Effect of levels of banana marmalades on quality of stirred yoghurt

الملخص EN

The effect of levels of banana marmalades (BM) and storage period on quality of stirred yoghurt made from cow’s milk was investigated.

Starter culture 5% was added after the pasteurization of the milk at 85°C for 10 minutes.

The milk was incubated at 45°C for four hours, thereafter cooled to the temperature of 6 ± 2°C, and BM and rate of 5%,10%,15%, and 20% were added, the sugar at 8% at added for each levels of BM.

The physicochemical, minerals, vitamins, and sensory evaluation were determined at storage intervals of 0,4,8,12, and 16 days.

The physicochemical properties of stirred yoghurt found the highest total solids (63.0%), protein (4.91%), ash (1.81%), fat (3.58%), carbohydrate, (24.0) fiber (1.71g/100g) and energy (759.56 K.Cal.) obtained by sample yoghurt containing 20% BM and the lowest total solids (21.2%), protein (4.21%), ash (1.42%), fat (3.16%), carbohydrates (12.22%), fiber (0.19 g/ 100g) and energy (396.23K.Cal.)by 5% BM.

The total solids, protein, ash, carbohydrate, fiber and energy of stirred yoghurt increased with increasing levels of banana marmalades.

The pH-values of all samples decreased significantly (P≤0.05) during storage period where the highest value (4.71) was recorded by sample 5% and the lowest (4.24) by sample treated with 20% BM.

The addition of BM has significantly (P≤0.05) decreased pH levels in all samples of stirred yoghurt.

The titratable acidity increased significantly (P≤0.05) during storage period.

The highest value (1.21%) was obtained by 20% BM and the lowest (0.89%) by 5% BM.

The mineral and vitamin contents increased with increasing levels of banana marmalades.

The highest calcium, phosphorus, sodium, potassium, iron, magnesium, vitamin E and vitamin C (25.2, 28.1, 393,384, 238, 213, 1.02 and 21.3 µg/100g) were obtained by 20% BM, while the lowest value (17.2, 12.6, 134, 326, 104, 112, 0.23 and 9.21 µg/100g) by sample 5% BM.

The organoleptic quality reavled that, sample 15 % BM gave the best appearance (4.84), texture (4.88), flavour (4.86) and overall acceptability (4.86) compared with other samples.

The storage period significantly (P ≤ 0.05) affected the quality of stirred yoghurt.

The four sensory parameters gave the best qualities at the eighth day of the storage Period and the worst at the end.