阅读说明：本技术 一种延长馒头保质和保鲜时间的方法 (Method for prolonging quality guarantee and preservation time of steamed buns ) 是由 林红 王志坚 于 2021-08-13 设计创作，主要内容包括：本发明食品保质保鲜技术领域,涉及一种延长馒头保质和保鲜时间的方法,包括：先将植酸涂覆在馒头表面,再采用钴-60γ射线和电子束射线辐照馒头；辐照前,先检测馒头的初始微生物负载量,然后确定辐照灭菌剂量。利用该方法获得馒头,能够保质和保鲜长达480天。(The invention relates to a method for prolonging the quality guarantee and preservation time of steamed bread, belonging to the technical field of quality guarantee and preservation of food, comprising the following steps: coating phytic acid on the surface of the steamed bread, and irradiating the steamed bread by using cobalt-60 gamma rays and electron beam rays; before irradiation, the initial microbial load of the steamed buns is detected, and then the irradiation sterilization dose is determined. The steamed bread obtained by the method can be preserved and kept fresh for 480 days.)

1. A method for prolonging the quality guarantee and preservation time of steamed bread is characterized by comprising the following steps: coating phytic acid on the surface of the steamed bread, and irradiating the steamed bread by using cobalt-60 gamma rays and electron beam rays; before irradiation, the initial microbial load of the steamed buns is detected, and then the irradiation sterilization dose is determined.

2. The method for prolonging the shelf life and freshness of steamed bread as claimed in claim 1, wherein the radiation sterilization dose is 3-9 kgy.

3. The method for prolonging the shelf life and freshness of steamed bread as claimed in claim 2, wherein the radiation sterilization dose is 6.6 kgy.

4. The method of claim 1, wherein the steamed bread comprises 25-35 wt% wet gluten; the water content of the steamed bread is 30-36 wt%.

5. The method for prolonging the shelf life and freshness of steamed bread as claimed in claim 1, wherein the initial microbial detection is performed by detecting the total number of colonies, coliform bacteria, mold and yeast.

6. The method for prolonging the quality and freshness of steamed bread as claimed in claim 1, wherein the uniformity of the Co-60 gamma irradiation is 1.28.

7. The method for prolonging the shelf life and freshness of steamed bread as claimed in claim 1, wherein the uniformity of electron beam irradiation is 1.13.

8. The method for prolonging the quality and freshness keeping time of the steamed bread as claimed in claim 1, wherein the irradiated product is monitored by microorganism and absorbed dose to determine the microorganism amount of the irradiated product and the actual absorbed dose of the irradiated product; and determining the quality guarantee time and the fresh-keeping time of the product according to the microbial quantity of the irradiated product.

9. The method for prolonging the quality and freshness time of the steamed bread as claimed in claim 1, wherein the quality and freshness time of the steamed bread obtained by the method is 180-480 days.

10. Use of the method for extending the shelf-life and freshness-keeping time of steamed bread as claimed in any one of claims 1 to 9 for the shelf-life and freshness-keeping of fancy steamed bread.

Technical Field

The invention belongs to the technical field of food quality and freshness preservation, and relates to a method for prolonging the quality and freshness preservation time of steamed bread.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

As is known, steamed bread is a staple food of daily diet mainly in northern areas of China, the processing method mainly comprises the steps of fermenting wheat flour and then steaming, and the classification of steamed bread mainly comprises the steps of preparing auxiliary materials and distinguishing the formed shapes. The fancy steamed bread in the Weihai area has complex manufacturing process, more material requirement types and single body purely manual manufacturing, because the fancy steamed bread takes animal modeling and flower modeling as three-dimensional holding, pinching and tool carving, the manufacturing period of each fancy steamed bread is overlong, the whole wheaten food manufacturing process is exposed in the air for a longer time, and meanwhile, the time for manually manufacturing holding and pinching products is longer, so that the overall microbial infection is more seriously polluted than the manufacturing process of other steamed bread; the fresh-keeping time is different according to the water content of the cooked wheaten food, and particularly like steamed bread with relatively high water content, the quality guarantee period of common staple food in a refrigerator with 5-8 ℃ is not longer than 3-5 days; even in winter, these products suffer from mildew or acid and rot on the surface of the product for 3-5 days. If the product is preserved by adopting a freezing mode, the three-dimensional pattern of the product appearance needs to be changed (reduced) and the water content of the product needs to be reduced, so that the product appearance and the taste need to be changed, and the products are too short to be preserved and preserved, so that processing enterprises cannot produce in a large scale, and meanwhile, the products need to be customized in advance and cannot be prefabricated. Particularly, products cannot be delivered in time in social activities and folk-custom folk wind activities, so that the loss of enterprise interests is caused; if the special products sent to all over the country cannot be mutually communicated or circulated due to the quality guarantee period problem, and the circulation is near to cold chain transportation, the quality guarantee and the preservation of the fancy steamed bread are a technical problem which is not solved.

