Nonfat torba (strained) yoghurt enriched with different levels (1w/w and 2w/w) of whey protein isolates (WPI) was produced, to study the effects of WPI addition levels on the physicochemical characteristics and free fatty acid levels of control (fatty) and nonfat yoghurts during 14-day storage. Increasing the WPI decreased the syneresis level of the torba yoghurt samples (P < 0.05), but other physicochemical properties were not affected compared to the nonfat yoghurt during storage. However, WPI addition decreased the butyric acid, caproic acid and long-chain fatty acid levels across the storage period (P < 0.05). Therefore, addition of WPI at a level of 2w/w could be considered as an acceptable option for the manufacture of nonfat torba yoghurt with improved nutritional value.

ObjectiveThe current study compared the effects of dietary levels of two phase stoned olive cake (OC) in form of silage (OCS) on milk production and quality of Saanen goats.MethodsThe OCS included in total mixed ration (TMR) at dry matter proportions of 0.0 (OC0), 0.10 (OC10), and 0.20 (OC20). The TMR were fed to a total of 18 goats in a completely randomized design for a period of 5 weeks.ResultsDietary treatments had no effect on the milk yield of Saanen goats, but the daily milk fat production was greater (p<0.05) at feeding OC20. The total phenolic (TP) compounds contents increased (p<0.01) in each increment of OCS in TMR and this was also reflected in the TP contents of milk. The C8:0, C10:0, C12:0, and C14:0 saturated fatty acids (FAs) in milk fat decreased (p<0.01) with increasing dietary level of OCS, but the decrease (p<0.001) in C16:0 and the increase (p<0.01) in C18:0 in milk fat occurred similarly at each inclusion level of OCS. Only OC20 reduced (p<0.05) the total saturated FA, yet the reduction (p<0.01) in n6/n3 ratio and atherogenicity index occurred in both OC10 and OC20.ConclusionTwo phase stoned OCS increases milk quality not only through modifying the milk FA composition, but also by increasing the milk TP content. These favorable changes in milk quality are closely associated with the dietary level of OCS.

In this study, the microbiological, physicochemical, and sensory properties and volatile aromatic compounds of kefir produced by secondary fermentation were investigated. Cow milk samples containing 1.5 % fat were fermented with kefir grains until the pH reached certain levels (pH 5.0-5.5), and then each of them was inoculated with a different starter culture (thermophilic, probiotic, mesophilic aromatic, and yeast) for secondary fermentation. In kefir samples produced traditionally or by secondary fermentation, the pH values, carbon dioxide levels, and tyrosine and lactic acid contents increased during storage. However, the counts of lactococcus, lactobacillus, leuconostoc, and yeasts decreased. Acetaldehyde and ethanol increased during storage, but diacetyl decreased in kefir samples produced traditionally or by secondary fermentation. The butanone contents changed very little but they showed an upward trend within the storage period. Kefir samples produced by secondary fermentation found greater acceptance during sensory testing than samples produced by the traditional method. Kefir inoculated with mesophilic aromatic and yeast cultures were the most preferred by panelists.

Yoghurt production was modeled in this study based on different incubation temperatures, inoculum ratio of starter culture and incubation times. Experimental yoghurts were produced in two replicates and incubation final pH values of 343 yoghurt samples were measured. Resultant pH values were used in fuzzy logic modeling system. Fuzzy logic modelling was conducted in two sections: fuzzy rules were set and membership function was generated in the first section and defuzzification was conducted in the second section. Three different fuzzy sets (triangle membership function) were used for fuzzification of incubation temperature, inoculum ratio of culture and incubation time values. Since there were 7 membership functions of input parameters, 343 (7 x 7 x 7) rows of rule were generated. Mamdani method was used to tabulate fuzzy rules. Three trapezoidal sections of membership functions generated for defuzzification were used and membership function values were determined with the use of weighted average method. Incubation final pH values of 343 samples were assessed in modeling study and model outputs were compared with the expert decisions. Matlab (R2016b) software was used to assess model performance and model general performance was calculated as 90.27%. For present model to be used in industrial scale, automated yoghurt production lines should be designed and put into service of food industry.

Bu çalışmada yumurta akından ve biyoteknolojik yolla elde edilen lizozim enzim preparatlarının antibakteriyal ve antifungal aktiviteleri araştırılmıştır. Çalışmada yumurta lizozimin 50, 100, 150 ve 200 ppm konsantrasyonu ile biyoteknolojik lizozimin 8, 10, 15 ve 20 ppm konsantrasyonu Laktik asit bakterileri, mayalar ve küfler üzerine denenmiştir. Sonuçta yumurta lizoziminin ve biyoteknolojik lizozim preparatlarının tüm konsantrasyonları laktik asit bakterilerin gelişimini etkilememiştir. Maya mikroorganizmaları da laktik asit bakterilerine benzer şekilde 200 ppm de bile üreme göstermiştir. Yumurta lizoziminin küfler üzerine antifungal aktivitesi 50 ppm konsantrasyonda görülmüştür. Biyoteknolojik lizozimde ise 15 ppm de maya gelişimi olurken 20 ppm de maya gelişimi görülmemiştir. Buna karşın biyoteknolojik lizozimin tüm konsantrasyonlarında küf gelişmiştir. Sonuç olarak yumurta laktik asit bakterileri ve mayaların gelişimini etkilemezken küfler üzerine antifungal aktivite göstermiştir. Biyoteknolojik lizozimin antibakteriyal ve antifungal aktivitesi sınırlı olmuştur.