Hot-air dried mango fruit drying process

Abstract

The invention discloses a dried mango hot air drying technology, and particularly relates to the technical field of energy-saving production technologies. Comprising the following steps: mixing food-grade lactobacillus plantarum with a 1-3wt% trehalose solution, adjusting the pH value to 5.5 + / -0.5, and soaking mango slices for 2-4 minutes; after draining, placing in equipment with top and bottom independent air supply systems, and firstly carrying out bidirectional alternate pulse air supply; then, only top air supply is adopted; only bottom air supply is adopted; and moisture regaining in a closed environment with the temperature of 25 DEG C and the relative humidity of 65%. According to the method, lactobacillus plantarum biological preservation and trehalose shape protection are combined, and multi-stage directional air supply is matched, so that the problems of mouth feel hardening, browning, non-uniform drying, high energy consumption, low percent of pass and the like in a traditional process are effectively solved, and high-quality, low-energy-consumption and high-efficiency clean production of the dried mangoes is realized.

Description

Technical Field

[0001] This invention relates to the field of energy-saving production technology, specifically to a hot air drying process for mangoes. Background Technology

[0002] Mango slices, a popular snack, are primarily produced industrially using traditional hot air drying technology. However, this technology has revealed several serious technical flaws over its long-term application, becoming a key bottleneck restricting industrial upgrading and efficiency improvement. Traditional processes employ a single-direction, constant-parameter drying mode, making precise temperature and humidity control difficult. This results in inconsistent product quality, low production efficiency, and an inability to meet the comprehensive requirements of modern food industry for quality, efficiency, and safety.

[0003] Specifically, traditional processes have the following prominent problems: In terms of product quality, rapid and uneven moisture loss during the drying process leads to severe surface hardening, resulting in products that are hard and lack toughness, and are prone to sanding during storage; in terms of safety control, they mainly rely on sulfur fumigation or chemical preservatives to inhibit microorganisms, posing a risk of excessive sulfur dioxide residue, which contradicts the trend of clean labeling; in terms of production efficiency, uneven airflow distribution in the drying chamber causes significant differences in drying rates, with some products being over-dried and scorched while others still contain a wet core, making it difficult to guarantee the pass rate; at the same time, the extensive drying strategy results in a drying cycle of 15-20 hours, low energy utilization, and high energy costs, seriously affecting economic benefits.

[0004] The combined effect of these problems has resulted in traditional processes performing poorly across multiple dimensions, including product quality, safety control, production efficiency, and energy consumption. Overall, the pass rate is generally low, failing to meet consumer demand for high-quality, healthy food and hindering adaptation to the green and low-carbon industrial development trend. Therefore, developing an innovative drying process that can systematically address the comprehensive issues of hardening of texture, microbial safety, drying uniformity, and energy efficiency has become a pressing technical challenge for the industry. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a mango hot air drying process, which solves the problems of hard texture, difficulty in microbial control, uneven drying, long drying time, high energy consumption and low pass rate in the traditional process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A hot air drying process for mangoes includes the following steps: S1: Mix food-grade Lactobacillus plantarum with trehalose solution evenly and control the pH, then soak the sliced ​​mango in the solution and finally drain it. S2: Place the mangoes processed in S1 into the hot air drying system, then open the top and bottom air ducts and ventilate alternately; S3: Change the air supply mode to supply air only from the top, and control the air supply time to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, and control the air supply time to 2-3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment where temperature and humidity can be precisely controlled for 1 to 2 hours.

[0007] Preferably, the trehalose solution used in S1 has a mass fraction of 1 to 3 wt%.

[0008] Preferably, in step S1, the pH of the uniformly mixed solution is adjusted to 5.5 ± 0.5, and the Lactobacillus plantarum colony count is controlled at 10. 6 CFU / mL.

[0009] Preferably, in step S1, the cut mango slices are placed in the prepared mixed solution and soaked for 2 to 4 minutes.

[0010] Preferably, in S2, the hot air temperature is controlled at 60-65℃, the wind speed at 1.5-2.0m / s, and the drying time at 2-3 hours.

