A method for post-harvest quality monitoring of bayberries

Abstract

This invention relates to the field of postharvest storage and preservation technology for fruits, and discloses a method for monitoring the postharvest quality of bayberries. This method predicts the consumer acceptance of a batch of bayberries by collecting signals of volatile markers related to bayberry flavor quality. These volatile markers include one or more combinations of the following: caprylic acid, acetaldehyde, ethanol, phenethyl alcohol, 2-n-pentylfuran, benzaldehyde, hexanal, 2,4-hexadienal, and methyl 3-hexenoate. This invention can predict the consumer acceptance of a batch of bayberries based on changes in volatile components in the bayberry storage and transportation space, providing a technical means for predicting shelf life during large-scale storage and transportation.

Description

Technical Field

[0001] This invention relates to the field of postharvest storage, transportation and preservation technology of fruits, and more specifically, to a method for monitoring the quality of bayberries after harvest. Background Technology

[0002] The Chinese bayberry (Myrica rubra Sieb. et Zucc.) is a fruit with a rich flavor, delicious taste, and juiciness, making it one of my country's distinctive and economically valuable fruit varieties. The bayberry is a berry-like drupe without an outer pericarp. The edible flesh is arranged in a columnar pattern, with tender, radiating columns, making it susceptible to pests, diseases, and mechanical damage. Its quality deteriorates rapidly after harvest, making it extremely intolerant of storage and transportation; a saying goes, "The taste changes in one day, the color changes in two days, and both color and taste change in three days." Besides the inherent structure of the bayberry fruit, which makes it unsuitable for storage and transportation, the ripening period easily attracts fruit flies to lay eggs inside the fruit. Wounds caused by fruit fly larvae activity after harvest are easily infected by bacteria and fungi. Furthermore, the fruit's metabolism is vigorous after harvest, with the respiration rate reaching its peak during full ripening, leading to rapid quality deterioration. Therefore, post-harvest storage and transportation have always been bottlenecks restricting the development of the bayberry industry.

[0003] In actual storage and logistics processes, once diseased or rotten fruit appears, it should be promptly removed, and storage, transportation, and sales strategies should be adjusted according to the actual situation to ensure early sales. During the storage or long-distance transportation of bayberries, a large number of fruits are piled up in a relatively enclosed space. Currently, in actual production, monitoring for deterioration mainly relies on regular inspections by personnel, which is time-consuming and labor-intensive, and often makes it difficult to observe quality changes in fruits located inside the stack.

[0004] Spoiled bayberries emit a pungent odor, making them easily identifiable. Therefore, the volatile components in the storage and transportation space of bayberries can reflect changes in fruit quality. However, because human olfaction is easily adapted to the environment and its sensitivity decreases rapidly, and because there are significant individual differences in olfactory sensitivity, evaluations are often highly subjective. Therefore, identifying characteristic volatile markers associated with quality and developing more sensitive and objective detection techniques are effective means to promptly detect deteriorated fruit and assess the flavor and quality of stored fruit. Summary of the Invention

[0005] This invention utilizes the easily identifiable aroma of bayberries at different freshness levels to provide a method for post-harvest quality monitoring of bayberries. Based on changes in volatile components in the bayberry storage and transportation space, the method predicts the consumer acceptance of the quality of a batch of bayberries according to the collected signals, providing a technical means for predicting shelf life during large-scale storage and transportation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for post-harvest quality monitoring of bayberries involves extracting gas samples from the bayberry storage and transportation space. By collecting signals from volatile markers related to bayberry flavor quality, the method predicts the consumer acceptability of the batch of bayberries, categorizing them as acceptable or unacceptable. The volatile markers related to bayberry flavor quality include: caprylic acid, acetaldehyde, ethanol, phenethyl alcohol, 2-n-pentylfuran, benzaldehyde, n-hexanal, 2,4-hexadienal, and methyl 3-hexenoate. The criteria for determining unacceptable fruit based on a single compound are as follows:

[0008] markers Content (μg / g FW) bitter ≥0.65 Acetaldehyde ≥13.00 ethanol ≥108.00 Phenylacetyl alcohol ≥0.90 2-n-pentylfuran ≥1.35 benzaldehyde ≥1.30 hexanol ≤0.45 2,4-Hexadienal ≤5.60 methyl 3-hexenoate ≤1.00

[0009] As a preferred method, the gas sample is extracted from the storage and transportation space of bayberries and analyzed using gas chromatography-mass spectrometry.

[0010] Preferably, the detection parameters of the gas chromatography-mass spectrometry (GC-MS) instrument are as follows:

[0011] Component separation was performed using a DB-5MS capillary column;

[0012] Temperature program: First, hold at 40℃ for 5 min, then increase from 40℃ to 145℃ at a rate of 3℃ / min, then increase from 145℃ to 240℃ at a rate of 5℃ / min, and finally hold at 240℃ for 4 min. Carrier gas flow rate is 1.0 mL / min, ion source temperature is 230℃, and ionization is achieved by electron bombardment with 70 eV electron energy.

