A new headspace-GC-sniffing method is proposed. Using a recently developed headspace cell, the vapor phase is collected under conditions that mimic well those of an aroma above a food. Data treatment is based on detection frequency, rather than on perceived intensity or successive dilutions as used in other approaches. Repeatability appears satisfactory, and independent panels are even able to generate similar aromagrams, without training prior to the analysis. Using a minimum of six assessors, this technique seems to be more reliable than classical ones. To compare detection frequencies between two aromagrams, an estimation of the least significant difference is given. A theoretical justification of this approach is suggested, on the basis of determination of detection thresholds. Keywords: Headspace-GC-sniffing; impact odorants; detection frequency

As considerable inconsistencies are found in the literature regarding the influence of roasting and subsequent operations on the ochratoxin A (OTA) content of green coffee, experiments were undertaken to assess the evolution of OTA along an industrial soluble coffee manufacturing line. Both the variability and the amount of OTA naturally present in a lot of Thai Robusta green coffee were drastically reduced during soluble coffee manufacture. A small proportion of OTA was eliminated during green coffee cleaning, but the most significant reduction took place during roasting. The roast and ground coffee contained only 16% of the OTA originally present in the green coffee. Two phenomena are responsible for the elimination of OTA during roasting: a thermal degradation and a removal with chaff. Thermal degradation is the most important route of elimination, with <20% accounted for by the chaff. A further 20% reduction was observed during soluble coffee manufacture, so that the powder contained only 13% of the OTA initially present in the green beans.

Some mineral waters have a high calcium content and may contribute a significant part of the human daily requirements. Calcium bioavailability from a calcium- and sulfate-rich mineral water (CS-W) containing 11.2 mmol Ca/L (467 mg/L) was compared with that from milk in nine healthy young women. Calcium absorption was measured in the fasting state with a dual-label stable-isotope technique. Fractional absorption rates from milk and CS-W were 25.0 +/- 6.7% and 23.8 +/- 4.8% (means +/- SD), respectively, and did not differ significantly (P = 0.05). Urine was collected for 36 h after the administration of the oral stable isotope while the subjects consumed a controlled diet and a quantity of milk or CS-W providing 25 mmol (1000 mg) Ca. No significant difference was found in the excretion of calcium, nor in the excretion of the two stable isotopes. Mean urinary sulfate excretion was significantly increased by 35% when the CS-W was consumed. No significant correlation was found between 36-h urinary excretion of the intravenous calcium tracer and sulfate, sodium, or urine volume. Therefore, calcium from the CS-W was as well absorbed and retained as that from milk, and no calciuric effect of sulfate was found, showing that such mineral waters can be valuable dietary sources of calcium.

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Absorption of a zinc stable isotope was measured on two consecutive occasions in nine young and eight elderly healthy men aged 24-40 and 70-83 y, respectively. A zinc stable-isotope label (0.8 mg 70Zn) was added to a test meal of either high or low zinc bioavailability, depending mainly on phytic acid content. Zinc absorption from the high-bioavailability test meal was not significantly different (P > 0.05) in the young (38.9 +/- 9.8%, mean +/- SD) and elderly (35.0 +/- 10.9%) subjects. Zinc absorption from the low-bioavailability test meal was 40% and 43% lower, at 23.4 +/- 10.2% and 19.8 +/- 6.1% in these young and elderly men, respectively. Again, no significant effect of age was found. These results show that aging does not lead to nutritionally relevant changes in zinc absorption and in the effect of dietary inhibitors on zinc absorption. Thus, zinc absorption ability seems to be preserved in healthy elderly people, at least until the age of 80 y.