[0011] Preferably, S2 uses an alternating pulse mode, which means that air is supplied from the top for 2 minutes and then paused for 30 seconds, followed by air supply from the bottom for 2 minutes and then paused for 30 seconds.

[0012] Preferably, the air supply system used in S2 is a hot air supply drying system with two independently controllable systems at the top and bottom.

[0013] Preferably, in S3, the supply air temperature is set to 55-60℃ and its air velocity is reduced to 1.0m / s.

[0014] Preferably, in S4, the supply air temperature is set to 45-50℃ and its air velocity is reduced to 0.5m / s.

[0015] Preferably, after drying in step S5, the dried mangoes are placed in an environment of 25±5℃ and 65±5% relative humidity to rehydrate for 1 to 2 hours.

[0016] The technical effects and advantages of the hot air drying process for mangoes according to this invention are as follows: 1. This invention uses a specific Lactobacillus plantarum to pre-treat mango slices, replacing the traditional sulfur or alkali treatment; it uses a hot air mode that combines bidirectional air supply and staged temperature pulses to solve the problems of uneven drying and surface hardening in traditional drying processes; and finally, it uses a brief period of uniform moisture rehydration to ensure consistent product quality.

[0017] 2. This invention uses *Lactobacillus plantarum* soaking to colonize the surface of mango slices, effectively crowding out and inhibiting the growth of spoilage and pathogenic bacteria through competitive inhibition. This method achieves biological preservation without the use of chemical preservatives. The slightly acidic environment generated by *Lactobacillus plantarum* metabolism effectively inhibits the activity of polyphenol oxidase (PPO), thereby significantly reducing enzymatic browning and maintaining the natural color of the mango. Trehalose, as an excellent protective agent, forms a glassy structure during the drying process. This structure effectively protects the mango's cellular structure, preventing the dried mango from hardening excessively and giving it a certain degree of softness.

[0018] 3. In this invention, the first stage of air drying is a high-speed dehumidification period. It uses bidirectional alternating pulsed wind energy to instantly blow away the saturated water vapor layer stagnating on and around the mango slices, creating the maximum humidity gradient. This forces the internal moisture to migrate outward quickly, greatly improving the initial drying rate. At the same time, due to the continuous change of wind direction, it avoids uneven drying caused by the mango slices sticking tightly to the screen due to unidirectional wind force.

[0019] 4. In this invention, the second stage of air drying is a constant-speed shaping period, which adopts unidirectional permeation air. The gentle unidirectional air makes the heat and moisture transfer more stable, so that the mango slices shrink and shape evenly. The top air supply can avoid blowing dust or impurities on the screen onto the product.

[0020] 5. In this invention, the third stage of air drying is a low-speed shelf life, and the bottom low-temperature air supply is used. At the end of the drying process, the temperature is greatly reduced to prevent the Maillard reaction from occurring excessively, thereby avoiding the darkening of color and loss of nutrients. The bottom air supply can take special care of the moisture that may remain at the bottom of the mango slices, ensuring the uniformity of the final moisture and preventing the situation of dry outside and wet inside.

[0021] 6. This invention employs dynamic uniform moisture rehydration. This step allows for moisture exchange and balance between parts of the product that have slight differences in dryness, resulting in extremely uniform moisture distribution and a consistent texture. This avoids some products being too brittle while others are too soft. At the same time, this process allows trehalose and residual plant lactobacillus metabolites to further interact, making the dried fruit even softer and more moist. Attached Figure Description

[0022] Figure 1 This is a flowchart of the mango hot air drying process of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Example 1

[0025] This embodiment provides a hot air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, food-grade Lactobacillus plantarum, trehalose.

[0026] Experimental objective: The drying process utilizes Lactobacillus plantarum combined with staged, bidirectional, variable-temperature hot air drying.

