Method for regulating and controlling fruit quality based on sound waves

Abstract

The invention provides a method for regulating and controlling fruit quality based on sound waves. According to the method, fruits are stimulated through a sound wave environment with set frequency and sound pressure intensity, and the ripening process and commodity of the fruits are adjusted. Different from existing continuous sound wave treatment, the intermittent circulation type sound wave mode is introduced for the first time, dynamic balance of sound stimulation and self-adjustment of picked fruits is achieved through periodic sound wave starting and pausing, and quality deterioration is avoided. Meanwhile, ethylene fumigation treatment is coupled, and synergistic release of ethylene is achieved through an ethylene controlled release agent in the sound wave treatment process. The method does not need heating or chemical addition, has the advantages of being non-thermal, non-invasive, green, environmentally friendly and the like, is particularly suitable for postharvest regulation and control of fruits sensitive in flavor and poor in heat resistance, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of preservation technology, specifically relating to a method for regulating fruit quality based on sound waves. Background Technology

[0002] With the continuous development of the fruit and vegetable industry and the increasing demand from consumers for high-quality agricultural products, how to effectively regulate the appearance and internal quality of fruits in the postharvest stage has become an important research direction in the field of postharvest biology. Therefore, non-invasive and environmentally friendly fruit quality regulation technologies have gradually attracted research attention and have become a research hotspot in recent years.

[0003] Existing postharvest quality control technologies for fruits mainly rely on methods such as light, controlled atmosphere, heat treatment, edible coatings, natural hormone induction, and biocontrol microorganisms. Although these methods have achieved some success in delaying fruit senescence, suppressing diseases, or regulating ripening, they still have many limitations. Most of these methods depend on specific physical environments or exogenous substances, have complex processing conditions, and require high standards for equipment, operation, and environment, making them difficult to widely apply in diverse storage and transportation scenarios. Furthermore, these technologies often suffer from superficial effects, insufficient control precision, damage to fruit sensory quality, or poor adaptability, affecting actual effectiveness and consumer acceptance. Therefore, there is an urgent need to develop a new postharvest control method that is gentler, more controllable, more adaptable, and combines commercial protection with quality improvement.

[0004] Sound waves, as a form of mechanical wave, possess significant potential for green regulation. The article "Sound waves delay tomato fruitripening by negatively regulating ethylene biosynthesis and signaling genes" by Kim et al., published in *Postharvest Biology and Technology*, 2015-6, Vol. 110, discloses a method for treating postharvest tomato fruit with sound waves, including the following steps: 1) Selecting tomato fruits (Solanum lycopersicum L.cv. Dotaerang) at the green-ripe stage; 2) Generating a 1kHz single-frequency sound signal using Pro Tools software and playing it through a speaker (1kHz, 100dB); 3) Treating the fruit in a custom-made soundproof enclosure; 4) The treatment temperature is 23±1℃, with a single treatment lasting 6 hours. Experimental results show that sound wave treatment delays tomato fruit ripening by altering the expression of important genes in ethylene biosynthesis and ethylene signal transduction pathways. Several years later, the team published an article in *Postharvest Biology and Technology*, Vol. 10, 2023-11, entitled "Epigenetic regulation for delaying tomato fruit ripening through histone modification by specific soundwave treatment," which disclosed a method for treating postharvest tomato fruit with sound waves. The treatment steps were the same as described above, and the results showed that sound wave treatment could affect histone modification of fruit ripening regulators to inhibit tomato ripening. This method uses a single, single-frequency sound wave treatment, unlike the intermittent, cyclical sound wave treatment of postharvest fruit used in this invention.The article "Ethylene Induced by Sound Stimulation Enhances Anthocyanin Accumulation in Grape Berry Skin through Direct Upregulation of UDP-Glucose:Flavonoid 3-O-Glucosyltransferase" by Yamazaki et al., published in *Cells* 2021-10 Vol.10, also discloses a method for sound treatment of grape berries (*Vitis labruscana* (Bailey) × *V. vinifera* (Muscat Hamburg)). The method includes the following steps: 1) Selecting field-grown grape berries in the green-ripe stage for treatment; 2) Generating a 1000Hz sound signal using Wave Gene software, with a sampling rate of 44.1kHz and a quantization depth of 16-bit; 3) Playing the sound through an HSS-300 high-frequency loudspeaker, approximately 70cm away from the grape bunches, with a single treatment lasting 8 hours. The results show that sound treatment can increase the anthocyanin content of grapes in the early ripening stage. This method involves a single-frequency acoustic treatment of pre-harvest green-ripe grapes, which differs from the indirect, cyclic acoustic treatment method of this invention for post-harvest fruit.

