Organic zinc-rich Kluyveromyces martensii and its compositions and their application in quick-frozen rice and flour products

Abstract

This invention belongs to the field of biotechnology, specifically relating to a zinc-rich Kluyveromyces martensii yeast and its application in the preparation of quick-frozen rice and flour products. The zinc content of the zinc-rich Kluyveromyces martensii yeast is 1000-15000 mg / kg, and the proportion of organic zinc is not less than 90%. Furthermore, by adding Kluyveromyces martensii yeast containing a high concentration of organic zinc... Kluyveromyces marxianus It can increase the organic zinc content of products, effectively prevent frozen rice and flour products from cracking during freezing, and significantly improve the taste of frozen rice and flour products, enrich their nutritional elements, and promote growth and development.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology. Specifically, this invention relates to a nutritionally fortified Kluyveromyces martensii and its application in the preparation of quick-frozen rice and flour products. Background Technology

[0002] Max Kluyveromycin ( Kluyveromyces marxianus It is a generally recognized as safe (GRAS) microorganism, characterized by rapid growth and simple nutritional requirements.

[0003] Zinc is an essential trace element for the human body, participating in the synthesis and activation of hundreds of enzymes and playing a crucial role in growth and development, immune function, intellectual development, and taste formation. Children, adolescents, pregnant women, and the elderly are high-risk groups for zinc deficiency. Currently, most zinc-fortified foods on the market use inorganic zinc (such as zinc sulfate and zinc gluconate) as additives. However, inorganic zinc has disadvantages such as low bioavailability, easy binding with phytic acid and other components in food to form precipitation, and some irritation to the gastrointestinal tract. In comparison, organic zinc, especially yeast zinc, has higher bioavailability, better taste, and is gentler on the gastrointestinal tract, making it a more ideal form of zinc fortification. Existing technologies include research on the enrichment of trace elements using yeast, but most studies focus on chromium.

[0004] Frozen rice and flour products (such as pizza, beef rolls, dumplings, steamed buns, glutinous rice balls, and noodles) are widely popular due to their convenience. However, during freezing, storage, and transportation, these products are prone to cracking and internal structural damage due to the formation and growth of ice crystals, severely affecting their appearance, taste, and commercial value. Currently, the problem is often alleviated by adding improvers (such as emulsifiers and thickeners) or improving the freezing process, but the effects are limited and do not fundamentally improve the nutritional value of the products.

[0005] Studies on the enrichment of trace elements using yeast have mainly focused on nutritional supplements. There are no reports of using yeast directly as a functional ingredient in quick-frozen rice and flour products to simultaneously achieve nutritional fortification, freeze-cracking resistance, and quality improvement.

[0006] Therefore, developing a quick-frozen rice and flour product that can effectively solve the problem of freezing and cracking, significantly improve nutritional value and taste is of great practical significance and market value. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a zinc-rich Kluyveromyces martensii yeast and its application in the preparation of quick-frozen rice and flour products. This product is not only high in organic zinc and rich in nutrients, but also effectively prevents cracking during freezing and significantly improves the product's texture.

[0008] On the one hand, the present invention provides a zinc-rich Kluyveromyces martensii (Kluyveromyces masculinii) Kluyveromyces marxianus The zinc content is 1000-15000 mg / kg, and the proportion of organic zinc is not less than 90%. For example, the zinc content can be 1000, 2000, 3000, 3250, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000 or 15000 mg / kg, etc., and the proportion of organic zinc can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%, etc.

[0009] In some embodiments, the organic zinc-rich Kluyveromyces martensii contains 3250 mg / kg of zinc and 93% organic zinc.

[0010] In some embodiments, the zinc-rich Kluyveromyces macrocarpa is prepared by fermenting Kluyveromyces macrocarpa in a zinc-containing medium containing a zinc source.

[0011] In some embodiments, the zinc ion concentration of the zinc-containing culture medium is 100-500 mg / L, for example, 100, 200, 300, 400 or 500 mg / L, preferably 100-300 mg / L.

