蔬菜品种对发酵蔬菜质量及纯乳酸菌发酵过程的影响

就影响发酵质量及成败的关键因素--乳酸菌对不同蔬菜品种的发酵质量的影响进行了实验.当发酵进行到第5天时尽管三种发酵蔬菜在感官上都已成熟,但实验中检测的某些指标上却显示出比较大的差异,黄瓜中的总糖含量已明显少于其余两种蔬菜.发酵萝卜与甘蓝中的维生素C的含量出现增长趋势,而黄瓜中的维生素C含量减少的势头趋缓.三种蔬菜的"亚硝峰"基本上在第3天附近出现,对应同一时段的pH值可以大致确定三种发酵蔬菜的"亚硝峰"均出现在pH值4附近.     

XIIXVI. Yeast sequencing reports. Mapping and sequencing of two yeast genes belonging to the ATP-binding cassette superfamily

ATP-binding cassette (ABC) transporters share significant sequence identity within their ATP-binding domains. Degenerate oligonucleotides based on highly conserved portions of the ATP-binding domain genes were used to clone portions of two members of the ABC gene superfamily from Saccharomyces cerevisiae DNA. These genes were designated MDL1 and MDL2 (for multidrug resistance-like). Each MDL gene is predicted to encode a single set of transmembrane domains and a single ATP-binding domain, thus the MDL gene products are ‘half-molecule’ ABC proteins. The two genes were mapped to precise regions on chromosomes XII and XVI and show a considerable similarity to the mammalian P-glycoprotein/multidrug resistance (MDR) and peptide transporter (TAP) genes. Preliminary analysis of null mutants constructed by gene replacement has indicated that the MDL genes are not essential for viability of yeast. The sequences have been deposited in the GenBank data library under Accession Numbers L16958 (Locus YSCBCSA) and L16959 (Locus YSCBCSB).     

The taxonomy, ecology and cultivation of bacterial genera belonging to the family Flavobacteriaceae

The group known as the 'flavobacteria' has previously been regarded as synonymous with the genus Flavobacterium. Today, however, flavobacteria refers to the family Flavobacteriaceae comprising 10 genera. This review deals with the rapid changes in the taxonomy of these bacteria, especially over the last decade. It also briefly reviews the ecology of the genera in this family and describes the media that have been utilized in the general and selective cultivation of these organisms.     

日粮中添加不同油脂对鸡蛋工艺特性及质构指标的影响

摘 要：目的 本试验旨在探究蛋鸡饲粮添加不同油脂后对鸡蛋起泡性、乳化性、凝胶特性及蛋黄TPA、剪切力及蛋黄膜强度的影响。方法 在玉米-豆粕型基础日粮的基础上,分别添加1.5％豆油、1.5％猪油、1.5％混合油脂。结果 试验结果表明：与对照组相比,添加1.5％的猪油和混合油脂会不同程度的降低鸡蛋的工艺特性,显著增加蛋黄的硬度、咀嚼性;而1.5％豆油对鸡蛋的工艺特性及质构指标不会造成不良影响。结论 因此,为了满足蛋鸡生长能量需求及蛋品功能特性,建议在日粮中添加1.5％豆油。     

The effects of Lactobacillus buchneri with or without a homolactic bacterium on the fermentation and aerobic stability of corn silages made at different locations

Whole-plant corn (31 to 39% dry matter) from several locations was chopped, treated with nothing (U), Lactobacillus buchneri 40788 (4 × 10⁵ cfu/g; LB), or L. buchneri (4 × 10⁵ cfu/g) and Pediococcus pentosaceus (1 × 10⁵ cfu/g; LBPP), and packed into quadruplicate 20-L silos to determine their effects on silage fermentation and aerobic stability after 120 d of storage. The experiment was a randomized complete block design with main effects of treatment (T), block (location; L), and T × L interaction. Dry matter recovery was different among locations but unaffected by T. The population of lactic acid bacteria was greater in LB and LBPP than in U, and the opposite was true regarding the population of yeasts. Numbers of L. buchneri (colony-forming unit equivalents), determined by a real-time quantitative polymerase chain reaction, were higher in 4 of 5 locations for LB and LBPP compared with U (T × L interaction) with an average 6.70 log cfu/g for LB and LBPP versus 4.87 log cfu/g for U. Silages inoculated with LB and LBPP had higher silage pH and higher concentrations of acetic acid and 1,2 propanediol but lower concentrations of ethanol and water-soluble carbohydrates; there was a T × L interaction for all these variables. Aerobic stability was improved by LB and LBPP (mean of 136 h) compared with U (44 h), but there was an interaction between T × L. In general, locations with the highest population of L. buchneri had the largest increases in acetic acid and, consequently, the greatest improvements in aerobic stability. The addition of L. buchneri 40788 alone or with P. pentosaceus resulted in similar effects on silage fermentation and aerobic stability, but the effects were variable among locations, suggesting that unidentified factors; for example, in the field or on the forage crop, may alter the effectiveness of microbial inoculation.     