[0005] Existing methods mostly employ single-stage acoustic treatment, failing to fully consider the dynamic changes and physiological rhythms of different fruits during storage and transportation. Furthermore, in-depth research and systematic application of the interaction effects between acoustic waves and endogenous hormones, especially ethylene, are lacking. In contrast, this patent innovatively introduces an intermittent cyclic acoustic treatment mode, simulating the naturally disturbed environment of fruits through periodic acoustic stimulation, thus improving the physiological adaptability and regulatory precision of the treatment. Simultaneously, this method also considers the interaction regulation strategy between ethylene and acoustic waves. This method overcomes the limitations of the singularity and randomness of traditional acoustic treatments, possessing higher controllability, adaptability, and potential for standardized application. Summary of the Invention

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a method for regulating fruit quality based on sound waves, specifically implemented through the following method:

[0007] A method for regulating fruit quality based on sound waves is disclosed. This method involves indirectly and cyclically exposing the fruit to a sound wave environment with specific frequencies and sound pressure levels to regulate fruit quality. The method involves intermittently and cyclically exposing the fruit to a sound wave environment with specific frequencies and sound pressure levels, coupled with ethylene treatment, to adjust fruit quality.

[0008] Furthermore, the specific steps of this method are as follows:

[0009] 1) Preparation of the acoustic treatment box: Make your own acoustic treatment box and attach sound insulation cotton to the inner wall of the box to reduce external noise and dry it.

[0010] 2) Install a Bluetooth speaker inside the sound wave processing box, and play the sound waves through the Bluetooth speaker;

[0011] 3) Fruit preparation: Select fruits that are not fully ripe, wash them and remove surface impurities, and set aside;

[0012] 4) The fruit treated in step 3) is sealed in a perforated plastic bag with ethylene controlled-release agent inside. The plastic bag is then placed in a treatment box for exposure to sound waves at specific frequencies and sound pressure levels.

[0013] Furthermore, the acoustic processing box in step 1) is a square wooden box.

[0014] Furthermore, in step 2), the Bluetooth speaker is suspended in the center of the inside of the processing box.

[0015] Furthermore, the amount of ethylene controlled-release agent used in step 4) on the fruit is 0.15-0.35 g / kg of fruit.

[0016] Furthermore, the ethylene controlled-release agent mentioned in step 4) is a commercially available ethylene controlled-release agent that has been activated by a water bath at 35-40°C for 2-3 minutes.

[0017] Furthermore, the specific frequency and sound pressure are 0.8–2.5 kHz, 60–110 dB, and the exposure time for intermittent cyclic acoustic treatment is 6–12 h / day, with continuous exposure for 5–15 days.

[0018] This invention uses intermittent, cyclical sound wave stimulation with specific frequencies and sound pressure levels to achieve non-thermal, non-chemical intervention on fruits. It can effectively promote fruit ripening without opening the sealed environment, causing heat damage, or affecting the appearance and texture. Attached Figure Description

[0019] Figure 1 A schematic diagram of the structure of a self-made acoustic wave processing box;

[0020] Figure 2 Images of bananas after postharvest acoustic treatment (ST) and control group (CT);

[0021] Figure 3 The color changes of bananas in the post-harvest acoustic treatment (ST) group and the control group (CT) are shown in the figure ((A) a* value (green-redness) and (B) b* value (blue-yellowness). "*" indicates p<0.05, "**" indicates p<0.01, and "*" indicates p<0.001. Data points are presented as mean ± standard deviation).

