首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Lactic acid bacteria （LAB） is widely used as culture starters in dairy fermentation. The aim of this study was to investigate the quality of fermented goat milk and cow milk, as well as the viability of LAB in the same products. Fermentations were performed with pasteurized goat milk or cow milk added with skim milk （18% of solids） using three separately different starters; yoghurt starter （a combination of Streptococcus thermophilus FNCC-0040 and Lactobacillus bulgaricus FNCC-0041）, single starter of Lactobacillus acidophilus FNCC-0029 and Lactobacillus casei FNCC-0051. The parameters observed were pH, acidity, nutritional quality including protein, fat and lactose content and product＇s viscosity. Acidity, pH and viability of LAB were also monitored during storage at refrigerated temperature （4 ℃） for 28 days. Results show that the different LAB starters did not affect the pH, acidity, lactose and protein content. Differences on LAB starters affected fat content and viscosity. The highest score of viscosity （30.00 Pa.s ± 7.02 Pa.s） was observed on products fermented by yoghurt starters, followed by products obtained using starter of L. acidophilus （17.7 ±11.4） and L. casei （8.62 ±0.35）. Protein content, acidity, pH and viscosity were not significantly different between products obtained from goat milk and cow milk. Fat content in fermented goat milk was higher （5.03% ±0.62%） than in fermented cow milk （3.52% ±0.37%）, however, lactose content was higher in fermented cow milk （5.16% ±0.40%） than in fermented goat milk （4.53% ±0.35%）. Total LAB concentration in fermented cow milk during storage was 8.03± 0.52 logt0 cfu/mL, while in fermented goat milk was 7.81 loglo cfu/mL ± 0.67 loglo cfu/mL. There was a 10.83% decrease in LAB viability in fermented cow milk and 11.40% in fermented goat milk after 28 days of storage. In conclusion, quality of fermented milk is affected by the starters applied, raw milk source and storage period.  相似文献   

2.
The purpose of this research was to incorporate Bifidobacterium angulatum and Bifidobacterium infantis in frozen fermented dairy desserts made from camel or cow milk and to determine their viability during freezing and storage at .20℃. To meet this objective, ice cream mixtures were formulated using camel or cow milk constituents, inoculated with regular yogurt starter （Lactobacillus delbruecldi ssp bulgaricus and streptococcus thermophilus） and incubated at 42℃ till a pH value of 5.0 was attained. The fermented mixes were heated to 80℃ for 5 min in water bath to inhibit yogurt organisms. Bifidobacteria were then added at 2 g/kg mix （1 gram from each Bifidobacterium strain）. The results showed that the initial counts of Bifidobacteria before freezing were 7.3 × 10^8 and 7.1 × 108 cfu/g for camel and cow mix respectively and decreased to 1.06× 10^8 and 1.1×10^8 in the same order （about 0.8 log reduction in the count of Bifidobacteria was observed） after freezing and storage for one day. No significant changes in counts of Bifidobaeteria were found during storage at -20℃ for 17 weeks. Changes in pH and titratable acidity were also studied. No significant changes in titratable acidities of frozen yogurt made from camel or cow milk constituents during storage period were observed.  相似文献   

3.
This study aimed to investigate the influence of pH,heat and enzymatic treatments on the activity of antibacterial substance in MRS,skim soy milk and bovine milk media fermented by a potential probiotic Lactobacillus fermentum F6.The antibacterial activity of the culture supernatant of L.fermentum F6 was tested against a wide range of Gram-positive and Gram-negative pathogenic bacteria including Staphylococcus aureus,Escherichia coli,Listeria monocytogenes,Salmonella typhimurium,and Shigella flexneri.Different antibacterial activities were detected in MRS and milk but not in soy milk.We presumed that three kinds of probable components including organic acids,heat-stable and heat-labile proteinaceous compounds were involved in antibacterial activity of fermented MRS and milk.The influence of acids on antibacterial activity was pH-dependent and this effect multiplied with thermal treatments seemed complex.Data analyses showed various significant differences of antibacterial activity among five pathogens were observed in pH and heat treatments.The untreated fermented milk showed higher inhibitory activity to Gram-positive pathogenic bacteria than Gram-negative bacteria （P 〈 0.05）,indicating antibacterial substances of fermented milk are greatly different from fermented MRS.An accurate stimulated gastrointestinal transit showed antibacterial substances would have no influence on intestinal flora.Acidic range of antibacterial substances from pH 2.0 to 6.0 can be potentially used as food biopreservatives and alternative therapeutics.  相似文献   