[0027] Experimental steps: S1: Mix edible-grade Lactobacillus plantarum with a 1-3% trehalose solution, adjust the pH to 5.5±0.5 to prepare a slightly acidic soaking solution, and control the Lactobacillus plantarum colony count to 10. 6 CFU / mL, then soak the sliced ​​mango in the solution for 2-4 minutes, and finally drain it; S2: Place the mangoes processed in S1 into a hot air drying system with two independently controllable top and bottom air ducts. Then open the top and bottom air ducts and start the alternating pulse mode. Continuously supply air from the top for 2 minutes and then pause for 30 seconds. Then supply air from the bottom for 2 minutes and then pause for 30 seconds. Control the total hot air temperature at 60-65℃, the wind speed at 1.5-2.0m / s, and the total duration at 2-3 hours. S3: Change the air supply mode to supply air only from the top, so that the air supply temperature is reduced to 55-60℃, the wind speed is reduced to 1.0m / s, and the total duration is controlled to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, so that the bottom air supply temperature is reduced to 45-50℃, the wind speed is reduced to 0.5m / s, and the total duration is controlled to 2-3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment with a temperature of 25℃ and a relative humidity of 65% for 1 to 2 hours, where the temperature and humidity can be precisely controlled.

[0028] Experimental results: See Table 1 for details.

[0029] Table 1: Test Results of Example 1

[0030] This embodiment serves as a baseline process, employing edible-grade *Lactobacillus plantarum* and a 1–3 wt% trehalose solution for pretreatment, controlling the pH at 5.5 ± 0.5. After soaking for 2–4 minutes and draining, a three-stage hot air drying process is performed: The initial stage uses alternating pulsed airflow from the top and bottom at a temperature of 60–65°C, an air velocity of 1.5–2.0 m / s, and a duration of 2–3 hours; the second stage uses only top airflow at a temperature of 55–60°C, an air velocity of 1.0 m / s, and a duration of 6–8 hours; the third stage uses only bottom airflow at a temperature of 45–50°C, an air velocity of 0.5 m / s, and a duration of 2–3 hours. Finally, rehydration is carried out in a sealed environment at 25°C and 65% relative humidity for 1–2 hours. The experimental results demonstrate optimal overall performance: a soft yet chewy texture, uniform drying, a drying time of 10–14 hours, energy consumption of 600 kWh, and a pass rate of 95%, showcasing the advantages of this process in terms of quality, efficiency, and energy consumption. Example 2

[0031] This embodiment provides a hot air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, food-grade Lactobacillus plantarum, trehalose.

[0032] Experimental objective: The pH value of the mixed solution of Lactobacillus plantarum and trehalose was changed.

[0033] Experimental steps: S1: Mix edible-grade Lactobacillus plantarum with a 1-3% trehalose solution, adjust the pH to 6.0±0.2 to prepare a slightly acidic soaking solution, and control the Lactobacillus plantarum colony count to 10. 6 CFU / mL, then soak the sliced ​​mango in the solution for 2-4 minutes, and finally drain it; S2: Place the mangoes processed in S1 into a hot air drying system with two independently controllable top and bottom air ducts. Then open the top and bottom air ducts and start the alternating pulse mode. Continuously supply air from the top for 2 minutes and then pause for 30 seconds. Then supply air from the bottom for 2 minutes and then pause for 30 seconds. Control the total hot air temperature at 60-65℃, the wind speed at 1.5-2.0m / s, and the total duration at 2-3 hours. S3: Change the air supply mode to supply air only from the top, so that the air supply temperature is reduced to 55-60℃, the wind speed is reduced to 1.0m / s, and the total duration is controlled to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, so that the bottom air supply temperature is reduced to 45-50℃, the wind speed is reduced to 0.5m / s, and the total duration is controlled to 2-3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment with a temperature of 25℃ and a relative humidity of 65% for 1 to 2 hours, where the temperature and humidity can be precisely controlled.

[0034] Experimental results: See Table 2 for details.

[0035] Table 2: Test Results of Example 2

[0036] This embodiment focuses on the effect of pH on the process. The pH of the pretreatment solution was adjusted to 6.0±0.2 to test the effect of a slightly acidic environment on the activity and drying effect of Lactobacillus plantarum. The results showed that the pass rate dropped slightly to 90%, but the taste and drying uniformity remained good. This indicates that pH has an impact on microbial inhibition and enzyme activity control, but the overall process can still maintain high performance, highlighting the importance of pH optimization. Example 3

[0037] This embodiment provides a hot air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, food-grade Lactobacillus plantarum, trehalose.

[0038] Experimental objective: Adjust the air supply time and pause time at the top and bottom.

