Rice oil coarse cereal black potato chips and preparation process thereof

Abstract

The invention discloses rice oil coarse cereal black potato chips and a preparation process thereof. The potato chip is composed of a substrate and an outer oil coating layer, the substrate is composed of potato powder, pregelatinized starch, coarse cereal powder, a rice oil phase, phospholipid, sodium bicarbonate and salt, and the outer oil coating layer is a compact oxygen barrier film formed by spraying palm oil with a low iodine value. The coarse cereal flour contains black rice flour and the like, the dry basis proportion is not less than 15%, and the rice oil phase is refined rice oil emulsified by phospholipid and is pre-emulsified and dispersed. The preparation process comprises the steps of raw material preparation, rice oil phase emulsification and the like. According to the process, through collaborative design, uniform oil distribution is realized, the oxidation rate is reduced, and a coarse cereal high-doping-amount system structure is stabilized. Compared with existing baked potato chips, the product is low in acid value, less in oil precipitation, stable in color and luster, crisp and uniform, and the shelf life can be remarkably prolonged without adding chemical antioxidants.

Description

Technical Field

[0001] This invention relates to the technical field of food processing, and in particular to a rice oil mixed grain black potato chip and its preparation process. Background Technology

[0002] Potato chips, as a typical puffed snack food, are traditionally produced by frying, resulting in high oil content and rapid oxidation. This not only affects storage stability but also contradicts modern healthy eating trends. Therefore, the industry is gradually promoting baking as a replacement for frying, improving the product's health benefits by reducing oil absorption.

[0003] However, several common problems still exist in the development of baked potato chips. On the one hand, to improve nutritional value, whole grain flours such as black rice flour, oat flour, rye flour, and quinoa flour are often added to the potato chip base. However, whole grain flours contain a lot of dietary fiber and polyphenols, which have strong water and oil absorption properties and uneven interfaces, easily leading to poor adhesion of the mixture, cracking during molding, and uneven texture. On the other hand, the moisture gradient and oxygen exposure during baking exacerbate oil oxidation, making the product prone to problems such as increased acid value, oil spot precipitation, and color and flavor degradation during storage, seriously affecting shelf life and sensory quality.

[0004] In existing technologies, a single emulsifier is often used to improve the oil phase distribution, or vegetable oil is sprayed in the post-processing stage to enhance the taste. However, such methods make it difficult to control the oxidation process from within the system. At the same time, in order to delay deterioration, synthetic antioxidants or chemical preservatives are generally relied upon, which increases the burden of food additives and contradicts the development direction of natural and clean labels.

[0005] Therefore, how to balance high nutrition, high content, and oil oxidation stability in baked potato chips containing whole grains without relying on chemical antioxidants has become a pressing technical problem in the current food industry. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a rice bran oil mixed grain black potato chip and its preparation process. By introducing rice bran oil emulsification and dispersion, vacuum premixing and oxygen suppression, nitrogen protection and multi-level structure protection of the outer oil layer into the composite potato chip system, the synergistic compatibility of oil stabilization and high content of mixed grains is achieved.

[0007] To achieve the above objectives, the first aspect of the present invention provides a rice bran oil mixed grain black potato chip, comprising a substrate composed of potato flour, pregelatinized starch, mixed grain flour, rice bran oil phase, phospholipids, sodium bicarbonate, and salt, and an outer oil layer covering the surface of the substrate; wherein: The mixed grain powder includes black rice powder, rye powder, oat powder and / or quinoa powder, and the mass percentage of the mixed grain powder in the dry substrate is not less than 15%. The rice bran oil phase includes refined rice bran oil that has been emulsified with phospholipids and is premixed with the mixed grain powder before mixing. The outer oil coating is a dense oxygen barrier film formed by 24-degree palm oil, the iodine value of the palm oil is not greater than 45, and the spraying film forming temperature is 60-75℃. The acid value of the potato chips in the finished product state is no greater than 1.0 mg KOH / g.

[0008] By introducing a three-layer composite structure of mixed grain powder, rice bran oil, and an outer oil coating into the traditional potato chip system, a dual regulation mechanism for oil phase distribution and oxygen migration was successfully achieved. Mixed grain powder is rich in unsaturated fatty acids and polyphenols, which are prone to oxidation under normal conditions, leading to a decline in product quality. To address this issue, this invention employs a pre-mixing treatment of phospholipid-emulsified rice bran oil with mixed grain powder, allowing the oil phase to uniformly adhere to the surface of the grain particles, forming a stable microemulsion film structure. This structure significantly reduces the probability of direct contact between oxygen and metal ions and the mixed grain powder, effectively inhibiting the initiation of oxidation chain reactions at the molecular level, thereby extending the product's shelf life.

[0009] Furthermore, this invention uses low-iodine palm oil to form an outer oil layer on the surface of the potato chips. During baking and cooling, this palm oil crystallizes to form a dense film structure, further blocking the penetration of external oxygen and enhancing the product's antioxidant capacity. The synergistic effect of the two oil phases creates a stable structure with internal protection and external sealing, which not only maintains lipid stability but also preserves the crisp texture of the chips, achieving the dual goals of increasing the amount of whole grains incorporated while extending the product's shelf life.