[0012] In some embodiments, the zinc source of the zinc-containing culture medium may be one or more of zinc sulfate, zinc acetate, or zinc gluconate.

[0013] In some embodiments, the carbon source of the zinc-containing culture medium may be one or more of glucose, fructose, sucrose, molasses, maltose, starch, etc.

[0014] In some embodiments, the nitrogen source of the zinc-containing culture medium may be one or more of corn steep liquor, ammonia, ammonium sulfate, whey powder, tryptone, etc.

[0015] In some implementations, the fermentation temperature is 25-45°C, for example, it can be 25°C, 30°C, 35°C, 40°C or 45°C.

[0016] In some implementations, the fermentation speed is 100-600 rpm, for example, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550 or 600 rpm.

[0017] In some implementations, the fermentation time is 25-60 h, for example, 25, 30, 35, 40, 45, 50, 55 or 60 h.

[0018] In some embodiments, the Kluyveromyces martensii accession number is CCTCC M 20211265.

[0019] In some implementations, the fermented zinc-rich Kluwer Maxwellia cells are collected.

[0020] In some preferred embodiments, the collected zinc-rich Kluyveromyces macrocarpa cells are dried to obtain zinc-rich yeast powder for use. The drying method can be spray drying or freeze drying.

[0021] On the other hand, the present invention provides a zinc-enriched Kluyveromyces yeast composition, wherein the zinc-enriched Kluyveromyces yeast composition is a zinc-enriched frozen rice and flour product, and the zinc-enriched frozen rice and flour product contains the above-mentioned organic zinc-enriched Kluyveromyces yeast. The dough of the zinc-enriched frozen rice and flour product is based on wheat flour and / or rice flour, and organic zinc-enriched Kluyveromyces yeast powder is added to the base material.

[0022] In some embodiments, the organic zinc-rich Kluwer yeast powder is prepared by inoculating Kluwer yeast strains into a liquid culture medium containing a zinc source (such as zinc sulfate, zinc acetate, or zinc gluconate) for zinc enrichment culture. After the culture is completed, the powder is obtained by centrifugation, washing, drying, and pulverizing.

[0023] In some preferred embodiments, the organic zinc content in the zinc-enriched Kluyveromyces martensii yeast powder is 2000-15000 mg / kg, for example, the zinc content can be 1000, 2000, 3000, 3250, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, or 15000 mg / kg, etc., and the zinc content of the final quick-frozen rice and flour products is not less than 3 mg / 100 g, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mg / 100 g. In some preferred embodiments, the zinc content of the final quick-frozen rice and flour products is 3-10 mg / 100 g. The zinc content in the above-mentioned quick-frozen rice and flour products meets the "rich in zinc" claim requirements (≥3.0 mg / 100 g solids) in GB 28050 "National Food Safety Standard General Rules for Nutrition Labelling of Prepackaged Foods".

[0024] In some embodiments, the dough ingredients of the zinc-enriched quick-frozen rice and flour products include flour and the zinc-enriched Kluwer yeast. The amount of the zinc-enriched Kluwer yeast added accounts for 0.5%-20% of the total weight of the dough, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, preferably 0.5%-5%, more preferably 0.7%-3%, and even more preferably 2%.

[0025] In some embodiments, the dough raw material further includes water, which is added at 30%-60% of the total weight of the dough. For example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 55%, or 60%, preferably 40%-60%.

[0026] In some embodiments, the dough raw materials further include one or more of sugar, oil, salt, emulsifier, and improver, with the total addition amount not exceeding 10% of the total weight of the dough, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0027] In some implementations, the dough ingredients also include wheat gluten, vegetable powder, etc.

[0028] In some embodiments, the zinc-enriched quick-frozen rice and flour products include fillings in addition to the dough.

