In-vitro digestibility tests

Experiments were conducted to determine if varying the conditions in the in vitro digestion procedure would affect post-digestion calcium solubility and in some cases, exchangeability. This was done with two purposes to test the use of the in vitro digestion procedure for studying factors which might influence calcium bioavailability and to use the results to modify the standard procedure. 

SBET, simple bioaccessibility extraction test PBET, physiologically based extraction test DIN, E DIN 19738 German method RIVM, in vitro digestion model, National Institute of Public Health and the Environment,... 

How might these oligomers be produced in the fruit The easiest answer is that limited PG action on cell wall pectins generates them, and we have tested this point in vitro. CDTA- and Na2C03-soluble pectins and PGA (included as a positive control) were incubated with purified tomato PGl. Surprisingly, only the carbonate-soluble material and PGA were digested (based on HPLC analysis of reaction mixtures and generation of... 

The protein digestibility values for pH-shift methods generally correlate well with in vivo digestibility methods in the sense that both tests yield the same relative ranking for test proteins (Pedersen and Eggum, 1983). The difficulty with an in vitro method is that it does not accurately estimate qualitative differences between samples with low and high protein digestibilities. 

C-PER is a PER calculated from the amino acid composition of the test protein and an in vitro protein digestibility measurement. Its calculation involves complicated algorithms provided as part of AOAC procedures. 

Tissues and cells that produce pheromones. Periplanone-B was identified 24 years ago, but its site of production remains in doubt, and even recent studies have implicated several unrelated tissues. Association of periplanone-B with the digestive tract, coupled with the pervasiveness of coprophagy in cockroaches, can result in tissue contamination when only static analytical methods are employed. A biochemical test of de novo pheromone production in vitro will be necessary for an unambiguous determination of the site of pheromone production. This should be a feasible approach with periplanone, but elucidation of its biosynthetic pathway will profoundly facilitate such studies. Pheromone production in other cockroaches has been localized primarily in the dorsal and ventral tegmina and intersegmental membranes of the abdomen. However, the precise tissue and cells that produce pheromones remain unknown in most species. 

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