With the conversion of nuclear radiation technology to civil use, China has application experience of over 50 years in food preservation and quality guarantee, and particularly, the limit value of the absorbed dose of food irradiation is determined by the international atomic energy agency in 1980. The food irradiation preservation technology in China is applied to a plurality of fields of food processing, and the purposes of quality guarantee and preservation of instant products, spices, food filling raw materials, seasonings, export marine products, meat products, fresh fruits and vegetables and the like are achieved by adopting the irradiation sterilization technology in a large range.

However, the inventor finds that, compared with flour food such as noodles and common small steamed buns, the fancy steamed buns are exposed in the air for a long time in the making process, the manual making time is long, the microbial infection of the fancy steamed buns with large heads is serious, the quality and freshness of the fancy steamed buns are high in difficulty, and the quality and freshness of the fancy steamed buns cannot be guaranteed and kept at high quality. Therefore, the storage time of the current fancy steamed bread is still short (7-10 days are common). As the quality and freshness keeping problems of the fancy steamed buns are not solved all the time, the fancy steamed buns cannot be customized in advance in social activities and folk-custom activities, products cannot be prefabricated, and huge losses of enterprise benefits are caused. In addition, for the fancy steamed bread, a problem needs to be overcome, the fancy steamed bread has different shapes and colors, and the key is how to ensure that the fancy steamed bread does not fade or oxidize during the processing process and does not influence the quality and freshness preservation.

Therefore, the method for sterilizing the fancy steamed bread can solve the problem that the quality guarantee and preservation time of the fancy steamed bread is short, and the sterilization method is researched to prolong the quality guarantee and preservation of the fancy steamed bread, so that the quality guarantee and preservation effects are more excellent, industrial large-scale popularization and use of wheaten food enterprises can be realized, and the storage and transportation cost of products is reduced.

Disclosure of Invention

The invention provides a method for prolonging the quality guarantee and preservation time of fancy steamed bread, aiming at solving the problems of higher quality guarantee and preservation difficulty and shorter quality guarantee and preservation time of the fancy steamed bread in the prior art, the method sets the radiation absorption dose according to the bacteria detection condition of the fancy steamed bread, uses cobalt-60 gamma rays and electron beam rays for irradiation, carries out irradiation outside a product body, and makes incident gamma particles or electrons penetrate into the product to generate physical, chemical and biological reactions so as to kill all or part of harmful microorganisms in the product, and simultaneously keeps aseptic or low bacteria in a closed environment, so that the product is kept in the aseptic or low bacteria environment, the purpose of aseptic or low bacteria non-reproduction of the product is achieved, and the long-term quality guarantee and preservation of the product are completed.

Specifically, the invention is realized by the following technical scheme:

in a first aspect of the invention, a method for extending the shelf-life and freshness-keeping time of steamed bread comprises: firstly coating phytic acid on the surface of a colored part of the steamed bun, and then irradiating the steamed bun by adopting cobalt-60 gamma rays or electron beam rays; before irradiation, the initial microbial load of the steamed buns is detected, and then the irradiation sterilization dose is determined.

In a second aspect of the invention, any of the methods for prolonging the quality guarantee time and the fresh-keeping time of the steamed bread is applied to the quality guarantee time and the fresh-keeping time of the fancy steamed bread.

One or more embodiments of the present invention have the following advantageous effects:

(1) the radiation sterilization technology is a cold sterilization technology, and can kill microorganisms in the fancy steamed bread without removing any package through the penetrating power of cobalt-60 gamma rays or electron beam rays to keep the taste and flavor of the steamed bread unchanged.

(2) The irradiation sterilization is to pass gamma particles and electron beams through physical, chemical and biological effects, and because the set doses in the experiment are not more than 10kGy (kilogray, the following irradiation dose units are all kGy), the irradiation treatment is indirect, and no harmful effect is caused on any component of the product. Meanwhile, the irradiated product has no product activation and no influence on human body.

(3) The phytic acid is coated on the surface of the fancy steamed bread, so that the problems of color fading, oxidation and the like of the color on the surface of the steamed bread in the irradiation process can be effectively solved, the color of the fancy steamed bread can be guaranteed under the condition that the quality guarantee time and the preservation time of the steamed bread are prolonged, and the problem cannot be expected in the prior art.

