CN115316650B - Slow digestion pearl powder ball containing resistant compound and preparation method thereof - Google Patents

Abstract

The invention provides a slow digestion pearl powder ball containing a resistance compound, which comprises the following raw materials in parts by weight: 50-60 parts of compound tapioca starch; 0.2 to 5 parts of hydroxypropyl distarch phosphate; 1 to 1.5 portions of sodium carboxymethyl cellulose; 0.01 to 0.05 portion of preservative; 0.1 to 0.8 part of sodium diacetate; 35-40 parts of water; the compound tapioca starch contains 5-15 wt% of starch-protein resistant compound. The invention also provides a preparation method of the slow digestion pearl powder containing the resistant compound. The slow digestion pearl powder ball containing the resistant compound has good digestion resistance, is not easy to cause rapid blood sugar reaction, has a certain health care function, can optimize the texture characteristics of the pearl powder ball, and has the advantages of small hardness, soft texture and better edible taste. The pearl powder ball prepared by the invention is easy to be accepted by consumers, the utilization rate of the pearl powder ball can be widened, and a new choice of healthy and delicious leisure food is provided for the consumers.

Description

Slowly digested pearl powder balls containing resistance complex and preparation method thereof

Technical field

The invention belongs to the technical field of snack food, and specifically relates to a slow-digesting pearl powder ball containing a resistance complex and a production method thereof.

Background technique

Tapioca starch is a snack food that is elastic, soft, glutinous and has a smooth texture. Pearl powder balls made of tapioca starch as the main ingredient have a delicate taste and unique flavor. They have their own unique appearance and taste when paired with any kind of dessert or tea drink. They are a particularly popular healthy and delicious supplement in the tea drink industry. As a starch product, in the process of bringing tapioca to the market, we should not only pay attention to the sensory quality characteristics of tapioca itself, but also pay more attention to the digestive properties of tapioca.

As the main source of energy required for human physiological activities, starch can be divided into rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) according to the speed of digestion. RDS blood sugar and insulin secretion increase rapidly after meals, promoting glycogen synthesis and fat accumulation; SDS blood sugar increases slowly and insulin is released steadily; RS ferments under the action of microbial flora in the colon and can participate through a series of mechanisms. Blood sugar regulation. Foods rich in RS and SDS have a lower glycemic index (GI). Such foods are not only suitable for diabetic patients, but also play a role in preventing diabetes for healthy people.

Tapioca pearls are often used in high-sugar products such as tea drinks and desserts. If the digestion rate of tapioca balls can be reduced, the burden of blood sugar and insulin when consuming tea drinks and desserts can be reduced. In some existing studies, modified and resistant starch are added to the production process of tapioca balls to improve sensory properties or slow digestion. However, the main ingredients of existing tapioca starch are mainly tapioca starch, which has a single nutrition. At the same time, the addition of modified starch does not significantly improve the problem of fast digestion rate of tapioca. In addition, the addition of resistant starch will have a certain impact on the textural properties of the tapioca balls, leading to problems such as a significant reduction in hardness, gumminess, and chewiness, thus affecting the consumer's eating experience.

Based on this, we provide a pearl powder ball with slow digestion, nutritional fortification and good texture properties to reduce the burden on blood sugar and insulin when consuming tea, drinks and desserts, and at the same time improve the quality of tapioca with good nutritional functions and texture properties. Public acceptance, broadening the utilization rate of pearl powder balls, and providing consumers with healthier snack food choices are technical issues that need to be solved urgently.

Contents of the invention

One of the objects of the present invention is to provide a slow-digestible pearl powder containing a resistant complex with slow digestion rate, nutritional fortification and good texture properties.

The second object of the present invention is to provide a method for making slow-digestible pearl powder balls containing resistant complexes with slow digestion rate, nutritional fortification and good texture properties.

The technical solution adopted to achieve one of the objectives of the present invention is to provide a slow-digesting pearl powder ball containing a resistant complex, the raw materials of which include the following components in parts by weight:

50 to 60 portions of compound tapioca starch;

0.2 to 5 parts of hydroxypropyl distarch phosphate;

1 to 1.5 parts of sodium carboxymethyl cellulose;

Preservative 0.01~0.05 parts;

Sodium diacetate 0.1 to 0.8 parts;

35 to 40 parts of water;

The compound cassava starch contains a starch-protein resistant complex accounting for 5 to 15 wt% of its total weight; in the starch-protein resistant complex, the mass ratio of starch to protein powder is 8 to 4:1 .

