Processing temperature curve control method for keeping characteristic flavor of freshly squeezed coconut juice

Abstract

The invention discloses a processing temperature curve control method for keeping the characteristic flavor of freshly squeezed coconut juice, and belongs to the technical field of beverage processing, and the processing temperature curve control method comprises the following steps: defining a key flavor preservation temperature threshold Tf and a core processing temperature Tp; performing low-temperature pretreatment and squeezing on the coconut meat; rapidly reducing the temperature of the squeezed coconut juice from an outlet to a Tp range within 30 seconds; blending is performed under Tp; carrying out ultrahigh-pressure or short-time pasteurization and immediately cooling; and finally, carrying out sterile cold filling. The whole process is monitored and controlled in real time to ensure that the total exposure time when the coconut juice temperature exceeds Tf is less than or equal to 5 minutes. According to the invention, through dynamic temperature curve management of instantaneous forced cooling and whole-process low temperature cooperation, the loss of heat-sensitive flavor substances is reduced to the greatest extent, so that the coconut juice product produced industrially can preserve fresh and refreshing taste and rich coconut fragrance excellently.

Description

Technical Field

[0001] This invention relates to the technical field of beverage processing, and in particular to a method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice. Background Technology

[0002] Freshly squeezed coconut juice is highly favored by consumers for its unique flavor of "refreshing taste and rich coconut aroma." However, the main flavor compounds in coconut juice are mostly low-boiling-point, volatile esters and aldehydes, which are extremely sensitive to heat. At the same time, endogenous enzymes such as lipoxygenase in coconut meat become more active at higher temperatures, easily leading to fat oxidation and the development of unpleasant flavors. These factors present a core contradiction in the industrial production of freshly squeezed coconut juice: the difficulty of simultaneously achieving "quality preservation" and "freshness preservation." Existing technologies have made various attempts to address this issue.

[0003] For example, Chinese invention patent CN100360060C discloses a method that uses microwave sterilization to replace traditional high-temperature sterilization, aiming to reduce protein denaturation and flavor loss. Although this method represents an improvement, its sterilization cycle is still relatively long, and it only focuses on the final sterilization step, failing to control the temperature rise in key stages such as pressing and pretreatment. This results in the material accumulating a high heat load before entering sterilization, leading to partial loss of flavor compounds.

[0004] Another Chinese invention patent, authorized by CN115708550B, primarily addresses the problem of "clogging" caused by precipitation after UHT sterilization of coconut water. Its technical solution involves adjusting the coconut water to a slightly alkaline state and heating it to 50-90℃ to pre-precipitate calcium phosphate and other precipitates. However, this active heating pretreatment step actually accelerates the volatilization and degradation of heat-sensitive flavor compounds, inherently conflicting with the goal of "preservation."

[0005] In summary, existing technologies either only perform mild treatment on localized stages, ignoring the cumulative heat effect throughout the entire process, or sacrifice fresh flavor for stability. Therefore, there is currently a lack of a processing solution that takes the end result as the starting point, is flavor-oriented, and provides systematic and synergistic low-temperature control for the entire process from raw material processing to bottling. Summary of the Invention

[0006] Therefore, it is necessary to provide a processing temperature curve control method to maintain the characteristic flavor of freshly squeezed coconut juice, addressing the technical problems of significant loss of heat-sensitive flavor substances, lack of prominent "fresh" taste and "rich" coconut aroma, and unstable quality caused by improper temperature control at each stage of the processing chain in the industrial production of freshly squeezed coconut juice.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for controlling the processing temperature profile to maintain the characteristic flavor of freshly squeezed coconut juice, comprising the following steps: S1. Define the temperature control baseline: A "critical flavor preservation temperature threshold" Tf is defined, wherein Tf is 8-12°C; and a "core processing temperature" Tp is defined, wherein Tp is 0-4°C and Tp <Tf。