[0029] In some implementations, the zinc-enriched frozen rice and flour products are frozen pizzas, beef rolls, steamed buns, dumplings, noodles, wontons, glutinous rice balls, twisted rolls, fried dough sticks, pancakes, spring rolls, rice noodles, or rice cakes, preferably frozen pizzas or dumplings.

[0030] In another aspect, the present invention provides a method for preparing the above-mentioned composition, comprising the following steps:

[0031] a) Preparation of zinc-enriched yeast powder;

[0032] b) Dough preparation;

[0033] c) Molding;

[0034] d) Quick-freezing;

[0035] e) Packaging and refrigeration.

[0036] In some embodiments, step a) includes collecting the fermented zinc-rich Kluwer Max Kluwer cells and drying them to obtain zinc-rich yeast powder.

[0037] In some implementations, the drying method described in step a) is spray drying or freeze drying.

[0038] In some embodiments, step b) includes mixing flour and / or rice flour, the zinc-enriched yeast powder obtained in step a), and water, and stirring to form a dough.

[0039] In some embodiments, step b) may also include other optional excipients, such as one or more of sugar, oil, salt, emulsifier, and improver; in some preferred embodiments, the other optional excipients may also include wheat gluten, vegetable powder, etc.

[0040] In some implementations, the dough prepared in step b) is left to rest and proof at a suitable temperature.

[0041] In some implementations, step c) includes processing the dough into a raw form of a predetermined shape.

[0042] In some implementations, the processing includes wrapping fillings or adding pizza toppings.

[0043] In some embodiments, step d) includes rapidly freezing the green blank at -30°C to quickly reduce the core temperature of the product to below -18°C.

[0044] In some embodiments, between steps c) and d), a proofing step is also included, with a proofing temperature of 30-38°C (e.g., 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, or 38°C), a humidity of 70-85% (e.g., 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, or 85%), and a time of 30-60 minutes (e.g., 30, 35, 40, 45, 50, 55, or 60 minutes).

[0045] In some implementations, step e) includes packaging the quick-frozen product and storing it at -18°C.

[0046] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a zinc-enriched quick-frozen rice and flour product and its preparation method. This product is rich in organic zinc, has high bioavailability, and can effectively promote growth and development while maintaining the good taste, flavor, and texture of traditional quick-frozen rice and flour products.

[0047] Advantages of this invention

[0048] 1. Nutritional Fortification and Efficient Zinc Supplementation: This application presents a zinc-fortified Kluyveromyces martensii yeast formulation with an organic zinc content of no less than 90%. By adding this zinc-enriched yeast to frozen rice and noodle products, inorganic zinc is converted into easily absorbed organic zinc (primarily bound to proteins and polysaccharides within the yeast), significantly increasing the zinc content of the frozen rice and noodle products and achieving efficient and safe nutritional fortification. The zinc-enriched frozen rice and noodle products contain natural organic zinc with high bioavailability, avoiding the drawbacks of inorganic zinc and more effectively supplementing the body with zinc to promote growth and development.

[0049] 2. Excellent resistance to freezing and cracking: The glucan, mannan and other components in the cell wall of Kluyveromyces maculae have good water retention and film-forming properties. Its intracellular proteins (including enriched zinc-binding proteins) have certain antifreeze protein characteristics, which can inhibit the growth and recrystallization of ice crystals and effectively reduce the migration and loss of water during freezing, thereby fundamentally preventing the surface of zinc-rich quick-frozen rice and flour products from cracking.

[0050] 3. Improved Taste and Quality: Max Kluwer yeast is rich in protein, B vitamins, and other nutrients, and its cells possess unique umami and flavor compounds, enhancing the flavor and nutritional value of products without the need for excessive seasonings. The addition of yeast promotes dough fermentation, creating a fine porous structure that makes the product softer and more elastic. Simultaneously, yeast autolysis products such as amino acids and nucleotides enhance the umami flavor, mask any potential metallic odor, and improve the overall sensory quality of the product.

[0051] 4. Cleanliness label: Max Kluyveromycin is a natural microorganism that meets current consumer demand for clean and natural ingredients.