(4) Compared with common wheaten food, the fancy steamed bun manufacturing process is complex, the quality guarantee and preservation technical requirements for the fancy steamed buns are high, the process disclosed by the invention can overcome the difficulty which cannot be overcome by the traditional process, not only can ensure that the fancy steamed buns are not faded, but also can prolong the quality guarantee and preservation time, the steamed buns treated by the method can be preserved for up to 480 days without vacuum preservation, and the process has very important significance.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The invention aims at specific fancy steamed buns and solves the special problems faced by fancy steamed buns. The fancy steamed bun is prepared by manual processes, the preparation process is complex, the preparation time is long, the fungus content of various types is high, and the propagation and pollution of the mould are serious in the storage process, so that the fancy steamed bun has high difficulty in long-term quality guarantee and preservation. Therefore, the invention provides a method for prolonging the quality guarantee and preservation time of steamed bread.

In one or more embodiments of the invention, a method for extending the shelf-life and freshness-keeping time of steamed bread comprises: firstly coating phytic acid on the surface of a colored part of the steamed bun, and then irradiating the steamed bun by adopting cobalt-60 gamma rays or electron beam rays; before irradiation, the initial microbial load of the steamed buns is detected, and then the irradiation sterilization dose is determined.

In the prior art, the change condition of components of a wheaten food product after being irradiated is mainly researched, but quality guarantee and preservation tests are not carried out, and how to greatly prolong the quality guarantee and preservation of patterned steamed bread is not disclosed. The fancy steamed bread is different from the traditional steamed bread with smooth surface and no special patterns and shapes. The fancy steamed bread has different shapes and colors, and particularly, the fancy steamed bread has the unique advantage of solving the problem of difficult quality guarantee and storage of large-size fancy steamed bread. The large dimension refers to the diameter: 40-90cm, height: 20-70 cm. For large-size fancy steamed buns, the quality guarantee and preservation difficulty is higher, and the quality guarantee and preservation time of the large-size fancy steamed buns cannot be improved to 50 days by the conventional process.

In the method, the phytic acid is coated on the surface of the steamed bread, so that the situations of fading and the like of the fancy steamed bread can be effectively avoided. Meanwhile, the addition of the phytic acid does not affect the sterilization of microorganisms on the irradiated surface of the steamed bread, and is favorable for realizing the antioxidation during the irradiation of uneven surfaces such as ditch cutting and the like. The quality guarantee and preservation time, color and appearance of the steamed bread are greatly improved through the synergistic cooperation of the antioxidant effect of the phytic acid and the irradiation technology.

The surface sterilization of the fancy steamed bread has higher requirements on irradiation dose, and any absorbed dose is not beneficial to the quality guarantee and the preservation of the fancy steamed bread. Because, the inventor absorbs 3-9kG y dose from radiation sterilization in order to prolong the quality guarantee and preservation time of the fancy steamed bread to the maximum extent; the lowest effective dose is preferably 6.6kGy, the highest limited dose is 9.5kGy, the uniformity of irradiation of cobalt-60 gamma rays selected in the experiment is 1.28 because of the nonuniformity of irradiation of different irradiation devices, so that the dose range can be selected from 6.6kGy to 9kGy 1.28 to 12.16, and if the uniformity of irradiation of electron beam rays is 1.13, the dose range can be selected from 6.6kGy to 9kGy 1.13 to 10.17kGy, and the dose range is selected from 6.6kGy to 9.5kGy due to the uniformity problem. At the moment, except for part of fancy steamed buns, the fancy steamed buns can not be packaged in vacuum, and can be stored for more than 180 days only by using common airtight packaging, but the storage and preservation time of the fancy steamed buns which can be packaged in vacuum is up to 480 days.

Before irradiation treatment, food-grade packaging materials are selected to package the steamed buns. Before traditional irradiation treatment, products need to be stored in vacuum packaging bags, and long-term storage can be achieved only by irradiation sterilization in a vacuum environment. However, when the steamed bread irradiated by the method of the invention can not be packed in vacuum, the PE food-grade packing bag with the thickness of more than 6 threads is adopted for packing in non-vacuum and tight air tightness, the quality guarantee and the fresh keeping can still be realized for a long time by using the lowest effective irradiation sterilization dose, and the quality guarantee can be realized for more than 180 days.

Compared with the common steamed bread, the fancy steamed bread comprises 25-35 wt% of wet gluten and 30-36 wt% of water content.