[0039] Experimental steps: S1: Mix edible-grade Lactobacillus plantarum with a 1-3% trehalose solution, adjust the pH to 5.5±0.5 to prepare a slightly acidic soaking solution, and control the Lactobacillus plantarum colony count to 10. 6 CFU / mL, then soak the sliced ​​mango in the solution for 2-4 minutes, and finally drain it; S2: Place the mangoes processed in S1 into a hot air drying system with two independently controllable top and bottom air ducts. Then open the top and bottom air ducts and start the alternating pulse mode. The top air supply will be paused for 45 seconds after 3 minutes, and then the bottom air supply will be paused for 45 seconds after 3 minutes. The total hot air temperature will be controlled at 60-65℃, the wind speed at 1.5-2.0m / s, and the total duration at 2-3 hours. S3: Change the air supply mode to supply air only from the top, so that the air supply temperature is reduced to 55-60℃, the wind speed is reduced to 1.0m / s, and the total duration is controlled to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, so that the bottom air supply temperature is reduced to 45-50℃, the wind speed is reduced to 0.5m / s, and the total duration is controlled to 2-3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment with a temperature of 25℃ and a relative humidity of 65% for 1 to 2 hours, where the temperature and humidity can be precisely controlled.

[0040] Experimental results: See Table 3 for details.

[0041] Table 3: Test Results of Example 3

[0042] This embodiment modifies the alternating pulse air supply parameters, extending the air supply time from 2 minutes to 3 minutes and the interval time from 30 seconds to 45 seconds to evaluate the impact of the air supply mode on drying uniformity and energy consumption. The experimental results showed a pass rate of 92% and a slight increase in energy consumption to 650 kWh, indicating that extending the air supply time may enhance drying uniformity, but will slightly increase energy consumption, requiring a trade-off between efficiency and cost. Example 4

[0043] This embodiment provides a hot air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, food-grade Lactobacillus plantarum, trehalose.

[0044] Experimental objective: Change the temperature of the top air supply.

[0045] Experimental steps: S1: Mix edible-grade Lactobacillus plantarum with a 1-3% trehalose solution, adjust the pH to 5.5±0.5 to prepare a slightly acidic soaking solution, and control the Lactobacillus plantarum colony count to 10. 6 CFU / mL, then soak the sliced ​​mango in the solution for 2-4 minutes, and finally drain it; S2: Place the mangoes processed in S1 into a hot air drying system with two independently controllable top and bottom air ducts. Then open the top and bottom air ducts and start the alternating pulse mode. Continuously supply air from the top for 2 minutes and then pause for 30 seconds. Then supply air from the bottom for 2 minutes and then pause for 30 seconds. Control the total hot air temperature at 60-65℃, the wind speed at 1.5-2.0m / s, and the total duration at 2-3 hours. S3: Change the air supply mode to supply air only from the top, so that the air supply temperature is reduced to 50±2℃, the wind speed is reduced to 1.0m / s, and the total duration is controlled within 6 to 8 hours; S4: Change the air supply mode to supply air only from the bottom, so that the bottom air supply temperature is reduced to 45-50℃, the wind speed is reduced to 0.5m / s, and the total duration is controlled to 2-3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment with a temperature of 25℃ and a relative humidity of 65% for 1 to 2 hours, where the temperature and humidity can be precisely controlled.

[0046] Experimental results: See Table 4 for details.

[0047] Table 4: Test Results of Example 4

[0048] This embodiment adjusted the top air supply temperature in the second stage from 55–60°C to 50±2°C to study the effect of low-temperature air supply on product color and nutrient retention. The results showed a pass rate of 92%, energy consumption of 620 kWh, and consistent taste and dryness, indicating that appropriately lowering the temperature can reduce Maillard reaction, prevent color darkening, and maintain product quality, although the drying rate may be slightly affected. Example 5

[0049] This embodiment provides a hot air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, food-grade Lactobacillus plantarum, trehalose.

[0050] Experimental objective: Change the bottom air supply temperature.