[0052] 5. Stable product quality: The quick-freezing process locks in freshness, preserving the product's optimal condition and nutritional components, resulting in a long shelf life and convenient consumption. Attached Figure Description

[0053] Figure 1 The images show a comparison of the appearance of the zinc-enriched frozen dumplings prepared in Example 2 and the ordinary frozen dumplings prepared in Comparative Example 1 (without added organic zinc-enriched Kluyveromyces masculinii), after being stored under the same freezing conditions for 30 days. Detailed Implementation

[0054] For the purpose of clarity and concise description, features are described herein as part of a number of identical or separate embodiments. However, it will be understood that the scope of this disclosure may include embodiments having combinations of all or some of the described features. The technical solutions of the present invention will now be described clearly and completely. Obviously, based on the specific embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0055] I. Definition

[0056] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly used in the field to which this invention pertains. For the purposes of interpreting this specification, the following definitions will apply, and where appropriate, terms used in the singular will also include the plural forms, and vice versa.

[0057] As used herein, the terms “contains,” “has,” “includes,” and “contains” should be interpreted as open-ended terms (i.e., meaning “including but not limited to”). “And / or” describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character “ / ” generally indicates an “or” relationship between the preceding and following related objects, while the character “+” generally indicates an “and” relationship.

[0058] As used herein, the terms “optional,” “any,” “arbitrary,” or “any item” mean that the event or situation described below may, but does not have to, occur, including the circumstances in which the event or situation occurs or does not occur. As used herein, “a,” “an item,” and “a kind” are used to refer to one or more grammatical objects. “Multiple,” “various,” or “multiple items” as used herein refer to two or more grammatical objects, such as two, three, four, five, etc. The terms “one or more / a kind or more / an item or more” and “at least one / a kind / item” are used interchangeably.

[0059] As used herein, references to “some embodiments,” “some implementations,” or “some implementation schemes” describe a subset of all possible embodiments, but it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0060] As used herein, the term "about" indicates a range of ±20% of the following value. In some embodiments, the term "about" indicates a range of ±10% of the following value. In some embodiments, the term "about" indicates a range of ±5% of the following value.

[0061] As used herein, "zinc-rich" and "organic zinc-rich" are interchangeable. They refer to food-grade microbial strains obtained through natural screening, targeted domestication, physical / chemical mutagenesis, or genetic engineering, which are capable of efficiently absorbing inorganic zinc (such as zinc sulfate, zinc acetate, zinc gluconate, etc.) in zinc-containing culture media and converting it into low-toxicity, bioavailable organic zinc forms (such as zinc-substituted methionine, zinc-substituted cysteine, zinc-containing small molecule peptides, zinc-protein complexes, etc.) through their own metabolic pathways. Furthermore, the proportion of organic zinc in the total zinc of the bacterial cells, the accumulation of organic zinc, and the biological activity of the strain itself all meet the characteristics of food-grade microbial strains that meet the preset application standards.

[0062] As used herein, the term "composition" refers to a product containing organic zinc-rich Kluyveromyces martensii and at least one physiologically acceptable excipient or additive, including but not limited to: other food ingredients, seasonings, modifiers, solvents, diluents, disintegrants, precipitation inhibitors, surfactants, flow aids, binders, lubricants, dispersants, suspending agents, isotonic agents, thickeners, emulsifiers, preservatives, stabilizers, hydrating agents, emulsification accelerators, buffers, colorants, flavorings, sweeteners, ion exchangers, taste enhancers, or antioxidants. These components work together to provide a more comprehensive effect. In some preferred embodiments, the composition is a frozen rice or flour product. In some preferred embodiments, the composition is frozen dumplings or frozen pizza.

[0063] As used in this article, the term "dough blank" refers to a semi-finished dough product made primarily from rice flour or wheat flour, mixed with water or other auxiliary materials, and kneaded, but not yet fully cooked (or only initially shaped). It includes various forms such as dough sheets, pancake sheets, noodle blanks, steamed bun blanks, and dumpling blanks.

