Fresh-keeping technology of potato

In recent years, the total export of fresh potato in China shows an upward trend year by year. In 1996, exports totaled 440000 tons, with a total foreign exchange of 75 million US dollars. However, export fresh potatoes have more stringent requirements on quality. compared with the main potato producing countries in Europe, there is a gap in variety, classification, packaging, storage and transportation of fresh potatoes exported by China. In this paper, the fresh-keeping technology of potato is briefly introduced.

1. Anti-browning, sterilization and antisepsis

For potato anti-browning, the most effective concentration of sodium hypochlorite is 17.5ppm, the soaking solution ph is 4, and the soaking time is above 5min. The effective concentration of calcium hypochlorite is also 17.5ppm, but the color protection effect of soaking is not limited by the ph of the solution; the most effective concentration of ascorbic acid is 0.3%. 2-phosphoric acid-ascorbic acid is a newly developed non-sulfur color protecting agent with good effect.

2. Anticorrosion and preservation

To prevent the decay of fresh potato in the process of storage and transportation is also a problem that manufacturers of fresh potato must pay attention to and face. Before the 1980s, protective fungicides such as copper sulfate and carbendazim were mixed in cleaning and color protection solution for bacteriostatic and antiseptic treatment. In the antiseptic of potatoes, sec-butylamine fumigation and washing potato pieces can be used. When washing potatoes, the commercial preparation of sec-butylamine with a net content of 50% per kg can be diluted with water and 20000kg washable tubers. During fumigation, 50% sec-butylamine is used according to 50% of 60mg-14g/ cubic meters per kg tuber, fumigation time is above 12min, and the antiseptic effect is good.

Another newly developed fresh-keeping measure of potatoes is the use of film-forming antistaling agents. That is, chitin, chitosan, maltodextrin, konjac glucomannan, sodium alginate, paraffin, beeswax ester and other film-forming agents, adding certain antibacterial agents and antioxidants, the film was kept fresh by soaking into film, brushing film or spraying. The fresh-keeping effect of the film is very good, and it has the functions of controlling atmosphere and inhibiting respiration, especially chitosan and other film-forming agents which have strong bacteriostatic effect.

Recently, Japan has developed a new type of natural food antistaling agent, which is extracted from nuclear protein and has good antibacterial and antiseptic effect. The main ingredients are: fish protein extract 35%, glycine 35%, sodium acetate 25%, sodium polyphosphate 5%, tested for potato and "potato salad" fresh-keeping, the effect is good, and after 60-120 ℃ high temperature heating 30min, the antibacterial activity still maintains 100%, eating this protective agent into the human body, there is no harm to health. The protective agent has been approved by 6 national standards and patents such as fda.

3. Storage and inhibition of germination

Fresh potatoes are generally required to be stored under the conditions of cold, light protection and high humidity, and high humidity controlled atmosphere storage (rh90%-95%) should be carried out where possible. Bud inhibition is usually carried out before and during storage. There are several common bud suppressants:

The main ingredient of sprouting inhibitor popularized by some foreign companies in potato producing areas in China is anthocyanin, which is sprayed with 2500ppm 4-6 weeks before harvest.

Isopropyl n-(3-chlorophenyl) carbamate (cipc): cipc is the most widely used potato sprouting inhibitor in the world. Cipc is widely used in potato storage in all European countries, the United States, Australia and a few developing countries. The application methods of cipc include fumigation, powder application, spraying and washing potato, among which fumigation has the best sprouting inhibition effect, which can last as long as 9 months. The suitable range of fumigation is 0.5% Mui 1%, the time of one fumigation is about 48 hours, and the suitable concentration of washing potato pieces is 1%. Fda and EPA published in 1996 that the allowable residue limit of cipc in potato is 30mg/kg.