5121
MARWA MOHAMED EL-SAID
PRODUCTION OF HEALTHY MODIFIED FERMENTED MILK SUPPLEMENTED WITH POTENT ANTIOXIDANT SOURCES
pomegranate peel extract (PPE), total phenolic content (TPC), total flavonoidscontent (TFC), antioxidant activity, whey protein concentrate (WPC) and milk thistle seeds extract (MTSE).
The current study was designed to raise the antioxidant activity of low fat stirred yoghurt supplemented with natural sources of antioxidant (pomegranate peel (PP) and milk thistle seeds (MTS)) and raising its nutritive value by using whey protein concentrate (WPC). The PP (outside, inside and whole) were dried using oven (40°C/48 h.) and solar energy (50±2°C/24 h.). Aqueous and methanolic extracts were prepared from the dried peels, and their total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities (DPPH and ABTS), were determined. Both extracts of the dried whole peel showed the highest antioxidant activities as compared to other pomegranate peel extracts (PPE). Low fat stirred yoghurt was prepared from reconstituted skim milk powder (12% TS) supplemented with 5, 10, 15, 20, 25, 30 and 35% of the PPE. Increasing the conc. of PPE significantly increased its content of TPC, TFC and antioxidant activity until 25% PPE, but, further increase in the percentage of added PPE had insignificant effect. Additionof PPE had inhibited effect on the growth of yoghurt starter bacteria (S.thermophilus and L. delbrueckii subsp. bulgaricus) and it had insignificant effect on the chemical composition and sensory properties (appearance and color, body and texture and flavor) as compared to the control sample. Low fat stirred yoghurt supplemented with different concentration of WPC (0.25, 0.50, 0.75, 1.00, 1.25 and 1.5 g/100ml) had high TPC and antioxidant activity until 0.5 (g/100ml). Addition of WPC increased the total count of S.thermophilus and L. delbrueckii subsp.
2016
Ph.d
Ain Shams
Agriculture