[0064] II. Examples

[0065] The present invention will be described in detail below through specific embodiments. It should be understood that the following embodiments are for explanation and illustration only and do not limit the scope of the present invention in any way.

[0066] Where specific methods, techniques, or conditions are not specified in the examples, they shall be performed in accordance with the methods, techniques, or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0067] Example 1: Preparation of organic zinc-rich Kluyveromyces martensii

[0068] 1. Select a single colony of *Kluyveromyces martensii* CCTCC M 20211265 (deposited on October 13, 2021, at the China Center for Type Culture Collection (CCTCC, Wuhan University, Wuhan, China)) on a YPD agar plate and classify it as follows: Kluyveromyces marxianus CJ3113 was inoculated into a test tube containing 10 mL of YPD liquid medium and cultured overnight with shaking (culture temperature 30℃, shaker speed 200 rpm) as the primary seed culture.

[0069] 2. Inoculate the primary seed culture at a rate of 2% into 200 / 500 mL of YPD liquid medium for expansion culture (culture temperature: 30℃, shaker speed: 200 rpm) for 12-18 h to obtain the secondary seed culture.

[0070] 3. Inoculate the secondary seed culture at a rate of 10% into a 10 L fermenter for fed-batch fermentation. Use a zinc-containing medium for fermentation. The carbon source can be one or more of glucose, fructose, sucrose, molasses, maltose, and starch. The nitrogen source can be one or more of corn steep liquor, ammonia, ammonium sulfate, whey powder, and tryptone. The zinc source can be zinc sulfate (Zn²⁺ concentration of 100-300 mg / L). The fermentation temperature is 25-45℃, the fermentation speed is 100-600 rpm, and the fermentation time is 24-60 h.

[0071] 4. After fermentation, the *Kluyveromyces martensii* culture broth was centrifuged to collect the cells. The cells were washed three times with sterile water to remove residual inorganic zinc from the surface, then spray-dried, and finally pulverized through a 100-mesh sieve to obtain yeast powder rich in organic zinc. Atomic absorption spectrometry analysis showed that the zinc content in this yeast powder was 3250 mg / kg, with an organic zinc content of 93%.

[0072] Example 2: Preparation of quick-frozen dumplings containing organic zinc-rich Kluyveromyces martensii.

[0073] The recipe for zinc-enriched frozen dumplings is as follows: 500 g of high-gluten flour, 10 g of organic zinc-enriched Max Kluwer yeast powder prepared in Example 1 (accounting for 2% of the flour weight), 250 g of drinking water, and 300 g of minced pork (including seasonings).

[0074] Preparation method:

[0075] 1. Kneading the dough: Mix flour, zinc-enriched yeast powder and water, knead into a smooth dough, and let it rise at room temperature for 20 minutes.

[0076] 2. Making the wrappers and filling: Roll out the risen dough into dumpling wrappers, fill them with pork filling, and make dumpling dough pieces.

[0077] 3. Quick-freezing: Arrange the raw dumpling dough evenly on a tray and place it in a -35℃ quick-freezing tunnel to freeze for 30 minutes, so that the center temperature drops below -18℃.

[0078] 4. Packaging and warehousing: Vacuum pack the quick-frozen dumplings and store them in a cold storage at -18℃.

[0079] Comparative Example 1: Preparation of ordinary quick-frozen dumplings

[0080] Except for the absence of zinc-enriched yeast powder, the formula and process are exactly the same as in Example 2.

[0081] Example 3: Comparison of the effects of zinc-enriched frozen dumplings and ordinary frozen dumplings

[0082] 1. Crack Resistance Comparison: The quick-frozen dumplings from Example 2 and Comparative Example 1 were stored at -18°C for 90 days, during which time simulated transportation conditions with three temperature fluctuations (rising to -5°C and then falling back to -18°C). After storage, from... Figure 1 As can be seen, the zinc-enriched frozen dumplings of Example 2 were intact and without cracks, while the ordinary frozen dumplings of Comparative Example 1 showed obvious cracking on their skin. The cracking rate of Example 2 was ultimately measured to be 3%, while the cracking rate of Comparative Example 1 was as high as 25%.

