Tubers are derived from plant-based materials in the soil, such as cassava, sweet potatoes, potatoes, arrowroot, turmeric, yam, onion, ginger, kencur, purse, taro, yam, canna, yam and so forth. Tubers can be distinguished by its origin is the root and stem tuber. The root or stem is actually a part of the roots or stems are used as a place to store food reserves. Including cassava and yam tuber roots, while sweet potato, potato and yam is the tuber stem.
Tubers are the result of plant source of carbohydrates is important in addition to cereals. Type tubers with an important role in Indonesia, especially cassava and sweet potatoes. Pretreatment process is required before the raw material is processed into refined products tubers. Quality testing of raw materials processed products of tubers needed to keep the processed products of tubers remain qualified.
Quality testing is done physically, or organoleptic depend on the standard tests specified. Determination of ways of testing the quality of raw materials processed products of tubers by the industry to consider the cost, convenience, government regulation, testing purposes, the risks, the complexity, the requirements of raw materials, product quality demands and others. Therefore each industry to test the quality of the raw materials with the complexity and validity of different.
In general, the larger the industry more complete quality testing of raw materials are carried out. Most tubers processing industry small and medium enterprises (SME scale) testing the physical and organoleptic quality only. Testing is integrated in the process of sorting the raw material. Industrial large-scale testing in order to determine whether the quality of the raw material supplied or materials purchased or can be accepted or rejected.
Quality testing of raw materials in large industries are also intended to determine the price of raw materials purchased by the industry. Raw material quality standards set by the industry are made based on the experience of the industry or it can refer to the Indonesian National Standard (SNI). Industry sometimes take some quality criteria set out in SNI. But if the government established the agricultural produce diberlakuan SNI then the industry must implement fully the SNI.
a. The sweet potato quality requirements
1) general requirements
a) The sweet potatoes should not have foreign odors.
b) Sweet potatoes should be free of pests and diseases.
c) Sweet potatoes should be free of chemicals such as insecticides and fungicides.
d) Sweet potatoes should have a uniform color, shape and size of the tuber.
e) The sweet potatoes should have reached optimal physiological maturity.
f) Ubi Jakar must be in pristine condition.
2) Special requirements
Table 1. Specific Requirements Specifications Commodities yams
b. Quality requirements Fresh Potatoes
Table 2. Quality Requirements Specifications Fresh Potatoes
The second table above is a sweet potato quality requirements and quality persyatan fresh potatoes by the Indonesian National Standard.