[0010] Low-iodine palm oil partially crystallizes at spraying temperatures, forming a dense and orderly oxygen-barrier layer. The highly saturated fatty acid chain structure of this oil exhibits strong intermolecular forces, effectively preventing oxygen diffusion and reducing the propagation of lipid oxidation chain reactions, thereby further enhancing the product's antioxidant properties. Simultaneously, this oxygen-barrier layer also acts as a moisture barrier, slowing moisture migration and flavor loss, allowing the potato chips to maintain a crisp texture and stable aroma during storage, thus improving the consumer's eating experience. Through this multi-layered protective mechanism, this invention not only improves the nutritional value of the potato chips but also significantly extends their shelf life.

[0011] As a further improvement of the present invention, the phospholipid is liquid soybean phospholipid, and the mass ratio of refined rice bran oil to soybean phospholipid is 100:2-5.

[0012] Adding soybean lecithin to the rice oil phase, through its amphiphilic properties of polar head groups and nonpolar fatty chains, significantly reduces the surface tension of the oil phase and effectively improves its spreading performance on the surface of whole grain powder. This design allows the oil phase to form a uniform and continuous film between solid particles, thereby significantly enhancing the binding interface between the oil phase and starch and protein, reducing the migration of free oil, and ensuring the stable distribution of the system at the microscopic level. During baking, phospholipids and whole grain proteins undergo interfacial synergy, forming a continuous and stable emulsion-like network structure. This structure effectively inhibits oil droplet aggregation and pore structure collapse, thus significantly improving the structural density and texture uniformity of the baked sheets, resulting in a superior final product in terms of both texture and flavor.

[0013] As a further improvement of the present invention, the rice oil phase is formed into a stable emulsified dispersion structure through the following steps: (1) Refined rice bran oil and liquid soybean lecithin were mixed at a mass ratio of 100:2 to 5 at 45 to 55°C and emulsified for 5 to 8 minutes using a high shear homogenizer with a rotation speed of 8000 to 12000 r / min to obtain a rice bran oil emulsion with an average droplet size of 0.5 to 2.0 μm. (2) Add the rice oil emulsion to the mixed grain powder at a constant flow rate, and mix it at 35-40°C with a paddle stirring at 60-100 r / min for 3-5 min to make the emulsion droplets evenly distributed on the surface of the mixed grain powder. (3) Pre-dry in a hot air circulating dryer at 60-80℃ with a wind speed of 1.0-1.5m / s for 2-4 minutes to obtain a premixed powder with stable oil content and an oil film layer on the surface.

[0014] This emulsification process achieves precise control over the particle size, distribution, and solidification mode of the oil phase droplets through three stages: segmented shearing, low-temperature mixing, and short-range pre-drying. The high-shear stage produces small, narrowly distributed droplets, enhancing the adhesion and coating ability of the oil phase on the surface of the solid powder. The low-speed mixing stage prevents droplet re-agglomeration, ensuring the stability of the oil phase distribution. The pre-drying stage promotes the initial solidification of the emulsion film, reducing interfacial instability caused by moisture. This process achieves controllable fixation of the oil film from a kinetic and mass transfer perspective, providing a foundation for structural stability in subsequent powder mixing and baking processes.

[0015] As a further improvement of the present invention, the pregelatinized starch is a combination of spray-dried pregelatinized starch and roller-dried pregelatinized starch, wherein the mass ratio of spray-dried pregelatinized starch to roller-dried pregelatinized starch is 1:1 to 3.

[0016] By cleverly combining spray-dried pregelatinized starch and roller-dried pregelatinized starch, a dual-network system that is both rapidly soluble and possesses high viscosity support was successfully constructed. Spray-dried starch rapidly absorbs water in the initial stages of water addition and quickly forms a binder layer with rheological properties. This characteristic ensures uniform bonding of the raw materials during mixing, avoiding structural defects caused by uneven moisture distribution. Meanwhile, roller-dried starch, due to its high molecular orientation and strong support, effectively maintains the sheet's shape and structure during baking and heating, preventing deformation or cracking at high temperatures. The synergistic effect of these two different types of starch results in a fine and easily controllable pore structure within the sheet, thereby improving its mechanical strength while maintaining product crispness. This dual-network system effectively avoids structural inhomogeneity problems that may arise from grain fibers during processing, ensuring the quality and taste of the final product.

[0017] As a further improvement of the present invention, the substrate further comprises egg yolk powder.

[0018] Egg yolk powder was introduced as a functional additive into the substrate system, utilizing its naturally abundant phospholipid molecules to synergistically construct a composite emulsion interface layer with exogenous phospholipids. This interface forms a thermodynamically stable layered structure through the directional arrangement of amphiphilic molecules, significantly enhancing the interfacial affinity between oil and starch-protein matrix, and inhibiting dispersed phase aggregation through steric hindrance. Thermal analysis showed that this synergistic interface exhibited dynamic viscoelastic properties in the baking zone, effectively maintaining the continuity and extensibility of the oil film, reducing oil separation rate, and minimizing sheet structure collapse. The final product showed significantly better surface smoothness and standard deviation of tensile strength compared to the control group, achieving synergistic optimization of microstructure and macroscopic quality.

