Natural Antioxidants
As people’s requirements for food safety improve and doubts about the safety incidents of chemical synthetics increase, people are looking forward to the development of safe and efficient natural antioxidants.
There is a wide range of natural antioxidants, in addition to vitamin E (tocopherol), which is included in food fortification, there are ascorbic acid series, tea polyphenols, phytic acid, licorice antioxidants, ceruloplasma, rosemary extracts, etc. In particular, the dosage of sodium isoascorbate has been increasing rapidly year by year.
1、Vitamin C
Easily soluble in water, dry state is more stable, but the aqueous solution is easily oxidized and decomposed, especially in neutral or alkaline solution; heavy metal ions can promote its oxidation and decomposition, and the colour gradually becomes darker when exposed to light, so it should be protected from light and kept in airtight.
This product can combine with oxygen to become a deoxidiser and inhibit the oxidation of oxygen-sensitive food ingredients; it can reduce high-valent metal ions and play a synergistic role in chelating agents; it has the functions of treating scurvy, detoxification and maintaining capillary permeability. At present, the main production processes are natural substance extraction method, Lay’s method and twice fermentation method.
In practical use, this product can be applied in many food products, including fruits, vegetables, meat, fish, beverages and fruit juice. Applied to cured meat products, ascorbic acid as a colouring additive, 0.02% – 0.05% of the amount of addition, can effectively promote the production of meat red nitrosomyoglobin, Applied to fruit juice and carbonated beverage, the addition amount of 0.005%-0.002% can effectively prevent the beverage from discolouration and flavour change. Applied to fruit and vegetable processing, mainly used to inhibit browning, to maintain the flavour and colour.
2、Tea polyphenol
Tea polyphenols are a class of polyhydroxyphenolic compounds contained in tea, referred to as TP, the main chemical composition of catechins (flavanols), flavonoids and flavonols, anthocyanins, phenolic acids and phenolic acids, polymerisation of phenolic compounds and other compounds of the complex. Catechin compounds for the main components of tea polyphenols, accounting for about 65% of the total amount of tea polyphenols 80%. Catechin compounds mainly include catechin (EC), gallocatechin (EGC), catechin gallate (ECG) and gallocatechin gallate (EGCG) 4 kinds of substances.
Tea polyphenols have strong antioxidant effects, especially ester-type catechin EGCG, whose reducibility can even be up to 100 times that of VC. 4 main catechin compounds, the antioxidant capacity of EGCG>EGC>ECG>EC>BHA, and antioxidant performance with the increase in temperature and enhancement of antioxidant performance, the antioxidant effect of the animal oils and fats is better than that of the vegetable oils and fats, and VE, VC, lecithin, It can be used together with VE, VC, lecithin, citric acid, etc. It has obvious synergistic effect, and can also be used jointly with other antioxidants.
3、Phytic acid
Also known as cyclohexanol hexakisphosphate, inositol hexakisphosphate, PA for short, yellow to yellow-brown viscous towel-like liquid, aqueous solution of strong acidity, easy to decompose at high temperatures. Phytic acid has a strong antioxidant capacity, mixed with VE, with multiplying antioxidant effect. Phytic acid molecule in the 12 acid hydroxyl can be chelating metal ions, in the low pH can be quantitative precipitation of iron ions, medium pH or high pH can be with all the other polyvalent metal ions to form insoluble chelates.
In practical application, phytic acid is often used as antioxidant and metal ion chelating agent to prevent oxidation, browning or discolouration of food.
Adding 0.01% of phytic acid to vegetable oil can obviously prevent the rancidity of vegetable oil; used in canned aquatic products, phytic acid can prevent the formation of guano crystals and discolouration, adding 0.1%-5% of phytic acid can prevent the canned shellfish from turning black;
Add 0.1% of phytic acid and 1% of sodium citrate can prevent canned crab meat blue spots; add 0.01% -0.05% of phytic acid and 0.3% of sodium sulfite, to prevent blackening of fresh shrimp is very effective, and can avoid excessive sulfur dioxide residue, phytic acid can be used for preservation of fruits and vegetables, by the cucumber, tomatoes, bananas, etc., the test have obvious effect;
For meat products, phytic acid can chelate the iron in its myoglobin, preventing fat oxidation caused by iron catalysis; phytic acid can also be used in the wine industry.