Before irradiation, initial microbial detection is required to detect the total number of colonies, coliform bacteria, mold and yeast. According to the initial microbial load before actual detection irradiation, different microbial irradiation tolerance is considered, so that different microbes are irradiated and killedBacterial dose D₁₀The values are different, the radiation sterilization dose D₁₀Calculating the formula: d represents SD₁₀LgN₀N, wherein N is the number of microorganisms remaining after irradiation, N₀The initial number of microorganisms, SD, is such that the remaining microorganisms are reduced to the absorbed dose given by N.

The traditional wheaten food product has smooth wheaten food surface, no groove cutting and easy irradiation. However, different from the traditional wheaten food products, the fancy steamed bread has more channel chops on the surface, and the channel chops are easy to breed mold, so the radiation on the surface of the irradiated product has better uniformity, therefore, in order to prolong the quality guarantee and preservation time of the fancy steamed bread, the radiation uniformity of the cobalt-60 gamma ray is 1.28, and the radiation uniformity of the electron beam ray is 1.13.

Determining the microbial quantity of the irradiated product and the actual absorbed dose of the irradiated product by microbial monitoring and absorbed dose monitoring of the irradiated product; and determining the quality guarantee time and the fresh-keeping time of the product according to the microbial quantity of the irradiated product. The quality guarantee and preservation time of the steamed bread obtained by the method can reach 480 days at most, which is an effect that the traditional process cannot obtain at all and is also a contribution of the invention to wheaten food enterprises.

In one or more embodiments of the invention, the method for prolonging the quality guarantee time and the preservation time of the steamed bread is applied to the quality guarantee time and the preservation time of the fancy steamed bread.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

Example 1

1. Determining raw materials and type of flour food product and approximate water content

(1) The main materials of the fancy steamed bread are as follows: the flour is mainly made of special first-class flour and common flour, medium gluten flour, and wet gluten value is 25% -35%;

(2) auxiliary materials: eggs, sugar, beer, water, yeast, different colors of plant pigment, etc.;

(3) the colored steamed bread is dyed after the production and before the secondary fermentationThe parts are evenly coated by 0.1 percent₀Phytic acid is used for protecting color, and the phytic acid is not required to be coated on the primary color part of the steamed bread;

(4) water content: the measurement of the water content of the steamed fancy steamed bread by a food water content measuring instrument (model: JT-K6) is 30-36 percent.

2. The microorganism detection of the primary product is mainly the indexes of total bacterial count, coliform group, mould and yeast

The microorganism detection label is according to GB 4789.1-2016; GB 4789.2-2016; GB 4789.3-2016; GB4789.15-2016, four national standards for microbial detection.

(1) The basic method for detecting the microorganisms comprises the following steps:

1) in a microorganism laboratory, preparing culture solution for conventionally detecting 3 types of microorganisms such as total number of bacterial colonies, coliform group, mould and microzyme according to the 4 standards, and determining culture times;

2) taking 5 steamed bun samples of 25 g at different parts of the steamed bun and mashing the steamed bun samples;

3) dissolving the solid sample into the culture solution;

4) respectively dripping culture solution for detecting the total number of bacterial colonies into 5 90mm culture dishes by using a pipette, wherein the culture solution is 15ml-20ml in the sterile operation box;

5) placing the 5 culture dishes inoculated with the products into a 36 +/-1-degree incubator for culture; 5) culturing in an incubator for 48 +/-2 days;

6) the colonies on these 5 plates were observed to grow out, and the total number of colonies was determined by counting. In addition, a culture solution is prepared according to GB4789.3-2016 by culturing the mould and the yeast, and other steps are basically the same as the steps, but the culture temperature is 28 +/-1 ℃, and the culture time is 5-7 days.

(2) The detection method of coliform group bacteria comprises the following steps:

1) preparing a culture solution according to the national standard GB 4789.3-2016;

2) then, mashing 25 g of steamed bun samples and uniformly dissolving the steamed bun samples into a culture solution;

3) injecting 5 9ml test tubes by a pipette in a sterile operation box;

4) then sealing 5 test tubes with absorbent cotton, and culturing in an incubator at 36 + -1 deg.C for 48 + -2 days;

5) observing the gas production condition of each test tube, and if the gas production is positive, the plate counting method can be used for detecting the number of coliform groups.

(3) Original bacteria data before product irradiation:

3. setting the radiation absorption dose of the product according to the bacteria detection condition of the initial product;

according to the above-mentioned case of non-irradiated product and the requirement of D10 value of sensitivity of different bacteria to irradiation, the absorbed dose for 5 samples was set as: 3KG, 5KG, 6KG, 7KG, 9KG, 5 doses

4. The product is hermetically packaged in a mode of isolating external air, so that the irradiated product is prevented from contacting with air to cause secondary pollution, and meanwhile, the moisture of the product is ensured to have sufficient moisture retention, so that food-grade packaging materials with different thicknesses are selected according to the preservation requirement and the irradiation absorption dose of the product, common non-vacuumized packaging bags are adopted, food-grade packaging bags with more than 6 filaments are used, on the premise of good airtightness, the quality guarantee time is more than 180 days, vacuumizing storage is adopted, and the maximum quality guarantee time is up to 480 days.