[0019] As a further improvement of the present invention, the premixing of the rice oil phase and the miscellaneous grain powder is carried out by a vacuum drum mixer at a vacuum degree of -0.06 to -0.08 MPa for 5 to 10 minutes.

[0020] A vacuum drum mixer was used to premix the rice oil phase and grain powder under negative pressure. This process effectively reduced air entrainment and oxygen dissolution, significantly improving the uniformity of the oil phase distribution on the solid surface. Under the special effect of the vacuum environment, the capillary penetration effect was significantly enhanced, allowing oil droplets to penetrate deeper into the surface of the grain particles, forming a uniform and dense coating film. This structure not only greatly improved the interfacial stability between the oil and solid phases but also significantly reduced the risk of emulsion interface disruption during subsequent water addition. Ultimately, this process significantly improved the oxidative stability and oil retention rate of the finished product under high-temperature baking conditions, ensuring product quality and taste.

[0021] As a further improvement of the present invention, the sodium bicarbonate is dissolved in warm water at 40-50°C and then added to a salt solution with a mass fraction of 0.1%-0.3% to form a stable aqueous phase. The stirring speed is 200-300 r / min, and the aqueous phase and the powder phase are mixed at 10-15°C.

[0022] By first gently dissolving sodium bicarbonate in brine and then thoroughly mixing it with the powder under low-temperature conditions, the slow-release effect of the foaming agent and its uniform distribution throughout the mixture were successfully achieved. This refined process effectively avoids premature decomposition of sodium bicarbonate under localized high-temperature or alkaline conditions, ensuring a more concentrated and orderly gas release process during the baking stage. This results in the formation of a uniformly sized, dense, and stable puffing network during baking, significantly improving the texture and mouthfeel of the final product. Furthermore, maintaining low-temperature conditions not only effectively inhibits lipid hydrolysis but also prevents protein denaturation, ensuring the purity of the flavor and a high degree of consistency in texture throughout the system, further enhancing the overall quality of the product.

[0023] The second aspect of this invention provides a preparation process for the rice bran oil mixed grain black potato chips as described above, comprising the following steps: S1. Raw material preparation: Prepare potato flour, spray-dried pregelatinized starch and roller-dried pregelatinized starch, black rice flour, rye flour, oat flour, quinoa flour, egg yolk powder, salt, refined rice bran oil, liquid soybean lecithin, sodium bicarbonate and 24-degree palm oil in the following mass ratios. S2, Rice oil phase emulsification: Rice bran oil was mixed and emulsified with liquid soybean lecithin to obtain a rice bran oil emulsion with an average droplet size of 1.2 μm. S3, Mixed Grains Premix: Mix the mixed grain powder with rice bran oil emulsion evenly, and dry it with hot air to obtain a mixed grain premixed powder with an oil film on the surface. S4. Powder preparation: Mix potato flour, pregelatinized starch, egg yolk powder, salt and mixed grain premixed powder in sequence, and dry mix evenly to obtain a uniform powder phase; S5. Aqueous phase preparation: Dissolve sodium bicarbonate in an aqueous solution containing 0.2 wt% salt, stir well, and then cool for later use. S6, Mix the powder into a ball: Under nitrogen protection, the powder phase and the water phase are mixed evenly to obtain a uniform dough. S7. Shaping and Baking: The dough is rolled into a sheet of a specified thickness and cut into the required size. It is then baked at 160-180℃ and with a wind speed of 1-2m / s for 8-10 minutes. After cooling, the substrate is obtained. S8. Formation of the outer oil layer: Palm oil at 24 degrees Celsius is heated to 60-70 degrees Celsius and sprayed onto both sides of a substrate. The amount of sprayed oil accounts for 1.5% of the finished product's mass. After spraying, it is dried at room temperature to form a dense oxygen barrier film. The film is then cooled and packaged with nitrogen to obtain the finished product.

[0024] This preparation process establishes a logical closed loop through precise sequential control and temperature management, encompassing oil phase dispersion, powder phase shaping, and aqueous phase conditioning. The initial premixing of the mixed grain oil phase provides a foundation for lipid distribution; the mid-stage low-temperature nitrogen and powder treatment prevent oxidation; and the final stage, with its outer oil coating, forms a terminal oxygen barrier. The entire process achieves a balance between oxygen control and heat treatment, ensuring continuous antioxidant activity from raw materials to finished product. This structural system improves the shelf stability and sensory quality of the finished product without the use of chemical preservatives.

[0025] As a further improvement of the present invention, the nitrogen flow rate during the powder mixing stage in step S5 is 20-30 L / min, in order to suppress the oxidation reaction and control the acid value of the finished product to be no more than 1.0 mg KOH / g.

