Processing methods and techniques related to jujube
June 18 21:03:18, 2025
(1) Technology for Preserving Fresh Dates. The storage tolerance of fresh dates varies significantly based on their variety. Generally speaking, early maturing varieties are less tolerant of storage compared to late-maturing ones, which tend to store better. Large-fruited varieties are typically less resistant to storage, whereas smaller-fruited types show greater resilience. Dry and fresh varieties are often more common and easier to preserve than purely fresh types. Additionally, crack-resistant fruits tend to be more storage-friendly. Based on experiments, Xifengshan jujubes and Xifengshan small-tooth dates from Hebei and Beijing remain stable at 0°C with a relative humidity of 90%. After 45 days of storage in small packages, the good fruit rate reaches up to 79.4% to 98.7%. Other resistant varieties include North Che Zao jujube, Chang Xindian crispy jujube, and golden silk jujube. After 45 days, their good fruit rates range from 60.6% to 70.8%. Po dates and spotted jujubes are among the least resistant, retaining fewer intact fruits after 45 days. In Shanxi, the Linqun group dates, wolfberry jujubes, and Taigu hyacinth dates exhibit the best storage resistance, followed by jujubes like sinker, tuentun, and lang jujube.
The ideal storage conditions for fresh jujubes are crucial. Unlike regular fruits, the freezing point of jujube fruit is lower, usually between -4.8°C and -5.9°C. For this reason, storing at -1 to -2°C is preferable, with adjustments made at 0°C. Jujube fruits are highly prone to dehydration, so maintaining high relative humidity during storage—ideally between 90% and 95%—is essential.
The maturity level at harvest plays a critical role in jujube storage. Jujube ripening consists of two phases: the brittle phase (before the fruit transitions from green to white) and the mature phase (when the skin turns red and the fruit begins to shrink). Within the mature phase, there are three stages: initial red (coloring below 25%), semi-red (around 50% coloring), and fully red (100% coloring). Lower maturity levels allow for better storage tolerance. Studies suggest that jujubes intended for storage should be selected from early red fruits or harvested during the late stage of crisp ripening, between early red and semi-red. To enhance storability, a 0.2% calcium chloride solution or a 150-fold high-fat film combined with a 1000-fold thiophanate-methyl spray should be applied to the canopy and fruit 15 days before harvest to prevent fungal infections.
In addition to low temperatures, maintaining proper humidity is key during storage. Using perforated plastic bags ensures adequate air circulation, preventing ethanol buildup while enhancing humidity. Typically, 0.06mm thick PVC film bags are used, with eight holes punched on each side of a 15x22cm bag, totaling 16 holes. After several days of storage, these can be increased to 32 holes to avoid anaerobic respiration spoilage.
For sand storage, select durable varieties and harvest jujubes from early red to semi-red stages. Non-damaged fruits are placed in layers, alternating with wet sand, building up to 30cm tall stacks. Regularly mist the surface with water to maintain moisture. This method allows for over a month of storage while preserving freshness and minimizing nutrient loss.
Refrigeration involves selecting 25% to 50% colored jujubes, placing them in 1kg capacity plastic bags with three to four 3 to 4mm holes on each side. Before storage, the fruit is soaked in a 2% calcium chloride solution for 30 minutes, precooled at 7-8°C for 1 to 2 days, and then transferred to a cold storage at 0-1°C under a relative humidity of 60%. Inside the plastic bag, humidity should stay above 90%. Inspect the fruits every 3 to 5 days initially, then every 7 to 10 days thereafter.
(2) Low Sugar Candied Fruit Processing Technology.
Production Process: Raw Material Selection → Classification → Cleaning → Seam Cutting → Sugar Cooking → Dipping → Baking → Shaping → Baking → Classification → Packaging.
Key Steps:
Raw Material Selection: Choose larger varieties like big bell, big jujube, small fleshed, loose fleshed, thin skinned, etc., picking fruits at the "bridle ripening" stage. Remove any pests or rotten fruits.
Grading: Sort fruits into large, medium, and small categories for separate processing.
Seam Cutting: Use a needle to create rows of slits spaced about 1mm apart. The skin should be scratched neatly, aiming for two rows to prevent browning. After cutting, immerse the fruit in a 0.5% to 1% NaSO3 solution.
Candying: Maintain the sugar liquid’s pH at 2 to 2.5. Prepare a 20% sugar solution and bring it to a boil. Pour over the jujubes, stir, and boil again, then transfer to a tank for a 12-hour soak, keeping the sugar liquid at 20%. For the second round of candying, add more sugar to reach a final concentration of 45%, soaking for another 12 hours (ensuring the invert sugar content remains above 25%, accounting for 43% to 45% of total sugar). Starch syrup or glucose can be added when preparing the sugar solution.
Baking: Remove the sugar-coated jujubes from the tank, drain them, and bake for 12 hours at approximately 65°C (with temperature increasing gradually), ensuring they are no longer sticky.
Shaping: Pinch the baked jujubes into flat, rectangular, or square shapes.
Drying: After shaping, send them to a baking room at about 60°C for approximately 24 hours, reducing moisture content to 16% to 18%.
Packaging: To prevent moisture absorption, vacuum-seal or pack using N2.
Product Quality Requirements: Clear silk-like texture, dark amber color, moderate toughness, sticky consistency, free of impurities, sugar content around 45%, moisture content 16% to 18%, meeting food hygiene standards.
Hydroponics is a subset of hydroculture, the method of growing plants without soil, using mineral nutrient solutions in a water solvent. Terrestrial plants may be grown with only their roots exposed to the mineral solution, or the roots may be supported by an inert medium, such as perlite or gravel. The nutrients in hydroponics can come from an array of different sources; these can include but are not limited to waste from fish waste, duck manure, or normal nutrients.
Greenhouse Hydroponic System,Greenhouse A Hydroponics,Greenhouse Flat Hydroponics,Greenhouse Vertical Hydroponics