IMPROVEMENT OF NUTRITIONAL AND HEALTHY VALUES OF YOGHURT BY FORTIFICATION WITH RUTUB DATE

摘要

As is well known, the date fruits are good sources of many nutrients. Also, yoghurt especially bio-yoghurt has a lot of nutritional and healthy benefits. The aim of this study was to combine the benefits of date and bio-yoghurt in one product which can be made by simple manner. Six treatments of yoghurt were made from cow's milk fortified with 10 and 15% rutub date and using classic or ABT-5 cultures. Changes in rheological, chemical, microbial and organoleptic properties of yoghurt were monitored during refrigerated storage (4°C) of yoghurt for 15 d. Results showed that fortification with date accelerates the rates of fermentation and lowered coagulation time. For rheological analyses, curd tension, viscosity and water holding capacity values increased whereas curd syneresis values decreased in bio-yoghurt fortified with date. Redox potential values were lower in date yoghurt as compared with control. Acidity, carbohydrate, total solids, dietary fiber and ash contents of yoghurt supplemented with date were higher than those of control. Supplementation of date increased mineral contents (K, Ca, P, Mg, Na and Fe), total nitrogen, water soluble nitrogen, total phenols and total volatile fatty acids of yoghurt. The addition of date improved the viability of lactic acid bacteria and bifidobacteria. The bifidobacteria counts were sufficient to yield numbers of beneficial organisms that were higher than the accepted threshold (106cfu.g-1) for a probiotic effect. Also, date adding improved the body, texture and flavor of the yoghurt.