[0026] A stable flow of nitrogen is introduced during the dough mixing stage to create a low-oxygen reaction environment and reduce the accumulation of oxidative inducing factors. Nitrogen replaces oxygen in the air, preventing the oxidation of rice bran oil and phospholipids, while also carrying away heat generated by localized friction, maintaining a stable dough temperature. This measure, from a reaction kinetics perspective, inhibits the generation of free radicals in the initial stage of lipid oxidation, ensuring long-term stability of the finished product's acid value, delaying oil deterioration, and improving storage safety.

[0027] As a further improvement of the present invention, the mixed grain powder after step S2 is pre-dried with hot air at 60-80°C for 2-4 minutes.

[0028] Short-term hot air pre-drying of premixed grain oil-phase powder can remove surface free water without damaging the oil film structure, promoting semi-curing of the oil film. This treatment restricts water penetration in subsequent powder mixing stages, reduces oil-water interface reconstruction and droplet aggregation, and ensures the integrity of the emulsion system. The pre-dried powder exhibits better flowability and extensibility during tableting and baking, ultimately forming tablets with a smooth surface and uniform color.

[0029] The present invention, by adopting the above technical solution, has the following beneficial effects: 1. By using phospholipid emulsification technology to form an inner microfilm structure of rice bran oil, and at the same time using low-iodine palm oil to construct a dense outer protective film, this dual film structure can effectively inhibit oxygen migration and free radical generation, thereby ensuring that the acid value of the finished oil remains stable below 1.0 mg KOH / g for a long time, which greatly improves the shelf life and quality stability of the product.

[0030] 2. The vacuum premixing and short-path pre-drying process ensures that the oil phase is evenly coated on the surface of the grain particles, effectively preventing fiber stratification and oil precipitation. Even with a high content of grain powder, the product still has good formability and puffing performance, ensuring the taste and texture of the food.

[0031] 3. Combining spray and roller pregelatinization technologies enables the starch to form a stable skeletal structure. This technology not only allows for rapid water absorption and binding but also provides thermal support, balancing the crispy texture of the flakes with sufficient mechanical strength. This results in a uniform puffing process, low and stable breaking force, and improved overall product quality.

[0032] 4. By using nitrogen replacement and low-temperature liquid addition processes, the initial oxidation process is effectively suppressed, maintaining the integrity of the flavor components of oils and proteins. This significantly improves the color and aroma stability of the product during storage, extends the shelf life of the product, and ensures that consumers can enjoy the best flavor experience when consuming it. Detailed Implementation

[0033] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0034] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0037] The present invention will now be described in detail with reference to specific embodiments, which are intended to understand rather than limit the invention.

[0038] Example 1

[0039] This embodiment discloses a rice oil mixed grain black potato chip and its preparation process.

[0040] The preparation process of rice bran oil mixed grain black potato chips includes the following steps: S1 Raw Material Preparation Select the following raw materials: Potato flour: Selected whole potato flour with a moisture content of 6.8 wt% and a particle size of ≤150 μm; Pregelatinized starch: including spray-dried pregelatinized corn starch (cold water viscosity 1250 mPa·s) and roller-dried pregelatinized corn starch (cold water viscosity 410 mPa·s), with a mass ratio of 1:2; Mixed grain flour: Black rice flour (passed through 80 mesh, fat content ≥2.5%) 7.00kg, Rye flour (passed through 80 mesh, dietary fiber ≥13%) 6.00kg, Oat flour (passed through 80 mesh, β-glucan ≥3%) 3.00kg, Quinoa flour (passed through 100 mesh) 2.00kg; Rice bran oil phase: composed of 6.0 kg of refined rice bran oil and 0.18 kg of liquid soybean lecithin (mass ratio 100:3); Sodium bicarbonate (food grade), table salt (sodium chloride ≥99%), egg yolk powder (total phospholipids ≥20%), 24-degree palm oil (iodine value ≤45), and deionized water were used as solvents.

[0041] All powders should be placed in an environment of 25℃ and 45% relative humidity for 24 hours to equilibrate their moisture content before use.

[0042] S2 rice bran oil phase emulsification In a stainless steel emulsification kettle at a constant temperature of 50℃, 6.0 kg of refined rice bran oil and 0.18 kg of liquid soybean lecithin were added in proportion. A high-shear emulsifier was used, and the mixture was sheared at 10000 r / min for 6 min. After emulsification, the mixture was cooled to 45℃. The resulting emulsion was milky white, without stratification or oil separation. This emulsion is the stable rice bran oil phase.

[0043] S3 Mixed Grains Premix Add 18.0 kg of mixed grain powder to a 50 L vacuum drum mixer, and slowly add 6.18 kg of rice oil emulsion. Start the vacuum pump to achieve a vacuum of -0.07 MPa, and mix for 8 minutes at a drum speed of 20 rpm.

[0044] After discharge, spread the material to a thickness of 10mm and place it in a hot air circulating dryer (temperature 70℃, wind speed 1.2m / s) for pre-drying for 3 minutes.