Aiming at problems such as gelatinization of tapioca starch in tapioca balls, which will lead to a significant increase in starch digestibility and easily cause rapid rise in blood sugar levels, insulin resistance, etc., the present invention provides a method of using compound tapioca starch to replace conventional tapioca starch to make tapioca starch. New scheme for round making. The compound cassava starch used in the present invention contains a starch-protein resistant complex accounting for 5 to 15 wt% of its total weight. Compared with conventional resistant starch, the production method of starch-protein resistant complex is environmentally friendly and has no chemical by-products. The protein component can change the existing delicate and single dietary structure, improve the nutritional properties of cereal products, and achieve the purpose of nutritional enhancement; at the same time, the presence of protein also affects the gelatinization properties, thermal properties, rheological properties, gel properties, Microstructure characteristics and other physical and chemical properties that are closely related to the quality of starch products. The synergistic effect of the two not only slows down the digestion rate of the tapioca balls, but also does not change the original textural properties of the tapioca balls, making the tapioca balls have both a slow digestion rate and good texture properties.

In the present invention, limiting the dosage of the starch-protein resistant complex to 5 to 15 wt% of the total weight of the compound tapioca starch can better balance the digestion characteristics and textural characteristics of the prepared tapioca balls. When the dosage of starch-protein resistant complex is low, the improvement in the anti-digestion performance of tapioca balls is not obvious; when the dosage of starch-protein resistant complex is higher than the above range, although the digestion rate can be better controlled , but it will have an adverse effect on the texture properties, resulting in a reduction in the elasticity of the tapioca balls and a weakening of the gel structure, which in turn will have an adverse effect on the taste of the tapioca balls. Preferably, the dosage of the starch-protein resistant complex is 10 wt% of the total weight of compound cassava starch.

Further, research has found that in the starch-protein resistant complex, the ratio of starch to protein will also have a greater impact on the digestion rate and texture characteristics of the tapioca balls. In the present invention, the ratio of starch to protein is The mass ratio of the flour is controlled to be 8 to 4:1. When the starch content is too high, the starch digestion rate will not be significantly reduced; and if the protein content is too high, the protein will reduce the relative concentration of starch in the complex and weaken the starch gel. Preferably, the mass of starch and protein powder is 5:1.

Further, in the starch-protein resistant complex, the starch is selected from corn starch and/or potato starch.

Further, in the starch-protein resistant complex, the protein is selected from soybean protein isolate and/or ovalbumin.

Preferably, in the starch-protein resistant complex, the starch is corn starch, and the protein powder is ovalbumin. The study found that the compound prepared from the above raw materials at the same proportion had the lowest content of rapidly digestible starch (RDS).

In some preferred embodiments, the preparation method of the starch-protein resistant complex includes: controlling the moisture content of corn starch to 20%, obtaining the first product after sealing and equilibrating for 24 hours at 25°C; Add 20wt% of egg albumin to the first product, accounting for 20wt% of the total weight of corn starch, and mix to obtain a second product; seal the second product, first bake it at 110°C for 18 hours, and then place it at 50°C. Dry for 12 hours to obtain the third product; grind the third product and pass it through a 100-mesh sieve to obtain the starch-protein resistant complex.

In the above preparation method, the interaction between protein and starch and the protein network are used to wrap starch granules, reducing the contact between enzymes and starch, and forming a physical barrier against enzymatic hydrolysis.

In some preferred embodiments, the raw materials of the slow-digested tapioca balls containing the resistant complex include the following components in parts by weight: 54 parts of tapioca starch; 6 parts of the starch-protein resistant complex ( The mass ratio of corn starch to ovalbumin is 5:1); 3 parts of hydroxypropyl distarch phosphate; 1.5 parts of sodium carboxymethylcellulose; 0.05 parts of preservatives; 0.45 parts of sodium diacetate; 35 parts of water. Under the conditions of the above components and dosage, not only the produced raw tapioca dough has moderate softness and hardness, which is conducive to the formation of raw tapioca, but also the prepared slow-digesting tapioca has the best texture characteristics.

