷藏保质期内,功效双歧杆菌数和乳酸菌总数平均值分别达到4.8×106CFU/g和7.4×107CFU/g,成品理化指标检测为蛋白质含量2.8g/100g、脂肪含量0.2g/100g和酸度80°T,均符合食品安全国家标准GB 19302—2010《发酵乳:风味发酵乳》的要求,根据卫生部食品营养标签管理规范,本产品可标示为零脂风味发酵乳,从感官评价结果来看,此风味发酵乳具有非常柔和的风味及有较强鲜奶油感,质地平滑细腻,接受度好,具有一定商业前景。     

玉米干秸秆发酵生产优质粗饲料的优势菌株筛选

在玉米干秸秆中分别接种酵母菌、乳酸菌和纤维素分解菌，以筛选出适合玉米干秸秆发酵生产优质粗饲料的理想菌株。结果表明，对秸秆粉处理30d后，乳酸菌组发酵产物的酸碱度和氮损失均最低，即PH4．12，氨态氮和总氮比为6．4％；玉米秸秆粉发酵后感官评价得分最高的是乳酸菌组；酵母菌组，乳酸菌组，纤维素分解菌组的乙酸含量分别为33．35mg／mL、15．57mg／mL和6．32mg／mL，组间差异显著（P〈0．05）；乳酸含量分别为15．25mg／mL、30．89mg／mL和1．37mg／mL，组间差异显著（P〈0．05）；丁酸含量分别为5．35mg／mL，3．11mg／mL和20．53mg／mL，组间差异显著（P〈0．05）。试验结果提示，在本试验条件下，乳酸菌是玉米干秸秆发酵的最佳菌株。     

富含γ-氨基丁酸青春双歧杆菌的酸奶稳定性研究

本文研究了富含γ-氨基丁酸青春双歧杆菌酸奶在保质期内乳酸菌活菌数、γ-氨基丁酸含量以及感官指标变化。结果表明,富含γ-氨基丁酸酸奶在感官指标方面与普通酸奶相比无明显差异;随着保藏时间的增加,乳酸菌活菌数逐渐降低但始终保持在108cfu/mL以上;在保质期内γ-氨基丁酸含量相对稳定。     

豆基发酵乳的制备及过程机理分析

以轴流磨工艺所制豆浆、白砂糖、乳糖、葡萄糖、乳酸菌为原料制备豆基发酵乳,工艺设计实验结果表明：豆浆1000mL、白砂糖90g、乳糖10g、葡萄糖2g、乳酸菌0．2g,42℃发酵76h,产品品质佳。该豆基发酵乳产品在4℃、24h冷藏保质期内,活菌数平均值达3．0×10^CFU／g,蛋白质3．6％,脂肪2．5％,酸度90．05。T,pH4．52,大肠菌群79个／mL,脲酶阴性,致病菌未检出,符合国标GB19302-2010《发酵乳》要求。同时,该豆基发酵乳具有新鲜、操作方便、适合商业生产应用等优点,具有广泛的商业前景。     

牛初乳粉对凝固型酸奶质量的影响

本文主要研究了嗜热链球菌和保加利亚乳杆菌在发酵过程中对牛初乳IgG活性的影响,结果表明添加冻干牛初乳粉的酸奶在42～43℃发酵过程中,通过琼脂单向免疫扩散法(SRID)测得IgG活性约损失了20%,而在冷藏14天后,IgG活性约损失了28%;添加牛初乳粉可促进乳酸菌产酸。通过感官评定得出开发含有牛初乳的凝固型酸奶是可行。     

发酵乳冰淇淋质量影响因素的研究

研究了发酵乳添加比例对发酵乳冰淇淋膨胀率、抗融性及感官特性的影响；提出了发酵乳冰淇淋的生产工艺；分析了发酵乳冰淇淋在低温保藏下，乳酸菌活菌总数的变化。结果表明，发酵乳冰淇淋在低温贮藏（-180C）8N后，发酵乳含量不同的发酵乳冰淇淋其乳酸菌活茵数减少20％～32％。     

乳酸菌发酵法生产金丝枣饮料的研究

以河北沧州金丝小枣为原料，采用液态发酵工艺，研究了不同乳酸菌在金丝枣发酵基质中的产酸情况以及最佳发酵时间，并将发酵基质调糖后制成乳酸菌饮料进行品质评价。结果表明：供试5种乳酸菌中，以干酪乳杆菌产酸量最高，30℃发酵24h后，产酸量为0．42％，且能保持发酵基质原有的色泽。该菌在金丝枣发酵基质中的最佳发酵时间为20h，以发酵基质调制的金丝枣饮料，在色、香、味及大众接受性等方面均较佳。     

脱脂乳发酵体系中乳酸菌的高效离子交换色谱分析

应用高效离子交换色谱对脱脂乳发酵体系中的嗜热链球菌和保加利亚乳杆菌进行色谱表征。结果表明，单菌培养过程中保加利亚乳杆菌菌体形态的变化在其相应色谱行为上得到了体现，二者的色谱峰有比较好的稳定性。两种菌的峰面积与菌数之间呈现出良好的线性关系，可决系数R^2分别为0．9957和0．9916。因此本方法的建立，可用于酸奶发酵过程中乳酸菌的分析与表征，有望为乳酸菌混合物的研究提供一种快捷的新方法。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein