Antioxidant properties of Karanda (Carissa carandas Linn.) extracts and its application in Thai traditional fermented pork sausage (Nham)

Anthocyanin is the natural pigment which can easily extract from plants such as blackberry, mulberry and Karanda. Karanda (Carissa carandas Linn.) had the fully ripe dark violet fruit contains the large amount of natural anthocyanin. The effect of extraction conditions on anthocyanin content, total phenolic content, and antioxidant activity in the extract was investigated. The extract with highest antioxidant activity was selected to use as natural pigment and antioxidant in Thai traditional fermented pork sausage (Nham). Under controlled extraction condition, type of solvent is the major factor that significantly affected the amount of anthocyanin and phenolic compounds in the extracts, and also antioxidant properties. Extraction of Karanda with 1% HCl in 95% ethanol at the weight ratio of 1:10 and extraction time of 90 minutes yielded the anthocyanin enriched extracts with the highest antioxidant activity. The extract was homogeneously mixed into the batter of Nham prior to stuff into natural casing and ferment at 30°C. The amount of lactic acid bacteria (LAB) and lactic acid content were increased during the fermentation and hence reduce the pH of Nham. At 36 hours of fermentation, the pH of Nham reached to 4.5 and then the reaction was ceased. Anthocyanin did not affect the fermentation of LAB. Nham with Sodium nitrite and 0.50% (w/w) of the extract had the shelf-life at 20 days, which was higher than that of the control (10 days). The consumer accepted the products and could not detect the difference between the sample with Sodium nitrite and 0.50% (w/w) extract.