Profiles of phenolics,carotenoids and antioxidative capacities of thermal processed white,yellow,orange and purple sweet potatoes grown in Guilin,China

The objectives of this study were to systematically compare phenolic profiles,carotenoids profiles and antioxidant activities of raw and cooked sweet potatoes of five varieties(white,yellow,orange,light purple and deep purple).Total phenolic content(TPC),monomeric anthocyanin content(MAC),total carotenoid content(TCC),2-diohenyl-1-picryhydrazyl(DPPH)free radical scavenging capacities and ferric reducing antioxidant powder(FRAP)were determined by colorimetric methods.Higher anthocyanin contents and antioxidant capacities were detected in purple sweet potato species,while higher carotenoid contents were detected in yellow and orange sweet potato.All cooked sweet potato exhibited significantly(p<0.05)lower TPC,MAC,TCC,DPPH and FRAP values as compared to the respective raw samples.Under the same cooking time,steaming was good for the retention of TPC,roasting was good for keeping anthocyanins,and boiling was beneficial to preserve carotenoids.

Comparative Revenue, Obstacle Factors and Promoting Strategy of Sprinkling Irrigation in Wheat Field: A Case Study from Yanzhou, Shandong Province in China

This paper takes 30 hm2 wheat sprinkling irrigation land of Yunguo Family Farm in Yanzhou, Shandong Province, China as a sample, and draws a conclusion by comparing it with other households (including individual and large households). The conclusions are as follows: wheat sprinkling irrigation has a remarkable water-saving effect and comparative revenue. Water saving efficiency can reach 61.54% and a comprehensive income-increase rate can reach 38.67%. The main factors of increasing income and incentives of saving irrigation by sprinkling irrigation ranks as the following: saving land consolidation and water monitoring labors (accounts for 62.50%), saving land area of wheat bed to increase production and income (accounts for 23.44%), saving water bills (accounts for 14.06%). The incentive effect of water saving is not obvious mainly because the water price is low. The main obstacles to the promotion of sprinkling irrigation by individual household are the uneconomical scale and the barriers of coordination of proxy irrigation. Other large household’s (family farm) obstacles are mainly the instability of land tenure and mixed management. Suggestions on promoting sprinkling irrigation in wheat field: Accelerate land circulation and promote agricultural scale management to create basic scale conditions for spreading sprinkling irrigation;stabilizing farmland management rights as stabilizing farmland contractual rights, thus giving long-term business interests to all kinds of large household owners;guide the development of “scale + specialization” modern family farms;appropriate water saving subsidies should be given according to the positive externality of household water saving;confirm agricultural water rights to household and allow compensated transfer of “surplus water rights”.