Search

Ion-pair and hydrophilic interaction chromatographies are considered to be complementary methods of choice for analyzing intact glucosinolates from broccoli. Ion-pair chromatography resolves non-polar glucosinolates, such as those containing indole moieties, while hydrophilic interaction chromatography is superior for separating polar glucosinolates, such as glucoraphanin and glucoiberin. Reversed-phase separations using hydrophilic endcapped C18-bonded silica and a 50 mM ammonium acetate-methanol gradient mobile phase resolve both polar and non-polar glucosinolates negating the need for switching columns.

The erucic acid content of broccoli florets, sprouts, and seeds was found to be about 0.8, 320, and 12100 mg/100 g, respectively. Using the erucic acid limit established for canola oil in the U.S.A. and Canada as a guideline, the estimated dietary intake of erucic acid from florets and sprouts was considered of little consequence, whereas in seeds a relatively small amount (about 35 g/wk) equaled our calculated exposure limit for erucic acid. Additionally, the most complete fatty acid distribution yet published for the various forms of broccoli are presented.

The importance of dietary sulforaphane in helping maintain good health continues to gain support within the health-care community and awareness among U.S. consumers. In addition to the traditional avenue for obtaining sulforaphane, namely, the consumption of appropriate cruciferous vegetables, other consumer products containing added glucoraphanin, the natural precursor to sulforaphane, are now appearing in the United States. Crucifer seeds are a likely source for obtaining glucoraphanin, owing to a higher concentration of glucoraphanin and the relative ease of processing seeds as compared to vegetative parts. Seeds of several commonly consumed crucifers were analyzed not only for glucoraphanin but also for components that might have negative health implications, such as certain indole-containing glucosinolates and erucic acid-containing lipids. Glucoraphanin, 4-hydroxyglucobrassicin, other glucosinolates, and lipid erucic acid were quantified in seeds of 33 commercially available cultivars of broccoli, 4 cultivars each of kohlrabi, radish, cauliflower, Brussels sprouts, kale, and cabbage, and 2 cultivars of raab.

The analysis of Stevia leaves has been demonstrated without any sample preparation using desorption electrospray ionization (DESI) mass spectrometry. Direct rapid analysis was achieved using minimal amounts of sample ( approximately 0.15 cm x 0.15 cm leaf fragment). Characteristic constituents of the Stevia plant are observed in both the positive and negative ion modes including a series of diterpene 'sweet' glycosides. The presence of the glycosides was confirmed via tandem mass spectrometry analysis using collision-induced dissociation and further supported by exact mass measurements using an LTQ-Orbitrap. The analysis of both untreated and hexane-extracted dry leaves proved that DESI can be successfully used to analyze untreated leaf fragments as identical profiles were obtained from both types of samples. Characterization and semi-quantitative determination of the glycosides was achieved based on the glycoside profile within the full mass spectrum. In addition, the presence of characteristic glycosides in an all-natural commercial Stevia dietary supplement was confirmed. This study provides an example of the application of DESI to direct screening of plant materials, in this case diterpene glycosides.

Adsorption of 2.5 mM and 5.0 mM cholic acid and deoxycholic acid by plant materials high in dietary fiber (alfalfa and wheat bran) and fractions derived from sequential extraction of plant material to remove various components was measured. Results tend to support the hydrophobic nature of adsorption and indicate a lack of macromolecular interactions between dietary fiber and bile acid micelles. Lignin appears to be an extremely important component in the interaction of dietary fiber with bile acids, but holocellulose also plays a significant role. Fractionation of dietary fiber sources may provide a method for study of the effects of specific components of dietary fiber which avoids some of the harsh isolaprocedures.

A rapid and simple high performance liquid chromatographic method for the determination of lactose in milk was developed. Samples were diluted with 0.5% perchloric acid and centrifuged, and an aliquot of the supernate was mixed with acetonitrile. Lactose was separated on a 10 μm particle-size silica column with aqueous acetonitrile as the mobile phase. The recovery of lactose from whole, skim, and chocolate milk averaged 99.2, 101.1, and 100.4%, respectively. Coefficients of variation for routinely performed duplicate determinations are between 1.0 and 1.5%.

The possibility that certain saponins produce growth depression by complexing fat soluble vitamins with a mechanism similar to saponin-cholesterol complexation was studied. An in vitro procedure was developed to quantitate the formation of addition complexes in aqueous solutions. Saponins studied included digitonin, ammoniated glycyrrhizin, quillaja bark saponin, and saponin-containing extracts from alfalfa leaves and roots and soybeans. Vitamins tested included provitamin D3 and vitamins E, A and D3. The study demonstrated that the saponins did not complex fat soluble vitamins in a manner similar to the complexation of cholesterol.

The possibility that certain saponins produce growth depression by complexing minerals was studied. Saponins tested included digitonin, ammoniated glycyrrhizin, quillaja saponin and saponin-containing extracts from alfalfa leaves and roots. Minerals studied were zinc, iron and magnesium. Alfalfa root saponins and ammoniated glycyrrhizin, but not digitonin, quillaja and alfalfa leaf saponins, complexed zinc and iron, but not magnesium. It is proposed that one mechanism of action whereby saponins suppress growth is by the formation of insoluble saponin-mineral complexes. Such complexes could reduce the availability of minerals necessary for growth.

Administration of ammoniated glycyrrhizin for 14 days in the diets of rats at a 2% level caused a significant increase in iron excretion and a significant depletion in liver iron stores as compared to pair-fed control rats. Zinc and magnesium fecal and tissue levels were not significantly influenced by this dietary saponin. Body and fecal weights were also significantly increased in animals consuming the saponin-containing diet.