Subjective Satiety Following Meals Incorporating Rice, Pasta and Potato.

The satiating capacity of carbohydrate staples eaten alone is dependent upon the energy density of the food but relative satiety when starchy staples are incorporated into mixed meals is uncertain. Our aim was to assess the satiating effects of three carbohydrate staples; jasmine rice, penne pasta, and Agria potato, each consumed within a standard mixed meal. Cooked portions of each staple containing 45 g carbohydrate were combined with 200 g of meat sauce and 200 g of mixed vegetables in three mixed meals. The quantities of staple providing 45 g carbohydrate were: Rice, 142 g; pasta, 138 g and potato 337 g. Participants (n = 14) consumed each of the mixed meals in random order on separate days. Satiety was assessed with using visual analogue scales at baseline and for 3 h post meal. In an area-under-the-curve comparison, participants felt less hungry (mean (SD)) following potato 263 (230) than following rice 374 (237) or pasta 444 (254) mm∙min, and felt fuller, more satisfied, and wanted to eat less following the potato compared with the rice and pasta meals (p for all <0.01). The superior satiating effect of potato compared with rice and pasta in a mixed meal was consistent with its lower energy density.

Composition and structure of tuber cell walls affect in vitro digestibility of potato (Solanum tuberosum L.).

The digestibility of starchy foods, such as potatoes, can be characterized by the proportion of starch that is rapidly digestible by in vitro hydrolysis (rapidly digestible starch, RDS). This study evaluated the RDS content in a potato germplasm collection consisting of 98 genotypes and identified three advanced lines, Crop39, Crop71 and Crop85, where cooked potato RDS content was significantly lower than that of their respective isolated starches (P < 0.05). In Crop39, Crop71 and Crop85, the properties of their isolated starch did not differ significantly from that of five control lines with higher RDS contents. Cell wall analyses revealed that, compared with other lines tested, Crop39, Crop71 and Crop85 had at least four times the amount of rhamnogalacturonan-I (RG-I) galactan side-chains that were very firmly attached to the wall and requiring 4 M KOH for extraction. Pectin solubilization during cooking was also remarkably low (2-4%) in these three lines compared with other lines tested (7-19%). The findings suggest that possession of higher amounts of RG-I galactan that interact strongly with cellulose may provide a sturdier wall that better resists solubilization during cooking, and effectively impedes access of digestive enzymes for starch hydrolysis in an in vitro model.

A simple binding assay for the direct determination of biotin in urine.

BACKGROUND: We have devised a simple assay to detect adequate biotin intake, which uses an alternative configuration from most existing assays. METHODS: The assay depends on the competition of streptavidin peroxidase for immobilized biotin or soluble biotin in standards or samples. Immobilized streptavidin peroxidase is detected using tetramethylbenzidine, and the plates are read at 450 nm. The assay was normalised by determining the biotin/creatinine ratio in the urine of healthy adults. Urinary biotin excretion was measured in unsupplemented pregnant women. The half-life of biotin excretion after a single oral supplement was determined for healthy volunteers. RESULTS: Urinary biotin excretion in unsupplemented pregnant women was 2.9+/-1.9 micromol/mol creatinine (mean+/-S.D.) and was significantly lower (p<0.001) than those of healthy males and females, which were 9.0+/-5.4 and 7.0+/-2.1 micromol/mol creatinine (mean+/-S.D.), respectively. The half-life of a single oral biotin supplement was 30-40 h, with excretion returning to basal levels at 70 h. CONCLUSION: We have devised a novel binding assay for the direct determination of total biotin excretion in urine, which is suitable for routine clinical laboratory. The assay is inexpensive, simple, rapid, and could be fully automated.