Effect of using Adjunct culture of lactobacillus acidophilus and lactobacillus Plantarum on the quality of Set Yoghurt during storage period.

Abstract

This study was conducted at the Department of Dairy Science and Technology, College of Animal Production Science and Technology, Sudan University of Science and Technology to evaluate the effect of adding different levels of Adjunct culture and storage period to conventional yoghurt culture. Eight liters of fresh cows milk were purchased from dairy farm, college of Animal Production Science and Technology. the milk was pasteurized at 90°C/30min then cooled to 45 °C. The pasteurized milk divided into four equal portions. Four treatments were carried out. The first treatment wasthe control sample in which set yoghurt was from conventional yoghurt starter culture. In the second, third and fourth treatments 50%, 75% and 100% of adjunct starter culture (Lactobacillus acidophilus and Lactobacillus plantarum) were added respectively. The inoculated milk was incubated in all treatments at 43 °C for three hours. After complete coagulation the yoghurt samples were cooled in refrigeration with temperature (4°C). Chemical composition and sensory evaluation were carried out for the yoghurt samples in all treatments at intervals of 1, 5 and 10 days. The results indicated that significant variations (P<0.05) were observed in the fat%, acidity% and protein % while total solids and the ash % showed no significant difference (P>0.05) due to the adjunct starter cultures addition. However, the storage period had significant difference (P<0.05) on the fat, protein, total solids and acidity while the ash content did not affected by storage period. The sensory characteristics of the yoghurt samples found to be not affected significantly (P>0.05) by the storage period except the texture and overall acceptability. Addition of starter cultures had significant variations on the colour, flavor, texture, taste and overall acceptability. The results revealed that the treatments with 50% and 75% showed higher sensory scores