[0022] Figure 4 The changes in firmness of bananas in the postharvest acoustic treatment (ST) group and the control group (CT) are shown in the figure ((A) peel firmness, (B) flesh firmness; "*" indicates p<0.05, "**" indicates p<0.01, and "*" indicates p<0.001. Data points are presented as mean ± standard deviation).

[0023] Figure 5 The changes in the quality of bananas after postharvest acoustic treatment (ST) and control (CT) are shown in the figures ((A) chlorophyll a content, (B) chlorophyll b content, (C) total chlorophyll content). (* indicates p < 0.05, ** indicates p < 0.01, and * indicates p < 0.001. Data points are presented as mean ± standard deviation).

[0024] Figure 6 The determination of chlorophyll content in bananas after postharvest acoustic treatment (ST) and control (CT) groups (in the figure, "*" indicates p<0.05, "**" indicates p<0.01, and "*" indicates p<0.001. Data points are presented as mean ± standard deviation);

[0025] Figure 7 The effect of sound on the ethylene formation rate (in the figure, "*" indicates p < 0.05, "**" indicates p < 0.01, and "*" indicates p < 0.001. Data points are presented as mean ± standard deviation).

[0026] Figure 8 Sampling photos of citrus fruits that underwent postharvest acoustic treatment (ST) and control group (CT);

[0027] Figure 9 The change in the proportion of citrus color at each sampling point after acoustic processing (ST) is shown. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments in order to better understand the technical solution.

[0029] Example 1: Postharvest quality control of bananas based on acoustic processing

[0030] 1. Material Preparation

[0031] Banana materials: Select green, ripe bananas (Musa acuminata cv. Huangjinjiao, AAA) to ensure that each batch of bananas is of uniform size and free from external defects.

[0032] 2. Sound wave processing steps

[0033] 2.1 Banana Pretreatment: Remove impurities and moisture from the surface of the bananas after harvest. The bananas were divided into a control (CT) group and a sonic treatment (ST) group. Each group of bananas was placed in a separate homemade sonic treatment chamber.

[0034] 2.2 Acoustic Treatment: Bananas from the CT and ST groups were placed in separate acoustic treatment chambers, sealed in perforated plastic bags, and subjected to ethylene treatment. Bananas from the CT group underwent only routine ethylene gas fumigation. 5.76g of commercial ethylene controlled-release agent was activated via a water bath (40℃, 3 minutes) to release ethylene.

[0035] Bananas in group ST underwent 12 hours of indirect cyclic acoustic treatment daily. Frequency signals were generated using an online audio generator (https: / / www.onlinemictest.com / zh / tone-generator / ), and the sound was played through a Bluetooth speaker. The sound frequency was set to 1 kHz, the sound pressure level to 100 dB, and the treatment time was 8 days. On days 0, 2, 4, 6, and 8, 12 bananas were randomly sampled from each group for quality determination, with three replicates. The remaining samples were then flash-frozen in liquid nitrogen and stored at -80°C for subsequent analysis.

[0036] The structure of the acoustic wave processing box is as follows: Figure 1 As shown, it is a square wooden box with sound insulation cotton 2 pasted on the inner wall of the box to reduce external noise and dry it; a Bluetooth speaker 3 is installed in the sound wave processing box 1, and the sound waves are played through the Bluetooth speaker 3.

[0037] 3. Quality Inspection and Analysis Methods

[0038] 3.1 Color Measurement: The L*, a*, and b* values ​​of banana peel were measured using a colorimeter (KONICAMINOLTA, CR-400) to analyze color changes.

[0039] 3.2 Determination of hardness and weight loss rate: Hardness was determined using a texture analyzer (TA-XT2i). Eight bananas were randomly selected, and a 5mm diameter probe was used to measure the hardness of the fruit three times in the middle area of ​​the finger. The puncture depth was 10mm, and the testing speeds were 3mm / s (before testing), 5mm / s (during testing), and 3mm / s (after testing). The maximum force value was recorded as the peel hardness (N). After peeling, the flesh hardness was measured using the same method. Six bananas from each group were retained, and the weight on the sampling day was recorded. The weight loss rate was calculated based on the initial weight (day 0).