[0008] S2. Implement dynamic temperature curve control: S2.1. Low-temperature pretreatment of raw materials: The fresh coconut meat is washed and crushed at a temperature of Tp. S2.2. Low-temperature pressing and outlet temperature monitoring: The crushed coconut meat is cold-pressed at 0-8℃, and the coconut juice temperature T1 at the pressing outlet is monitored in real time; S2.3. Instantaneous forced cooling: The temperature of the pressed coconut juice is rapidly reduced from T1 to the Tp range within 30 seconds through a heat exchange device; S2.4. Low-temperature steady-state preparation and temporary storage: The cooled coconut juice is transported to a container where the temperature is maintained within the Tp range, and the pre-cooled auxiliary materials are added and mixed at this temperature; S2.5. Mild sterilization and post-cooling: The prepared coconut juice is sterilized by ultra-high pressure sterilization or short-time pasteurization; the juice is immediately cooled to 2-6℃ after sterilization. S2.6. Aseptic cold filling: The cooled coconut juice is filled in an aseptic environment; S3. Full-process "high temperature exposure time" control: By setting temperature sensors at key nodes, the total time t during which the coconut juice temperature exceeds Tf from the start of the coconut meat crushing step to before the start of the sterilization process in step S2.5 is recorded and calculated in real time. By adjusting the cooling efficiency and material flow rate, t is controlled within 5 minutes.

[0009] Compared with the prior art, the beneficial effects of the present invention include: 1. Significant Progress: This invention is the first to construct a full-chain dynamic temperature control model with "key flavor preservation temperature threshold" and "high-temperature exposure time throughout the process" as its quantitative core. This model systematically solves the problem of flavor loss caused by local optimization or heating pretreatment in existing technologies through two major technical means: "instantaneous forced cooling after pressing" and "low-temperature synergy throughout the process".

[0010] 2. Excellent Flavor Retention: By compressing the high-temperature exposure time to an extremely short period, such as <5 minutes, and rapidly reducing the "heat peak" of the material after pressing, volatile flavor components can be locked in to the greatest extent. Experiments show that the products processed by the method of this invention have a significantly higher retention rate of characteristic flavor substances than traditional microwave sterilization and heat pretreatment processes.

[0011] 3. Uniform and stable quality: Precise temperature profile control not only helps preserve flavor but also inhibits enzymatic reactions and microbial activity, improving product stability and quality consistency throughout the shelf life from both physical and chemical perspectives. Attached Figure Description

[0012] Figure 1 This is a schematic flowchart of a method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to the present invention. Detailed Implementation

[0013] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0014] Please see Figure 1 The present invention will be further illustrated below through three specific embodiments and comparative experiments, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, the equipment and raw materials used in the present invention are conventionally selected in the art. Example 1

[0015] This embodiment 1 aims to demonstrate a method for controlling the temperature curve in a heatless sterilization process.

[0016] 1. Parameter definition: Through preliminary experiments, it was determined that the key flavor substances of this batch of coconut meat have a significantly faster volatilization rate when the temperature exceeds 10℃, so Tf is defined as 10℃; the core processing temperature Tp is set as 2℃.

[0017] 2. Processing procedure and temperature control: Pretreatment: After the fresh coconut meat is removed, it is immediately rinsed with purified ice water at 2°C and crushed in a cooling room at 2°C.

[0018] Pressing and monitoring: The crushed coconut meat is fed into a screw press at 5°C. A temperature sensor is installed at the press outlet, and the juice temperature T1 is measured to be 19°C.

[0019] Instantaneous forced cooling: Juice is introduced into a multi-stage plate heat exchanger within 15 seconds through insulated pipes, the length of which is less than 3 meters. The refrigerant in the heat exchanger is a 1°C ethylene glycol aqueous solution. The outlet temperature sensor shows that the coconut juice temperature drops from 19°C to 2.8°C within 25 seconds, reaching the Tp range.

[0020] Low-temperature preparation: After cooling, the coconut milk is pumped into a jacketed cooling container, maintaining the temperature inside the container at 2-3°C. The granulated sugar is dissolved in 2°C water to make a syrup, which is then filtered and added to the container. The mixture is gently stirred and mixed for 5 minutes.

[0021] Sterilization: The well-mixed liquid is fed into an ultra-high pressure device and treated for 3.5 minutes at 550 MPa. This process involves adiabatic heating, with a temperature rise of approximately 3-5°C, and the liquid temperature does not exceed 8°C.

[0022] Filling: After ultra-high pressure treatment, the liquid is filled and sealed on a 3℃ aseptic filling line.

