QUALITY OF YOGHURT MADE FROM COW'S MILK FORTIFIED WITH WHEY PROTEIN ISOLATE | ||||
| Egyptian Journal of Dairy Science | ||||
| Public Titles, Volume 49, Issue 2, December 2020, Page 77-87 PDF (374.6 K) | ||||
| DOI: 10.21608/ejds.2020.235554 | ||||
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| Authors | ||||
| Ragab Badawi* ; Khamis Kebary; S Husien; M Habib | ||||
| Department of Dairy Sci. and Technol., Faculty of Agriculture, Menoufia University, Shibin ElKom, Egypt. | ||||
| Abstract | ||||
| Fiveyoghurt treatments were made to study the effect of fortifying cow's milk with whey protein isolate on the quality of yoghurt, control yoghurt was made by adding 3% non-fat dry milk to cow's milk while the other four treatments were made by fortifying cow's milk with 0.5, 1.0, 1.5 and 2.0% whey protein isolate respectively and 3.0% nonfat dry milk to each treatment. All yoghurt treatment was stored in refrigerator for 12 days and was sampled when fresh and at 3, 6, 9 and 12 days for chemical, rheological, microbiological analysis and sensory evaluation. The obtained results indicated that adding whey protein isolate to cow's milk caused a significant increase of total solids, total protein, ash contents and titratable acidity, while decreased pH values and whey syneresis of yoghurt treatments and these effects were proportional to the rate of adding whey protein isolate. Also, the values of Hardness, adhesiveness, cohesiveness, springiness and gumminess of the resulting yoghurt had increased and this increase was proportional to the rate of fortification. Adding whey protein isolate up to 1.5% increased the scores of organoleptic properties and treatment that made with adding 1.5% whey protein isolate was the most acceptable yoghurt treatments. Total solids, total protein, ash and fat contents of all yoghurt treatments did not change significantly, (P > 0.05) during storage period, while titratable acidity increased. Whey separation decreased during storage period up to the sixth day of storage period then increased up to the end of storage period, while the scores of organoleptic properties were almost stable up to the ninth day of storage period. | ||||
| Keywords | ||||
| Cow's milk; non-fat dry milk; whey protein isolate; yoghurt; syneresis; organoleptic properties | ||||
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