[0040] 3.3 Determination of chlorophyll a, chlorophyll b, and total chlorophyll content

[0041] Weigh 0.5g of frozen banana peel powder, add 1.5mL of extraction buffer (anhydrous ethanol: acetone = 1:1, v / v), vortex to mix, and centrifuge at 10000×g for 15 minutes. Measure the absorbance of the supernatant at 664.5nm and 647nm using a Tecan Spark microplate reader. Calculate the content (mg / L) according to formulas (1)-(3), repeating each group 4 times.

[0042] Chlorophyll a = 12.7 × A 664.5 -2.79×A 647 (1)

[0043] Chlorophyll b = 20.7 × A 647 -4.62×A 664.5 (2)

[0044] Total chlorophyll = 12.7 × A 647 +8.08×A 664.5 (3)

[0045] 3.4 Measurement of ethylene release rate

[0046] Fruits from different groups were placed in 2L sealed containers and incubated for 5 hours. 1ml of ethylene gas was extracted for subsequent analysis. Ethylene content was determined by gas chromatography. Ethylene was quantified by peak area and calibrated using the external standard method. A standard curve was constructed using the peak areas and concentrations of standard samples. The peak areas of the samples were then recorded, and the ethylene concentration was calculated using the standard curve. The ethylene formation rate was expressed as μL C₂H₄kg⁻¹. -1 h -1 Calculated using formula (3):

[0047] Ethylene formation rate = C × V / (W × T) (4)

[0048] Note: C represents the ethylene concentration in the container (μL / L); V is the container volume (L); W is the initial weight of the bananas (kg); T is the time (h).

[0049] 4. Experimental Results

[0050] 4.1 The effect of sound on banana color

[0051] like Figure 2 As shown, bananas in the ST group began to show significant yellowing on day 4 and completed the fading process much faster than those in the CT group. The b* value (yellowing intensity) of the ST group was significantly higher than that of the CT group on day 6, indicating that the fruit rapidly turned yellow. Figure 3 B).

[0052] 4.2 Effects of acoustic treatment on banana firmness and quality

[0053] like Figure 4As shown in AB, the skin and flesh firmness of the ST group were significantly lower than those of the control group, indicating that sound waves accelerated the ripening process. Except for day 8, there was no significant difference in weight loss between the two groups. Figure 5 ).

[0054] 4.3 Effects of acoustic treatment on chlorophyll degradation in bananas

[0055] The chlorophyll a and chlorophyll b contents in the ST group continued to decrease, and the degradation rate was significantly faster than that in the CT group. Figure 6 AB). Chlorophyll b decreased significantly on days 6 and 8, and the total chlorophyll content in the ST group was approximately one-third that of the CT group by day 8. Figure 6 C).

[0056] 4.4 Effects of acoustic treatment on ethylene synthesis

[0057] Our results show that the ethylene production rate in the ST group was significantly higher than that in the CT group. Figure 7 The results showed that exogenous ethylene could stimulate the synthesis of endogenous ethylene in bananas, and acoustic treatment further promoted this process.

[0058] This embodiment demonstrates that intermittent cyclic acoustic treatment significantly accelerates the degreening process of bananas, improving fruit maturity and marketability. Compared to existing treatment methods, intermittent cyclic acoustic treatment combined with ethylene treatment offers advantages in terms of controllability and non-invasiveness, while reducing the need for excessive reliance on chemical additives while promoting fruit quality improvement. This invention provides a novel, green, and environmentally friendly solution for post-harvest treatment of heat-sensitive fruits and vegetables such as bananas, with broad application prospects.

[0059] Example 2: Postharvest quality control of citrus based on acoustic processing

[0060] 1. Material Preparation

[0061] Citrus materials: Select green-ripe Tribute Citrus fruits to ensure that each batch of fruits is of uniform size and free from external defects.

[0062] 2. Sound wave processing steps

[0063] 2.1 Citrus Pretreatment: Remove impurities and moisture from the surface of post-harvest citrus fruits. They were divided into a control (CT) group and a sonic treatment (ST) group. Each group of citrus fruits was placed in a separate, self-made sonic treatment chamber.

