Determination of mineral bioavailability of traditional Usak tarhana using in vitro digestion methods

Tarhana is a traditional fermented grain product, obtained from flour, yoghurt, yeast, vegetables and spices mixture, leaving fermentation, drying and grinding. Generally tarhana is consumed as a thick soup form. The main ingredients of tarhana are wheat flour and yoghurt. The composition of tarhana varies according to the different areas. Tarhana is a good source of vitamins and minerals. Thiamin and pyridoxine are important terms of the B group vitamins. Also calcium, magnesium, iron, zinc, copper, manganese, sodium and potassium are important nutrients. Gastrointestinal in vitro methods are used widely to examine the bioavailability and bioaccessibility of nutrients. For this reason simulating intestinal and stomach model systems (body temperature, stomach and intestinal pH, enzymes) informs about degree of absorption chemicals and substance in the human body. In this study, the samples taken in different stages of tarhana fermentation (at the beginning of the fermentation process and at 3 day intervals) were subjected to in vitro digestion and determined the content of Na, K, Ca, Mg, Fe, Zn, Cu, Mn minerals and phytic acid and calculated mineral bioaccessibility and bioavailability. At the end of the 21 day fermentation of the tarhana pulp, the bioaccessibility values have increased; for copper from 25% to 55% ; for zinc from 23,27% to 51,38% ; for manganese from 19.76% to 39.51% ; for iron from 19.40% to 46.88%; for magnesium from 33,90% to 83,23%; for calcium from 13.13% to 51.65%. The bioavailability values have increased; for zinc from 1,76 to 2,52% ; for manganese from 1,47% to 2,64%; for iron from 1,03% to 2,58%; for magnesium from 2,92% to 5,86% ; for calcium from 1,84% to 6,80%. In addition, the protein content of the tarhana dough and tarhana powdered was determined 17,39% and 15,7% on dry matter basis respectively. Protein contents ranged from 12,25 to 14,34 g/100 g. During the fermentation period, the amount of phytic acid decreased from 524,93 mg/100 g to 50,38 mg/100 g, with a loss of 90,40%