短乳杆菌1.12发酵过程中去除粪臭素的条件优化(英文)

粪臭素是在公猪大肠内产生的一种会影响猪肉品质的物质。本研究利用短乳杆菌1.12(Lactobacillus brevis1.12,L.brevis1.12)对粪臭素进行去除实验,在此过程中应用响应面分析法对L.brevis1.12在发酵过程中去除粪臭素的发酵条件进行优化,并且研究各发酵参数之间的交互效应。经过实验得出L.brevis1.12在发酵过程中去除粪臭素的最佳条件是:接种量为77mL/L,发酵液量为107mL,发酵时间为4d,发酵温度为36.6℃,pH为5.61。在此优化条件下得到的粪臭素去除率是71.83%±0.07%。另外,研究表明,短乳杆菌1.12的发酵上清液对粪臭素的去除能力最强,其去除率为17.25%±0.79%(24h),并且证明了短乳杆菌1.12去除粪臭素的作用不是物理吸附。      

猪肉背膘中3-甲基吲哚测定方法的研究

3-甲基吲哚即粪臭素，是小肠中未消化的蛋白质在大肠厌氧微生物作用下的产物之一，对未阉割的公猪肉品质有显著的负面影响。本次实验就对猪肉背膘中3-甲基吲哚的测定方法进行了研究。结果为：标样浓度在120ng／ml范围内线性良好，回收率在97％左右，样品相对偏差在3％以下。表明该方法的灵敏度和准确度均较好。     

Reduction of Boar Taint Compounds in Kraski prsut through Dry-curing Process

Given that surgical castration of male pigs could be abandoned, the problem of product acceptability can become critical in dry-cured hams, especially when raw material comes from conventional pig husbandry. In this study, we have investigated 16 thighs harvested from 8 entire male fatteners that were submitted to 15 months of dry-curing process. Skatole and androstenone were determined in subcutaneous fat before (n = 8) and post processing (n = 16). After 15 months of dry-curing, markedly lower fat tissue concentrations of androstenone (36%) and skatole (20%) were determined. The reduction was independent of the level of boar taint substances.     

Investigation of factors responsible for the development of boar taint

The objective of this study was to evaluate the effect of 16-androstene steroids, skatole, size of accessory sexual glands and live weight on the development of boar taint in entire male pigs. In Trial I, 35 Yorkshire entire males were slaughtered at 116 ± 3.0 kg live weight. Levels of 16-androstene steroids in the salivary gland (STs), 16-androstene steroids in the fat (STf), skatole in the fat (SK), length of the bulbourethral gland (BG) and weight of the salivary gland (SG) were 44.2 ± 4.7 μg/g, 0.47 ± 0.06 μg/g, 0.20 ± 0.03 μg/g, 11.7 ± 2.2 cm and 63.50 ± 6.73 g, respectively. Samples of loin chops from the animals were evaluated by a trained sensory panel for the presence of boar odour and boar flavour. Sensory scores were correlated with all the investigated factors (P 0.05). Boar odour was particularly well correlated with SG (r = 0.61) and BG (r = 0.60); the correlation with STs was r = 0.53, with SK was r = 0.46 and with STf was r = 0.44. Similar results were obtained for boar flavour. Therefore, both skatole and 16-androstene steroids had significant effects on boar taint. The best explanation of boar taint was obtained by combining measurements of skatole levels in fat and bulbourethral gland length. Trial II involved 36 Yorkshire pigs, 12 each of entire males, gilts and castrates, slaughtered at 104.6 ± 1.1, 102.8 ± 1.8 and 101.0 ± 1.6 kg, respectively. Entire males were chosen which had low levels of 16-androstene steroids (in salivary gland: 13.4 ± 1.5 μg/g; in fat: 0.49 ± 0.09 μg/g) and low levels of skatole in the fat (0.10 ± 0.01 μg/g) but long bulbourethral glands (11.3 ± 0.2 cm). Sensory evaluation performed by a trained panel revealed stronger boar odour and boar flavour from meat from entire males than from other genders (P 0.05). The present results indicate that, although both 16-androstene steroids and skatole are important, they cannot completely account for the occurrence of boar taint detected by a trained sensory panel. Other factors, due to sexual maturity as indicated by the length of bulbourethral gland, are involved and should be considered when estimating boar taint in entire male pigs.     

