Problem description:
all
Analysis:
When the oxygen concentration is lower than 3% and the carbon dioxide concentration is higher than 10%, the flavor of lemon will be adversely affected. Carbon dioxide above 10% can increase the decay of lemon and reduce the sour taste. Less than 5% oxygen will cause lemon to taste bad. Paying attention to pre-harvest management, timely harvesting, selecting appropriate harvesting methods, timely antiseptic treatment, fruit selection, grading, waxing, packaging and storage management can prolong the storage period of lemons. In Sichuan, China, lemons are usually harvested in late June of10-10, and can be stored until May of the following year.
I. Recovery standards
1, expiration standard. Fruit juice content is 28%-30% (depending on the grade).
Color: dark green fruits have a long shelf life, and yellow fruits must be listed immediately after picking.
2. Quality standards. Yellowness and uniformity of the fruit, size, shape, smoothness and acidity of the fruit, no rot, freezing injury, dry fruit, no mechanical damage, no peel stain, erythema, shrinkage, mottle, etc.
Second, the preservation method
1, chemical preservation method. 1 supplies. 5% potassium permanganate solution, 5% bleaching powder solution, burnt honeycomb briquette residue or activated carbon, plastic woven bag. ② Preparation of preservatives. Soak the residue of honeycomb briquette combustion or activated carbon in 5% potassium permanganate solution for several hours, then take it out, drain the solution, air-dry it in a dark and ventilated place until it is half dry, and make it into small pieces or granules, which is the preservative. ③ Disinfection of plastic woven bags. Clean and disinfect the plastic woven bag with 5% bleaching powder and put it in the shade to dry. 4 bagging. Put the lemon and preservative together in a plastic bag according to the weight ratio of 4: 1, seal it, and store it at low temperature, preferably at 0℃- 12℃. Lemons can be stored in this way for 200 days.
2, coating preservation method (fruit preservation coating). This is a coating preservative suitable for citrus, lemon and other fruits. ① formula. Candelilla wax 4.0 kg, oleic acid 1.2 kg, xylene 0.05 kg, ethylene glycol 0. 1 kg, sodium carbonate 0.2 kg, morpholine 0.9 kg and water 22.2 kg. 2 preparation methods. After the above materials are heated to 80℃ for melting, they are added into 80℃ hot water and stirred evenly. ③ Method of use. When in use, the lemon can be washed, dried, dipped with a film coating agent, and then stored at 10℃-20℃. The fresh-keeping period can be extended from 1-7 weeks to 10-20 weeks.
3. Omni-directional fresh-keeping liquid preservation method. American researchers have recently invented a universal fresh-keeping liquid for fruit preservation and obtained an American patent. According to reports, this multifunctional fresh-keeping liquid is prepared by adjusting the pH value to below 3.5 with 3% citric acid or 75%-80% food-grade orthophosphoric acid, and adding 30%-40% sucrose, 0.3% sodium benzoate or ascorbic acid and 0.03% calcium hydrogen phosphate. Using this fresh-keeping liquid can not only prevent fruit from fading, inhibit bacterial reproduction, but also prevent fruit from shrinking and cracking, keep the texture of pulp unchanged, increase the sugar content and taste as good as new.
Third, disease control.
Physiological diseases of lemon include chilling injury and oil stain, while pathological diseases mainly include green mold, blue mold and black spot.
Prevention and control measures: carefully harvest to reduce injuries such as wounds, abrasions and lacerations; Before harvesting, it is treated with bactericide or biological antagonist; Rapidly cooling to a proper temperature; Maintain proper temperature and relative humidity during transportation and storage to reduce ethylene accumulation; The operating environment should be clean, etc.