4.
The presence of Geotrichum candidum in fresh cheese is considered to be a contaminant and may lead to the product spoilage. The oxidative yeast Candida maltosa firstly isolated from the spoiled fruit yoghurt surface in Slovakia belongs to the yeast contaminants of fermented dairy products. The effect of the cultivation temperature and the presence of Lactobacillus rhamnosus GG on the growth of dairy spoilage yeasts in ultrapasteurized milk was studied. Addition of Lb. rhamnosus GG in milk caused partial inhibition of the yeast growth dynamics in milk. The water activity transformation of Gibson model after the temperature modification （Tw） was applied to model growth dynamics of G. candidum in pure and mixed culture, respectively： In μ_Gc=-5.0376＋2.7281 Tw-0.4217Tw^2, lnμ_CC_LGG=-6.0033＋3.2996Tw-0.5553Tw^2. The effect of different Lb. rhamnosus GG addition and the incubation temperature on the C. maltosa growth dynamics was analyzed by linear regression methodology and described by using following equations： lnGr1=-5.3674＋0.2341T＋0.2599N0-0.0032T^2-0.0492N0^2-0.0068TN0 and lnGr11=-9.5457-0.249T＋2.3823N0 ＋0.0099T^2-0.2324N0^2＋0.0098TN0 Based on the principles of predictive microbiology, the mutual microbial interactions and potential application of the lactobacillus strains in food protection are discussed.  相似文献   

5.
The occurrence of the spore-forming bacteria in different segments of production lines of Ultra High Temperature （UHT） milk of a commercial plant and its transfer to the final product was studied. The samples were collected from different segments of production lines from reception to packaging sections, over a period of 75 days at a rate of one sampling a week, from plants in North West of Algeria. The total colony count of aerobic spore-forming bacteria was done using Plate Count Agar （PCA） method. The results showed that there was more than 1 ×10^3 CFU/mL at the level of 50%, 25%, 37.5%, 62.5% and 37.5% of the analyzed samples of milk powder, pasteurized milk, UHT milk （before storage）, UHT milk stored at 55℃ for 7 days and UHT milk stored at 30℃ for 14 days, respectively. The mean total colony count of aerobic spore-forming bacteria was considerably lower in the UHT milk than in the other samples, while the higher proportion of aerobic spore-forming bacteria was noticed to be 32.58% and 30.90% in the UHT milk stored at 55℃ and 30℃, respectively. The results obtained by the classic biochemical identification （Bacillus API 20E）, interpreted by software of calculation for microbial identification reflected the presence of especially Bacillus sphaericus. The other species found were： Bacillus cereus, Bacillus subtilis, Bacillus coagulans, Bacillus licheniformis and Bacillus stearothermophilus. The study reveals that the proportion of aerobic spore-forming bacteria in the final product depends on temperature and storage periods.  相似文献   

6.
The topical administration of the compound Chinese herbal medicine transdermal preparation has been widely used in treating the mastitis of cows. In order to understand the metabolic process, four cows suffering from clinical mastitis were selected for the pharmacokinetic study. The transdermal preparation was applied to the diseased part of breast. Then the plasma and milk samples were collected respectively at 0, 0.5, 1, 2, 4, 6, 8, 10, 12, 24, and 36 h, The concentrations of baicalin and phillyrin in plasma and milk were determined by HPLC and the data of time-concentrations were analyzed by the pharmacokinetic software. The results showed that two ingredients in the plasma were not detectable, but they in the milk had linear relationship with the time. The peak concentration of baicalin [（2.84 ±0.15）μg mL^-1] appeared at （4.93 ± 0.35） h, AUC0.1OQ was （27.32 ± 7.91） mg L^-1 h^-1, and the mean retention time was （28.31 ±0.49） h. The peak concentration of phillyrin [（0.49 ± 0.41） μg mL^-1] achieved at （3.68 ± 3.14） h, AUC0-LOQ was （4.10± 0.31） mg L^-1 h^-1, and the mean retention time was （14.52 ± 0.02） h. These suggested that two ingredients had slow absorbing speed and high absorbing degree. They could not be eliminated in a short time, thus exerted the topical curative effect.  相似文献   

