الفهرس 
Effect of Different Milk Types on Physicochemical and Rheological Properties of Stirred Greek-Style YoghurtOnly 14 pages are availabe for public view
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Abstract
Yoghurt (yogurt) is one of the most famous dairy products in the world. Yoghurt is widely accepted by the consumer due to its health benefits and basic nutrition. Greek-style yoghurt, also known as ”concentrated yoghurt”, it has the following traditional processing of yoghurt which is then concentrated again. Intensive stress removes a large amount of whey and sugar, which changes the nutritional and sensory properties of the yoghurt. Greek yoghurt has a more refreshing taste and creaminess texture. This study investigated the approach to developing a Greek yoghurt formulation using different fresh milk types (buffalo milk, cow milk, skimmed fresh cow milk), and adjusting the chemical properties using milk protein concentrate, skimmed milk powder, cream, modified starch and strawberry fruit preparation to produce a recombined acid milk gel with physicochemical and rheological aspects similar to those found in commercial Greek-style yoghurt.
A. Buffalo Greek-style yoghurt
1. There were no significant (P≥0.05) changes found in protein%, fat %, ash% and acidity% of the six treatments during storage at 4 ± 2°C for 14 days.
2. The total solids (TS %) increased during cold storage and the higher increasing was observed at the end of storage (day 14).
3. pH values of Greek yoghurt treatments were decreased with the progressing of storage time, but the pH value was not changed in treatments made with modified starch (treatments 310s and 410s).
4. There was no significant (P≥0.05) changes observed in ash % of all treatments after cold storage at 4 C for 14 days.
5. The addition of modified starch (MS) to Greek yoghurt caused significant (P≤0.05) increase in WHC%.
6. Increased in SMP: MPC (2:1) in conjunction with the addition of MS increased the WHC % in sample 310S, even with the decrease in protein content.
7. The addition of modified starch (MS) improved all sensory properties of Greek yoghurt during all storage times and the decreased in protein% in treatment 410s had no effect on sensory properties of Greek yoghurt.
8. The firmness values of all treatments (except treatment 110) were decreased during cold storage at 4±2°C after 14days and the higher decrease was found at the end of storage period.
9. The consistency values of all treatments were significantly (P≤0.05) decreased during storage period (14 days/4 C).
10. The addition of MS caused significant (P≤0.05) decreased in consistency of Greek yoghurt.
11. The decrease in protein% caused decreased in consistency value (treatment 410s).
12. Treatment 410s recorded the lowest Adhesiveness value compared with all other treatments.
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13. The viscosity values of all buffalo Greek yoghurt treatments were significant (P≤0.05) decreased during cold storage for 14 days and the higher decrease was found after 14 days storage.
14. The adhesiveness was decreased with the decreasing fat (6%) and protein (5%) value in treatment 410s.
15. The addition of MS improved the texture properties of Greek yoghurt (treatment 310s), while, the decreased in protein and fat values caused decreasing in texture properties (treatment 410s).
B. Cow Greek-style yoghurt
1. There were no significant (P≥0.05) changing in protein %, fat % and ash% in all treatments during cold storage at (4 ± 2 °C) for 14 days.
2. There were no significant (P≥0.05) changes in acidity % and pH values for all treatments during cold storage (4 °C) for 14 days except the pH value of treatment 620 that showed significant (P≤0.05) decreased.
3. TS% of all cow Greek yoghurt treatments was increased with the increasing of storage time.
4. The WHC% significantly decreased with the progressing of the storage time, in addition, the MS caused significant increasing in WHC% (treatment 110s), also, the decrease in protein and fat percentages caused decreasing in WHC% (treatment 210s).
5. The decreasing of protein% and fat % (treatment 210s) caused significant decreasing in overall acceptability and total sensory properties compared to treatment 110s.
6. Treatment 310 recorded the best acceptability and the higher total evaluation compared to all other treatments.
7. On the contrary with buffalo Greek yoghurt, the addition of modified starch was did not cause any improvement in total sensory evaluation of cow Greek yoghurt.
8. All texture properties of cow Greek yoghurts were significantly decreased during storage period.
9. The addition of SMP and FCMP by ratio 1:2 respectively increased the firmness value (treatment 820).
10. The reduction in fat% from 10% to 6% and protein % from 6% to 5% in Greek yoghurt caused decreasing in firmness values (treatment 210s).
11. The addition of MS caused significant decreasing in all texture properties (firmness, consistence, adhesiveness and viscosity) of cow Greek yoghurt.