[0013] Based on the total ion chromatogram of volatile substances, MS database searches and manual spectral analysis were performed using a computer. The relative content of each compound was determined using the peak area normalization method. Cyclohexanone was used as an internal standard for quantitative calculation of the content of each target substance, with a concentration of 4.75 μg·mL. -1 The amount added to each sample is 10 μL. The formula for calculating the content of each standard substance is as follows:

[0014] C = (C_internal_standard × V_internal_standard × A_target) / (A_internal_standard × M_target)

[0015] In the formula: M target represents the mass of the sample being tested (mg / Fw), C target represents the concentration of the target analyte (μg / g); V internal standard represents the volume of internal standard added to each sample (mL); A internal standard represents the peak area of ​​the internal standard; C internal standard represents the concentration of the internal standard (mg / mL); A target represents the peak area of ​​the target analyte.

[0016] This invention, by employing the above-mentioned technical solution, provides a method for post-harvest quality monitoring of bayberries. Based on the changes in volatile components in the bayberry storage and transportation space, it can predict the consumer acceptance of the quality of a batch of bayberries according to the collected signals, providing a technical means for predicting shelf life during large-scale storage and transportation. Attached Figure Description

[0017] Figure 1 The chemical structural formulas of 9 markers are shown; including octanoic acid, acetaldehyde, ethanol, phenylethyl alcohol, 2-pentyl furan, benzaldehyde, hexanal, 2,4-hexadienal, and 3-hexenoicacid methyl ester.

[0018] Figure 2 The content of nine markers in the freshness of bayberry fruit that is acceptable (F) and unacceptable (UF) (green represents F, yellow represents UF).

[0019] Figure 3 Receiver operating characteristic (ROC) curves for differentiating between acceptable (F) and unacceptable (UF) freshness fruits based on a combination of nine biomarkers. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 protection scope of the present invention.

[0021] Example 1: Application of volatile markers in distinguishing between acceptable (F) and unacceptable (UF) freshness of bayberry fruit.

[0022] 1) Test methods

[0023] Fully ripe 'Dongkui' bayberry fruits free from mechanical damage and pests were selected and stored in cold storage at 0℃, 4℃, 10℃, and 20℃ respectively. Every 24 hours, the pulp was harvested, flash-frozen with liquid nitrogen, and then stored at -80℃ for GC-MS analysis of volatile components. Nine fruits were randomly selected from each treatment group for each run, with three fruits constituting one replicate, for a total of three replicates.

[0024] The appearance of the bayberry fruit was observed every 24 hours. The appearance characteristics of the bayberry fruit, such as gloss, color, mold spots, water-soaked spots, pitted flesh, and firmness of the flesh, were evaluated.

[0025] Sensory evaluations were conducted every 24 hours. The sensory evaluation test team consisted of 30 randomly recruited volunteers aged 18-38. Before the formal sensory evaluation, a preliminary assessment was conducted to establish the aroma, texture, flavor intensity, and bitterness of the fruit as important indicators related to the post-harvest freshness of the bayberry. During the formal sensory evaluation, bayberries free from visible pests and diseases were selected. The aroma of the bayberries was first detected, followed by chewing and tasting. The aroma, texture, flavor intensity, bitterness, and overall sensory value of the bayberry were scored. The specific scoring criteria are shown in the table below:

[0026] Table 1 Scoring criteria for the appearance and flavor quality of bayberry fruit

[0027]

[0028]

[0029] The bayberry fruits were grouped according to the comprehensive sensory evaluation results. Fruits with a comprehensive sensory evaluation score of 3 or below were considered acceptable to consumers (F), while fruits with a comprehensive sensory evaluation score of 3 or above were considered to have deteriorated to the point of being unacceptable to consumers (UF).

[0030] The bayberry pulp, flash-frozen in liquid nitrogen, was freeze-ground into powder. 3g of the powder was weighed and added to 5mL of saturated NaCl solution. After mixing, 2mL of the suspension was transferred to a 10mL gas chromatograph (GC) vial. 10μL of 4.75μg / mL cyclohexanone solution was added as an internal standard, and the vial was sealed. Volatile components were extracted using a DVB / CAR / PDMS solid-phase microextraction head (Supelco Co., Bellefonte, PA, USA) at 45℃ for 20 min, followed by injection. GCMS analysis was performed using an Angilent 7890A-5975C GCMS system (Agilent J&W, Folsom, CA, USA).

[0031] GCMS detection parameters: Component separation was performed using a DB-5MS capillary column (30m × 0.25mm, 0.25μm, Agilent Technologies, USA). Temperature program: 40℃ for 5 min, then increased to 145℃ at a rate of 3℃ / min, followed by an increase to 240℃ at a rate of 5℃ / min, and held at 240℃ for 4 min. The carrier gas was high-purity He (99.999%) at a flow rate of 1.0 mL / min. Ion source temperature was 230℃, with electron bombardment ionization at 70 eV electron energy.