[0045] After being removed, the mixture was cooled to room temperature and sealed for storage, resulting in a mixed grain premix powder with a continuous oil film layer on the surface.

[0046] S4 powder preparation Add the following ingredients to the mixer: 50.00 kg of potato flake flour; 10.00 kg of pregelatinized starch was spray-dried. 20.00 kg of pregelatinized starch was dried using rollers. Egg yolk powder 1.00kg; 0.80 kg of salt; 18.00 kg of mixed grain premix powder.

[0047] Add the ingredients in sequence and dry mix at low speed (15 rpm) for 2 minutes, then dry mix at medium speed (30 rpm) for 3 minutes to ensure uniform mixing and obtain a homogeneous powder mixture.

[0048] S5 aqueous phase preparation Add 0.90 kg of sodium bicarbonate to deionized water (total volume 8.0 L) containing 0.2 wt% sodium chloride in a water bath at 45 °C, stirring at 250 rpm. After complete dissolution, cool to 12 °C for later use.

[0049] S6 and Pink Formation The powder mixture was added to a 100L closed mixing mill, and nitrogen was introduced for 2 minutes to purge the mixture, maintaining a nitrogen flow rate of 25L / min. At 12℃, the S5 aqueous phase was slowly added dropwise over a time of 3 minutes to achieve a water content of 30wt%. The mixture was first stirred at low speed (30rpm) for 2 minutes, then at medium speed (60rpm) for 4 minutes, for a total mixing time of 6 minutes. Continuous operation under nitrogen protection effectively inhibited oil oxidation and ensured an acid value below 1.0mgKOH / g.

[0050] S7 Shaping and Baking The resulting dough is rolled into a 1.4mm thick sheet using a roller press (double roller type, surface temperature 25℃). It is then die-cut into round pieces with a diameter of 45mm.

[0051] The raw sheet was placed in a multi-layer hot air baking oven and baked at a temperature of 170℃ for 9 minutes, with a wind speed of 1.5 m / s and a relative humidity of <10%.

[0052] After being removed from the oven and cooled to below 35°C, a dense, uniformly colored black potato chip base is formed.

[0053] S8 External Oil Coating Formation and Packaging Palm oil was heated to 65°C from 24°C and atomized at 1.5 wt% (based on substrate mass) onto both sides of the substrate using a spray system (nozzle orifice diameter 0.5 mm). After spraying, the substrate was dried for 2 minutes under a room temperature air curtain to form a continuous and dense oxygen barrier film.

[0054] After cooling to a surface temperature of 28°C, the product is sealed with nitrogen using an automatic packaging machine. The packaging bag is made of aluminum-plated film composite material, and the final product is rice bran oil mixed grain black potato chips.

[0055] Example 2

[0056] Example 2 has a similar formula and process to Example 1, except that the rice bran oil phase is composed of 6.00 kg of refined rice bran oil and 0.12 kg of liquid soybean lecithin (mass ratio 100:2).

[0057] The vacuum degree of the S3 grain premixing stage is −0.06MPa; the drum speed is set to 20rpm, and the mixing is continued for 6min; the drying time is 2min.

[0058] During the S6 and powder agglomeration stage, after the replacement is completed, maintain a nitrogen flow rate of 20L / min.

[0059] During the S7 molding and baking stage, the baking temperature is set at 160℃ and the baking time is 10 minutes.

[0060] Example 3

[0061] Example 3 has a similar formula and process to Example 1, except that the rice bran oil phase is composed of 6.00 kg of refined rice bran oil and 0.3 kg of liquid soybean lecithin (mass ratio 100:5).

[0062] The vacuum degree of the S3 grain premixing stage is −0.08MPa; the drum speed is set to 20rpm, and the mixing is continued for 8min; the drying temperature is 80℃, the wind speed is 1.5m / s, and the drying time is 2min.

[0063] During the S7 molding and baking stage, the baking temperature is set at 180℃, the baking time is 8 minutes, and the wind speed is 1.8m / s.

[0064] Example 4

[0065] Example 4 has a formula and process that are roughly the same as Example 1, except that: 45.00 kg of potato flake flour; 9.0 kg of black rice flour, 8.0 kg of rye flour, 5.0 kg of oat flour, and 3.0 kg of quinoa flour (total of grains 25 wt%); 1.20 kg of egg yolk powder; and the rice oil phase is composed of 6.50 kg of refined rice oil and 0.2 kg of liquid soybean lecithin (mass ratio 100:5).

[0066] The drying temperature for the S3 grain premixing stage is 75℃, the wind speed is 1.3m / s, and the pre-drying time is 3min.

[0067] Example 5

[0068] Example 5 has a formula and process that are largely the same as Example 1, except that: 15.00 kg of pregelatinized starch was sprayed; 15.00 kg of pregelatinized starch was roller-dried (spray: roller = 1:1).

[0069] The drying temperature for the S3 grain premixing stage is 75℃, the wind speed is 1.3m / s, and the pre-drying time is 3min.

[0070] Comparative Example 1 The formulation and process of Comparative Example 1 are roughly the same as those of Example 1, except that liquid soybean lecithin was not added.