[0023] 3. Calculation of high temperature exposure time t: The central control system records show that from the start of crushing to before ultra-high pressure treatment, the material temperature exceeds 10℃, that is, the time period Tf is only a short process from "pressing outlet" to "entering the heat exchanger in the early stage", with a cumulative time t=2.2 minutes. Example 2

[0024] This Example 2 demonstrates how to minimize flavor loss through extremely short "thermal shocks" and rapid cooling when heat sterilization is necessary.

[0025] 1. Parameter definition: Define Tf=9℃, Tp=3℃.

[0026] 2. Processing procedure and temperature control: Pretreatment to instantaneous forced cooling: Repeat the steps of Example 1 to reduce the temperature of the pressed coconut juice from T1=20°C to 3.5°C within 30 seconds.

[0027] Low-temperature preparation: Sugar, salt and other auxiliary materials are added and mixed at a low temperature of 3℃.

[0028] Mild sterilization and post-cooling: After preparation, the feed solution is rapidly heated to 90°C via a tubular heat exchanger and precisely maintained at this temperature for 12 seconds, i.e., short-time pasteurization. After sterilization, the feed solution immediately passes through the cooling section of the same heat exchanger and is cooled to 4°C within 5 seconds.

[0029] Filling: After cooling, the liquid is aseptically filled at 4°C.

[0030] 3. Calculation of High-Temperature Exposure Time t: The system calculates that from the start of crushing to the end of the pasteurization step, the material temperature exceeds 9℃, meaning the time Tf mainly consists of two parts: the post-pressing heating period, approximately 1.8 minutes, and the pasteurization period, 12 seconds. The total time t = 1.8 + 0.2 = 2.0 minutes. The short pasteurization stage is extremely short, therefore its impact on the overall heat load of the material is minimal. Example 3

[0031] This Example 3 demonstrates how to optimize parameters for a specific highly aromatic coconut variety, such as the fragrant coconut.

[0032] 1. Parameter Definition: GC-MS analysis showed that the characteristic flavor compounds of this variety are more sensitive to heat, therefore a stricter Tf value of 8℃ was defined. To enhance flavor retention, a lower Tp value of 0-1℃ was set.

[0033] 2. Processing procedure and temperature control: Enhanced pre-cooling: The coconut meat is sprayed and washed with 0℃ ice water and crushed in an environment of 0-1℃.

[0034] Pressing and enhanced cooling: A press with internal cooling function is used to control the juice temperature T1 ≤ 15℃. Then, an ice water heat exchanger, i.e., 0℃ water as the refrigerant, is used to lower the juice temperature to 1℃ within 20 seconds.

[0035] Preparation near freezing point: Preparation is carried out in a constant temperature cold storage at 1℃.

[0036] Sterilization: Ultra-high pressure sterilization is preferred, with parameters of 500MPa and 4 minutes.

[0037] Filling: Fill at 2°C 3. Calculation of high temperature exposure time t: Throughout the process, the material temperature exceeds 8℃, that is, the Tf time is controlled within 1.5 minutes.

[0038] Comparative Example 1 The process employs conventional methods: coconut meat is crushed and pressed at room temperature (25°C), and the juice is temporarily stored and blended at room temperature (25°C) for 30 minutes. Then, it undergoes microwave sterilization at 65°C for 15 minutes. After sterilization, it is cooled to 25°C for filling, i.e., non-aseptic cold filling. During this process, the material is exposed to temperatures exceeding Tf (Tf) by more than 45 minutes.

[0039] Comparative Example 2 Freshly squeezed coconut juice is heated to 75°C, the pH is adjusted to 8, and it is stirred and allowed to stand for 20 minutes to remove sediment. After filtration, the filtrate is heated to 95°C for 30 seconds for pasteurization, and finally cooled and bottled. This process involves prolonged exposure to medium temperatures, such as 75°C, and high-temperature sterilization, which greatly damages flavor compounds.

[0040] Effect verification experiment The products obtained in Examples 1, 2, and 3 and Comparative Examples 1 and 2 were tested. Freshly squeezed, untreated coconut juice was used as the reference sample, and the reference value for this type of coconut juice was set as 100%.