[0051] Experimental steps: S1: Mix edible-grade Lactobacillus plantarum with a 1-3% trehalose solution, adjust the pH to 5.5±0.5 to prepare a slightly acidic soaking solution, and control the Lactobacillus plantarum colony count to 10. 6 CFU / mL, then soak the sliced ​​mango in the solution for 2-4 minutes, and finally drain it; S2: Place the mangoes processed in S1 into a hot air drying system with two independently controllable top and bottom air ducts. Then open the top and bottom air ducts and start the alternating pulse mode. Continuously supply air from the top for 2 minutes and then pause for 30 seconds. Then supply air from the bottom for 2 minutes and then pause for 30 seconds. Control the total hot air temperature at 60-65℃, the wind speed at 1.5-2.0m / s, and the total duration at 2-3 hours. S3: Change the air supply mode to supply air only from the top, so that the air supply temperature is reduced to 55-60℃, the wind speed is reduced to 1.0m / s, and the total duration is controlled to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, so that the bottom air supply temperature is reduced to 40±2℃, the wind speed is reduced to 0.5m / s, and the total duration is controlled within 2 to 3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment with a temperature of 25℃ and a relative humidity of 65% for 1 to 2 hours, where the temperature and humidity can be precisely controlled.

[0052] Experimental results: See Table 5 for details.

[0053] Table 5: Test Results of Example 5

[0054] This embodiment adjusted the bottom air supply temperature in the third stage from 45-50℃ to 40±2℃ to test the effect of low-temperature bottom air supply on the final moisture uniformity. The results showed a pass rate of 92%, energy consumption of 620kWh, and consistent dryness inside and outside the product. This indicates that low-temperature bottom air supply can effectively remove residual moisture and prevent the outside from being dry while the inside is moist, but energy consumption control is still necessary. Example 6

[0055] This embodiment provides a hot air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, food-grade Lactobacillus plantarum, trehalose.

[0056] Experimental objective: Change the environment in which dried mangoes absorb moisture.

[0057] Experimental steps: S1: Mix edible-grade Lactobacillus plantarum with a 1-3% trehalose solution, adjust the pH to 5.5±0.5 to prepare a slightly acidic soaking solution, and control the Lactobacillus plantarum colony count to 10. 6 CFU / mL, then soak the sliced ​​mango in the solution for 2-4 minutes, and finally drain it; S2: Place the mangoes processed in S1 into a hot air drying system with two independently controllable top and bottom air ducts. Then open the top and bottom air ducts and start the alternating pulse mode. Continuously supply air from the top for 2 minutes and then pause for 30 seconds. Then supply air from the bottom for 2 minutes and then pause for 30 seconds. Control the total hot air temperature at 60-65℃, the wind speed at 1.5-2.0m / s, and the total duration at 2-3 hours. S3: Change the air supply mode to supply air only from the top, so that the air supply temperature is reduced to 55-60℃, the wind speed is reduced to 1.0m / s, and the total duration is controlled to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, so that the bottom air supply temperature is reduced to 45-50℃, the wind speed is reduced to 0.5m / s, and the total duration is controlled to 2-3 hours; S5: Immediately after drying, remove the dried mangoes and place them in a sealed environment with a temperature of 30℃ and a relative humidity of 60% that can be precisely controlled for 1 to 2 hours.

[0058] Experimental results: See Table 6 for details.

[0059] Table 6: Test Results of Example 6

[0060] This embodiment altered the uniform moisture rehumidification conditions, increasing the ambient temperature from 25°C to 30°C and decreasing the relative humidity from 65% to 60%, aiming to evaluate the impact of rehumidification parameters on moisture balance. The results showed a pass rate of 93%, energy consumption of 600 kWh, and good taste and dryness, indicating that fine-tuning of rehumidification conditions has little impact on the final product quality and that the process has a certain degree of flexibility. Comparative Example 1

[0061] This comparative example provides a traditional hot-air drying process for mangoes, the specific implementation steps of which include: Experimental materials: Mango, sodium metabisulfite Experimental objective: The exhibition showcases the effects of traditional processes, highlighting their differences from innovative processes in terms of taste, drying uniformity, energy consumption, and yield.

