With the improvement of people's living standards and changes in dietary structure, people's demand for food has also changed significantly. Quick-frozen dumplings have become more and more popular with consumers because of their hygienic convenience and maintaining their original nutrition and reasonable price. 2. Relationship between freezing rate and ice crystal size At the same time, CSL-SSL can combine with glutenin and gliadin in flour protein by hydrophobic chain and hydrophilic bond, respectively, to connect the proteins scattered in the flour to form a gluten network with the following structure:
However, due to the lack of corresponding technical level and the one-sided understanding and misunderstanding of food additives in some production enterprises, the quality of the products produced is not guaranteed, the products lack market competitiveness, and at the same time restrict the further development of the enterprises to a certain extent. In view of the above phenomena, this paper expounds a new way to improve the quality of quick-frozen dumplings by adding CSL-SSL, reinforced agent, composite colloid and modified starch as the main compound.
First, the theoretical basis of the production of quick-frozen dumplings
Quick-frozen dumplings, generally required to be below -30 °C, the frozen dumplings can be quickly frozen within 15-30 minutes in a short time, especially when passing through the largest ice crystal zone (0 °C - 5 °C), the speed is fast, the product Stored and circulated in a small package at -18 °C.
Under this condition, most of the water contained in the dumplings forms ice crystals with the loss of heat, which reduces the liquid water required for life activities and biochemical reactions, inhibits the activity of microorganisms, and delays the quality change of food. Thereby effectively maintaining the original nutrition and flavor of the dumplings.
Second, analysis of common problems in the production of quick-frozen dumplings
The main problems in the production of quick-frozen dumplings are as follows:
1. In the process of production of dumplings, if the amount of water added is large, the phenomenon of dough sticking is serious, and the breakage rate of dumplings is high. In order to improve this situation, it is often necessary to add a large number of facets, which affects the appearance and color of the mouth; if the amount of water is small, the gluten is less absorbed, and the perfect gluten network cannot be formed, resulting in rough skin and quick freezing. The epidermis ruptured due to drying during the process.
2. During the quick freezing process, due to the uneven distribution of water in the dough and the poor water holding capacity of the dough, large ice crystals are formed in the dough to swell the dumpling skin. At the same time, the surface of the dumpling skin is sublimated, causing dumplings. The epidermis is dry and cracked; the water dumplings have more water content, and the expansion of the water ice during the freezing process will also cause the dumpling skin to rupture. The above factors seriously affect the freezing crack rate of quick-frozen dumplings.
3. Due to the limitations of China's national conditions, the flour used in most quick-frozen dumpling manufacturers has a shorter formation time, a shorter settling time, a higher degree of weakening, and a stronger mechanical agitation on the surface to expose the formed gluten network. Destruction caused the produced dumplings to be weak and taste bad.
4. During the storage process, due to frequent fluctuations in storage temperature, the following changes occur in the entire food system:
During this change, the fine ice crystals will gradually disappear and disappear, and the large ice crystals will gradually grow. The sublimation of the epidermal ice crystals will directly lead to the drying of the epidermis, which will seriously affect the appearance and intrinsic quality of the products.
5, the rest such as color, taste, etc. also have a greater impact on the quality of the product.
Third, the theoretical basis for solving the above problems and the general approach to improvement
1. Food freezing process
The thermal dynamics of food during freezing have a great influence on the changes of its physical and chemical properties: during the transition from liquid to solid, the so-called nucleation is produced.
During the actual freezing of the food, the particles in the food can act as crystal nuclei. Once the nucleus is formed, the ice crystals will grow at a certain rate, and the size of the formed ice crystal can be adjusted by the number of crystal nuclei, which is controlled by the rate of energy transfer (the more the number of crystal nuclei, the faster the energy transfer The smaller the ice crystals formed).
The interaction between nucleation and ice crystal growth affects the size of the ice crystal and also affects the quality of the frozen food: generally during the rapid freezing process, the growth rate of the initial ice crystal is lower than the heat transfer rate, resulting in subcooling. The phenomenon increases the nucleation rate, thereby reducing the ice crystal volume; while in the slow freezing process, the ice crystal growth rate is consistent with the heat transfer rate, the number of crystal nuclei formed is small, and the ice crystal is large.