Nonfloral sources of chemicals that attract male euglossine bees (Apidae: Euglossini)

We present chemical analysis of four rotten or fungus-infected logs that attracted fragrance-collecting male euglossine bees. Eight of the 10 volatile compounds detected have never been found in the fragrances of orchids pollinated by male euglossine bees. Nonfloral sources of chemicals such as rotting wood may constitute an important fragrance resource for male bees. Since rotten logs produce large quantities of chemicals over long periods of time, such nonfloral sources might be more important than flowers as a source of certain fragrances for some euglossine bee species. Fragrance collecting in euglossine bees might have evolved originally in relation with rotting wood rather than flowers.     

Chemistry of the defensive secretion of the caddisflyPycnopsyche scabripennis (Trichoptera: Limnephilidae)

From a pair of exocrine glands located on the fifth abdominal sternite, the caddisflyPycnopsyche scabripennis secretes a defensive exudate which containsp-cresol, indole, and skatole. This secretion effectively repels invertebrate predators such as ants. The probable significance of this secretion in the biology of these caddisflies is discussed.     

Effect of different condensed tannin‐containing forages,forage maturity and nitrogen fertiliser application on the formation of indole and skatole in in vitro rumen fermentations

The objectives of this work were to establish the effect of seven different forages with a varied condensed tannin (CT) content, plant maturity and nitrogen fertiliser application on the ruminal formation of skatole and indole using an in vitro method designed to mimic rumen fermentation conditions. After 10 h of incubation, the concentration of indole and skatole was highest when incubating white clover (P < 0.05). Polyethylene glycol addition, to inhibit CT, showed that CT significantly reduced the formation of indole and skatole when incubating Lotus corniculatus, sulla, Dorynium rectum and Lotus pedunculatus (P < 0.01). Mature forage growth resulted in a significantly lower concentration of indole and skatole being formed in vitro compared to the incubation of new spring growth (P < 0.001). A higher application of nitrogen fertiliser to perennial ryegrass‐based pasture resulted in a higher crude protein concentration in the plant and a significantly higher concentration of skatole formed in vitro (P < 0.001). Forages containing CT reduced the conversion of endogenous protein to indole and skatole and plants containing a higher CT concentration tended to be more effective, but compositional differences of CT between forages may also have had an influence. New forage growth or swards that had a high application of nitrogen fertiliser promoted the formation of indole and skatole. Copyright © 2007 Society of Chemical Industry     

Method for the determination of indole and skatole in pig fat

A quantitative method was developed to determine by gas-liquid chromatography the concentrations of indole and skatole in pig fat. Methanolic extracts of subcutaneous adipose tissue were de-fatted by cooling, concentrated using solid-phase extraction columns, and analysed in a gas chromatograph fitted with a polar capillary column and a flame ionisation detector. The method detects indole and skatole to below 0-002 mg kg^?1 fat.     

Spatial variation of intestinal skatole production and microbial community in Jinhua and Landrace pigs

BACKGROUND: An excessive accumulation of skatole in pigs is a major contributor to boar taint. Intestinal skatole concentrations may vary among different pig segments and breeds. The objective of this study was to evaluate the spatial variation of intestinal skatole production and the microbial community in local Jinhua and exotic Landrace pigs. RESULTS: For both breeds, skatole concentration increased towards the rectum and segment had a significant effect on skatole (P < 0.001). The caecal skatole concentration in Landrace was significantly lower than proximal, distal colonic and rectal skatole levels (P < 0.05). Compared with Jinhua pigs, the rectal skatole and proximal and distal colonic indole levels were significantly higher in Landrace pigs (P < 0.05). Volatile fatty acids were significantly affected by breed except for isobutyrate and isovalerate (P < 0.05), with higher butyrate level and lower pH in Landrace pigs (P < 0.05). There were no significant differences in mitosis and apoptosis for the two breeds. The denaturing gradient gel electrophoresis profile showed differences between breeds and segments within one breed, though some bands were common to all samples. CONCLUSION: The higher skatole levels in Landrace pigs may be not associated with higher intestinal apoptosis. The results suggested that pig genotype plays a role in the establishment of the host‐specific microbiota and that the variations in fermentation patterns are more likely to explain differences in intestinal skatole production. Copyright © 2009 Society of Chemical Industry