[0062] Experimental steps: S1: Slice the mango, then soak it in a 0.5% sodium metabisulfite solution for 3 minutes, and finally drain it; S2: Place the mango slices processed in S1 in a hot air dryer, with air supplied only from the top, and control the hot air temperature to be constant at 65℃ and the air speed to be constant at 1.5m / s. The total drying time is 18 hours. S3: After drying, remove the dried mangoes and let them cool at room temperature for 1 hour.

[0063] Experimental results: See Table 7 for details.

[0064] Table 7: Test Results of Comparative Example 1

[0065] This comparative example uses a traditional hot air drying process for mangoes, soaking them in a 0.5% sodium metabisulfite solution for 3 minutes for color protection and preservation. They are then continuously dried in a hot air dryer with only top-mounted, constant airflow for 18 hours, and finally cooled at room temperature. The experimental results show that while the basic taste is acceptable, the drying time is long (18 hours), energy consumption is as high as 900 kWh, and the product qualification rate is low, only 75%. This highlights the core problems of traditional processes: high energy consumption, low efficiency, poor drying uniformity leading to unsatisfactory qualification rates, and reliance on chemical additives, posing potential food safety and hygiene labeling issues. This, in turn, demonstrates the significant progress of the innovative process of this invention in improving efficiency, reducing energy consumption, and ensuring quality and safety.

[0066] Example 1 employs basic process parameters, including pretreatment with edible-grade Lactobacillus plantarum and a 1-3 wt% trehalose solution, three-stage hot air drying, and uniform rehumidification. The mechanism involves Lactobacillus plantarum competitively inhibiting spoilage bacteria and reducing polyphenol oxidase activity, achieving biological preservation and color protection; trehalose forming a glassy structure protects cells and prevents hardening; alternating pulsed airflow breaks the saturated moisture layer, improving drying uniformity and efficiency; staged temperature control optimizes moisture migration; and uniform rehumidification promotes moisture balance and enhances taste consistency.

[0067] Example 2 involved adjusting the pH of the pretreatment solution to 6.0 ± 0.2, while keeping other parameters the same as in Example 1. The mechanism involved testing the effect of a slightly acidic environment on the activity and enzyme inhibition of *Lactobacillus plantarum*. Increased pH may weaken the competitive inhibition and enzyme activity control of *Lactobacillus plantarum*, leading to a slight decrease in the pass rate, but the overall process still maintained high performance, highlighting the importance of pH optimization in microbial control.

[0068] Example 3 uses extended alternating pulse air supply parameters, while other parameters are the same as in Example 1. The mechanism is to evaluate the impact of air supply mode on drying uniformity and energy consumption. Extending the air supply time may enhance airflow penetration and improve moisture diffusion, but increasing the interval time may lead to uneven heat accumulation and a slight increase in energy consumption. A trade-off between efficiency and cost is required.

[0069] Example 4 uses a method that lowers the top air supply temperature in the second stage to 50±2℃, while keeping other parameters the same as in Example 1. The mechanism is to study the effect of low-temperature air supply on Maillard reaction and nutrient retention. Lowering the temperature can reduce non-enzymatic browning and prevent the color from darkening, but may slow down the drying rate and have a slight impact on energy consumption and yield.

[0070] Example 5 uses a method that lowers the bottom air supply temperature in the third stage to 40±2℃, while other parameters are the same as in Example 1. The mechanism is to test the effect of low-temperature bottom air supply on the final moisture uniformity. Low-temperature air supply can specifically remove residual moisture at the bottom and prevent the outside from being dry and the inside from being wet, but energy consumption needs to be controlled to avoid efficiency loss.

[0071] Example 6 uses adjusted uniform humidity rehumidification conditions, with other parameters the same as in Example 1. The mechanism lies in evaluating the flexibility of the rehumidification parameters in maintaining moisture balance; fine-tuning temperature and humidity has minimal impact on product quality, indicating that the process has a certain degree of tolerance during the rehumidification stage and can adapt to different environmental conditions.

[0072] Comparative Example 1 uses a traditional process, including soaking in sodium metabisulfite and drying with unidirectional constant air supply. Its mechanism relies on chemical additives for color protection and corrosion prevention, but the drying is uneven, energy consumption is high, and the pass rate is low, highlighting the limitations of traditional processes in terms of efficiency, safety, and uniformity.