3. Vitrification in frozen food systems
At lower temperatures, the molecular thermal energy of the styling polymer is very low. Only small moving units, such as side groups, branches and links, can move, while the molecular chains and segments are frozen. The mechanical properties of the polymer are similar to those of glass, which is called the glass state. As the temperature increases, the segment motion is excited, but the entire molecular chain is still frozen. When subjected to external force, the polymer exhibits After a large deformation, the deformation can be restored after the external force is removed. This state is called high elastic state; the temperature continues to rise, not only the segment can move, the entire molecular chain can move, and the amorphous polymer exhibits viscous flow. State, called the viscous flow state. The glassy state, the high elastic state, and the viscous flow state are called three mechanical states of the amorphous polymer.
As the temperature increases, the transition of the polymer from a glassy state to a highly elastic state is called a glass transition, and its transition temperature is the glass transition temperature, expressed as Tg. At this time, the concentration of the unfrozen solute will continue to increase, the viscosity will gradually increase, and finally the viscosity will be high to limit the free movement of water molecules, and at this time, the growth of ice crystals cannot be performed.
4. The general way to improve the quality of quick-frozen dumplings
For the common problems in the production of quick-frozen dumplings, manufacturers generally adopt the following methods to improve the quality of quick-frozen dumplings:
1) Reduce the amount of water added to the dumplings during processing, so that the total volume of ice crystals during the freezing process is small. However, this causes the surface of the dumplings to dry, and the surface moisture rises during freezing to cause cracks; and the reduction of the amount of water added does not control the formation of local large ice crystals.
2) Reduce the water content in the dumplings so that the total volume of ice crystals in the filling is small during the freezing process. This leads to an increase in the production cost of the enterprise, which affects the economic benefits of the enterprise and affects the inherent quality and flavor of the product.
3) Improve the quick-freezing conditions to make the quick-freezing level more perfect and the process control more reasonable. This requires the enterprise to modify or adjust the existing equipment and processes, which will increase the burden on the enterprise and may not achieve good results.
Although the above methods have certain feasibility, they are inevitably limited and unreasonable. Therefore, they are not the solution to the problem that enterprises hope to solve. Enterprises are looking forward to a new way to improve the frozen dumplings. quality.
4. A new way to improve the quality of quick-frozen dumplings
According to the common problems in the production of quick-frozen dumplings and the above theoretical basis, a new way to improve the quality of quick-frozen dumplings is proposed:
1. Add emulsifier with CSL-SSL as the main component. CSL-SSL has two groups, which are oleophilic and hydrophilic. The good activity of these two groups can achieve the best control of various substances at the time of processing.
Therefore, even if the food is stored at a temperature higher than Tg, a long shelf life can be maintained; the addition of CSL-SSL can reduce the surface tension of water by more than 30%. When the surface tension of water is lowered, the wettability is greatly increased, it is not easy to aggregate, and smaller crystals can be formed upon freezing without damaging the dough structure; CSL-SSL has good dispersibility. The good dispersibility of the emulsifier allows the various components in the pasta to be uniformly dispersed during the freezing process and safely passed through the process of glass transformation.
As can be seen from the above figure, the presence of CSL-SSL gives the gluten network a certain strength, thereby improving its resistance to mechanical agitation, prolonging the dough stabilization time, and reducing the degree of weakening.
Therefore, after the addition of the emulsifier based on CSL-SSL, the size and crystal form of the ice crystals are controlled, and the dumplings can safely pass through the transformation process of the vitreous, so that the quality of the quick-frozen dumplings is guaranteed.
2. Add a composite colloid stabilizer based on various plant gums. During the freezing process of frozen dumplings, colloidal molecules are squeezed into the area around the ice crystals, resulting in a sharp increase in the concentration of unfrozen phases, reducing the free volume of solute molecules, improving the Tg and low temperature stability of frozen food systems, and controlling freezing. The growth rate of ice crystals and the size of ice crystals in dumplings, thereby improving the quality and shelf life of frozen foods; because the colloids have strong water absorption capacity, the dough can absorb more moisture during processing without sticking to the machine, and colloid The adhesive properties also make the dumpling skin more delicate and bright.
