Determination of sucralose in Splenda and a sugar-free beverage using high-performance anion-exchange chromatography with pulsed amperometric detection

Sucralose is a chlorinated carbohydrate nonnutritive sweetener of food and beverage products. The determination of sucralose in food and beverages is important to ensure consistency in product quality. Sucralose was determined in two commercial products without sample preparation using high-performance anion-exchange (HPAE) chromatography coupled with pulsed amperometric detection (PAD). Sucralose was determined with a 10 min isocratic separation. To determine sucralose and other carbohydrates (e.g., dextrose) simultaneously, a gradient separation was developed. The linear range of electrochemical response extended over 3 orders of magnitude, from 0.01 (LOD) to 40 microM (16 microg/mL; 25 microL injection). High precision, high spike recovery, and method ruggedness were observed for both samples.     

The incidence of Pythium spp. and Aphanomyces cochlioides associated with the sugar-beet growing soils of Britain

In a survey of fungi causing seedling diseases of sugar beet using a soil bioassay, Aphanomyces cochlioides and Pythium spp. were found to occur in 39% and 31%, respectively, of 341 sugar-beet fields selected in a stratified random sample in England, The frequency of A. cochlioides-infested soils varied widely in the different sugar-beet growing areas of the country. Soil pH was the single factor most strongly associated with the distribution of the pathogen, but regression models applied to combinations of factors indicated that soil texture and the interval between sugar-beet crops were also relevant to its frequency. It was detected less often in soils of high pH (≥ 75). heavy texture and where the interval between sugar-beet crops exceeded 5 years. No significant associations were found between the proportion of soils with Pythium spp. and soil or cropping factors.     

Fate of mucilage cell wall polysaccharides during coffee fermentation.

Effects of a 20-h fermentation on cell wall polysaccharides from the mucilage of pulped coffee beans were examined and compared to those of unfermented beans, on alcohol insoluble residues (AIRs), their hot-water-soluble crude pectic substances (PECTs), and their hot-water-insoluble residues (RESs). Yields and compositions were very similar: AIRs, which consisted of approximately 30% highly methylated pectic substances, approximately 9% cellulose, and approximately 15% neutral noncellulosic polysaccharides, exhibited no apparent degradation. However, PECTs from fermented beans were shown to have undergone a slight reduction of their intrinsic viscosity and weight-average molecular weight by capillary viscosimetry and high-performance size-exclusion chromatography. After fermentation, hot-water-insoluble pectic substances of RES exhibited partial de-esterification. Removal of coffee bean mucilage by natural fermentation seems to result from a restricted pectolysis, the mechanism of which remains to be elucidated.     

Effect of glucocorticoids on cows suspected of subclinical infection with M. paratuberculosis

Summary

Glucocorticoids were administered to 10 heifers suspected of subclinical infection with Mycobacterium paratuberculosis. Three animals remained untreated.

M. paratuberculosis was isolated from the internal organs of 2 animals after this treatment but not from any of the control group. Delayed type hypersensitivity and lymphocyte reactivity towards Johnin and purified protein derivates of M. avium and M. bovis were depressed. A sharp increase in total leucocyte count, due loan increase in neutrophil numbers, occurred. In the three untreated animals these parameters did not change during the experiment.

A decrease of specific immunological reactivity towards M. paratuberculosis occurred, but not to such an extent that clinical disease developed.     

Biotypes of the citrus nematode (Tylenchulus semipenetrans Cobb) in Israel

Two biotypes of the citrus nematode, Tylenchulus semipenetrans Cobb, were identified among five populations occurring in different regions in Israel. These biotypes originated from Sour orange and Troyer citrange roots and differed in their ability to infestPoncirus trifoliata hybrids (particularly Troyer citrange). They appear to be close to two recognized biotypes known to be present in other countries and designated as the “Poncirus” and “Mediterranean” biotypes. The different infectivity of the two biotypes on Troyer citrange roots was maintained even after they were cultured for 6 months on Sour orange. Both biotypes readily reproduced on persimmon, but failed to infest olive and grapevine. Two newP. trifoliata x Poorman orange hybrids exhibited good resistance to both biotypes.     

The pyrethrins and related compounds. Part XXXV. Esters of aryl-substituted cyclopentane alcohols and analogues

Synthesis of a range of 1-, 2-and 3-phenyl, benzyl and phenethyl substituted cyclopentanols and cyclopentylmethyl alcohols and related unsaturated compounds is reported. Results of bioassays of their esters with known pyrethroidal acids against two species of insect lead to recognition of some structure-activity relationships in this series. The distance and relative orientation between the alcoholic and aryl functions appears crucial, but in other respects the nature of the spacer group between them is less important. The most effective alcoholic components are based on cyclopentenes.