Studies on umami taste. Synthesis of new guanosine 5'-phosphate derivatives and their synergistic effect with monosodium glutamate

A number of N2-alkyl and N2-acyl derivatives of guanosine 5'-phosphate (GMP) have been synthesized and tested for their synergistic effect with monosodium L-glutamate (MSG), the prototypical substance imparting umami taste to savory-based foods. Capacities to enhance the taste intensity of MSG (gamma values) were estimated through subjective comparisons of MSG/nucleotide mixtures in water with appropriate solutions of MSG alone. Assuming beta = gamma[nucleotide]/gamma[IMP], beta values of the N2-substituted GMPs were found in the range 1.2-5.7. Such values appear to be related to the chain length of the substituent in the 2-position of the purine nucleus and dependent on the replacement of a CH 2 group with an S atom and/or with an alpha-CO group. These findings indicate that the exocyclic NHR group of the guanine moiety is actively implicated in the synergism between GMP derivatives and MSG. Theoretical calculations suggest that an anti conformation is probably assumed by ribonucleotide molecules interacting with umami receptors.     

Juice quality of two new mandarin-like hybrids (Citrus clementina Hort. ex Tan x Citrus sinensis L. Osbeck) containing anthocyanins

Tacle and Clara [Monreal clementine (Citrus clementina Hort. ex Tan) x Tarocco orange (Citrus sinensis L. Osbeck)] are two new triploid citrus hybrids developed by the CRA-Istituto Sperimentale per l'Agrumicoltura (Acireale, Italy). The fruits are easy-peeling and juicy, have a pleasant taste like the Tarocco orange, and are sweet like the Monreal clementine. In addition, a distinctively attractive characteristic of these mandarin-like fruits is the red-pigmented flesh caused by the presence of anthocyanins. This study reports the juice quality attributes of fresh fruits harvested at different ripening stages and of cold-stored fruits kept for 104 days at 6+/-1 degrees C and 90-95% relative humidity. Physico-chemical analyses showed that the fresh-fruit juice yield ranged between 39 (Tacle) and 41% (Clara); these values were 11-14% lower after 104 days of storage. Vitamin C content in the Clara juice was decisively higher than that in the Tacle juice. Juice anthocyanins and other polyphenols increased during cold storage. These results show that low-temperature storage enhances the functional attributes of Tacle and Clara fruit juices.     

Factors affecting the synergy of thiabendazole, sodium bicarbonate, and heat to control postharvest green mold of citrus fruit

The efficacy of thiabendazole (TBZ) to control postharvest decay caused by Penicillium digitatum of citrus fruit can be enhanced by co-application with sodium bicarbonate (SBC) and/or heat treatment. The impact of these treatments was investigated in citrus fruit, as a function of TBZ and SBC concentration and temperature, and were related to the amount of TBZ residues in fruit (total residues), in fruit surface, in the cuticular wax, and in the inner fruit. The residue levels of TBZ were determined in 'Valencia' oranges following a 1 min dip in an aqueous mixture of SBC at 0.5, 1, or 2 wt %/vol and TBZ at 600 or 400 mg/L (active ingredient, a.i.) at 20 or 40 degrees C and after 0 and 20 days at 17 degrees C and 90% relative humidity. The influence of SBC and heat on the TBZ residue concentration on the fruit surface, in cuticular wax, and on the inner cuticle tissue was determined in 'Salustiana' oranges after a 1 or 3 min dip in TBZ alone at 600 mg/L and 20 or 50 degrees C or for 1 min in TBZ at 600 mg/L and SBC at 2% and 20 degrees C. The efficacy of heat treatments with water, SBC, and TBZ, applied separately or in combination, was investigated on artificially inoculated 'Nova' mandarins and 'Valencia' oranges for the control of postharvest green mold caused by a TBZ-sensitive (TBZ-s) or TBZ-resistant (TBZ-r) isolate of P. digitatum. The residue levels of TBZ in fruit, evaluated as total residues, were not affected by the co-application of SBC in most samples. While TBZ residues in the fruit surface were not significantly affected by the dip temperature or by co-application of SBC, the rates of diffusion and penetration of TBZ into cuticular wax markedly increased in the presence of SBC or when TBZ was applied in combination with heat. TBZ residues in the inner tissue of fruits treated at 20 degrees C were not dependent upon the dip time or by the presence of SBC and were similar to those found in fruit treated with TBZ at 50 degrees C for 1 min, whereas significantly higher values were recorded in samples treated with TBZ at 50 degrees C for 3 min. When TBZ at 600 mg/L and 20 degrees C was applied in the presence of SBC at concentrations of 1-2 or 0.5-2%, it effectively reduced decay caused by the TBZ-resistant isolate of green mold in 'Nova' mandarins and 'Valencia' oranges. This treatment was also significantly more effective than TBZ alone to control green mold caused by a TBZ-s isolate in 'Valencia' oranges. The combination with SBC and mild heat (40 degrees C) and TBZ at 400 mg/L generally improved the control of a TBZ-r isolate of green mold with respect to the combined treatment at 20 degrees C. TBZ efficacy was also improved when applied at reduced rates (200 mg/L) and 50 degrees C, significantly suppressing green mold caused by a TBZ-s isolate of P. digitatum and effectively controlling a TBZ-r isolate. The rate of weight loss of 'Valencia' oranges was significantly increased by SBC treatment and was positively dependent upon the concentration of SBC used in the treatment, while the temperature of the treatment solution had little influence on later weight loss.     

