Non-target bioactive compound profiles of coffee roasts and preparations.

Coffee is an inherent part of our daily nutrition and seems to have protective effects against diseases, whereby it is often not fully understood, which ingredients are responsible for the observed effect. Hence, a non-targeted bioactivity profiling was developed to investigate 27 hand-filtered coffee brews of differently roasted coffee beans and 14 differently prepared and stored coffee brews. After separation, multi-imaging, and densitometry, six planar effect-directed assays were performed to reveal individual antioxidative, antibacterial, anti-cholinesterase, anti-diabetic, and estrogenic effects. Individual compounds were mainly responsible for the observed effects, e.g. 5-O-caffeoylquinic acid regarding antioxidative potential and α-glucosidase inhibition, while coffee brews made by a fully automated coffee machine showed the highest antioxidative potential. Unlike preparation and storage conditions, applied roasting conditions and origin of coffee samples played a less important role. Therefore, the way we daily consume our coffee has an impact on the magnitude of potential health effects.

Investigation of Reduced ELISA Recovery of Almond and Hazelnut Traces from Roasted Nut Samples by SDS-PAGE and Mass Spectrometry.

Western society is facing an increase in the number of food-allergic individuals, with rising incidence in the past years. Therefore, allergen-free food and accurate and reliable analysis of allergen contamination are essential for the protection of consumers. Yet, there is limited understanding on the effect of food processing on allergenicity and on the ability of available methods to detect trace contamination in processed food. Available studies addressing this have relied on sample processing on a laboratory scale. In this study, industry-like processing under precisely defined conditions (ranging from 110 to 150°C roasting temperatures) was employed to better understand the limitations of state-of-the-art methods for detecting traces of hazelnut and almond in processed food. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated an overall reduction in extracted proteins from roasted nut samples, and with matrix-assisted laser desorption ionization time-of-flight Cor a 9 and Prunin, were identified as majorly expressed proteins for hazelnut and almond, respectively. A commercial ELISA kit detected nut traces only up to a 130°C roasting temperature. Untargeted MS (Orbitrap) analysis was able to detect traces of nuts roasted up to 150°C while also confirming Cor a 9 and Prunin as the major expressed proteins for hazelnut and almond, respectively. Preparing cookie dough spiked with roasted nut samples, a complex food matrix was simulated. Analysis by ELISA showed the same limitations encountered for pure nuts samples, hardly detecting traces of nuts roasted above 130°C. Targeted MS (linear ion trap) using multiple reaction monitoring methods for one proteotypic peptide for Cor a 9 and Prunin, respectively, enabled a detection of nut traces up to 150°C. The results indicated that a reduced extractability because of temperature-related effects (e.g., protein denaturation, cross-linking, poor solubility) caused the significant differences between the ELISA and MS analysis. Overall, the results of this study may form the basis to improve allergen detection after roasting through improved extraction methods and refined ELISA formats.

Multi-photon microscopy of cell types in the viable taste disk of the frog.

The morphology of viable taste disks of the frog was explored with multi-photon microscopy. In order to identify single sensory or supporting cells within the tissue, we searched for fluorescent dyes that stained subsets of the cell population or possibly cell types. Some cell types indeed stained preferentially with certain fluorescent dyes. A subset of glia-like cells (type Ic) stained with BCECF, a H+-sensitive dye, and indo-1, a Ca2+-sensitive dye, both presented in the membrane-permeant ester form. BCECF-ester also stained the dendrites of type III receptor cells, but indo-1 ester did not. Receptor cells of type II stained with MQAE, a positively charged Cl- -sensitive dye. A subset of type II cells accumulated amiloride, a positively charged fluorescent diuretic. Certain supporting cells, i.e., wing cells (type Ib) and glia-like cells (type Ic), were labeled by negatively charged dyes, e.g., calcium green-1 dextran. Mucus cells (type Ia) were stained with only two of the 19 dyes examined, and Merkel-like basal cells (type IV) were stained only with a membrane-labeling voltage-sensitive dye, presumably by endocytosis. No dye was found which would stain all types of cells or all receptor cells. This finding reveals a potential problem for future functional imaging aiming at population responses, as the responses of unstained cells then would remain unobserved. Specificity of dyes with respect to cell types was sufficient to identify supporting cells and receptor cells. Cell shape could then be reconstructed, using optical slicing and rendering techniques. Thus populations of dye-loaded elongated cells, especially types Ic, II and III, could for the first time be visualized in three dimensions.

Leptin and sweet taste.

Leptin, the product of the obese (ob) gene, is a hormone primarily produced in adipose cells, and also at smaller amounts in some other peripheral organs. It regulates food intake, energy expenditure, and body weight. Leptin is thought to promote weight loss, at least in rodents, by suppressing appetite and stimulating metabolism. Mutant mice that lack either leptin or functional leptin receptors, such as ob/ob and db/db mice, are hyperphagic, massively obese, and diabetic. Central hypothalamic targets are mainly responsible for the effects of leptin on food intake and weight loss. However, there are also direct effects on peripheral tissues. Recently, the taste organ was found to be one of the peripheral targets for leptin. The hormone specifically inhibits sweet taste responses in lean mice and not in db/db mice. Thus leptin appears to act as a modulator of sweet taste, provided a functional leptin receptor is expressed by the taste cells. This chapter reviews the genetics and molecular biology of leptin and its receptors, the receptor mechanisms for sweet taste, the modulating action of leptin on taste receptor cells, and the consequences for the regulation of food intake.