ChapterPDF Available

Rheology and Functionality of Ayran—A Yogurt Drink



Milk is considered a miracle natural food in which fat exists as an emulsion. Yogurt is known for its health benefits, being a fermented milk product. It has a viscoelastic gel structure. Both are regarded as healthy foods and there have been many reports about their health functionality. These healthy foods have also received attention from consumers, researchers, and manufacturers. The concept of new product design starts from the consumer needs and demands, based on daily life requirements. This concept includes not only designing a new product but also making the product functional. These two characteristics of designing a new product can only be realized by understanding the structure–function relations of components in foods. It appears that this point is missing in the literature. Ayran, a yogurt drink, is a traditional fermented drink in Turkey and neighboring countries, with various reported benefits. Its rheological properties have continued to be studied to understand its stability and textural problems during manufacture, transportation, storage, and consumption. As functional foods have become a trend, its functional properties have also been studied with additions of “functional” ingredients such as probiotics or prebiotics. In this review, functional and rheological studies of ayran are discussed.
A preview of the PDF is not available
... However, they did not have a gel-like viscoelastic structure like yogurt [13]. The flow behavior index values were between 0 and 1 which means the structure had non-Newtonian behaviour. ...
Conference Paper
Full-text available
Koumiss is a traditional fermented milk product containing 1–3% alcohol and mostly produced from mares’ milk. The consumer’s interest in kefir, koumiss and similar products due to the pieces of evidence of health benefits caused to develop the newer food-processing techniques. A few studies have been conducted so far, but homemade koumiss produce practising needs more research. Thus, we examined to produce a fermented beverage by adding koumiss culture to cow’s milk and determine the rheological behaviour of the beverage by using a rheometer (Haake Rheostress 1, Germany). According to the results, our beverage exhibited non-Newtonian as thixotropic behavior (n<1) and the thixotropy was also confirmed from the apparent viscosity values as viscosities for the down ramp were lower than the viscosities for the up ramp. The apparent viscosity values of the samples were between 168 and 195 mPa.s in up shear ramp and 91 and 102 mPa.s in down shear ramp. Flow behavior index (n) and consistency index (K) values for the samples ranged from 0.12 to 0.60, 0.63 to 10.72 (, respectively.Whereas adding lactose decreased the apparent viscosities for both ramps, adding sucrose increased viscosity for up ramp and decreased viscosity for down ramp. Consequently, adding different sugars did not cause any statistical significant difference between samples’ viscosity values (p>0.05).
Ayran is a salty drinkable yoghurt, but lactose in ayran induces lactose intolerance. This can be overcome by production of lactose-free or lactose-reduced ayran. Milk with 50% and 100% lactose hydrolysis by β-galactosidase was therefore used for alternative lactose-reduced or lactose-free ayran production. Physicochemical, microbiological, and sensory analyses were performed during storage at 4 °C for 28 days. Syneresis and flow behaviour index values increased, and apparent viscosity and consistency coefficient values decreased with increasing lactose hydrolysis level, salt content (0.5 and 1%), and storage period. No significant effects of lactose hydrolysis level and salt content on the counts of S. thermophilus and L. delbrueckii subsp. bulgaricus were found, while counts of these bacteria decreased during the storage period. Sensory evaluation highlighted that the 1% salt-containing ayran samples, which had higher scores of overall liking than 0.5% salt-containing ones, were significantly different from commercial ayran within the storage period.
Conference Paper
Full-text available
Batter coatings are used for improving fried food quality by reducing fat uptake, preventing moisture loss and enhancing appearance, flavor, texture, weight and volume of final product. The objectives of this study are to evaluate the effects of quinoa and corn flour incorporation on rheological and thermal properties of tempura batters. Quinoa and corn flour were mixed at four levels (w/w, % of flour) namely 40:45; 45:40; 50:35 and 55:30, respectively. The rheological characteristics of batters were evaluated using DHR3 rheometer with parallel-plate geometry at 15°C. The batters exhibited shear-thinning behavior. Storage modulus (Gʹ ) was higher than loss modulus (Gʹʹ ) and both values increased with increasing frequency for all samples. Shear stress (Pa) versus shear rate (s-1) data provided a good fit to Power-law (R2>0.98) and Herschel-Bulkley model (R2>0.97). The consistency index determined with Power-law varied between 176.00-213.10, while for Herschel-Bulkley model it varied between 166.70-198.90 Increasing rate of quinoa flour resulted in higher consistency index. Thermal properties of quinoa and corn flour were analyzed with DSC. Gelatinization onset and peak temperatures of quinoa and corn flours were found as 57.45°C-64.35°C and 64.69°C-70.40°C, respectively, and the gelatinization enthalpies were determined as 1.513 and 1.077 J/g.
ResearchGate has not been able to resolve any references for this publication.