Cross-sectional study on acrylamide hemoglobin adducts in subpopulations from the European Prospective Investigation into Cancer and Nutrition (EPIC) Study

Acrylamide exposure was investigated in subgroups of the EPIC study population (510 subjects from 9 European countries, randomly selected and stratified by age, gender, and smoking status) using hemoglobin adducts of acrylamide (HbAA) and its primary metabolite glycidamide (HbGA). Blood samples were analyzed for HbAA and HbGA by HPLC/MS/MS. Statistical models for HbAA and HbGA were developed including body mass index (BMI), educational level, and physical activity. A large variability in acrylamide exposure and metabolism between individuals and country groups was observed with HbAA and HbGA values ranging between 15-623 and 8-377 pmol/g of Hb, respectively. Both adducts differed significantly by country, sex, and smoking status. HbGA values were significantly lower in high alcohol consumers than in moderate consumers. With increasing BMI, HbGA in nonsmokers and HbAA in smokers decreased significantly. In the assessment of potential health effects related to acrylamide exposure, country of origin, BMI, alcohol consumption, sex, and smoking status should be considered.     

Flavonoids of white lupin roots participate in phosphorus mobilization from soil

The impact of flavonoids released by phosphorus-deficient white lupin roots on inorganic P and soil microorganisms is largely unknown. We report that flavonoids isolated from white lupin roots mobilized inorganic phosphorus and decreased soil microbial respiration, citrate mineralization, and soil phosphohydrolase activities, but did not reduce the soil ATP content. The results suggest that white lupin's release of flavonoids into the rhizosphere plays a significant role in its efficient P-acquisition strategy by solubilizing Fe-bound P and by limiting the microbial mineralization of citrate.     

The severity of smouldering peat fires and damage to the forest soil

Smouldering wildfires propagate slowly through surface and subsurface organic layers of the forest ground and severely affect the soil, producing physical, chemical and biological changes. These effects are caused by the prolonged heating and the large loss of soil mass but are poorly documented in the literature. A series of smouldering experiments with boreal peat have been conducted under laboratory conditions to quantify these effects using small-scale samples. Peat samples of 100 mm by 100 mm in cross section and 50 mm in depth of different moisture were exposed to an external ignition source. Thermocouples placed throughout the sample bed measured the temperature evolution and tracked the peat ignition, intensity and spread of the smouldering front. The results show that moisture content controls peat ignition and that moisture below 125 ± 10% (in dry base) are required. The severity of the smouldering peat on the soil has been quantified in terms of temperature vs. residence time curves and mass loss. The measurements show temperatures in excess of 300 °C for residence times of 1 h leading to sterilization of the soil and mass loss in burnt layers above 90%.     

Cutaneous sterile pyogranuloma/granuloma syndrome in a dog

A case of canine cutaneous sterile pyogranuloma/granuloma syndrome (SPGS) with generalized asymmetrical alopecia and plaques is described. Results from histopathologic examination were suggestive of SPGS and failed to demonstrate any etiological agent. A systematic approach on how to definitively rule out infectious skin diseases is discussed.     

Comparison of magnetic resonance imaging sequences in dogs with multi-focal intracranial disease

OBJECTIVES: To compare the value of different magnetic resonance sequences in the detection of brain lesions in dogs with multi-focal intracranial neurolocalised lesions and abnormal cisternal cerebrospinal fluid analysis. METHODS: T2-weighted, T1-weighted, T1-weighted-Gd, FLAIR (fluid attenuated inversion recovery) images of 73 dogs with multi-focal intracranial localised lesions were reviewed retrospectively. Control dogs (19) were selected on the basis of normal neurological examination, magnetic resonance images and cerebrospinal fluid analysis. Two board-certified radiologists blindly reviewed the magnetic resonance images. Magnetic resonance sequence sensitivities were compared using the chi-squared test and logistic regression, accounting for clustering at the patient level. Statistical significance was set at the 5 per cent level. RESULTS: The FLAIR sequence was found to have the highest sensitivity (84 per cent, 61 of 73), followed by T2-weighted (63 per cent, 46 of 73), T1-weighted postcontrast (62 per cent, 45 of 73) and T1-weighted (23 per cent, 17 of 73) (P<0.001). FLAIR images were 106.1 times (95 per cent confidence interval 25.2 to 447.5) more likely to correctly identify cerebrospinal fluid-positive patients than T1-weighted, 6.4 times (95 per cent confidence interval 2.2 to 18.2) than T1-weighted postcontrast and 5.8 times (95 per cent confidence interval 2.0 to 16.4) than T2-weighted. FLAIR identified 14 per cent of cases that were classified as normal based on the three others sequences. CLINICAL SIGNIFICANCE: Routine use of FLAIR sequence should be encouraged in dogs undergoing a brain magnetic resonance imaging and probably more specifically in cases of suspected inflammatory brain disease.