What is glucono-δ-lactone of food additives?

Traditionally, tofu is made with gypsum and brine, but now a better product than gypsum and brine has been invented – lactone gluconate. The tofu made with it is more tender, with higher flavor and nutritional value, and it is absolutely not bad for the body. The boxed tofu you see in the supermarket is made with lactone tofu.
Overview
Glucono-delta-lactone is abbreviated as lactone or GDL, with molecular formula C6Hl0O6, which has been proved to be a non-toxic edible substance by the toxicological test conducted by Shandong Province Labor and Health Institute. White crystal or white crystalline powder, almost odorless, sweet and then sour in taste. Soluble in water. Gluconic acid-δ-lactone is used as coagulant, mainly used in the production of bean curd, also used as protein coagulant of milk products.
Principle
The principle of gluconolactone coagulation of tofu is that when the lactone is dissolved into gluconic acid by adding water, the acid has an acidic coagulation effect on the proteins in the soymilk. Because of the slow decomposition of lactone, therefore, the coagulation reaction is uniform and consistent, high efficiency, so the tofu made white and delicate, good analysis of water, resistant to cooking and frying, delicious flavor, distinctive flavor. Add other coagulants such as: gypsum, brine, calcium chloride, fresh seasonings, etc., can also make a variety of flavors of tofu.
Uses
3.1 Tofu coagulant Using glucono-δ-lactone as protein coagulant to produce tofu, the texture is white and tender, without the bitter and astringent flavor of traditional brine or gypsum, no protein loss, high yield of tofu, and easy to use. A comparison of the use of CaSO4 and GDL is shown below:

In view of the GDL used alone, the tofu has a slightly sour taste, and the sour taste of the tofu is inappropriate, so the production of tofu is often GDL and CaSO4 or other coagulants composite use.
It is reported that the production of tofu (i.e., tender tofu), it is appropriate to use GDL/CaSO4 ratio of 1/3-2/3, the amount of dry beans added to the weight of 2.5%, the temperature is controlled at 4 ℃, the rate of tofu for the weight of dry beans 5 times, and the quality of the better.
However, there are some problems to be noted in the production of tofu with GDL, such as: the toughness and chewiness of tofu made by GDL is not as good as traditional tofu, in addition to the low amount of water used for washing residue, the loss of protein in the residue of the soybean is more.
3.2 Dairy protein coagulant GDL is not only used as a protein coagulant for tofu production, but also as a dairy protein coagulant for yogurt and cheese production.
Studies have shown that the strength of buttermilk gel formed by acidification with GDL is twice as strong as that of fermented type, while the strength of goat yogurt gel made by acidification with GDL is 8-10 times stronger than that of fermented type. They suggested that the reason for the poor gel strength of fermented yogurt could be due to the interference of fermenter substances (biomass and cellular polysaccharides) with the gel interactions between proteins during fermentation.
It has also been shown that milk gels made by acidification with the additive 3% GDL held at 30°C have a similar structure to those made by lactic acid bacteria fermentation. It has also been reported that the addition of 0.025%-1.5% GDL to buffalo milk can achieve the desired curd PH, and the specific amount added varies with the content of buffalo milk fat and thick ripening temperature.
3.3 Quality Improver GDL used in canned luncheon meat and pork, can increase the effect of coloring agent, thus reducing the amount of more toxic nitrite, while GDL also has an emulsifying effect, preservative effect and gel effect, thus improving the quality of minced meat canned goods, at this time, the maximum additive amount of 0.3%.
The addition of GDL at 4°C was reported to improve the elasticity of myofibrillar proteins, and the addition of GDL increased the strength of the gel both in the case of coexistence of myofibrillar proteins and myosin and in the case of myosin alone.
In addition, the addition of GDL (0.01%-0.3%), ascorbic acid (15-70 ppm), and sucrose fatty acid esters (0.1%-1.0%) to the dough improved the quality of bread. Adding GDL to fried food can save oil.
3.4 Preservatives Saniea, marie-Helence et al. showed that GDL has a significant delay and inhibitory effect on the production of phage of lactic acid bacteria, thus ensuring the normal growth and reproduction of lactic acid bacteria.
Addition of appropriate amount of GDL to milk can prevent the instability of cheese product quality caused by phage.Qvist, Sven et al. investigated the preservative properties of GDL in large red sausage and found that the growth of Listeria monocytogenes could be effectively inhibited by the addition of 2% lactic acid and 0.25% GDL to the product.
Samples of large red sausage inoculated with Listeria monocytogenes were stored at 10°C for 35 d without bacterial growth, and samples without preservatives or with only sodium lactate were stored at 10°C where the bacteria grew and multiplied rapidly.
However, it is worth noting that individuals were able to detect the off-flavor caused by GDL when it was used in excessively high amounts. It has also been reported that a mixture of GDL and sodium acetate at a ratio of 0.7-1.5:1 can prolong the shelf life and freshness of bread.
3.5 Acidifying agent GDL as an acidifying agent can be added to vanilla extract, cochineal banana and other sweet fruit drops and fruit jellies. It is the main acidic substance in the compound puffing agent, which can slowly produce carbonic acid gas, with uniform and delicate bubbles, and can produce pastries with other flavors.
3.6 Chelating agent GDL as a chelating agent used in dairy industry, beer industry can prevent the generation of milk stone, tartar.
3.7 Protein flocculant in the protein-containing industrial wastewater, add by the beggar salt, magnesium salt and GDL mixed flocculant can make the protein coagulation and precipitation, in the physical method to remove. Precautions
Gluconolactone is white powdery crystal, can be stored for a long time under dry condition, but it is easy to be decomposed into acid in humid environment, especially in aqueous solution, the lactone in the solution at room temperature will be partly decomposed into acid in 30 minutes, the hydrolysis speed will be accelerated when it is above 65 degrees, and it will be completely transformed into gluconic acid when it is above 95 degrees soon, so it is necessary to use lactone as a coagulant to be melted with cold water, and it will be used up in half an hour, and it is important not to store its aqueous solution for a long time. Do not store its aqueous solution for a long time.