Potential Effects of cooking conditions and substitution with carrot and pumpkin on quality attributes of orange sweet potato jam

The current study designed to explain the appropriate cooking method of sweet potato and evaluate the effect of various substitution ratios with carrot and pumpkin on the quality attributes of sweet potato jam (sensory characteristics, chemical composition, total phenolic and flavonoid components, antioxidant activity, and color). The heat pretreatments included microwave heating, grilling, traditional boiling, and under pressure boiling. The Jam was prepared from under pressure pretreated sweet potatoes (control) and from different supplementation from pumpkin and carrot. The results showed that under pressure boiling was the best heat pretreatment for sweet potato maintaining the maximum levels of total phenolic and flavonoid components and antioxidant activity. Also, the results indicated that there was a slight decrease was observed, due to heat processing, of total polyphenol contents and antioxidant activity of sweet potato, which was ranged from 0.51 ± 0.1 to 0.78 ± 0.1 g/g dried extract and 55.54 ± 0.3 to 68.22 ± 0.5 % respectively. In this respect, pressure boiling was exhibited the lowest decrease among the four processing methods (microwaving, boiling, grilling and pressure boiling). The results indicated that potato jam blended with carrot and pumpkin had the highest total polyphenol contents and antioxidant activity 0.77± 0.0g/g dried extract and 65.41± 0.4 % respectively. The overall acceptability of the jam is good.