[0071] Comparative Example 2 The formulation and process of Comparative Example 2 are roughly the same as those of Example 1. The difference is that the S3 grain premixing stage is carried out at normal pressure, 20 rpm and 8 min; and no 70 ℃ pre-drying is carried out, and it directly enters S4.

[0072] Comparative Example 3 The formulation and process of Comparative Example 3 are roughly the same as those of Example 1. The difference is that conventional soft palm oil (iodine value of about 55) is used in the outer oil layer and packaging stage of S8. It is heated to 55°C and sprayed at 1.5 wt% with an air curtain for 1 minute.

[0073] According to the standard GB 17401-2014 "Puffed Foods" Article 3.2.

[0074] Method and steps: The samples were placed under natural light to observe their color, shape, and surface condition; the taste and aroma were assessed for normality; and the integrity of the tissue structure was determined by light pressure. Independent evaluations were conducted by five trained testing personnel, and the results were considered consistent.

[0075] Standard based on: GB 5009.3-2016 "National Food Safety Standard - Determination of Moisture in Food" - Method I.

[0076] Method and steps: (1) Weigh 5.00 g (accurate to 0.01 g) of the chopped and mixed sample and place it in a pre-weighed aluminum box; (2) Dry in a 105 ℃ forced-air drying oven to constant weight; (3) After cooling to room temperature in a desiccator, weigh the product; (4) Calculate the moisture content using the following formula: Moisture (%) = (Initial mass − Constant weight mass) ÷ Initial mass × 100%.

[0077] According to the standard: GB 5009.229-2025 National Food Safety Standard - Determination of Acid Value in Food - Method I.

[0078] Method and steps: (1) Take a 2.00 g sample (accurate to 0.0001 g) and place it in an Erlenmeyer flask; (2) Add 50 mL of ethanol-diethyl ether (1:1, v / v) mixed solvent; (3) Place in a 30°C water bath and gently shake to dissolve; (4) Add 2-3 drops of phenolphthalein indicator; (5) Titrate with KOH standard solution until a faint red color remains for 30 seconds without fading; (6) Calculate the acid value using the following formula: AV (mg KOH / g) = (C KOH × (V − V0) × 56.1) / m

[0079] According to the standard: GB 5009.227-2023 National Food Safety Standard - Determination of Peroxide Value in Food - Method I.

[0080] Method and steps: (1) Weigh an appropriate amount of the sample and dissolve it in a glacial acetic acid-chloroform mixed solvent; (2) Add saturated potassium iodide solution and react; (3) Let it sit in the dark; (4) After adding distilled water, titrate with sodium thiosulfate standard solution; (5) Calculate POV by developing color with starch indicator.

[0081] 5.1 Lead (Pb) According to the standard: GB 5009.12-2023 Determination of Lead in Food - Method II.

[0082] Method and steps: After digestion, the samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) or atomic absorption spectrometry, and the results were expressed in mg / kg.

[0083] 5.2 Benzoic acid, sorbic acid and cyclamate According to the standard: GB 5009.28-2016 Determination of Benzoic Acid and Sorbic Acid in Food - Method I; GB 5009.97-2023 Determination of cyclamate in food - Method I.

[0084] Method and steps: (1) Extract the sample in a water bath; (2) Inject the sample after filtration; (3) Quantification was performed using high performance liquid chromatography (HPLC); (4) The detection concentration is compared with the limit value to determine whether it meets the standard.

[0085] According to the standard: GB 5009.22-2016 Determination of aflatoxin B1 in food - Method III.

[0086] Method and steps: After centrifugation and column purification, the samples were detected by liquid chromatography-fluorescence detector, and the results were expressed in μg / kg.

[0087] 7.1 Total bacterial count According to the standard: GB 4789.2-2022 Food Microbiology Examination: Determination of Total Colony Count.

[0088] Method and steps: (1) The sample was diluted according to the specifications; (2) Cultured using the plate coating method or the pour method; (3) Incubate at 36 ℃ ±1 ℃ in a constant temperature incubator; (4) The counting results are expressed as CFU / g.

[0089] 7.2 Coliform bacteria According to the standard: GB 4789.3-2025 Food Microbiology Examination - Determination of Coliform Bacteria - Method II.

[0090] Method and steps: (1) Use the multi-tube fermentation method or the confirmation method; (2) Observe the acid and gas production during lactose fermentation; (3) Results are expressed as CFU / g.

[0091] 7.3 Salmonella According to the standard: GB 4789.4-2024 Food Microbiology Examination: Determination of Salmonella.

[0092] Method and steps: (1) Perform pretreatment and enrichment culture as required; (2) Isolate to a selective culture medium; (3) Identified by biochemical and serological methods; (4) The result is expressed as “not detected / 25g”.

[0093] 7.4 Staphylococcus aureus According to the standard: GB 4789.10-2016 Food Microbiology Examination - Determination of Staphylococcus aureus - Method II.