[0083] 2. Nutritional Analysis: The zinc content of the dumplings in Example 2 was measured to be 5.6 mg / 100g (detection method was GB5009.14-2017 "National Food Safety Standard - Determination of Zinc in Food" Method II), which meets the "rich in zinc" claim requirement (≥3.0 mg / 100g solid) in GB 28050 "National Food Safety Standard - General Rules for Nutrition Labelling of Prepackaged Foods". In contrast, the zinc content of the dumplings in Comparative Example 1 was only 1.2 mg / 100g.

[0084] 3. Sensory evaluation: After being evaluated by a sensory evaluation panel of 10 people, the dumplings in Example 2 had a more chewy and resilient dumpling skin after cooking, and the taste was significantly better than that of Comparative Example 1, and there was no unpleasant odor.

[0085] The results above can be compared in Table 1.

[0086] Table 1

[0087]

[0088] Example 4: Preparation of pizza containing zinc-rich Max Kluyveromyces yeast

[0089] The pizza in this embodiment consists of two parts: the crust and the sauce filling, which are then assembled.

[0090] 1. Ingredients and proportions for Max Kluwer yeast-infused organic zinc pizza:

[0091] (1) The dough is prepared from the following raw materials in the following weight ratio:

[0092] Wheat flour: 460 g (42.7% of total dough ingredients)

[0093] Ice water: 450 g (41.8% of the total dough ingredients)

[0094] Butter: 50 g (4.6% of total dough ingredients)

[0095] Gluten powder G60: 83.5 g (7.8% of total dough ingredients)

[0096] Sugar: 10 g (0.9% of total dough ingredients)

[0097] Vegetable powder: 10 g (0.9% of the total dough ingredients)

[0098] Zinc-enriched yeast powder: 7.5 g (0.7% of total dough ingredients)

[0099] Salt: 5.5 g (0.5% of total dough ingredients)

[0100] The total weight of the crust ingredients is 1076 g.

[0101] (2) Sauce and filling ratio:

[0102] The sauce filling is composed of the following ingredients in the indicated weight ratios:

[0103] Cheese: 25.0 g (35.7% of the total sauce filling)

[0104] Bacon: 15.0 g (21.4% of total sauce filling)

[0105] Margarine: 6.0 g (8.6% of total sauce filling)

[0106] Carrots: 6.0 g (8.6% of the total sauce filling)

[0107] Vital gluten powder G70: 6.0 g (8.6% of the total sauce and filling)

[0108] 5.0 g of diced potatoes (7.1% of the total sauce filling)

[0109] Pizza sauce: 3.0 g (4.3% of total sauce and toppings)

[0110] Corn: 2.0 g (2.9% of the total sauce filling)

[0111] Green peas: 2.0 g (2.9% of the total sauce filling)

[0112] The total weight of the sauce filling is 70 g.

[0113] (3) Final product mix:

[0114] The prepared cooked dough (50 g) was combined with the sauce filling (70 g) to obtain a final pizza product with a total weight of 120 g. The sauce filling accounted for 58.3% and the cooked dough accounted for 41.7%.

[0115] 2. Preparation process:

[0116] Step 1: Preparation and Fermentation of the Dough

[0117] Combine wheat flour, vegetable flour, zinc-enriched yeast, sugar, and salt in a dough mixer and mix well. Add ice water, melted butter, and G60 (a type of yeast starter), and mix at medium speed until the dough is smooth and the gluten is fully developed. Let the dough ferment at 28°C and 75% humidity for 60-90 minutes.