[0073] By comprehensively comparing the embodiments and comparative examples, Example 1 achieves the optimal balance in terms of quality, energy consumption, and efficiency. Specific pretreatment with *Lactobacillus plantarum*, bidirectional pulsed airflow, and staged temperature control improve the drying uniformity, safety, and taste of the product, making it suitable for high-yield industrial production. Example 2, although slightly lower in the pass rate, demonstrates the crucial role of pH in microbial control. Example 3, employing an extended airflow mode, enhances drying uniformity, but slightly increases energy consumption. Example 4, using low-temperature top airflow, effectively protects the color, but slightly affects the drying rate. Example 5, using low-temperature bottom airflow, ensures uniform moisture content, but requires careful energy control. The comparative examples highlight the limitations of traditional processes, including high energy consumption, low pass rate, and chemical dependence. Therefore, the innovative process of this invention, through comprehensive optimization of pretreatment, airflow mode, and rehumidification conditions, systematically solves the pain points of traditional processes, achieving high-quality, low-energy, and high-efficiency mango dried fruit production.

[0074] refer to Figure 1 The flowchart illustrates the mango hot air drying process. First, mango slices are pre-treated by soaking them in an edible-grade Lactobacillus plantarum and trehalose solution to achieve biological preservation and shape protection. Then, a three-stage directional airflow drying process is employed: first, bidirectional alternating pulsed airflow for rapid dehumidification; then, top unidirectional airflow to promote uniform shaping; and finally, bottom low-temperature airflow to ensure balanced moisture content. After drying, the mangoes are rehydrated in a constant temperature and humidity environment, ultimately resulting in soft, uniformly dried, and consistently high-quality dried mangoes. The overall process is characterized by high efficiency, energy saving, and clean production.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0076] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hot air drying process for mangoes, characterized in that, Specifically, the following steps are included: S1: Mix food-grade Lactobacillus plantarum with trehalose solution evenly and control the pH, then soak the sliced ​​mango in the solution and finally drain it. S2: Place the mangoes processed in S1 into the hot air drying system, then open the top and bottom air ducts and ventilate alternately; S3: Change the air supply mode to supply air only from the top, and control the air supply time to 6-8 hours; S4: Change the air supply mode to supply air only from the bottom, and control the air supply time to 2-3 hours; S5: After drying, immediately remove the dried mangoes and place them in a sealed environment where temperature and humidity can be precisely controlled for 1 to 2 hours.

2. The mango hot air drying process as described in claim 1, characterized in that, The trehalose solution used in S1 has a mass fraction of 1–3 wt%.

3. The mango hot air drying process as described in claim 1, characterized in that, In S1, the pH of the uniformly mixed solution is adjusted to 5.5 ± 0.5, and the Lactobacillus plantarum colony count is controlled at 10. 6 CFU / mL.

4. The mango hot air drying process as described in claim 1, characterized in that, In step S1, place the sliced ​​mangoes into the prepared mixed solution and soak for 2-4 minutes.

5. The mango hot air drying process as described in claim 1, characterized in that, In S2, the hot air temperature is controlled at 60-65℃, the wind speed at 1.5-2.0m / s, and the drying time at 2-3 hours.

6. The mango hot air drying process as described in claim 1, characterized in that, The S2 uses an alternating pulse mode, which means that air is supplied from the top for 2 minutes and then paused for 30 seconds, followed by air supply from the bottom for 2 minutes and then paused for 30 seconds.

7. The mango hot air drying process as described in claim 1, characterized in that, The air supply system used in S2 is a hot air supply drying system with two independent and controllable systems at the top and bottom.

8. The mango hot air drying process as described in claim 1, characterized in that, In S3, the supply air temperature is set to 55-60℃ and its air velocity is reduced to 1.0m / s.

9. The mango hot air drying process as described in claim 1, characterized in that, In S4, the supply air temperature is set to 45-50℃ and its air velocity is reduced to 0.5m / s.

10. The mango hot air drying process as described in claim 1, characterized in that, After drying in S5, place the dried mangoes in an environment of 25±5℃ and 65±5% relative humidity for 1-2 hours to rehydrate.

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