Further, the preservative is sodium dehydroacetate.

The technical solution adopted to achieve the second object of the present invention is to provide a method for making slow-digested pearl powder balls containing a resistance complex according to the first object of the present invention, which includes the following steps:

S1. Premix cassava starch and starch-protein resistant complex to prepare compound cassava starch, and then mix the compound cassava starch with hydroxypropyl distarch phosphate, sodium carboxymethyl cellulose, preservatives, and diacetic acid. Mix sodium thoroughly to obtain powder;

S2. Pour the powder into boiling water and knead it into raw pearl powder dough while it is hot;

S3. Knead the raw tapioca dough into small balls with a diameter of 5 to 6 mm, and cover the surface of the small balls with tapioca starch to obtain rice balls I. The rice balls I are evacuated and frozen to obtain rice balls II. ;

S4. Pour the pearl powder II into a container containing boiling water, heat for 10 to 15 minutes, stop the fire and simmer for 5 minutes, and take out the supercooled water to obtain a slow-digesting pearl powder containing a resistant complex.

In some better embodiments, in step S1, the preparation method of compound cassava starch includes: accurately weighing cassava starch and starch-protein resistant complex, mixing the two and putting them into a centrifuge tube. Mix on the MM 400 refrigerated mixing ball mill for 2 minutes, take out a sample and repeat mixing three times to make the materials evenly mixed.

Furthermore, in the step S2, the powder is poured into boiled water, which can avoid the situation that the water becomes cold caused by directly pouring water into the powder and affects the dough forming.

Further, in step S4, the mass ratio of the powder balls II to boiling water is 1:10; when pouring the powder balls II into a container containing boiling water, stir the powder balls II in the container to prevent sticky.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The invention provides a kind of slow-digested pearl powder containing a resistant complex. Its raw material composition uses a starch-protein resistant complex to replace 5 to 15 wt% of tapioca starch. The addition of the starch-protein resistant complex , on the one hand, it can reduce the quickly digestible starch content of pearl powder balls, making it less likely to cause rapid blood sugar reactions. It has a certain anti-digestion effect and good health care function; on the other hand, it can optimize the textural characteristics of the tapioca balls, and the resulting tapioca balls have smaller hardness, soft texture and better eating taste.

(2) The slow-digestion tapioca pearls containing the resistance complex prepared by the present invention have obvious anti-digestion effect compared with the tapioca pearls without adding the resistance complex, and are better than the anti-digestion resistance of resistant starch at the same concentration. Digestive capacity. In addition, by controlling the addition amount of the starch-protein resistant complex and the ratio of starch and protein contained therein, the present invention enables the prepared pearl powder balls to have relatively low hardness, soft texture, and edible taste similar to those made from pure tapioca starch. There is no obvious difference in pearl powder balls, providing consumers with a new choice of healthier and more delicious snack foods.

Description of the drawings

Figure 1 is a comparative diagram of the digestion characteristics of tapioca balls prepared in Example 1 of the present invention and Comparative Examples 1 and 2;

Figure 2 is a comparison chart of the texture characteristics of tapioca balls prepared in Example 1 of the present invention and Comparative Examples 1-3.

Detailed ways

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without any creative work fall within the scope of protection of the present invention.

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

The present invention will be further described below with reference to specific embodiments, but shall not be used as a limitation of the present invention.

The mass parts of each raw material involved in Examples 1-5 and Comparative Examples 1-3 of the present invention are as shown in Table 1 below:

Table 1

Example 1

A method for preparing slow-digested pearl powder balls with a resistant complex, including the following steps:

Step 1: According to the parts by weight shown in Table 1, make compound tapioca starch from tapioca starch and starch-protein resistant complex (mass ratio of corn starch to egg white protein 5:1);

Step 2: Stir compound tapioca starch, hydroxypropyl distarch phosphate, sodium carboxymethylcellulose, sodium dehydroacetate, and sodium diacetate thoroughly to obtain powder;

Step 3: Pour the powder into boiling water and knead it into raw pearl powder dough while hot;

Step 4: Knead the dough into small balls with a diameter of 5 mm, and cover the surface of the small balls with tapioca starch to obtain powdered balls I. Vacuum the powdered balls I and freeze them at -20°C to obtain powdered balls. II;

Step 5: Pour the pearl powder II into a container containing boiling water, heat for 12 minutes, stop the fire and simmer for 5 minutes, take out the supercooled water, and obtain a slow-digesting pearl powder containing a resistant complex.

