Farklı ısıl sistemi uygulanmış sütlerden elde edilen yoğurtların duyusal ve reolojik özellikleri

Abstract

T. O. Yuksekc^T

SUMMARY In yoghurt production, it is known that the or ganolapt ical and Theological, properties of yoghurt which are the significant, factors to, distinct its quality, are firstly effected thy the rau milk composition, anrf then by the conditions of all technological processes applied such as homogenizat ion, standardization, heat treatment, inoculation, incubation, cold storage and delivery. Among these processes, heat treatment, uhich causea the phys-ico-chemical changes, and the effects of denatured serum proteins and* the casein micelles, is considered having an important role on developing the stability of t-he yoghurt curd1. The aim auf this study is to investigate the influences of different temperatures and times, applied in heat treatments, on the organoleptical and; rheolocigal properties of yoghurt. For this purpose, milk samples taken from same source uere homogenized and then treated in batch heater.. During the yoghurt manufacturing the heat treatments at 80°C and 90 C for 10, 20 and' 3Ü min. uere applied, and then the products stored at 4°C` At the interval of 1 st, 7 th and' 14» th days, the yoghurt samples uere analyzed in accordance uith their or ganopleptical properties such as apperance, odour, texture, flavor, and their Theological properties such as consistency, viscosity, syneresis and uater holding capacity of curd.VI The results of an evaluation of the findings obtained from; study are summarized as follows; 1.. As regards the or ganoleptical properties; There were no significant difference between the parameters (P>0.05), 2. As regards the Theological properties; a) The highest and optima®: values of consistency and viscasity were obtained' from the heat treatment at 80 C for 20 rain. It was also found statistically important (P<0..Q5). b) During st-orage increased ualues of syneresis and water holding capacity af yoghurt curd obtained from all other treatments^ are statistically important (P<(0J35), but the difference between the nocms applied, are not significant. (P> 0.05),. As a result, it can be suggested that the heat treatment of 80 C for 20 min. may be applied in yoghurt production where batch heating process is used.