Asuman Gürsel

Role of milk protein–based products in some quality attributes of goat milk yogurt

Goat milk yogurts were manufactured with the fortification of 2% (wt/vol) skim goat milk powder (SGMP), sodium caseinate (NaCn), whey protein concentrate (WPC), whey protein isolate (WPI), or yogurt texture improver (YTI). Yogurts were characterized based on compositional, microbiological, and textural properties; volatile flavor components (with gas chromatography); and sensory analyses during storage (21d at 5 °C). Compared with goat milk yogurt made by using SGMP, the other goat milk yogurt variants had higher protein content and lower acidity values. Goat milk yogurts with NaCn and WPC, in particular, had better physical characteristics. Using WPI caused the hardest structure in yogurt, leading to higher syneresis values. Acetaldehyde and ethanol formation increased with the incorporation of WPI, WPC, or YTI to yogurt milk. The tyrosine value especially was higher in the samples with NaCn and YTI than in the samples with WPC and WPI. Counts of Streptococcus thermophilus were higher than the counts of Lactobacillus delbrueckii ssp. bulgaricus, possibly due to a stimulatory effect of milk protein-based ingredients other than SGMP on the growth of S. thermophilus. Yogurt with NaCn was the best accepted among the yogurts. For the parameters used, milk protein-based products such as NaCn or WPC have promising features as suitable ingredients for goat milk yogurt manufacture.

A STUDY ON USING EXOPOLYSACCHARIDE-PRODUCING CULTURE IN LOW FAT KASAR CHEESE

In this study, the impacts of an exopolysaccharide-producing (EPS+) starter culture on some quality characteristics of low fat Kasar cheese samples were investigated. For this purpose, four cheese samples were manufactured: cheeses containing 20% fat-in-dry matter with added 0.5% EPS+ and 1.0% EPS+ culture (EPS+0.5 and EPS+1.0), control cheese containing 20% fat-in dry matter (K20) and control cheese containing 40% fat-in-dry matter (K40). The samples were allowed to ripening for 90 days at 4 ± 1 °C and were evaluated for chemical, physical, sensory and microstructure qualities on the 1 st, 15th, 30th, 60th and 90th days of ripening. SEM images showed that textural characteristics of low-fat cheese samples could be improved by using EPS+ starter culture and of which had similar texture to the control cheese with 40% fat-in-dry matter. However, it was determined that defects in body and flavor became definite with an excessive increase in moisture level and the cheese with 1.0% EPS+ culture preferred less than the cheese with 0.5% EPS+ culture.

Formation of Flavour and Aroma in Turkish Yoghurts

To search the effects of technological developments in manufacturing of yoghurt, two strains each of Streptococcus thermophilus and Lactobacillus bulgaricus, were chosen according to their acid and acetaldyde production and they were combined in pairs.