Storage and fresh-keeping Technology of Peach, Plum and Apricot (2)

III. Agricultural measures before storage of peaches, plums and apricots

1. Early-maturing varieties for storage are not resistant to storage and transportation, such as peach and May fresh. Middle and late ripening varieties have good storage and transportation resistance, such as Feicheng peach, Qingzhou peach, Shaanxi winter peach, Okubo, Gangshan white, Yanhong and other varieties also have good storage and transportation resistance. The storage and transportation resistance of seedless and soft solute varieties was poor, and the storage and transportation resistance of plum and apricot was similar to that of peach. Niuxin plum and Hebei Bingtang plum were of good quality and resistant to storage.

2. Pre-harvest agrotechnical measures have a great influence on the storability of peach, plum and apricot. Peach, plum and apricot are easy to be infected with microorganisms and rot during storage, which is one of the main factors that make it difficult for peach, plum and apricot to be stored for a long time. There are three main diseases that cause fruit rot, namely, brown rot, soft rot, root rot and so on. Among them, the fruit has been infected by soft rot and root rot in the field, the pathogen invaded the fruit through insect injury and lenticels, grew and propagated in large quantities when the storage and transportation conditions were suitable, and infected the nearby fruit, resulting in a large number of rot. Therefore, strengthening the prevention and control of diseases and insect pests during fruit growth can reduce the occurrence of rot during storage. The specific method is to spray Baume 5 degree stone sulfur mixture before germination, and to spray 65% Dyson zinc wettable powder or Baume 0.3 degree stone sulfur mixture every half a month from half a month to June, which can prevent the occurrence of these two diseases. When fertilizing, we should pay attention to the reasonable combination of nitrogen, phosphorus and potassium. Too much nitrogen fertilizer has poor fruit quality and poor storage and transportation. The orchard with more organic fertilizer has good fruit storage and transportation. Irrigation should be stopped 7-10 days before harvest, and fruits used for storage and transportation should not be sprayed with ethephon before harvest.

IV. Harvest of peaches, plums and apricots

Fruit harvest is not only the first step to transform agricultural products into commodities, but also a key step in the success of fruit storage. Among them, the harvest maturity is very important, the harvest maturity of fruits used for different purposes is different, short-term storage requires high maturity, long-term storage requires low maturity. Different tree species have different harvest maturity requirements.

1. Matters needing attention during peach harvest ① peaches with different maturity have different characteristics. Medium well's peach fruit has been fully developed, the background color is green, but fluffy, thick; medium well's peach background color becomes pale and white, the fruit is plump, hairy and thin, the fruit is still slightly hard, but has some elasticity; well-done 's peach skin is milky white, light yellow, furry sparse, elastic and fragrant; the peach peel of ten ripe peaches has fully shown its unique skin color, hairy and easy to fall off. The pulp of peach has a variety of performance due to different varieties. The pulp of peach with flesh solute is soft and juicy, and the peel is easy to peel off and is not resistant to storage. Hard-meat peaches can change, while meat-insoluble peaches are still elastic. Peaches used for fresh consumption should be harvested at eighty to nine percent ripe; peaches for storage can be picked earlier, usually when they are ripe; ten mature peaches cannot be used for storage and must be nearby. ② peach should be harvested in the morning and evening when it is cold and cool. When picking, it should be picked and placed gently to prevent mechanical injury. Do not press the fruit noodles with your hands or pull the fruit rudely. You should pick the fruit with a stalk. Generally speaking, the capacity of each container (box, basket) does not exceed 5 kg, too much fruit is easy to squeeze, causing mechanical injury.

2. The varieties of plums harvested are mainly Chinese plums. The stalk of Chinese plum is thick and short, and it is generally separated from the layer when it is ripe, so it should be harvested with a stalk. There are many plum fruit powder, so we should try to avoid multiple operations during harvest to reduce the loss of fruit powder, which is beneficial to storage and fresh-keeping. Plums for storage must be picked timely and early, and it is appropriate to mature seven or eight. Harvesting should also be carried out in the morning and evening when there is no cold dew, and should not be caught in the rain after harvest, so as not to cause decay.

3. Apricot and cherry harvest apricot and cherry maturity is relatively concentrated, after ripening can hardly be stored and transported, so it must be picked early according to different uses. Apricots and cherries must be harvested with stalks. In order to prevent the fruit stalk from falling off during storage and transportation, calcium can be sprayed before harvest or soaked in calcium after harvest. The commonly used calcium salt is calcium chloride, the concentration is 1% Mel 8%, and the soaking time is 5-60 minutes. The concentration and time must be matched well, the time can be short with high concentration, and the soaking time can be prolonged with low concentration. Spraying calcium chloride solution on cherries regularly before harvest could significantly reduce the decay, stem loss rate and browning index of cherries during storage and transportation. Apricot, cherry packaging should be controlled within 2 kg-2.5 kg, and there are vents in the packaging.

Postharvest treatment of peach, plum, apricot and cherry.

1. Select products that are infected by diseases and insect pests and products that suffer from mechanical injuries. Because injured products are extremely susceptible to germs and rot, and susceptible products will spread a large number of germs to healthy products around them, they must be selected.

The manual method is generally used for selection. When the quantity is small, it can be carried out by changing the packaging; when the quantity is large and the processing time is short, it can be manually selected by a special conveyor belt. Operators must wear gloves and handle the selection process gently to avoid new mechanical injuries. The general selection process is often combined with grading, packaging and other processes to save manpower and reduce costs.

2. The purpose of pre-cooling is to quickly reduce the product temperature, respiratory intensity and consumption, and to make the fruit temperature reach the optimal temperature for storage and transportation as soon as possible, so as to facilitate the early use of plastic film packaging for controlled atmosphere storage without dew. If the fruit temperature is high, but the storage temperature is low, the difference is more than 3 ℃, it is easy to dew. Dew tends to rot the fruit. Several precooling methods are introduced below: ① air cooling method. The cooler of the mechanical refrigeration system circulates cold air and cools the fruit with the help of heat conduction and latent heat of evaporation. When the wind is cold, the larger the contact area between the fruit and the cold air, the faster the cooling rate; the greater the wind speed, the faster the cooling rate. ② cold method. Direct contact with the ice can cool the fruit. Ice melting per kilogram can take away 80 kcal of heat from the inside of the fruit, and the heat conductivity of ice is higher than that of water and air, while the use of crushed ice to cool down can increase the contact area and improve the speed of cooling. ③ water cooling method. Also known as ice-water cooling method, this is because water cooling fruits often add crushed ice or use an ice maker to cool the water. Simple water cooling method is to impregnate the fruit in cold water, if the cold water is static, its cooling efficiency is low, generally using running water, adopting the combination of drifting, spraying or immersion spraying, the effect is better. ④ vacuum precooling method. Vacuum precooling is to put the fruit into a vacuum precooling chamber to vacuum. Under the condition of decompression, the water on the fruit surface evaporates quickly, absorbs a lot of heat and cools the fruit.

Peach, plum, apricot and cherry are generally precooled by air cooling and water cooling. O ℃ water can be used when the water is cooled, and a certain concentration of fungal fungicide can be added to the water. When the fruit is cooled to O ℃, the water can be drained. Vacuum precooling method is not suitable for peach precooling.

The precooling temperature of peach, plum, apricot and cherry for storage should be 0 ℃, which should not be too low to avoid chilling injury.

4. Peach, plum and apricot are easy to rot during storage, and low temperature and controlled atmosphere storage can inhibit the occurrence of diseases. The storage effect of low temperature and modified atmosphere plus antiseptic and antistaling agent is better.