Diosgenin quantification,characterisation and chemical composition in a tuber collection of Dioscorea spp. in the state of Jalisco,Mexico

Dioscorea spp. tubers are known commonly as camote de cerro to the state of Jalisco, México. Besides its use as food, it contains diosgenin, a raw material used widely for synthesising steroid hormones. The purpose of the present research was to determine diosgenin contents by gas chromatography‐mass spectrometry (GC‐MS), as well as physical and chemical characteristics of sixty Dioscorea spp. accessions cultivated in mesh shade coming from eleven localities in the state of Jalisco. Extraction protocol for diosgenin was maceration combined with ethanol 80%. Significant statistical differences for diosgenin content were found between accessions, finding levels between 0.02 and 0.16 mg kg^?1 in dry basis. Length, weight tuber, proportion pulp/skin, percentage of pulp and percentage of skin showed significant differences. Chemical composition based in fresh weight presented in moisture percentage a range of 71.93–83.26%, crude protein 1.42–1.74%, ashes 0.80–1.16%, lipid 0.13–0.17%, crude fibre 3.80–4.02% and total carbohydrates 13.97–25.44%. Results show that tubers from Jalisco can be an important source of nutrients for consumers.     

Characterization of Bioactive Compounds from Monovarietal Virgin Olive Oils: Relationship Between Phenolic Compounds-Antioxidant Capacities

The characterization of bioactive components of virgin olive oil from nine varieties (Cuquillo, Empeltre, Manzanilla, Cornicabra, Picual, Arbequina, Lechin, Picudo, and Hojiblanca) has been carried out. Carotenoids, chlorophylls, α-tocopherol, fatty acids, total phenols, and individual phenols were determined. The antioxidant capacity was evaluated by 2,2′-diphenyl-1-picrylhydrazyl and 2,2′-azinobis (3-ethylbenzothiaziline-6-sulfonate) radical scavenging capacity assay, ferric reducing antioxidant potential assay, and oxygen radical absorbance capacity assay. Twelve phenolic compounds were detected and quantified by high-performance liquid chromatography with diode-array detection. Dialdehydic form of elenolic acid linked to tyrosol and hydroxytyrosol, oleuropein, and ligstroside aglycones were the major components in all the samples. Principal component analysis confirmed that Manzanilla, Lechin, Cuquillo, and Hojiblanca var. were the most similar. Furthermore, these results showed that the antioxidant capacity measured by different assays was highly influenced by the phenolic content, especially the dialdehydic form of elenolic acid linked to tyrosol and hydroxytyrosol.     

Use of β-hydroxyacyl-CoA-dehydrogenase (HADH) activity to differentiate frozen from unfrozen fish and shellfish

 Further work on an enzymic method to differentiate frozen from unfrozen fish and shellfish is reported. The method is based on the release of the β-hydroxyacyl-CoA-dehydrogenase (HADH) from mitochondria during freezing. Enzymic activity was evaluated in fresh and frozen thawed samples from sole (Solea solea), sea bream (Pagellus centrodontus), hake (Merluccius merluccius), gilt headed bream (Sparus aurata), sea bass (Dicentrarchus labrax), salmon (Salmo salar), prawn (Penaeus japonicus) and Norwegian lobster (Nephrops norvegicus). Changes in the HADH activity of fresh and frozen thawed samples were compared after freezing at –196  °C for 15 min. Two values were obtained: U (by dividing: HADH activity of samples frozen at –196  °C, then thawed/HADH activity of unfrozen samples) and F (by dividing: HADH activity of samples frozen at –18  °C, thawed, then frozen at –196  °C /HADH activity of samples frozen at –18  °C, then thawed). Statistical analysis showed significant differences (P≤0.05) between both quotients for gilt headed bream, salmon, sea bream, sole and prawn, and an arbitrary limit was set at 2 to differentiate frozen thawed from unfrozen samples. The application of this limit made it possible to discriminate the unfrozen from the frozen thawed state of around 90% of the total samples analysed. Best results were obtained for prawn (100% of samples differentiated). In the present paper, a laboratory routine is proposed based on the comparison of the HADH activity of a sample analysed straight away and that of a sample frozen at –196  °C and then thawed. The reported method is simple and fast. The entire laboratory procedure can be performed in 45 min. Received: 20 July 1998 / Revised version: 2 November 1998     

Estimation of heterogeneous variances using empirical Bayes methods: theoretical considerations.

Procedures are described to estimate variances when heterogeneity of genetic and residual dispersion parameters exists for some criterion. Genetic and residual variances are considered to follow distributions with either known or unknown parameters. The estimates of variances obtained are weighted averages of the corresponding parameter and of a data-based statistic. Although the techniques presented are largely inspired by Bayesian ideas, the procedures can be given a frequentist interpretation, and the parameters of the prior distributions can be estimated from the data at hand. Techniques are described and illustrated for situations in which animals are related or unrelated across herds. We conjecture that the proposed estimators have smaller mean squared error than those obtained by grouping observations in some way and then applying REML within each group.     

A filtration-based real-time PCR method for the quantitative detection of viable Salmonella enterica and Listeria monocytogenes in food samples

We developed a novel filtration-based method that can eliminate dead or severally damaged Salmonella enterica and Listeria monocytogenes in food samples. This new method can recover all viable bacteria in less than 30 min, and can be coupled with a subsequent bacterial DNA extraction and real-time PCR. No statically significant differences (p < 0.01) were found between real-time PCR results obtained separately from S. enterica and L. monocytogenes when different ratios of living and dead cells were used. The analytical sensitivity in both cases was 1 genome equivalent (GE), and the quantification was linear (R² > 0.9969) over a 5-log dynamic range with PCR efficiencies >0.9754. When compared with the standard microbiological methods for the detection of these foodborne pathogens, the relative accuracy was excellent ranging from 95.72% to 104.48%. Finally, we applied the pre-treatment method to the direct detection of viable forms of these foodborne pathogens in food samples using yogurt as a model, the results being similar to those obtained using pure cultures.     

Fertility trends in Sri Lanka and future prospects

Effects of reciprocal forebrain transplantation on the embryonic motility and the hatching behavior in the chick and the duck embryos were studied. The forebrains were transplanted before the establishment of circulation. The grafted tissue formed the telencephalon, diencephalon, eyes, upper beak and part of the cranium. Data indicate that the size of the forebrain has no significant influence on the early embryonic motility (Type I and II) in the chick and the duck embryos. The initiation and maintenance of the pre-hatching behavior (Type III motility) does not reside in the forebrain. The final stage of hatching (climax) on the other hand may be controlled by the forebrain.