[0118] Step 2: Shaping and Pre-baking the Pastry

[0119] After the fermented dough is divided, rounded, and relaxed, it is rolled out into a round base of the predetermined diameter. The shaped base is placed in an oven preheated to 200℃ and baked for 5-7 minutes, until about 70% cooked, to obtain the "cooked crust". This step helps to fix the crust structure and prevent deformation or water seepage during subsequent freezing and secondary baking.

[0120] Step 3: Preparing the sauce and filling

[0121] Pre-cook the filling ingredients, such as bacon, diced potatoes, carrots, green peas, and corn, by blanching or lightly stir-frying. Mix the pizza sauce, G70, margarine, and pre-cooked filling ingredients and cheese according to the specified ratio.

[0122] Step 4: Assembly and quick-freezing

[0123] Spread 70g of sauce evenly onto 50g of cooked pizza dough. Quickly transfer the assembled pizza to a freezer tunnel at -30°C or below for rapid freezing, ensuring the core temperature of the product drops below -18°C within 30 minutes.

[0124] Step 5: Packaging and Storage

[0125] The frozen pizzas are vacuum-packed or nitrogen-filled and stored and transported at -18°C.

[0126] 3. Product Features and Beneficial Effects:

[0127] Nutrition and Taste: By adding vegetable powder and various vegetable fillings, the product's dietary fiber and vitamin content are enriched. The combination of G60 and butter ensures that the crust maintains a crisp texture after pre-baking and re-baking.

[0128] Advantages of industrialized production: The unique "cooked crust + quick-freezing" process ensures that the product maintains its excellent quality after frozen storage, and consumers can obtain a flavor close to freshly made by simply baking. The weight ratio of crust to filling (~4:6) has been optimized to both support the filling and ensure a rich filling texture in every bite.

[0129] Unique flavor: The addition of G70 and ingredients such as margarine creates a unique savory flavor that distinguishes it from traditional pizzas.

[0130] The organic zinc content of Kluwer's yeast was determined according to Method II of GB5009.14-2017 "National Food Safety Standard - Determination of Zinc in Food". The zinc content of the pizza with organic zinc of Kluwer's yeast in Example 4 was 6 mg / 100g, which meets the claim requirement of "rich in zinc" (≥3.0 mg / 100 g solid) in GB 28050 "National Food Safety Standard - General Rules for Nutrition Labelling of Prepackaged Foods".

[0131] Example 5: Comparison of zinc-enriched quick-frozen noodles with added Max Kluwer yeast rich in organic zinc

[0132] 1. Experimental groups: Three groups of zinc-enriched noodles were set up with the following amounts of organic zinc-enriched Kluyveromyces yeast (0.5%, 1%, and 2%, based on the total weight of the dough): ordinary noodles were used as the control. The quality differences after 30 days of frozen storage were measured.

[0133] 2. Evaluation indicators:

[0134] (1) Zinc content (mg / 100 g): The zinc content in the product was determined according to the second method of GB5009.14-2017 "National Food Safety Standard for the Determination of Zinc in Food". According to the provisions of GB 28050 "National Food Safety Standard for General Rules for Nutrition Labeling of Prepackaged Foods", the zinc content of the product ≥3.0 mg / 100 g solid can meet the claim requirements of "rich in zinc".

[0135] (2) Breaking strength (N): Breaking strength refers to the maximum force required for noodles to break under external force, measured in Newtons (N). It reflects the toughness and resistance to breakage of noodles. A moderate value (2.5-3.5 N) indicates that the noodles are chewy yet not easily broken, meeting consumers' taste requirements for frozen noodles. Test method: A three-point bending test was conducted using a texture analyzer (TA-XT2i), probe model P / 36R, test speed 3 mm / s, span 50 mm.

[0136] (3) Cooking loss rate (%): Cooking loss rate is the percentage of the dry matter mass of the noodles dissolved in water after cooking relative to the initial dry mass of the sample. It is used to measure the water retention and textural stability of the noodles. The lower the value (usually <8%), the less nutrients are lost during the cooking process and the chewier the texture.

