A survey on composition and microbiota of fresh and fermented yak milk at different Tibetan altitudes

Yak milk is a type of milk that people are less familiar with due to its remote geographical location, the particular geographical environment and climatic conditions in Tibet, which may have significant effects on composition, microbiota and fermentation outcome. To investigate the chemical composition and microbiota of fresh and fermented yak milk, and to isolate and characterize the predominant microorganisms in the fermented milk, yak milk (24 fresh and 30 fermented milk samples) was collected from four areas of different altitudes in Tibet, and their microbiological profile and chemical composition were investigated. Yak milk had a higher fat, crude protein, lactose and dry matter content than cow milk. The fermented yak milk showed a great diversity in fat and dry matter levels due to the different ways of processing in different localities, and lower pH and higher lactic acid content compared with commercial cow milk yogurt. Fermented yak milk had a better sanitary quality than fresh yak milk. Three species of lactobacilli (Lactobacillus fermentum, Lactobacillus helveticus and Lactobacillus curvatus) and five species of yeast (Saccharomyces cerevisiae, Candida kefyr, Candida lambica, Candida famat and Candida holmii) were identified phenotypically and encountered as predominant fermentation microbiota. The predominant lactic species in fermented milk was L. fermentu

A Gravitational Potential with Extra-dimensions and Spin Effects In Hadronic Reactions

The impact of the KK-modes in d-brane models of gravity with large compactification radii and TeV-scale quantum gravity on the hadronic potential at small impact parameters is examined. The effects of the gravitational hadronic form factors obtained from the generalized parton distributions (GPDs) on the behavior of the gravitational potential and the possible spin correlation effects are also analysed.Comment: 13 pages, 7 figure

Search for Doubly-Charged Higgs Bosons at LEP

Doubly-charged Higgs bosons are searched for in e^+e^- collision data collected with the L3 detector at LEP at centre-of-mass energies up to 209 GeV. Final states with four leptons are analysed to tag the pair-production of doubly charged Higgs bosons. No significant excess is found and lower limits at 95% confidence level on the doubly-charged Higgs boson mass are derived. They vary from 95.5 GeV to 100.2 GeV, depending on the decay mode. Doubly-charged Higgs bosons which couple to electrons would modify the cross section and forward-backward asymmetry of the e^+e^- -> e^+e^- process. The measurements of these quantities do not deviate from the Standard Model expectations and doubly-charged Higgs bosons with masses up to the order of a TeV are excluded

Search for Single Top Production at LEP

Single top production in e+e- annihilations is searched for in data collected by the L3 detector at centre-of-mass energies from 189 to 209 GeV, corresponding to a total integrated luminosity of 634 pb-1. Investigating hadronic and semileptonic top decays, no evidence of single top production at LEP is obtained and upper limits on the single top cross section as a function of the centre-of-mass energy are derived. Limits on possible anomalous couplings, as well as on the scale of contact interactions responsible for single top production are determined

Effects of temperature, water activity and gas atmosphere on mycelial growth of tempe fungi Rhizopus microsporus var. microsporus and R. microsporus var. oligosporus

Rhizopus microsporus var. microsporus and var. oligosporus are used in the manufacture of various Asian fermented foods (tempe, black oncom, sufu). In view of solid-substrate fermentation (SSF) control, mycelial growth of strains of both varieties was tested for sensitivity to fluctuations of temperature, water activity and interstitial gas composition. This was achieved by measuring radial growth as well as biomass dry weight of pre-germinated microcolonies on defined media. The optimum conditions were temperature 40°C, aw 0.995 and a gas composition of air for the growth of both strains on a model medium. Whereas radial growth rates of var. microsporus and var. oligosporus were similar, biomass growth rates of var. oligosporus were higher than those of var. microsporus under optimum conditions. The temperature-dependent growth of Rhizopus spp. at aw > 0.98 could be described by the Ratkowsky Equation. Carbon dioxide (5-10␟/v) inhibited the growth of Rhizopus spp. at non-limiting levels of oxygen. The two strains were able to grow at low (0.5␟/v) oxygen levels, but the mycelial density was rather low. No interrelation of water activity and gas composition was observed, but at high water activity the fungi were more sensitive to changes of temperature. The implications for process control are discussed

Iron, zinc and phytic acid content of selected rice varieties from China

Rice is the major Chinese staple food (per capita approx 250 g day-1) and, as such, is an important source of essential minerals. However, due to a number of factors the bio-availability of these minerals is limited. In this study, the variation of phytic acid (PA), iron (Fe) and zinc (Zn) levels in 56 varieties of Chinese rice was investigated. The samples included in this study were collected in proportion to the importance of the rice-growing regions in China. Fe levels showed the biggest variation (9-45 mg kg-1) and were not related with PA content or grain shape although growing locations were identified yielding higher (25.2 mg kg-1) and lower (14.2 mg kg-1) Fe levels. Zn showed a moderate variability (13-39 mg kg-1), which was narrower than for Fe, while broader than for PA (7.2-11.9 g kg-1). Zn content is correlated (R2 = 0.5; P <0.01) with PA content, and shows a relation with growing region and kernel shape. Variation of PA content is the least among the three components. Molar ratios of PA to Fe and Zn ranged from 15 to 105 and 27 to 67, respectively. The results of the mineral contents and PA content can be interpreted in terms of expected bio-availability. This study shows that the mineral bio-availability of Chinese rice varieties will b

Effect of different Bacillus strains on the profile of organic acids in a liquid culture of Daqu

A reversed-phase high-performance liquid chromatography method for the analysis of malic, lactic, acetic, citric, succinic, propionic and butyric acids, during the incubation of Bacillus spp., was developed. All samples taken from cultivation were centrifuged (20 min, 11,500g at 5 degrees C) and filtered through a 0.45 mu m membrane filter before injection. A programme pumping phosphate buffer at pH 2.50 and acetonitrile was used to separate the compounds on a C-18 column. Various parameters affecting analysis were optimized to take less than 30 min with a good linearity (R > 0.999). Bacillus licheniformis or B. subtilis, isolated from Daqu, was inoculated to ferment a liquid culture of Daqu. Growth of bacteria and organic acid production during the fermentation were investigated. Although there were no significant differences in the production of organic acids between B. licheniformis and B. subtilis during the first 8 h, significant differences in the production rates of organic acids, except for citric acid, were observed between B. licheniformis and B. subtilis from 8 to 48 h, with the final concentration of each organic acid varying. Copyright (C) 2013 The Institute of Brewing & Distillin