engleski

Sweet potato a „Superfood“

The Oxford Dictionary definition states a superfood is “a nutrient-rich food considered to be especially beneficial for health and well-being”, or ‘’Superfood is a marketing term used to describe foods with supposed health benefits.’’ Sweet potato (Ipomoea batatas) could be considered as a „superfood“, since it contains high amount of starch, natural sugars, vitamins, polyphenols (TPC), and has a high antioxidative activity (AOA). Listed substances have a positive effect on human body in form of energy, or in the form of preventing the oxidation in the body. Processing and preservation affects these substances and thus the positive effect, which can occur by eating such food. The aim of this work was to evaluate the influence of processing (baking and steaming) as well as preservation (freezing and freeze-drying) for 3 months on starch, polyphenols, and antioxidative activity in three varieties of sweet potatoes, orange (OFSP), white (WFSP) and purple (PFSP) fleshed sweet potatoes. Results of the study showed that processing caused hydrolysis of starch and the increase of reducing sugars. The reducing sugars were higher three times (in baked) and two times (in steamed) compared to the quantity in raw orange and white flashed SP. The highest increase in reducing sugar content was determined in PFSP. PFSP also had the highest content of TPC. The AOA was not significantly different among varieties under this study. Processing affects the TPC and AOA by increasing it, but without statistically significant differences between baked and steamed samples. Considering a preservation of sweet potato purees, from the results, it can be concluded that freeze - drying produced a stable food product since water activity of all purees was below 0.3. The amount of starch and polyphenols of freeze–dried purees were not significantly different then in the fresh purees. However, in the frozen purees, the amount of starch was lower, compared to fresh and freeze – dried purees. The levels of TPC of purees were not significant different compared to freeze-dried purees. Preservation of both, freeze–dried and frozen, purees caused slightly increase of the AOA levels.

Sweet potato, polyphenols, antioxidant activity, sugars, freeze-drying

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