The slow-digestible pearl powder containing the resistant complex prepared in this embodiment has the characteristics of slow digestion, nutritional enhancement, and good texture properties.

Example: 2

A method for preparing slow-digested pearl powder balls with a resistant complex, including the following steps:

Step 1: According to the weight parts shown in Table 1, make compound cassava starch from cassava starch and starch-protein resistant complex (mass ratio of corn starch to soybean protein isolate 4:1);

Step 2: Stir compound tapioca starch, hydroxypropyl distarch phosphate, sodium carboxymethylcellulose, sodium dehydroacetate, and sodium diacetate thoroughly to obtain powder;

Step 3: Pour the powder into boiling water and knead it into raw pearl powder dough while hot;

Step 4: Knead the dough into small balls with a diameter of 6 mm, and cover the surface of the small balls with tapioca starch to obtain powdered balls I. Vacuum the powdered balls I and freeze them at -20°C to obtain powdered balls. II;

Step 5: Pour the pearl powder II into a container containing boiling water, heat for 10 minutes, stop the fire and simmer for 5 minutes, take out the supercooled water, and obtain a slow-digesting pearl powder containing a resistant complex.

The slow-digestible pearl powder containing the resistant complex prepared in this embodiment has the characteristics of slow digestion, nutritional enhancement, and good texture properties.

Example 3

Step 1: According to the parts by weight shown in Table 1, make compound tapioca starch from tapioca starch and starch-protein resistant complex (mass ratio of potato starch to egg white protein 8:1);

Step 2: Stir compound tapioca starch, hydroxypropyl distarch phosphate, sodium carboxymethylcellulose, sodium dehydroacetate, and sodium diacetate thoroughly to obtain powder;

Step 3: Pour the powder into boiling water and knead it into raw pearl powder dough while hot;

Step 4: Knead the dough into small balls with a diameter of 5 mm, and cover the surface of the small balls with tapioca starch to obtain powdered balls I. Vacuum the powdered balls I and freeze them at -20°C to obtain powdered balls. II;

Step 5: Pour the pearl powder II into a container containing boiling water, heat it for 15 minutes, simmer for 5 minutes, and take out the supercooled water to obtain a slow-digesting pearl powder containing a resistant complex.

The slow-digestible pearl powder containing the resistant complex prepared in this embodiment has the characteristics of slow digestion, nutritional enhancement, and good texture properties.

Example 4

Step 1: According to the weight parts shown in Table 1, make compound cassava starch from cassava starch and starch-protein resistant complex (mass ratio of potato starch to soybean protein isolate 5:1);

Step 2: Stir compound tapioca starch, hydroxypropyl distarch phosphate, sodium carboxymethylcellulose, sodium dehydroacetate, and sodium diacetate thoroughly to obtain powder;

Step 3: Pour the powder into boiling water and knead it into raw pearl powder dough while hot;

Step 4: Knead the dough into small balls with a diameter of 6 mm, and cover the surface of the small balls with tapioca starch to obtain powdered balls I. Vacuum the powdered balls I and freeze them at -20°C to obtain powdered balls. II;

Step 5: Pour the pearl powder II into a container containing boiling water, heat for 13 minutes, stop the fire and simmer for 5 minutes, take out the supercooled water, and obtain a slow-digesting pearl powder containing a resistant complex.

The slow-digestible pearl powder containing the resistant complex prepared in this embodiment has the characteristics of slow digestion, nutritional enhancement, and good texture properties.

