How should Double Concentrated Tomato Paste be stored after opening?

Double Concentrated Tomato Paste is a seasoning holy product in modern kitchens. Its unique umami flavor comes from the 10-12 hours slow cooking and concentration process. However, improper storage after opening often leads to problems such as surface conjunctivitis and rancidity. Research by the United States Department of Agriculture (USDA) shows that properly stored tomato paste can extend the shelf life by 4 times and increase the vitamin C retention rate by 60%.

1. The four golden rules for blocking oxidation reactions
Surface treatment technology
Immediately after opening, use a sterilized spoon to smooth the surface of the product to eliminate air pockets. Experiments at the University of Parma in Italy have confirmed that a flat surface can reduce the oxidation area by 40%. It is recommended to cover the surface with a 1cm thick olive oil film to isolate oxygen using lipids. This method can increase the preservation rate of carotenoids by 35%.

Packaging and freezing plan
Pack the remaining paste into silicone ice cubes (about 15g per cube), freeze into blocks and transfer to sealed bags. German DLG test data shows that freezing at -18°C can inhibit 99.7% of microbial activity, and the loss of flavor substances after thawing is only 2.8%. Note: Avoid repeated freezing and thawing, and use independent units each time.

Precise temperature control in the refrigerated area
For short-term use, it is recommended to store it on the back wall of the refrigerator (usually 2-4°C), where the temperature fluctuation is less than 80% of the door area. The British Food Standards Agency recommends using it with a sealed glass jar and placing a food-grade deoxidizer in the jar to extend the shelf life to 14 days.

2. Preservation details in professional kitchens
• Tool disinfection: Boil the metal spoon with boiling water each time to avoid introducing bacteria
• Anti-crystallization treatment: Mix 3% grape seed oil before freezing to prevent ice crystals from destroying cell structure
• Storage away from light: Ultraviolet rays will accelerate the degradation of lycopene, and it is recommended to use amber storage containers

3. Shelf life and quality judgment
Preservation method Best tasting period Acidity change Safety warning
Original can refrigeration 5-7 days pH≤4.2 Discard immediately if white film appears
Oil seal storage 10-12 days Acidity↑15% Bubbling is considered deterioration
Vacuum freezing 3-4 months Stable flavor Use up within 24 hours after thawing

4. Correction of common misunderstandings
Error: Directly refrigerate the original can
Damage to the internal coating of the metal can will cause metal ion migration. The German Federal Institute for Risk Assessment (BfR) found that the iron content increased by 27% after opening the can and refrigerating for 3 days
Correct answer: Must be transferred to glass/ceramic containers

Wrong: Sprinkle salt on the surface for preservation
Salt penetration will cause cell dehydration and accelerate the Maillard reaction. Experiments at the University of Reading in the UK show that the browning speed of salt-containing samples increases by 2.3 times
Correct answer: Using oil isolation is safer

Scientific preservation can not only avoid food waste (about 2.3 million tons of tomato products are discarded worldwide due to improper preservation each year), but also ensure the bioavailability of fat-soluble nutrients such as β-carotene and lycopene. It is recommended to mark the opening date on the package and cooperate with the solution in this article to keep the concentrated deliciousness fresh for a long time.