[0137] (4) Sensory evaluation (out of 10): The average score is calculated by 10 professional judges from the following dimensions:

[0138] Appearance (3 points): Color uniformity, surface smoothness, degree of absence of cracks;

[0139] Texture (4 points): elasticity, chewiness, smoothness, no gritty feeling;

[0140] Flavor (3 points): Wheat aroma, umami flavor, no off-flavor.

[0141] It can comprehensively reflect the consumer acceptance of a product; a score of 8 or above indicates a high-quality product, while a score below 6 indicates a substandard product.

[0142] 3. Experimental Results:

[0143] The results are shown in Table 2. They indicate that after 30 days of frozen storage, the amount of yeast added can significantly improve the zinc content and freeze crack resistance of noodles in the range of 1%-3%. The 2% addition group has the best overall quality, with moderate breaking strength, low cooking loss rate and smooth texture.

[0144] Table 2. Comparison of zinc-enriched frozen noodles with different yeast addition amounts

[0145]

[0146] In summary, this invention creatively utilizes Kluyveromyces martensii, which is rich in organic zinc (… Kluyveromyces marxianus Adding zinc to frozen rice and flour products (such as dumplings and pizzas) can not only effectively prevent frozen rice and flour products from cracking during freezing, but also significantly improve the taste of frozen rice and flour products, enrich the zinc content of frozen rice and flour products, meet the requirements of being rich in zinc, and play a role in promoting the growth and development of the body.

[0147] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of the present invention are covered within the scope of the present invention.

Claims

1. The application of a zinc-rich Kluyveromyces martensii yeast in the preparation of zinc-rich quick-frozen rice and flour products with freeze-cracking resistance, characterized in that, The zinc-enriched quick-frozen rice and flour products contain a zinc-rich Max Kluyveromycin yeast ( Kluyveromyces marxianus The zinc content of the *Kluyveromyces martensii* is 1000-15000 mg / kg, and the proportion of organic zinc is not less than 90%. The *Kluyveromyces martensii* is prepared by fermentation culture of *Kluyveromyces martensii* in a zinc-containing medium containing a zinc source. The preservation number of *Kluyveromyces martensii* is CCTCC NO: M 20211265. The zinc ion concentration of the zinc-containing medium is 100-500 mg / L. The zinc source of the zinc-containing medium is one or more of zinc sulfate, zinc acetate, or zinc gluconate.

2. The application as described in claim 1, characterized in that, The zinc-enriched quick-frozen rice and flour products contain flour and zinc-enriched Max Kluwer yeast as their dough ingredients, with the amount of zinc-enriched Max Kluwer yeast added accounting for 0.5%-20% of the total weight of the dough.

3. The application as described in claim 2, characterized in that, The dough ingredients also include water, which is added at a rate of 30%-60% of the total weight of the dough and yeast.

4. The application as described in claim 3, characterized in that, The dough ingredients also include one or more of sugar, oil, salt, emulsifier, and improver, with the total amount added not exceeding 10% of the total weight of the dough.

5. The application as described in claim 1, characterized in that, The zinc-enriched quick-frozen rice and flour products are dumplings, noodles, or wontons.

6. The application as described in any one of claims 1-5, characterized in that, The preparation method of the zinc-enriched quick-frozen rice and flour products includes the following steps: a) Preparation of zinc-enriched yeast powder: Collect the fermented organic zinc-enriched Kluyveromyces martensii cells, dry them to obtain zinc-enriched yeast powder; b) Dough preparation: Mix flour and / or rice flour, the zinc-enriched yeast powder obtained in step a), and water, and stir to form a dough; c) Shaping: Processing the dough into raw pieces of a predetermined shape; d) Quick-freezing: Rapidly freezing the raw material at temperatures below -30°C; e) Packaging and refrigeration; The drying method described in step a) is spray drying or freeze drying.

7. The application as described in claim 6, characterized in that, Step b) also includes other optional excipients.

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