Physicochemical Properties of Yoghurt Fortified With Different Zinc Salts

Abstract

Fresh buffalo's milk of 6% fat was heated. Each of three zinc salts (Zinc gluconate, zinc sulphate and zinc acetate) was added to individual milk sample at levels of 30 mg Zn/L milk with the addition to the control treatment. Then, cooled, and inoculcated with 3% mixed culture of Lactobacillus delbrueckii sub sp. bulgaricus and Streptococcus salivarius sub sp thermophilus. and incubated at 42°C until firm curd was formed at pH 4.6. The resultant yogurt was kept in refrigerator (6±1°C) for 10 days. Results showed a reduction in pH values, lactose content and the wheying off resulting in from the prepared yoghurt which supplemented with zinc salts. Whereas, an opposite trend was noticed for acidy, curd tension. While, yoghurt supplemented with zinc acetate recorded the highest value of acetaldehyde content. Moreover the zinc sulphate gained the highest viscosity till the 7 th day of storage. Concerning the sensory properties, enriching yoghurt with zinc gluconate recorded the highest score in flavor, body & texture.

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“…Titratable acidity (%) of both control and fortified samples was 0.80% and 0.79% on 1 st day. After 10 days, titratable acidity of control and fortified samples increased to 0.89% and 0.85%, respectively, which is analogous with El-Sabie et al, (2010), who reported an increase in acidity of control and fortified samples to 1.19% and 0.85%, respectively. Al-Shaikh, (2020) also observed an increase up to 0.90% and 0.87% for control and Zinc fortified yogurt, respectively, for 14 days storage.…”

“…This may be since a decrease in pH with time results in electrostatic attraction between caseins molecules which in turn causes reorganization of protein matrix and exudation of water (Lee & Lucy, 2010). El-Sabie et al, (2010) also reported decreased syneresis in zinc fortified yogurt samples as compared to control and increase in syneresis in all samples during 10 days of storage.…”