The effects of industrial pre-frying and domestic cooking methods on the nutritional compositions and fatty acid profiles of two different frozen breaded foods

This study was carried out to determine the effects of manufacturer pre-frying in olive and sunflower oil, as well as domestic cooking methods (deep-frying in olive and sunflower oil and baking) on the proximate compositions and fatty acid profiles of tuna pasties and ham nuggets. The pre-frying processes reduced moisture and carbohydrates and increased ash, fat and protein content in both pre-fried products. During cooking, the frying processes caused a reduction in moisture content and an increase in fat content in relation to pre-fried samples, while baking did not modify the proximate composition. The fatty acid profiles of products during both the pre-frying and frying processes became similar to those of the culinary fat used. Thus, the frying processes reduced the proportion of saturated fatty acids (SFA) and increased the proportion of monounsaturated fatty acids (MUFA) in the foods when olive oil was used, whereas increased the proportion of polyunsaturated fatty acids (PUFA) in products fried in sunflower oil. The fatty acid profiles of fried samples tended to be more similar to the frying fat than to the pre-frying fat, whereas the fatty acid profiles identified during the pre-frying process for baked products were not significantly modified. Thus, samples pre-fried in olive oil and subsequently baked showed the best proportion of fat content and PUFA/SFA, MUFA + PUFA/SFA and n-6/n-3 ratios of the tested products.     

不同果胶酶和酵母菌对葡萄酒中白藜芦醇及其二聚体的影响

采用高效液相色谱直接进样分析,测定了3种果胶酶处理、4种酵母发酵的葡萄酒中res、ε-viniferin、δ-viniferin等葡萄主要芪化物的含量.结果表明:7种葡萄酒中都含有较多的res、ε-viniferin和8-viniferin,不同果胶酶、酵母的选用均能影响到葡萄酒中的res、ε-viniferin和ε-viniferin的浸出效果.Uhrazyme Premium果胶酶酒样中ε-viniferin含量为2.187 mg/L,而Ex-v酒样中为1.926mg/L,796酵母酒样中res含量为1.193 mg/L,而CMS酒样仅为0.682 mg/L,δ-viniferin在D254酵母酒样中的含量为2.297 mg/L,而在Oneferm Color酒样中仅为1.850 me/L.Uhrazyme Premium果胶酶和D254、796酵母对果皮中上述芪化物的浸提效果较好.     

The effect of yoghurt and milk fermented with a porcine intestinal strain of Lactobacillus reuteri on the performance and gastrointestinal flora of pigs weaned at two days of age

Piglets weaned on to yoghurt at 2 days of age were compared with piglets fed the unfermented base milk. The feed to gain ratio was significantly poorer in piglets fed yoghurt. Yoghurt also depressed the coliform count and increased the lactobacillus count throughout the gut. There was a small but significant reduction in the pH of the stomach contents. Base milk acidified with lactic acid to the same pH as yoghurt had similar effects on growth and on the coliform counts but also depressed the lactobacillus count. Milk fermented with a strain of Lactobacillus reuteri gave results similar to those obtained with yoghurt but the effects did not persist after withdrawal. In yoghurt-fed pigs L. bulgaricus was recovered from the stomach and duodenum but not from the colon. It was concluded that the decrease in coliform count was due to the low pH produced by the lactic acid present in all three experimental diets (yoghurt, acidified base milk, and ‘poghurt’).     

小米粉含量对小米小麦混合粉及其挂面品质特性的影响研究

将小米粉按照10%~80%的比例添加到小麦粉中,对小米小麦混合粉的粉质特性和糊化特性进行了分析,同时对由混合粉制作成的挂面的品质特性进行了分析研究。结果表明:1)随着小米粉添加量的增加,小米小麦混合粉的峰值黏度、最低黏度、最终黏度、回生值、衰减值和峰值时间都在降低,形成时间、稳定时间、粉质指数都是先降低再升高。2)挂面蒸煮损失率不断升高,干物质吸水率不断下降。小米添加量≤30%时,挂面品质比较好,添加量≤60%时,品质尚可,添加量60%时,挂面品质下降比较大。3)小米粉的添加量、小米小麦混合粉的RVA特性、粉质特性与混合粉挂面的蒸煮品质特性有非常高的相关性。     

The ability of the ropy slime-producing lactic acid bacteria to form ropy colonies on different culture media and at different incubation temperatures and atmospheres.

