Iv. Post-harvest Processing Technology of Sweet Potatoes in Sichuan, China

Sweet potato is one of the important crops in China, its growing area and yield rank the first in the world. Sichuan Province has the largest growing area of sweet potatoes in China which amounted to 873,000 ha with total yield of 3,314,000 tons in 2000. Therefore, production of sweet potatoes is of great importance to agricultural production and increase of farmers’ income in this province. The whole process of production of sweet potatoes can be divided into three periodic stages: fast increase, stagnation and fast growing again in which post-harvest technology has played an important role. Post-harvest technology of sweet potatoes dominated by instant vermicelli and straight vermicelli processing came into being in early 1990s and this technology has been improved in practice ever since. And up to now, quite sophisticated technology and complete sets of equipment have been developed because such technology and equipment are suitable for current production conditions, and by utilizing this technology people have explored and tapped the potential of the market. Now this technology has been disseminated positively. Development and application of post-harvest technology of sweet potatoes have played an important role in promoting the operational model of the industry in the form of Company Plus Farming Household in Sichuan. Based on the concept of processing on production bases, a batch of enterprises engaged in processing instant vermicelli and straight vermicelli has grown up. These enterprises, running in enterprise mechanism and carrying out standardized management in production under total quality control, have gained reputation and created their own product brands. At present, some 150,000 tons of straight vermicelli and 30,000 tons of instant vermicelli are produced every year in Sichuan with output value of 1 billion yuan. Farmers at the production bases earned 700 million yuan. Products are sold all over the country. There are some problems encountered by the post-harvest processing industry of sweet potato. They are as follows: single type of the post-harvest technology. Market volume for sweet potato products dominated by vermicelli is almost saturated. Low extraction rate of starch from sweet potato, thus causing much waste of raw material. New technological process that is better for food safety needs to be improved and popularized. Solutions to address the pollution on rivers caused by production of starch in production bases need to be studied. 1 Director, Sichuan Research & Design Institute of Agricultural Machinery, Chengdu, Sichuan, China.