Example 5

Step 1: According to the parts by weight shown in Table 1, make compound tapioca starch from tapioca starch and starch-protein resistant complex (mass ratio of potato starch to egg white protein 8:1);

Step 2: Stir compound tapioca starch, hydroxypropyl distarch phosphate, sodium carboxymethylcellulose, sodium dehydroacetate, and sodium diacetate thoroughly to obtain powder;

Step 3: Pour the powder into boiling water and knead it into raw pearl powder dough while hot;

Step 4: Knead the dough into small balls with a diameter of 5 mm, and cover the surface of the small balls with tapioca starch to obtain powdered balls I. Vacuum the powdered balls I and freeze them at -20°C to obtain powdered balls. II;

Step 5: Pour the pearl powder II into a container containing boiling water, heat for 11 minutes, simmer for 5 minutes, take out the supercooled water, and obtain a slow-digesting pearl powder containing a resistant complex.

The slow-digestible pearl powder containing the resistant complex prepared in this embodiment has the characteristics of slow digestion, nutritional enhancement, and good texture properties.

Comparative example 1

On the basis of Example 1, the starch-protein resistant complex in step S1 was replaced with equal parts by weight of tapioca starch, and other conditions remained unchanged to prepare pearl powder balls.

Comparative example 2

On the basis of Example 1, the starch-protein resistant complex in step S1 was replaced with equal parts by weight of corn starch, and other conditions remained unchanged to prepare tapioca balls.

Comparative example 3

On the basis of Example 1, the starch-protein resistant complex in step S1 was replaced with equal parts by weight of food-grade resistant starch (Shandong Ruifan Biotechnology Co., Ltd.), and other conditions remained unchanged to prepare a preparation containing resistant starch. Starch-based tapioca balls.

Performance Testing

(1) Digestive characteristics

The digestion characteristics of the tapioca balls prepared in Example 1 and Comparative Examples 1 and 2 were tested. The specific test method is as follows: prepare 8 mg/mL α-amylase, 10000 U/mL amyloglucosidase, 0.2 mol/L (pH=5.2) acetic acid-sodium acetate buffer. Freeze-dry the mature pearl powder balls, grind them through a 100 mesh sieve, then place 200 mg of the powder into a 30 mL sample bottle, add 5 mL of deionized water, mix and gelatinize in boiling water for 30 min, cool to 37°C, and add 10 mL of acetic acid. -Sodium acetate buffer, 5 mL of alpha-amylase and 65 μL of amyloglucosidase. A constant temperature oscillator was used for water bath heating (temperature 37°C, rotation speed 160r/min). At 3 time points of 0, 20, and 120 min, use a pipette to take 0.2 mL of the reaction solution and add 1 mL of absolute ethanol into the centrifuge tube. After centrifugation at 8000 r/min for 5 min, take 0.2 mL of the supernatant and use it with a glucose assay kit ( Glucose oxidase method) measure the glucose content and record the data. Among them, the calculation formulas for the contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) are as follows:

In the formula:

G0: Glucose content in starch before hydrolysis (mg);

G20: Glucose content generated by hydrolysis for 20 minutes (mg);

G120: Glucose content generated by hydrolysis for 120 minutes (mg);

TS: Total starch content in the sample (mg).

The results are shown in Figure 1, where RDS (Rapidly digestible starch) is rapidly digestible starch, SDS (Slowlydigestible starch) is slowly digestible starch, and RS (Resistant starch) is resistant to digestible starch. Different letters indicate significant differences (P<0.05).

As can be seen from Figure 1, compared with Comparative Examples 1 and 2, the tapioca pearls prepared in Example 1 of the present invention contain the lowest content of rapidly digestible starch RDS and the lowest content of resistant starch RS due to the addition of the resistant complex. The highest content.

(2) Textural characteristics

The TPA texture of the pearl powder balls prepared in Example 1 and Comparative Examples 1-3 was measured using a Shanghai Baosheng TA touch texture analyzer, and a TA-36 flat-bottomed cylindrical probe was installed. Specific test conditions: probe descent speed 1.0m/s, test speed 1.0m/s, return speed 1.0m/s, compression distance 5mm, return distance 10mm, contact force 5g, deformation force 50%.

Please see Figure 2 for the test results. Different letters indicate significant differences (P<0.05).