[0094] Method and steps: (1) The sample was inoculated in a selective culture medium; (2) Identification and confirmation of classic colonies; (3) Expressed as CFU / g.

[0095] The test results are shown in Tables 1 to 4 below: Table 1 sample Color odor Structural integrity Overall score Example 1 9.5 9.3 9.4 9.4 Example 2 9.4 9.2 9.1 9.2 Example 3 9.6 9.4 9.5 9.5 Example 4 9.2 9 9.1 9.1 Example 5 9.3 9.1 9.2 9.2 Comparative Example 1 8.2 7.8 7.9 8 Comparative Example 2 8 7.7 7.5 7.7 Comparative Example 3 7.5 7.2 7 7.3 Table 2 sample Moisture (%) Acid value day0 Acid value day 7 ΔAV POV (g / 100g) Example 1 2.6 0.78 0.92 0.14 0.018 Example 2 2.7 0.85 1 0.15 0.02 Example 3 2.5 0.8 0.94 0.14 0.017 Example 4 2.8 0.88 1.03 0.15 0.021 Example 5 2.6 0.82 0.96 0.14 0.019 Comparative Example 1 3.4 1.32 1.7 0.38 0.032 Comparative Example 2 3.2 1.2 1.5 0.3 0.028 Comparative Example 3 3.8 1.15 1.44 0.29 0.03 Table 3 project Limited Edition Examples 1–5 Comparative Examples 1–3 Lead (Pb) (mg / kg) ≤0.5 Not detected Not detected Benzoic acid (g / kg) Do not use Not detected Not detected Sorbic acid (g / kg) Do not use Not detected Not detected Cyclamate (g / kg) ≤0.2 Not detected Not detected Aflatoxin B1 (μg / kg) / Not detected Not detected Table 4 sample Total bacterial count (CFU / g) Coliform bacteria (CFU / g) salmonella Staphylococcus aureus Example 1 42 <10 Not detected <10 Example 2 58 <10 Not detected <10 Example 3 37 <10 Not detected <10 Example 4 66 <10 Not detected <10 Example 5 49 <10 Not detected <10 Comparative Example 1 118 15 Not detected 20 Comparative Example 2 163 22 Not detected 18 Comparative Example 3 247 30 Not detected 25 The test results show that the present invention achieves significantly better oxidative stability, oil distribution stability and molding texture consistency than the comparative example in the high proportion of mixed grains roasted potato chip system.

[0096] Firstly, regarding lipid oxidation control, the initial acid values ​​of Examples 1-5 were maintained in the range of 0.78-0.88 mgKOH / g, significantly lower than the 1.15-1.32 mgKOH / g of the comparative example. After acceleration at 45°C for 7 days, the ΔAV of the examples was only 0.14-0.15, while that of the comparative example reached 0.29-0.38. Comparing Example 1 with Comparative Example 1 without added phospholipids, ΔAV decreased from 0.38 to 0.14, a decrease of approximately 63%, indicating that the emulsified premixed system of the present invention can effectively stabilize the initial lipid distribution and inhibit the initiation of the peroxidation chain reaction.

[0097] Secondly, significant differences were also observed in the peroxide value (POV) regarding oil distribution and oil separation control. The POV of the example was 0.017-0.021 g / 100 g, while that of the comparative example was 0.028-0.032 g / 100 g, further confirming the greater stability of the oil phase. Combining the acid value and POV indicators, it can be confirmed that the synergistic effect of the inner emulsification oxygen control and the low-oxygen environment in the powder mixing stage of this invention can significantly reduce the early oxidation rate and the accumulation of oxidation chain reactions.

[0098] Regarding the stability of the forming texture, the sheet thickness of the examples remained at 1.39-1.42 mm, and the puffing index ER was 1.35-1.42, which was generally better than the 1.30-1.33 of the comparative examples. In terms of brittleness, the maximum breaking force Fmax of the examples was 12.3-13.2 N, while that of the comparative examples was 14.2-15.0 N. Specifically, the breaking force of Example 1 decreased from 15.0 N to 12.5 N compared to Comparative Example 1, a reduction of approximately 17%. This change indicates that the double pregelatinized starch structure and the emulsified oil film together improve the uniformity of puffing, while reducing stress concentration during the forming process, making it easier to achieve a crisp but not hard texture.

[0099] In terms of sensory characteristics, the examples maintained a more natural color and intact sheet structure, contrasting with the browning tendency of the comparative examples. Regarding microbiological safety, the total bacterial count in the examples remained at 30-66 CFU / g, while the comparative examples reached 118-247 CFU / g, indicating that the pre-drying, low-oxygen, powdering, and rapid baking steps of the present invention have better process stability in controlling microbial load. Furthermore, coliform bacteria, Salmonella, and Staphylococcus aureus were not detected or were far below the limits, meeting the food safety requirements for puffed foods.

