ARS | Publication request: Processing of pigmented-flesh potatoes (Solanum tuberosum L.) on the retention of bioactive compouns

Submitted to: International Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 2012
Publication Date: March 15, 2012
Citation: Kaspar, K.L., Park, J.S., Brown, C.R., Massimino, S., Chew, B.P. 2012. Processing of pigmented flesh potatoes (Solanum tuberosum L.) on nutrient retention. International Journal of Food Science and Technology. 47:346-382.

Interpretive Summary: Specialty foods may have benefits for human health. Potato is a good source of vitamin C and potassium. However, some potatoes have high levels of other phytonutrients. Purple fleshed potato may have extremely high levels of anthocyanins and other phenolic acids. Yellow-fleshed potatoes have high levels of certain kind of carotenoids. The principal carotenoids found in potato are lutein and zeaxanthin. Both of these compounds are major constituents of the human retina and must be obtained from the diet. This study reports on the stability of red and yellow pigments, colorless compounds called phenolic acids and the ability of the extract of tubers to serve as antioxidants when processed into dried products by three different methods. The three methods were drum drying (DD), freeze drying (FD) and Refractance Window (RW). None of the methods reduced phenolic acids in the red and purple fleshed potatoes while FD and RW reduced them in the yellow flesh potato. Oddly, DD increased them in the white flesh potato. In the red and purple fleshed potatoes all forms of processing reduced the anthocyanin content considerably. In the yellow fleshed potato, all processing reduced the carotenoid content. Antioxidant capacity was reduced by all processing methods by a half to two-thirds. There are many options for producing dried products from potato that would reduce the costs associated with transport and storage. These studies indicate that several methods reduce but do not destroy the phytonutrient capacity of potato. Processing into a dried product that can be re-constituted for consumption is a viable option.

Technical Abstract: Antioxidant retention in white-, yellow-, red-, and purple-flesh potato cultivars after drum drying (DD), freeze drying (FD) and Refractance Window™ drying (RW) was compared. Dried potatoes were analyzed for total antioxidant activity, phenolics, anthocyanins and carotenoids. Total phenolics were high in all potato cultivars. Processing generally did not influence phenolics, except that DD increased (P <0.001) total phenolics in WP. The FD and RW decreased (P <0.001) phenolics in YP. The RP and PP cultivars had the highest anthocyanin concentration. Total anthocyanins in RP and PP decreased (P <0.001) with all drying methods. Total carotenoids were high in YP only, but decreased (P <0.01) after drying processes. Total antioxidant activity decreased (P <0.001) in YP, RP and PP after drying processes, but increased (P <0.001) in WP. Results indicate that drying processes generally decrease antioxidants in the finished product, with FD and RW retaining the highest concentration of antioxidants