7.
The purpose of the study was to investigate the pharmacokinetics of cefquinome in plasma and milk samples of lactating Chinese Holstein following a single intramammary administration into one quarter at the dose of 75 mg. Residue depletion of cefquinome in milk administrated at one quarter following three consecutive infusions at the same dose were also carried out. Cefquinome concentrations in plasma and milk were determined by high-performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） method. A non-compartmental analysis was used to obtain the pharmacokinetic parameters of cefquinome. Following the single treatment, cefquinome wasn’t detected in any of the plasma samples. The concentration of cefquinome in milk reached peaked values （Cmax） of （599.00±322.00） μg mL-1 at 2 h after administration （Tmax）, elimination half-life （t1/2λz） was （4.63±0.26） h, area under the concentration-time curve （AUC0-∞） was （4 890.19±1 906.98） μg mL-1 h, and mean residence time （MRT） was （6.03±2.27） h. In residue depletion study, cefquinome concentrations in 5 out of 6 milk samples at 72 h were lower than the maximum residue limit ifxed by the European regulatory agency （20μg kg-1 for cefquinome） and cefquinome still could be detected in milk of treated quarters at 120 h post-treatment. The maximum concentration （Cmax） of cefquinome in milk from treated quarters was （486.50±262.92） μg mL-1 and arrived at 6 h after administration （Tmax）, elimination half-life （t1/2λz） was （6.30±0.76） h, area under the concentration-time curve （AUC0-∞） was （44 747.79±11 434.43） μg mL-1 h, and mean residence time （MRT） was （10.09±1.40） h. This study showed that cefquinome has the feature of poor penetration into blood and was eliminated quickly from milk in lactating cows after intramammary administration.  相似文献   

8.
A polymerase chain reaction （PCR） assay was employed for direct detection of Staphylococcus aureus without enrichment in dairy products. A solvent extraction procedure was successfully modified for the extraction of Staphylococcus aureus DNA from artificially contaminated whole milk, skim milk, and cheese. A primer targeting the thermostable nuclease gene （nuc） was used in the PCR. A DNA fragment of 279 bp was amplified. The PCR product was confirmed by DNA sequencing. In this study, the PCR, GB-4789.10-94, Perifilm RSA.Count Plate, and Baird-Parker ＋ RPF Agar were compared. The sensitivity of the PCR was 10 CFU mL^-1 of whole milk, skim milk, and 55 CFU g^-1 of cheese. The developed methodology allowed for detection of Staphylococcus aureus in dairy products in less than 6 h. The time taken for the development of this PCR assay was 12-24 h, less than the time taken by the general PCR assay using the enrichment method, and the coincidence rate of this developed PCR was 94.3%, the sensitivity was 100%. It was a rapid, sensitive, and effective method for PCR to detect Staphylococcus aureus in milk and milk products.  相似文献   

9.
Methionine(Met)and lysine(Lys)have been reported as the first two limiting amino acids(AA)for maximum milk yield and milk protein production.Supplying these AA may improve microbial protein synthesis and therefore improve milk production without adding excess N to the environment.This observation utilized fermented soybean meal(SBM),cottonseed meal(CSM),rapeseed meal(RSM)and corn by Bacillus subtilis 168 and Leuconostoc mesenteroides as core feedstuffs to produce special biological protein feed for dairy cow.The results showed that the milk production,milk protein percentage,milk fat percentage and milk DM percentage of test groups in trial period were significantly more than those of the control group(P<0.01),the results showed that adding fermenting protein feed in dairy cow diets could significantly improve milk yield,milk protein and milk fat content.The economic benefits of actual application were analyzed,the group of 0.5%was the best compared with the other groups.  相似文献   