3. Add modified starch to improve the whiteness and taste of quick-frozen dumplings. The modified starch used in the production of quick-frozen dumplings is a food additive which is emulsified and thickened by physical or chemical modification based on potato or tapioca starch. Adding modified starch can significantly improve the whiteness, brightness, skin slip and transparency of the frozen dumplings, and the addition of modified starch can greatly increase the amount of water added.
4. Add a composite reinforcing agent with Vc as the main body. Vc can oxidize the sulfur-hydrogen bond (-SH) in the gluten protein and connect it through the disulfide bond (-S-S-), thereby strengthening the gluten network, improving the gluten strength of the quick-frozen dumplings and improving the bite.
According to the above four points, a compound quick-frozen dumpling improver mainly composed of CSL-SSL, composite colloid, reinforced agent and modified starch is compounded.
Five, quick-frozen dumpling improver experiment
1. Time: September 23, 1999
2. Location: a frozen food company in Zhengzhou, Henan Province
3. Experimental materials:
Flour: a flour mill in Zhengzhou
Additive (CSL-SSL): Henan Xingtai Technology Industrial Co., Ltd.
Vegetable gum, modified starch, oxidizing agent: commercially available
4. Production process: according to the production process of the company's quick-frozen dumplings (the amount of water added is 2%)
5, quick freezing conditions: quick freezing tunnel temperature: -38 ° C
Quick freezing time: 15 to 20 minutes
6, storage conditions: -18 ° C exposed in the cold storage stored under the cooling fan
7. Experimental process:
1) Improvement of flour quality: After adding 0.4% and 5% modified starch of composite modifier, the powder curve and tensile curve were measured by Brabender (manufactured by Germany). The results are as follows: see Table (1)
2) Evaluation of frozen frozen dumplings: see table (2)
3) Evaluation of dumplings after cooking: see table (3)
flour
Project control group
Powder curve water absorption rate (%) 58.260.8
Formation time (min) 2.33.4
Stabilization time (min) 4.36.9
Weakening degree (Bu) 7020
Evaluation value 4652
Tensile curve 45min elongation (mm) 170162
45min anti-extensibility (Bu) 460570
Table (1):
Finished product
Project control group
Water addition (%) 3840
The amount of face puff is almost no need
Processing breakage rate>2<0.1
Cracking rate (%)>6<0.4
The dumplings look white, bright, rougher, whiter, brighter and more delicate.
The cracking rate (%) after storage for 10 days. 2<0.2
Table (2):
product
Project control group
Appearance whiteness, poor brightness, dark color after placement, bonding to each other, poor transparency of the skin, rough whiteness, brightness, smoothness, good color and brightness after cooling, no mutual adhesion, skin Transparent and delicate
Breakage rate after cooking (%)>3<0.1
Soup soup
The taste is smooth and slippery, slightly sticky, smooth, delicate, non-sticky
Biting is biting, but there is a bite in the improved group.
Table (3):
Conclusion
1. The quality of quick-frozen dumplings has a great relationship with the production process and additives. In the dough process, the more complete the gluten formation, the more uniform the water dispersion, the more perfect the freezing process, and the better the finished quality of the dumplings.
2. After adding the quick-frozen dumpling improver, the quality of the flour can be obviously improved, the formation time is increased, the time is stabilized, the degree of weakening is reduced, and the mechanical agitation of the dough is obviously improved.
3. After adding quick-frozen dumpling improver and modified starch, the water addition rate can be increased by about 2%, and the glass transition temperature can be increased, the growth rate of ice crystals can be inhibited, and the low temperature stability of the product during freezing is beneficial. The adaptability of temperature fluctuations.
4. After adding quick-frozen dumpling improver, the amount of face puff can be reduced to the greatest extent, and the processing breakage rate, cracking rate and storage failure rate can be reduced.
5. Because the water retention of the modifier is strong, the surface water dispersion of the dumplings during the quick freezing process is less, which is beneficial to the stability of the product quality and the improvement of the product yield.
6. After adding the modifier, the whiteness, brightness, gluten strength, smoothness and boiling resistance of the finished dumplings are improved, which is beneficial to the improvement of the level of the dumplings.
7. After adding the modifier, a better finished product can be produced with relatively lower grade flour, thereby effectively reducing the cost.
It can be seen that the addition of CSL-SSL as the main compound type quick-frozen dumpling improver is undoubtedly a new way to solve many problems in the production of quick-frozen dumplings.