[0064] 2.2 Acoustic Treatment: Citrus fruits from the CT and ST groups were placed in separate acoustic treatment chambers, each sealed in a perforated plastic bag, and treated with ethylene. 0.72g of a commercially available controlled-release ethylene agent was activated in a water bath (40℃, 3 minutes) to release ethylene. Bananas in the ST group received intermittent, cyclical acoustic treatment for 12 hours daily. The acoustic waves were generated by an online audio generator (https: / / www.online-mictest.com / zh / tone-generator / ) and played through a Bluetooth speaker. The frequency of the acoustic waves was set to 2kHz, the sound pressure level to 100dB, and the treatment lasted for 12 days. On days 0, 3, 6, 9, and 12, 12 citrus fruits were randomly sampled from each group for quality observation.

[0065] The structure of the acoustic wave processing box is as follows: Figure 1 As shown, it is a square wooden box with sound insulation cotton 2 pasted on the inner wall of the box to reduce external noise and dry it; a Bluetooth speaker 3 is installed in the sound wave processing box 1, and the sound waves are played through the Bluetooth speaker 3.

[0066] 2.3 Color measurement: Take pictures of the citrus fruits at the sampling points and record the percentage of yellowing area on their peel.

[0067] 4. Experimental Results

[0068] like Figure 8 As shown, the citrus fruits in the ST group began to show significant yellowing after 6 days and completed the fading process much faster than those in the CT group. On the 12th day of storage, 61.17% of the citrus fruits in the ST group were completely yellow, and there were no completely green citrus fruits. Figure 9 ).

[0069] This example demonstrates that the intermittent cyclic acoustic treatment combined with ethylene regulation of postharvest fruit quality effectively avoids quality deterioration caused by continuous acoustic treatment, achieving controllable adjustment of postharvest fruit quality. Acoustic treatment coupled with ethylene controlled-release significantly accelerated the chlorosis of citrus peels. This technology requires no chemical additives or external heating throughout the process, offering advantages such as non-invasiveness and environmental friendliness, making it particularly suitable for heat-sensitive fruits and vegetables with sensitive flavors and poor heat resistance. This method is applicable to postharvest treatment scenarios with limited cold chains or strict control over pesticide residues, and has broad prospects for industrial application.

Claims

1. A method for regulating fruit quality based on sound waves, characterized in that, This method regulates fruit quality by intermittently and cyclically exposing the fruit to an acoustic environment with specific frequencies and sound pressure levels.

2. The method for regulating fruit quality based on sound waves as described in claim 1, characterized in that, The specific steps of this method are as follows: 1) Preparation of sound wave processing box: Make a sound wave processing box (1) and attach sound insulation cotton (2) to the inner wall of the box to reduce external noise interference; 2) Install a Bluetooth speaker (3) inside the sound wave processing box (1), and play the sound waves through the Bluetooth speaker (3); 3) The fruit is sealed in a perforated plastic bag containing an ethylene controlled-release agent. The plastic bag is then placed in a treatment box for exposure to sound waves at specific frequencies and sound pressure levels.

3. The method for regulating fruit quality based on sound waves as described in claim 2, characterized in that... The acoustic processing box in step 1) is a square wooden box.

4. The method for regulating fruit quality based on sound waves as described in claim 2, characterized in that... In step 2), the Bluetooth speaker is suspended in the center of the inside of the processing box.

5. A method for regulating fruit quality based on sound waves as described in claim 2, characterized in that... The amount of ethylene controlled-release agent used in step 3) for fruit is 0.15-0.35 g / kg of fruit.

6. The method for regulating fruit quality based on sound waves as described in claim 2, characterized in that... The ethylene controlled-release agent mentioned in step 3) is a commercially available ethylene controlled-release agent that has been activated by a water bath at 35-40°C for 2-3 minutes.

7. A method for regulating fruit quality based on sound waves as described in claim 1 or 2, characterized in that... The specific frequencies and sound pressure levels are 0.8-2.5kHz and 60-110dB, respectively. The intermittent cyclic acoustic treatment exposure time is 6-12h / day, with continuous exposure for 5-15 days.

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