[0041] Quantitative analysis of flavor compounds: The contents of ethyl decanoate and γ-nonanolide, two recognized key characteristic compounds of coconut flavor, were determined by GC-MS, and their relative retention rates were calculated.

[0042] Sensory evaluation: A blind test was conducted by 10 trained evaluators to rate “coconut aroma intensity”, “freshness” and “overall acceptability” on a scale of 0-100.

[0043] Table 1: Comparison of retention rates of key flavor compounds (%)

[0044] Table 2: Comparison of Average Sensory Evaluation Scores

[0045] Based on the data in Tables 1 and 2 above, it is evident that the temperature curve control method provided by this invention, as in Examples 1-3, can extremely effectively preserve the characteristic flavor substances of freshly squeezed coconut juice, achieving sensory scores far superior to the comparative examples. Among them, Example 1, with no heat treatment throughout the process, and Example 3 with optimized parameters, performed the best. Even with heat sterilization, Example 2, through strict control of the high-temperature exposure time, achieved significantly better results than existing technical solutions. This fully demonstrates that the dynamic temperature curve constructed by this invention through controlling the "high-temperature exposure time throughout the process" and implementing "instantaneous forced cooling after pressing" is remarkably effective and innovative in solving the problem of flavor preservation in freshly squeezed coconut juice.

[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice, characterized in that, Includes the following steps: S1. Define temperature control baselines: Determine a critical flavor preservation temperature threshold Tf, where 8℃ ≤ Tf ≤ 12℃; and a core processing temperature Tp, where 0℃ ≤ Tp ≤ 4℃, and Tp <Tf; S2. Implement dynamic temperature curve control: S2.

1. Low-temperature pretreatment of raw materials: Fresh coconut meat is washed and crushed at a temperature of Tp. S2.

2. Low-temperature pressing and outlet temperature monitoring: The crushed coconut meat is cold-pressed at 0-8℃, and the coconut juice temperature T1 at the pressing outlet is monitored in real time; S2.

3. Instantaneous forced cooling: The temperature of the pressed coconut juice is rapidly reduced from T1 to the range of Tp within 30 seconds through heat exchange; S2.

4. Low-temperature steady-state preparation and temporary storage: Mix the cooled coconut juice with the auxiliary materials pre-cooled to Tp at Tp temperature; S2.

5. Mild sterilization and post-cooling: The blended coconut juice is sterilized by ultra-high pressure sterilization or short-time pasteurization, and the juice is immediately cooled to 2-6℃ after sterilization. S2.

6. Aseptic cold filling: The cooled coconut juice is filled in an aseptic environment; S3. Control the high temperature exposure time throughout the process: Monitor and control the total time t from the start of step S2.1 to the start of step S2.5, ensuring that t ≤ 5 minutes.

2. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: The Tf was determined by analyzing the volatility characteristics of characteristic flavor compounds in freshly squeezed coconut juice using gas chromatography-mass spectrometry.

3. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: In step S2.3, the heat exchange is achieved through a multi-stage plate heat exchanger, and the temperature of the cooling medium used is 0-2℃.

4. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: In step S2.5, the conditions for ultra-high pressure sterilization are: pressure 400-600MPa, pressure holding time 2-5 minutes.

5. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: In step S2.5, the conditions for short-time pasteurization are: temperature 85-92℃, holding time ≤15 seconds.

6. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: The Tp is 1-3℃.

7. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: The total duration t ≤ 3 minutes.

8. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: In step S2.3, the pipe used to transport the pressed coconut juice to the heat exchange device is an insulated pipe, and its length is controlled within 3 meters to achieve the heat exchange within 30 seconds.

9. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: In step S3, the temperature sensor data of each key node is integrated through the central control system, the total duration t is calculated and displayed in real time, and when t approaches 5 minutes, a control prompt is issued or the cooling power and material flow rate are automatically adjusted.

10. The method for controlling the processing temperature curve to maintain the characteristic flavor of freshly squeezed coconut juice according to claim 1, characterized in that: When processing high-aroma coconut varieties, the critical flavor preservation temperature threshold Tf is defined as 8℃, the core processing temperature Tp is defined as 0-1℃, and a press with internal cooling function is used to ensure that the coconut juice temperature T1 at the press outlet is ≤15℃.

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