Evaluation of shelf stability of antioxidant rich seabuckthorn fruit yoghurt

Antioxidant rich fruit yoghurt was developed utilizing seabuckthorn fruit syrup using yoghurt culture. The resultant product had higher content of fat, protein, carbohydrate and antioxidants (vitamin C, vitamin E, carotenoids, phenols, anthocyanins) when compared to a commercial yoghurt. The shelf stability studies of yoghurt were assessed at room temperature, 15°C and 4°C. The product stored at room temperature exhibited off flavor and acidic taste within a day of storage, while the product stored at 4°C and 15° C exhibited significant increase in acidity and syneresis during 9nth and 6th day of storage period respectively. The total solids, pH and viscosity significantly decreased on 18nth, 9nth and 6th day of storage at 4°C and for 15˚C it was on 9nth, 6th and 3rd day of storage respectively. No remarkable change was noted for fat, protein, carbohydrate and antioxidants during storage. The sensory quality of product drastically reduced after 18 days at 4°C and 9 days at 15°C. The count of both yoghurt cultures viz. Lactobacillus bulgaricus and Streptococcus thermophilus significantly decreased during the entire storage period. The yeast and mould count was absent in fresh samples, but were detected on 21st day at 4˚C and 6th day at 15˚C. Likewise, the coliform count was initially absent but was detected on 15th and 6th day when stored at 4 and 15˚C temperature respectively. The product was found to be acceptable up to a period of 12 days at 4˚C and 3 days at 15˚C without posing any threat to the consumers.