10.
Fungus Rhizopus oryzae has a probiotic potential, but the potency is not yet explored. Probiotics are usually used as feed additive, including to the chicken. Probiotic needs a suitable medium for their life. The aim of the study was to know which preparations can produce suitable medium for the growth of Rhizopus oryzae on the dried culture formed. The study used two preparations. Preparation 1 （a） consisted of rice bran （1 kg） and culture ofRhizopus oryzae on Potato Dextrose Broth （PDB medium） （500 mL）; then preparation 1 （b） consisted of corn grain （1 kg） and culture of Rhizopus oryzae on PDB medium （500 mL）. Preparation 2 （a） consisted of rice bran （1 kg）, culture of Rhizopus oryzae on Potato Dextrose Agar （PDA medium） （seven petri dishes） and was added with sterile distilled water （500 mL）; preparation 2 （b） consisted of corn grain （1 kg）, culture of Rhizopus oryzae on PDA medium （seven petri dishes） and was added with sterile distilled water （500 mL）. The culture of Rhizopus oryzae even both on PDB and PDA were 3 d of incubation. All preparations were incubated for 7 d then they were dried under the sun. Parameter evaluation was the growth performance of the fungus in the dried culture media. The growth performance was analyzed by microscopic analysis and the number of colony of the fungi in the two dried culture media. The results showed that from the macroscopic analysis, the sample of both dried culture media which were placed on PDA medium showed the growth of mycelia and spores of the same kind of fungus and it was proved by microscopic observation that the fruiting bodies （mycelia and spores） of that ftmgus was Rhizopus oryzae. The colonies number of the fungi from preparation 1 （a） and 1 （b） were 0,4 × 10 cfu/gr and 2.4 × 10^3 cfu/gr, respectively, and from preparation 2 （a） and 2 （b） were 1.3 × 10^5 cfu/gr and 8.3 ×10^2 cfu/gr, respectively. It could be concluded that the product of the dried culture of probiotic  相似文献   

11.
This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer （UCRF） and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations： the first-order kinetics equation [N1=N0 （1-e^-kt）], Elovich equation （N1=a ＋ blnt）, and parabola equation （N1=a ＋ bt^0.5）, with the best fitting by the first-order kinetics equation for different N （r= 0.9569^＊＊-0.9999^＊＊）. The release potentials （No values estimated by the first-order kinetics equation） of different N in the UCRF decreased in the order of total N 〉 DON 〉 urea-N 〉 NH4^＋-N 〉 NO3^-N in water, and total N 〉 NH4^＋-N 〉 DON 〉 urea-N 〉 NO3^--N in soil, respectively, being in accordance with cumulative amounts of N release. The constants of N release rate （k values and b values） for different N forms were in decreasing order of total N 〉 DON 〉 NH4^＋-N 〉 NO3^--N in water, whereas the k values were urea- N 〉DON 〉 NH4^＋-N 〉 total N 〉 NO3^--N, and the b values were total N 〉 NH4^＋-N 〉 DON 〉 NO3^--N 〉 urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg^-1, and 5.17 kg kg^-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0 （l-e^kt）] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.  相似文献   

12.
  相似文献   

13.
A total of 90 cows from two farms (farm A 30 cows, farm B 60 cows) were used to study the effect of Bospro on milk production, milk quality and subclinical mastitis incidence. The cows in the test group were supplied with 20 g of Bospro per head per day and meanwhile, the percentage of milk fat, protein and lactose and moisture of the milk samples were analysed. The results showed that the milk yield of both high production and mid-to-low milk producting cows increased by 3.3% to 5.3% respectively compared with their control group of cows, but there was no changes on the milk content between the treated and the control cows. The treated cows also showed an increased body weight (P>0.05) and significantly reduced incidence of mastitis, as Compared with that of the control group. The experiment dcmonstrats that Bospro can increase milk yield, but not at the expense of milk quality and body weight.  相似文献   