The ability of the ropy slime-producing lactic acid bacteria to form ropy colonies aerobically and anaerobically on APT, MRS, MRS-S and Rogosa SL agars at 15, 20 and 30 degrees C was tested. Wide variation was observed in the proportion of ropy colonies produced with different culture methods and different test periods. The percentage of viscous colonies was usually highest at 15 degrees C. No suitable uniform method for all strains was found; and the results varied according to the bacterial strain studied. For testing purposes, use of the method producing the highest proportion of ropy colonies for each bacterial strain is recommended.     

The relationship between concentration and time in the toxicity of phosphine to adults of a resistant strain of Tribolium castaneum (Herbst)

The toxicity of phosphine to adults of a resistant strain of Tribolium castaneum was studied over a range of concentrations and exposure periods from 0.0095 to 100 mg/l. From 0.025 to 5 mg/l a probit plane, without interaction, was fitted to mortality data obtained from a range of exposure periods at each concentration. The limits of this probit plane were higher than those previously obtained for the susceptible reference strain. The lower limit for linear response was 5 times higher than the corresponding threshold in the susceptible strain while the upper limit, at which a narcotic effect was observed, was 10 times higher. This shift in the narcosis threshold suggests that phosphine-induced narcosis is not involved in the resistance of this strain. A toxicity index, n in the expression Cⁿt = k, of 0.65 was obtained for the resistant strain which was less than that obtained for the susceptible strain. Because of the lower toxicity index in the resistant strain, the level of resistance varied with concentration and was lower at lower concentrations. It is concluded that when the dosage of any toxicant, drug or other stimulus is comprised of more than 1 variable, e.g. concentration and time, a single resistance factor derived either from one fixed concentration, for each of a graded series of exposure times, or from one fixed exposure period, for each of a graded series of concentrations, could be quite misleading.     

The measurement of the responses to different odour intensities of `boar taint' using a sensory panel and an electronic nose

This study explored the possibility of using an electronic nose (e-nose) with a 12-conducting-polymer sensor array combined with pattern recognition routines to discriminate between varying intensities of boar taint. A set of samples in a model system comprising a neutral lipid base containing varying combinations of androstenone and skatole were tested, as were pork fat samples. The e-nose responses for pork fat were calibrated against those given by a trained 10-member sensory panel for abnormal odour of the same samples from a total of 60 Large White cross-bred pigs. The e-nose responses related strongly to those of the sensory panel with a significant (p<0·01) canonical correlation of 0·78. The data set was used to develop a discriminant function for grouping pork samples into three `response classes': normal, doubtful and abnormal. Based on this, the e-nose identified all the abnormal samples correctly. However, 16% of the normal samples were also classified as abnormal. It was concluded that, in general, the electronic nose can discriminate between different levels of boar taint and that although a high specificity of sensors to androstenone and skatole may be desirable it may not be entirely important to the development and configuration of a boar taint sensor array.     

The application of flow cytometry to the characterisation of a probiotic strain Lactobacillus reuteri DPC16 and the evaluation of sugar preservatives for its lyophilization

In this study, we applied flow cytometric (FCM) analyses to characterize the resistance of a probiotic strain Lactobacillus reuteri DPC16 (DPC16) against diverse stresses. Two fluorescent probes, propidium iodide (PI) and carboxylfluorescein diacetate (cFDA), were combined to the FCM method to reveal multiple cellular statuses of DPC16. The FCM results confirmed that the DPC16 strain had probiotic potential in respect of acid tolerance and bile acid resistance, whereby more than 60% of DPC16 bacteria remained intact after 1 h exposure to pH 2.0, and over half of DPC16 bacteria were unaffected by the presence of bile salts at a concentration of 0.2 g/100 mL for 1 h even without nutrient supply. In addition, the comparison among a number of lyo-preservatives for the DPC16 strain confirmed that lactose was able to maintain over 60% viable DPC16 bacteria after the lyophilization and subsequent storage period, outperforming all the other selected sugars. To conclude, the superior stress resistance of the novel DPC16 strain was confirmed by the FCM analyses in this study. The FCM technique also proved to be readily incorporated into probiotics research, and capable of providing insightful information.     

II. Yeast sequencing reports. The two genes encoding yeast ribosomal protein S8 reside on different chromosomes,and are closely linked to the hsp70 stress protein genes SSA3 and SSA4

A 7·4 kb segment of chromosome II was sequenced and analysed. This segment is part of the 25 kb insert of cosmid clone α1004.10 which is located on the left arm of chromosome II. Sequence analysis revealed four open reading frames (ORFs), of which two had been characterized previously (SSA3, AAR2) and one was not identified. The other ORF was precisely 600 bp long and the deduced protein sequence predicted a very basic protein (pI=11·1; molecular weight=22·5 kDa). Evidence was found that the ORF is the S40 ribosomal protein gene (RPG) S8. Consensus splice signals were found in the 5′ leader sequence and also potential RPG-specific sequences. Chromoblot analysis revealed a second copy of the S8 RPG on chromosome IV or VIII. This copy is also closely linked to an hsp70 protein gene, SSA4. The sequence has been deposited in the EMBL data library under accession number Z26879.     

