Application and analysis of the most fire dragon e

2022-08-01
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Application analysis of longan fresh-keeping technology (Part 2)

the key technical points are:

3.2.1.1 harvesting. The maturity of longan fruit is artificial whole ear picking (the picking period is determined according to the color, size and sugar content of the fruit. Generally, the peel changes from green brown to yellowish brown, and the fruit can be harvested when the pulp content is more than 18%. Lean the bamboo ladder against the tree right, and the harvester climbs up with a basket)

3.2.1.2 select fruits and put them in baskets. Grade the collected longan fruits (grade 1 fruits 6o-79 grains/kg, grade 2 fruits 7o-80 grains/kg), put them in plastic baskets, each basket is about 10kg, and transport them to the treatment plant

1. Improve product quality 3.2.1.3 sulfur fumigation treatment. SO2 needs to be evaporated for disinfection, sterilization and bleaching. The longan exported from Thailand is fumigated with sulfur. Taking the longan fresh-keeping treatment plant in Yala Phuket, nambeng, Thailand as an example, the operation process was explained. The treatment plant has three fumigation rooms with capacities of 5O0, 600 and 7o0 baskets of longan, and exports 3000t longan every year. The specific method is as follows: put the baskets of longan into three fumigation rooms (18oo baskets can be steamed each time, with a weight of OT). Each treatment time is 4O minutes, and more than 100t is treated every day. SO2 concentration is 1_ 2% (no more than 2%). After 20 minutes of fumigation, extract air for 2O minutes (the extracted SO2 mixed gas is absorbed by activated carbon and then dissolved in water). The SO2 residue in longan is specified, with peel < 300ppm and pulp < 3oppm. The fumigated longan is loaded into a refrigerator truck (ice cubes are placed on the refrigerator truck) in a basket, and the temperature drops rapidly from 35 ℃ to 25 ℃_ 28 ℃ (pre cooling treatment, note that the ice melting water can not contact the longan fruit), and transport it to the fresh-keeping warehouse for cold storage

every 6_ For 7 T longan, only 3.5kg sulfur needs to be burned. The cost of each basket of longan fruit is equivalent to 0.35 yuan (i.e. 0.o34 yuan/kg). After the company has a good reputation, the color of longan becomes lighter and the peel becomes thinner, resulting in partial decomposition of materials and peculiar smell; After all, the odor of modified PP particles is qualified. Therefore, the varieties with thick peel and high sugar content are most suitable for fumigation and refrigeration export

3.2.1.4 cold storage. Transport the fumigated and pre cooled longan to the fresh-keeping warehouse for cold storage. The cold storage temperature is 3_ 5 ℃ for 50 days

3.2.1.5 transportation. It can be divided into refrigerated truck and ship (cold chain) transportation and short-term normal temperature air transportation

3.2.1.6 sales. Wholesale the fruits transported to offset the expenses, temporarily store them in the local cold storage (freezer) and gradually sell them

3.2.2 the technology is mature in the experimental stage and is in the stage of small batch promotion and application (represented by various domestic comprehensive technology combinations)

this technology is based on the combination of low-temperature spontaneous air conditioning and drug preservation. Its technical process is: pre harvest treatment → timely harvest → fruit selection → drug treatment → pre cooling → packaging → cold storage → transportation → sales

its technical key points are:

3.2.2.1 pre harvest treatment. Generally, it is treated with B, or 2,4-D (for example, 1000ppmb is used to spray longan trees before harvest, which can keep the ethylene release of postharvest fruits at a low level and prolong the postharvest storage life of longan)

3.2.2.2 timely collection. Fruit 8_ The whole panicle is lightly harvested at 90% maturity (the total soluble solid content is used as the maturity index of the heel, the peel color and overall appearance are used as the auxiliary bidding, the soluble solid content is 18 Λ 2o%, and the fruit presents its inherent color, aroma, taste and shape). It is better to harvest in the morning or evening. When harvesting, it is required to bring the ear and compound leaves (let the ear branches continue to supply the fruit with water and nutrients during the storage period, so as to improve the storage capacity). Avoid picking fruit in rainy days and typhoon days

3.2.2.3 fruit selection. Strictly select the fruit, and remove the pest fruit, damaged fruit and cracked fruit. Select the fruits with the same maturity to ensure the quality. At the same time, cut the seeds and long ear stems on the ear to make the ear neat. It shall be collected every day, treated on the same day and warehoused on the same day

3.2.2.4 drug treatment. Select effective preservatives to soak or fumigate in a timely and appropriate amount, take polystyrene yogurt cup as an example, and then cool in a ventilated place. The drug treatment had a great effect on the fresh-keeping period of longan. At present, it is considered that the more mature drugs include SO2 fumigation, sodium bisulfite and color protecting agent Hsj_ 1. Hsj-2, SEC butylamine, fisb-1, fis9_ 2。

fumigate longan with sodium dithionite or sulfur. If the dosage is appropriate, Sufficient fumigation time [according to the volume of free space in the fumigation room (ml or L): fruit weight (g or kg) =5: The best effect was achieved when the SO2 residue in the whole fruit was 2oo-350ppm after fumigation. The maximum allowable residue of pulp is 30ppm. Commercially, sulfur burning by electric heating to produce SO2) can effectively inhibit the action of enzymes and molds, thus inhibiting fruit decay; The reduction of SO2 can reduce the loss of vitamin C and maintain fruit quality; It can also prevent the peel from browning, thus prolonging the storage life of longan

use color fixative Hsj_ l. Hsj-2 soak fruit, cool and dry, store in cold storage, cold chain transportation, fresh-keeping period of 2O days, normal temperature shelf life of hours, good fruit cluster 90%

wash the fruit with fisb-1 and fisb-2 for minutes, then put it into a plastic box, put on an o.o4mm polyethylene film bag, or seal it with a large polyethylene film tent, adjust the ratio of CO2 and O2 (the concentration of CO2 and O2 is 6_8%), and set it at 2_ 4 cold storage. The good fruit rate of "Dongbi" longan was 95 O% and 95.2%, basically maintaining the original flavor and quality, but the vitamin C decreased significantly

using o.15m1/kg of SEC butyl gum to fumigate or soak the fruit in 3O fold solution, combined with low temperature (℃) storage and film packaging, has a significant effect on reducing the decay of fresh longan fruit and prolonging the storage life. The storage period is 30 days

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