14.
Four Holstein dairy cows in the 7th month of late lactation were sampled, and self-control method was used. Daidzein was added to the concentrated feed at the dose of 10mg/kg during the treatment stage. Results showed that daidzein lessened the declining tendency of milk yield in late lactation and increased the milk yield to some extents. Lactoprotein was evidently increased （P〈0.01）, while milkfat was not affected evidently. The level of T4 in serum was evidently increased （P〈0.05）; the levels of GH, PRL, E2 and TSH in. serum were prone to rising while T3 was prone to decreasing . It was concluded that daidzein could indirectly affect milk yield and components of milk by regulating the levels of intrinsic hormones.  相似文献   

15.
Culture condition of every phase for fermentation of yeast culture was studied, and its solid and liquid conditions of elaboration were optimized to improve the total counts of living cells. Results showed that microzyme grew best at 30℃ when solid fermented, and the count of the living cells reached the tiptop with pH 5.5. The count of Candida tropicalis could reach 137.96× 10^9 cfu·g^-1, the count of Saccharomyces cerevisia could reach 134.62× 10^9 cfu·g^-1 the best liquid fermentation condition for cell-wall broken was 50℃ for 28 h, the rate of cell-wall broken could reach 80% at least; the rate of vitamin loss in yeast could be the minimun, the loss rate of vitamin B6 in Candida tropicalis and Saccharomyces cerevisiae was 8.71% and 19.54% respectively, the loss rate of vitamin B2 was 19.39% and 13.18%, respectively, and the loss rate of vitamin B6 was 6.3% and 3.04%, respectively.  相似文献   

16.
Production of monoclonal antibody against porcine adipocyte plasma membrane proteins to explore a new way of controlling body fat deposition and improving carcass quality is discussed in this article. Membrane proteins of pig adipocyte plasma membrane proteins were extracted with the help of sucrose density gradient centrifugation, and two kinds of proteins were obtained. The monoclonal antibody （designated 3B2 and 3F3） of IgG1 and IgG2b subclass against adipocyte membrane proteins were produced by immunization, with adipocyte membrane proteins as an antigen, and its titer was 1：105 detected by enzyme-linked immunoadsorbent assay （ELISA）. The cell strains were identified by analyzing the number of chromosomes, the heat stability, the acid and alkali, the types and subtypes of immnoglobulin, and its peculiarities and affinities. Through identification, the chromosome number of hybridoma cell strains was from 80 to 100 and the strains formed good hybridomas colonies. The strains＇ affinity constants were 4.63 × 10^9 and 3.75 × 10^9 （mol L^-1）-1, respectively. At the same time, the McAb secreted was stable to environmental factors, such as, temperature, acid, alkali and so on. The monoclonal antibodies had been obtained and their specificity to porcine adipocyte plasma membrane proteins had been identified.  相似文献   

17.
The phylogenetic relationships of the subfamily Nymphalinae （sensu Chou 1994） were analyzed based on 1 488 bp of mtDNA cytochrome oxidase subunit I （COI） gene sequence data obtained from 24 individuals, along with those of eight species obtained from GenBank. The base compositions of this COI fragment varied among the individuals as follows： T 39.9%, C 14.6%, A 32.2%, and G 13.4%, with a strong AT bias （72.1%）, as usually found in insect mitochondrial genomes. The A ＋T contents of the third, second, and first codon positions of the COI fragments in this study was 92.4, 62.2, and 61.4%, respectively. The phylogenetic trees were reconstructed by neighbor-joining （NJ）, maximum likelihood （ML）, and Bayesian methods by using Byblia anvatara as outgroup. Phylogenetic analyses based on the COI gene sequence data created very similar topologies, which were producing trees with two main clades A and B, and five subclades. The data indicated that the tribes Nymphalini and Hypolimni （sensu Chou 1994） are not monophyletic groups, and the genus Junonia should be removed from Nymphalini to Hypolimni （=Junoniini）. On the basis of the data, the Symbrenthia and Araschnia had a relative distant relationship with the rest of Nymphalini. The relationships of species in the Nymphalini were confirmed via the NJ, ML, and Bayesian methods, namely （（（（Nymphalis ＋ Kaniska） ＋ Polygonia） ＋Aglais） ＋ Vanessa） ＋ （Symbrenthia ＋Araschnia）. This investigation provides a little novel information for Chinese researches of butterflies.  相似文献   