As can be seen from Figure 2, Comparative Example 2 is a tapioca starch made from a compound of corn starch and tapioca starch. Its hardness, adhesiveness and chewiness are all improved to varying degrees, which affects the original soft and chewy taste of tapioca starch; Ratio 3 is a tapioca starch made from a mixture of commercially available resistant starch and tapioca starch. Although the resulting tapioca has good anti-digestion properties, the addition of resistant starch also seriously affects the textural properties of the tapioca. . Its hardness, gumminess and chewiness are significantly reduced, and the unique sensory experience of tapioca is lost.

The texture of the tapioca pearls made by compounding the starch-protein resistant complex and tapioca starch provided in Example 1 of the present invention is basically the same as the tapioca pearls made of pure tapioca starch in Comparative Example 1. This fully demonstrates that the slow-digestible tapioca pearls containing a resistant complex provided by the present invention not only have the functions of slow digestion and nutritional enhancement, but also have good texture characteristics.

The above are only preferred embodiments of the present invention, and are not intended to limit the implementation and protection scope of the present invention. Those skilled in the art should be able to realize equivalent substitutions and obvious changes made by applying the contents of the description of the present invention. The solutions obtained should be included in the protection scope of the present invention.

Claims (6)

1. A slow-digestible pearl powder ball containing a resistant compound, characterized in that its raw materials include the following components in parts by weight: 50 to 60 portions of compound tapioca starch; 0.2 to 5 parts of hydroxypropyl distarch phosphate; 1 to 1.5 parts of sodium carboxymethyl cellulose; Preservative 0.01~0.05 parts; Sodium diacetate 0.1 to 0.8 parts; 35 to 40 parts of water; The compound cassava starch contains 10wt% of its total weight of starch-protein resistant complex; in the starch-protein resistant complex, the mass ratio of starch to protein powder is 5:1; In the starch-protein resistant complex, the starch is corn starch, and the protein powder is ovalbumin; The preparation method of the starch-protein resistant complex includes: adjusting the moisture content of corn starch to 20wt%, obtaining the first product after sealing and balancing at 25°C for 24 hours; adding 10% of the corn starch to the first product. The total weight of starch is 20wt% ovalbumin, and mixed to obtain the second product; the second product is sealed, baked at 110°C for 18h, and then dried at 50°C for 12h to obtain the third product; The third product is ground and passed through a 100-mesh sieve to obtain a starch-protein resistant complex. 2. The slow-digested tapioca pearls containing resistance complex according to claim 1, characterized in that its raw materials include the following components in parts by weight: 54 parts of tapioca starch; starch-protein resistance complex 6 parts; 3 parts hydroxypropyl distarch phosphate; 1.5 parts sodium carboxymethyl cellulose; 0.05 parts preservative; 0.45 parts sodium diacetate; 35 parts water. 3. The slow-digested tapioca pearls containing a resistant complex according to claim 2, wherein the preservative is sodium dehydroacetate. 4. The method for making slow-digested pearl powder balls containing resistant complexes according to any one of claims 1-3, characterized in that it includes the following steps: S1. Premix cassava starch and starch-protein resistant complex to prepare compound cassava starch, and then mix the compound cassava starch with hydroxypropyl distarch phosphate, sodium carboxymethyl cellulose, preservatives, and diacetic acid. Stir sodium thoroughly to obtain powder; S2. Pour the powder into boiling water and knead it into raw pearl powder dough while it is hot; S3. Knead the raw tapioca dough into small balls with a diameter of 5 to 6 mm, and cover the surface of the small balls with tapioca starch to obtain rice balls I. The rice balls I are evacuated and frozen to obtain rice balls II. ; S4. Pour the pearl powder II into a container containing boiling water, heat for 10 to 15 minutes, stop the fire and simmer for 5 minutes, and take out the supercooled water to obtain a slow-digesting pearl powder containing a resistant complex. 5. The production method according to claim 4, characterized in that, in the step S1, the preparation method of compound cassava starch includes: weighing cassava starch and starch-protein resistant complex, mixing the two and then placing Put it into a centrifuge tube, place it on the MM400 refrigerated mixing ball mill and mix for 2 minutes. Take out the sample and repeat mixing three times to make the materials evenly mixed. 6. The production method according to claim 5, characterized in that, in the step S4, the mass ratio of the powder balls II to boiling water is 1:10; the process of pouring the powder balls II into a container containing boiling water , stir the powder balls II in the container to prevent them from sticking.