[0100] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A type of rice oil mixed grain black potato chip, characterized in that, A substrate composed of potato starch, pregelatinized starch, mixed grain flour, rice oil phase, phospholipids, sodium bicarbonate, and salt, and an outer oil coating covering the surface of the substrate; wherein: The mixed grain powder includes black rice powder, rye powder, oat powder and / or quinoa powder, and the mass percentage of the mixed grain powder in the dry substrate is not less than 15%. The rice bran oil phase includes refined rice bran oil that has been emulsified with phospholipids and is premixed with the mixed grain powder before mixing. The outer oil coating is a dense oxygen barrier film formed by 24-degree palm oil, the iodine value of the palm oil is not greater than 45, and the spraying film forming temperature is 60-75℃. The acid value of the potato chips in the finished product state is no greater than 1.0 mg KOH / g.

2. The rice oil mixed grain black potato chip according to claim 1, characterized in that, The phospholipid is liquid soybean phospholipid, and the mass ratio of refined rice bran oil to soybean phospholipid is 100:2-5.

3. The rice bran oil mixed grain black potato chips according to claim 2, characterized in that, The rice bran oil phase is formed into a stable emulsified dispersion structure through the following steps: (1) Refined rice bran oil and liquid soybean lecithin were mixed at a mass ratio of 100:2 to 5 at 45 to 55°C and emulsified for 5 to 8 minutes using a high shear homogenizer with a rotation speed of 8000 to 12000 r / min to obtain a rice bran oil emulsion with an average droplet size of 0.5 to 2.0 μm. (2) Add the rice oil emulsion to the mixed grain powder at a constant flow rate, and mix it at 35-40°C with a paddle stirring at 60-100 r / min for 3-5 min to make the emulsion droplets evenly distributed on the surface of the mixed grain powder. (3) Pre-dry in a hot air circulating dryer at 60-80℃ with a wind speed of 1.0-1.5m / s for 2-4 minutes to obtain a premixed powder with stable oil content and an oil film layer on the surface.

4. The rice oil mixed grain black potato chip according to claim 1, characterized in that, The pregelatinized starch is a combination of spray-dried pregelatinized starch and roller-dried pregelatinized starch, wherein the mass ratio of spray-dried pregelatinized starch to roller-dried pregelatinized starch is 1:1 to 3.

5. The rice oil mixed grain black potato chips according to claim 1, characterized in that, The substrate further contains egg yolk powder.

6. The rice bran oil mixed grain black potato chips according to claim 1, characterized in that, The premixing of the rice oil phase and the mixed grain powder was carried out using a vacuum drum mixer at a vacuum of -0.06 to -0.08 MPa for 5 to 10 minutes.

7. The rice oil mixed grain black potato chip according to claim 1, characterized in that, The sodium bicarbonate is dissolved in warm water at 40-50°C and then added to a salt solution with a mass fraction of 0.1%-0.3% to form a stable aqueous phase. The stirring speed is 200-300 r / min, and the aqueous phase and the powder phase are mixed at 10-15°C.

8. A preparation process for rice oil, miscellaneous grain, and black potato chips according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Raw material preparation: Prepare potato flour, spray-dried pregelatinized starch and roller-dried pregelatinized starch, black rice flour, rye flour, oat flour, quinoa flour, egg yolk powder, salt, refined rice bran oil, liquid soybean lecithin, sodium bicarbonate and 24-degree palm oil in the following mass ratios. S2, Rice oil phase emulsification: Rice bran oil is mixed and emulsified with liquid soybean lecithin to obtain rice bran oil emulsion; S3, Mixed Grains Premix: Mix the mixed grain powder with rice bran oil emulsion evenly, and dry it with hot air to obtain a mixed grain premixed powder with an oil film on the surface. S4. Powder preparation: Mix potato flour, pregelatinized starch, egg yolk powder, salt and mixed grain premixed powder in sequence, and dry mix evenly to obtain a uniform powder phase; S5. Aqueous phase preparation: Dissolve sodium bicarbonate in an aqueous solution containing salt, stir well, and then cool for later use. S6, Mix the powder into a ball: Under nitrogen protection, the powder phase and the water phase are mixed evenly to obtain a uniform dough. S7. Shaping and Baking: The dough is rolled into a sheet of a specified thickness and cut into the required size. It is then baked at 160-180℃ and with a wind speed of 1-2m / s for 8-10 minutes. After cooling, the substrate is obtained. S8. Formation of the outer oil layer: Palm oil at 24 degrees Celsius is heated to 60-70 degrees Celsius and sprayed onto both sides of a substrate. The amount of sprayed oil accounts for 1.5% of the finished product's mass. After spraying, it is dried at room temperature to form a dense oxygen barrier film. The film is then cooled and packaged with nitrogen to obtain the finished product.

9. The preparation process of rice bran oil mixed grain black potato chips according to claim 8, characterized in that, In step S6, during the mixing stage, nitrogen gas is introduced at a flow rate of 20-30 L / min to suppress the oxidation reaction and control the acid value of the finished product to be no greater than 1.0 mg KOH / g.

10. The preparation process of rice bran oil mixed grain black potato chips according to claim 8, characterized in that, The premixed grain powder after step S2 is pre-dried with hot air at 60-80℃ for 2-4 minutes.