5. The type of the adopted radiation is gamma rays or electron beams, the gamma ray irradiation device is a JB-400 type cobalt-60 irradiation device, and the irradiation uniformity is 1.28; the electron beam device IS an IS10/20 type linear electron accelerator, and the irradiation uniformity IS 1.13; the dose absorption monitoring system employs a U.S. GEX film dose test strip and system.

6. And (5) conveying the irradiated product to the irradiation chamber through a conveying chain according to the set dose for irradiation.

7. And determining the microbial quantity of the irradiated product and the actual absorbed dose of the irradiated product by microbial monitoring and absorbed dose monitoring of the irradiated product.

(1) Product radiation dose monitoring 5 radiation absorption set doses for dose slice reading by Genesys30 spectrophotometer of GEX system were:

(2) microbiological statistics of 5 samples after 5 doses of irradiation

Colony detection table for 5 samples after No. 1 dosage 3.2kGy irradiation

Colony detection table for 5 samples after No. 2 dosage 5.1kGy irradiation

Colony detection table for 5 samples after No. 3 dosage 6.2kGy irradiation

Colony detection table for 5 samples irradiated with No. 4 dosage of 7.3kGy

Colony detection table for 5 samples after No. 5 dosage of 8.9kGy irradiation

The microbial inspection statistics of 5 samples respectively irradiated by 5 irradiation absorbed doses indicates that mould, microzyme and coliform flora of products irradiated by 1 and 2 irradiation doses are all larger than 3, namely a small amount of mould exists on the surface of the steamed bread, the culprit of mould generation of the steamed bread is mould, especially partial products which cannot be packed in vacuum, air exists in the package, and oxygen in the air is beneficial to the propagation of aerobic mould, so that the aims of long-term quality guarantee and fresh keeping are not enough.

3. After 5 samples are respectively irradiated by the three irradiation absorbed doses of 4 and 5, the mould, the microzyme and the coliform group of the samples are all less than or equal to 1 and are regarded as undetected in the national standard GB4789-2016, so the three irradiation absorbed doses can be used as the irradiation absorbed doses of products for an irradiation process, but for the sake of higher safety, the minimum effective dose is increased by about 0.05 percent on the basis of 6.3kGy, and the minimum effective dose is set to 6.6 kGy; as the 5 th dose is close to 9kGy, the maximum limit dose is also relaxed a little bit due to the unevenness of the irradiation apparatus, and is set to 9.5kGy, and this maximum limit dose meets the regulation of food average irradiation dose at 10kGy (kilogray) in "food irradiation safety report by the united nations food and agriculture organization/international atomic energy agency/world health organization expert committee.

8. Determining the quality and freshness time of the product based on the microbial count of the irradiated product

No. 1 product is packaged for no more than 15 days (room temperature is 15-20 ℃); the product is kept fresh under vacuum packaging, and the moisture of the product is basically not lost, but slightly lost in common packaging;

the quality guarantee time of the No. 2 product is about 15 days by adopting common packaging, and the No. 2 product is packaged for 30-40 days by adopting vacuum; the product is kept fresh under vacuum packaging, and the moisture of the product is basically not lost, but slightly lost in common packaging; the 2 samples described above are short shelf and fresh keeping products.

The quality guarantee time of the No. 3 product is about 60 days by adopting common packaging, and the quality guarantee time is about 90-120 days by adopting vacuum packaging; the product is kept fresh under vacuum packaging, and the moisture of the product is basically not lost, but the moisture loss of the product is slightly higher in common packaging;

4. the radiation absorption dose of the product No. 5 exceeds 7kGy, 6.6kGy is the lowest effective dose, when the radiation absorption dose in the range of 6.6kGy-9.5kGy is selected, the common air-tight package is adopted for more than 180 days, and the vacuum package is adopted for 480 days; the moisture of the product is basically not lost under the condition of vacuum packaging, but the moisture loss is relatively high in the common packaging. 4. The No. 5 product is irradiated into a long quality-keeping and fresh-keeping product, more than 8 filaments are recommended to be used for vacuum packaging, and all the storage conditions of the product are at room temperature, and other auxiliary fresh-keeping equipment is not needed.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.