The impact of closures, including screw cap with three different headspace volumes, on the composition, colour and sensory properties of a Cabernet Sauvignon wine during two years' storage

This paper presents the results from an investigation to assess the development of a Cabernet Sauvignon wine bottled with different closures including a screw cap (ROTE, roll-on-tamper-evident) and different ullage volumes (4, 16 and 64 mL of air). The wines were filled manually, sealed using commercial equipment and stored under controlled temperature and humidity conditions. The concentration of free and total SO₂, and phenolic compounds including anthocyanins, selected pigments, pigmented polymers and tannins, and colour measurements using spectral and CIELAB methods, have been determined in the wines over a two-year storage period. In addition, sensory analysis of the aroma and palate properties of the wines was performed after 6, 9, 11, 18 and 24 months' storage. The wines sealed under the screw cap with either 4 or 64 mL ullage volumes were clearly different from each other and the other treatments in the study, and these differences were seen within the first year after bottling. The wines bottled under the more commercially relevant conditions, screw cap with 16 mL headspace, synthetic closure or natural bark closure, were more similar in both composition and sensory characters, although subtle differences between different closures were evident. 'Rubbery' and 'struck flint' like aromas (generically termed reduced aroma) were detected in some of the wines in the study but were not a large or dominating character. The scores for this character were highest in the wine sealed under the screw cap with the smallest ullage volume.     

XIV. Yeast sequencing reports. A 21·7 kb DNA segment on the left arm of yeast chromosome XIV carries WHI3, GCR2, SPX18, SPX19, an homologue to the heat shock gene SSB1 and 8 new open reading frames of unknown function

We report the amino acid sequence of 13 open reading frames (ORF > 299 bp) located on a 21·7 kb DNA segment from the left arm of chromosome XIV of Saccharomyces cerevisiae. Five open reading frames had been entirely or partially sequenced previously: WHI3, GCR2, SPX19, SPX18 and a heat shock gene similar to SSB1. The products of 8 other ORFs are new putative proteins among which N1394 is probably a membrane protein. N1346 contains a leucine zipper pattern and the corresponding ORF presents an HAP (global regulator of respiratory genes) upstream activating sequence in the promoting region. N1386 shares homologies with the DNA structure-specific recognition protein family SSRPs and the corresponding ORF is preceded by an MCB (MluI cell cycle box) upstream activating factor. The sequence has been deposited in the EMBL data library under Accession Number X78898.     

The influence of attachment to beef surfaces on the survival of cells of Salmonella enterica serovar Typhimurium DT104, at different a(w) values and at low storage temperatures

This study investigated the influence of attachment to beef surfaces on the survival, injury and death of stationary phase cells of Salmonella enterica serovar Typhimurium DT104, compared to cells free in solution. The effects on cells are considered at different a(w) values and low temperatures in relation to osmotic and cold temperature shock effects. Attachment of cells to meat surfaces prevented cell injury and death from hyperosmosis and low temperatures, compared to meat solutions. Storage of cells for 72h resulted in higher levels of cell death on cells attached to meat surfaces. The improved survival of cells in solutions was considered to be related to adaptation to osmotic stress as a result of exposure to a previous hyperosmotic shock and the ability of the cells to produce cold shock proteins. Pathogen cell growth at low temperatures is discussed in relation to the presence of low levels of NaCl. Finally the data is discussed in relation to pathogen survival on beef carcass surfaces during refrigeration.     

X. Yeast sequencing reports. The sequence of a 36 kb segment on the left arm of yeast chromosome X identifies 24 open reading frames including NUC1, PRP21 (SPP91), CDC6, CRY2, the gene for S24, a homologue to the aconitase gene ACO1 and two homologues to chromosome III genes

A 36 kb fragment from the left arm of chromosome X, located at about 50 kb from the telomere, was sequenced and analysed. The segment contains a new putative ARS, a new tRNA for threonine, remnants of a solo delta and 24 open reading frames (ORFs) numbered from J0310 to J0355. Six of them, NUC1, PRP21 (also called SPP91), CDC6, CRY2, the gene encoding the ribosomal protein S24 and the gene coding for a hypothetical protein of 599 amino acids, have been sequenced previously. Three ORFs show high homology to the yeast gene ACO1 encoding mitochondrial aconitase and to the chromosome III genes YCR34W and YCR37C of unknown function. Three other ORFs show lower but significant homology: a first one to UNP, a gene related to the tre-2 oncogene from mouse and to the gene coding for the yeast deubiquitinating enzyme DOA2; a second one to SLY41, a suppressor of the functional loss of YPT1 and a third one to the gene encoding the proline utilization activator PUT3. The complete nucleotide sequence of 36 016 bp was submitted to the EMBL database (accession number X77688).