Effect of long-chain inulin and modified starch on the physicochemical and rheological properties of doogh (Iranian yogurt drink)

Karim, M. and Alimi, M. and Shokoohi, S. and Fazeli, F. (2017) Effect of long-chain inulin and modified starch on the physicochemical and rheological properties of doogh (Iranian yogurt drink). Acta Alimentaria, 46 (1). pp. 51-60. ISSN 0139-3006

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Abstract

In this research, simultaneous contribution of long-chain inulin (0–2.34%) and modified starch (0–0.58%) on the physical stability and rheological properties of doogh within 30 days of production was studied. Increased concentration of both hydrocolloids redounded to improvements in physical stability, apparent viscosity, flow behaviour, and viscoelastic properties compared to the control sample. Fitting the data to Herschel—Bulkley model showed a decrease in flow behaviour index, while consistency coefficient (k) increased. Furthermore, for samples containing inulin and starch, G′ was greater than G″, unlike control sample. Indeed, contribution of long-chain inulin at concentrations above 1.18% and modified starch at above 0.3% promote the formation of gel network structure. The expected viscosity increases in the continuous phase in the presence of starch, and also the interactions established between inulin and yoghurt casein aggregates seem to be responsible in the improvement observed in physical characteristics of the product. Among the concentrations studied here, two samples, containing 2% inulin and 0.5% modified starch and 1.18% inulin and 0.58% modified starch, respectively, were recognized as functional doogh samples presenting premier physicochemical and rheological properties.

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