Effect of adding inulin on microbial and physicochemical properties of low fat probiotic yogurt

Document Type: Full paper (Original article)

Authors

1 Department of Nutrition, School of Health and Nutrition, Shiraz University of Medical Sciences, Shiraz, Iran

2 Department of Food Hygiene and Public Health, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

3 Ph.D. Student in Food Hygiene, Department of Food Hygiene and Public Health, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

4 Department of Physiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran

Abstract

Currently, due to their beneficial effects, there is interest in adding prebiotics to food products. This
study investigated the effect of the addition of inulin (1% and 2%) on microbial and physico-chemical
properties of probiotic low fat yogurt manufactured with Lactobacillus acidophilus. Six experimental
preparations of yogurt were produced. Homogenized, standardized and pasteurized low fat milk were divided
into six portions. Four portions were fortified with 1% and 2% inulin and two portions were used without
inulin. All of the preparations were heated up to 85°C and fermented at 42°C until a pH of 4.6 was reached.
Titratable acidity and pH were determined during the incubation period of the samples and a storage time up
to 14 days. Syneresis, color, sensory evaluation and bacterial counts were determined during the storage time. The results showed that inulin did not significantly affect the titratable acidity and pH of the yogurts after 4 h of fermentation at 40°C. There were no significant differences between pH, titratable acidity, syneresis, color and sensory evaluation of all treatments on days 1, 7 and 14 of storage. The counts of L. acidophilus and L. delbrueckii ssp. bulgaricus declined over time, but the addition of inulin to the milk increased the viability of these bacteria during the storage of synbiotic yogurt. In conclusion, inulin can be used to manufacture low fat synbiotic yogurt with additional nutritional benefits without affecting the physico-chemical properties of yogurt.

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