18.
Black carrots （Daucus earota L. spp. sativus. ） were fermented for 4 weeks by using six different starter dough formulations. Some of the samples were pasteurized to detemaine the effects of heat treatment on fermentation. Fermentation was followed by physicochemical and microbiological analysis. Some characteristics such as dry matter, crude fiber, water soluble extract, alcohol soluble extract, ether soluble extract, crude energy, total sugar, pH, salt and colour values and mineral contents of black carrot were determined. In the beginning of the fermentation, dry matter is highest in the brines with coriandrium and dry matter of the other brines are close to each other and lower than that of the brines with coriander. The number of Lactic acid bacteria, total bacteria, moulds-yeasts and coliform bacteria decreased through the end of fermentation. Heat treatment had a considerable effect on microbial growth. The microbial growth was higher in the nnpastenrized samples. Total bacteria number reached the highest level for the pasteurized samples （ 104 cfu/mL - 105 cfu/mL ） and for the unpasteurized samples （106 cfu/mL - 107 cfu/mL） in the second day. After the fermentation, sensory analyses were carried out to determine the storage stability of the last products. While ＂a＂ value increased, ＂b＂ and ＂L＂ values decreased during storage time. Yoghurt inoculated brine were preferred from the colour, odour and acceptability points of view.  相似文献   

19.
To determine the effect of dietary supplementation with vegetable oilseeds on the composition of bovine milk fatty acids （FAs）, 40 Holstein dairy cows were used with a complete randomized design. At the beginning of the experiment, the cows were 150±25 day in milk （DIM）. Total duration of the experiment was six weeks. Measurements were made during the last three weeks. Cows in four treatments were fed with a basal diet （CT） or basal diet supplemented with either whole full fat soybean （WFS）, full fat expanded soybean （FPS） or whole full fat soybean with whole cottonseed and full fat expanded soybean （MIX）. The composition of the milk fat was analyzed by gas chromatography. Relative to control, the conjugated linoleic acid （CLA） concentration in milk fat from cows on FPS was significantly increased by 83.88% （P〈 0.05）. The proportions of C12：0 were decreased by 35.7, 35.51, and 38.65% in milk fat from cows on WFS, MIX, and FPS compared with cows on CT. Similar decreases in C 14：0 were 23.83, 24.85, and 31.48% in WFS, MIX, and FPS treatments, respectively. Feeding vegetable oilseeds increased the proportion of healthy FAs （mainly CLA）, whereas decreased the concentratiofi of C12：0 and C14：0. Therefore, milk and dairy products would have higher nutritive and therapeutic value.  相似文献   

20.
《农业科学与技术》2013,(10):1500-1502
[Objective] The aim was to analyze sugar components in fermented rice wine by ion chromatography. [Method] The optimal condition for chromatography system of sugar analysis was selected by measuring sugars in fermented rice wine with ion chromatography and pulsed amperometric detection. [Result] The optimal measurement conditions were as follows： Leacheate （Leachate）, consisting of NaOH and CH3COONa, was eluted by gradient concentrations, with column temperature at 35 ℃ and flow rate at 0.4 ml/min. In the condition, sugars in rice wine were ana- lyzed and the results showed that the method is featured by low detection limit, good repetition and high recovery rate. [Conclusion] The research establishes and determines the approaches and optimum conditions for sugar analysis in rice wine by ion chromatography and pulsed amperometric detection, providing references for advancement of research on quality improvement of fermented rice wine.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号