[0032] Based on the total ion spectrum of volatile substances, MS database retrieval and manual spectral analysis were performed using a computer. The relative content of each compound was determined using the peak area normalization method. Cyclohexanone was used as an internal standard for quantitative calculation of the content of each target substance. The calculation formula is as follows: C = (C 内标 ×V 内标 ×A 目标 ) / (A 内标 ×M 目标 )

[0033] In the formula: M_target represents the mass of the sample being tested (mg / Fw), C_internal_standard represents the concentration of the target analyte (μg / g); V_internal_standard represents the volume of internal standard added to each sample (mL); A_internal_standard represents the peak area of ​​the internal standard; C_internal_standard represents the concentration of the internal standard (μg / mL); and A_target represents the peak area of ​​the target analyte.

[0034] 2) Test Results

[0035] The nine markers in this invention (chemical structures such as...) Figure 1 In the microenvironment of UF fruit (as shown), the contents of 3-hexenoic acid methyl ester, hexanal, and 2,4-hexadienal were significantly decreased (P < 0.05), therefore they can be used to characterize the characteristic aroma of fresh bayberry. Figure 2 The levels of octanoic acid, acetaldehyde, ethanol, phenylethyl alcohol, 2-pentylfuran, and benzaldehyde were significantly increased in the microenvironment of UF fruit (P > 0.05), and therefore can be used to characterize the degree of off-flavor in bayberries. Figure 2 ).

[0036] ROC curves were plotted for UF and F fruits using combinations of nine compounds, and the results are as follows: Figure 3 As shown, the AUC of the nine marker combinations is 1.

[0037] Example 2: Application of volatile biomarkers in predicting consumer acceptance of postharvest bayberry fruit quality

[0038] Waxberry fruits stored at different temperatures and during different storage stages were selected post-harvest for consumer flavor sensory evaluation, and gas chromatography-mass spectrometry (GC-MS) was used to detect and quantify gas components in the fruit environment. The consumer flavor sensory evaluation, fruit gas collection methods, GC-MS detection methods, and quantification methods were the same as in Example 1. The contents of various volatile markers in the microenvironment of waxberry fruits at different storage temperatures and periods, as well as the sensory evaluation results, are shown in Table 2. The results indicate that the volatile marker contents of deteriorated fruits are within the range defined in this specification.

[0039] Table 2. Consumer sensory evaluations and compound contents of bayberry fruits at different storage temperatures and storage stages.

[0040]

[0041]

[0042]

[0043] The data on pass rates indicate that octanoic acid, ethanol, benzaldehyde, and hexanal are more suitable for determining acceptable (F) fruits, while acetaldehyde, phenylethanol, 2-n-pentylfuran, 2,4-hexadienal, and methyl 3-hexenoate are more suitable for determining unacceptable (UF) fruits. The optimal approach is to combine all nine markers.

[0044] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A method for post-harvest quality monitoring of bayberries, comprising: analyzing the samples using gas chromatography-mass spectrometry; extracting gas samples from the bayberry storage and transportation space; extracting volatile components using a DVB / CAR / PDMS solid-phase microextraction head at 45 °C for 20 min before injection; then predicting the consumer acceptance of the batch of bayberries by collecting signals of volatile markers related to bayberry flavor quality, classifying the fruit as acceptable or unacceptable; characterized in that... Volatile biomarkers related to the flavor quality of bayberry fruit include: caprylic acid, acetaldehyde, ethanol, phenethyl alcohol, 2-n-pentylfuran, benzaldehyde, n-hexanal, 2,4-hexadienal, and methyl 3-hexenoate. The criteria for determining unacceptable fruit based on combinations of these nine compounds are as follows: The waxberry mentioned is a fully ripe 'Dongkui' variety; the detection parameters of the gas chromatography-mass spectrometry (GC-MS) instrument are as follows: Component separation was performed using a DB-5MS capillary column; Temperature program: First, hold at 40℃ for 5 min, then increase from 40℃ to 145℃ at a rate of 3℃ / min, then increase from 145℃ to 240℃ at a rate of 5℃ / min, and finally hold at 240℃ for 4 min. Carrier gas flow rate is 1.0 mL / min, ion source temperature is 230℃, and ionization is achieved by electron bombardment with 70 eV electron energy. Based on the total ion spectrum of volatile substances, MS database search and manual spectral analysis were performed using computer. The relative content of each compound was determined by peak area normalization. Cyclohexanone was used as an internal standard to quantitatively calculate the content of each target substance. The concentration of cyclohexanone was 4.75 µg / mL, and the amount added to each sample was 10 µL. The formulas for calculating the content of each standard substance are as follows: C 目标 = (C 内标 × V 内标 × A 目标 ) / (A 内标 × M 目标 ) Where: M 目标 The C represents the weighed mass of the sample being tested, in g / Fw. 目标 V represents the concentration of the target analyte in μg / g; 内标 Indicates the volume (mL) of internal standard added to each sample; A 内标 C represents the peak area of ​​the internal standard; 内标 Indicates the concentration of the internal standard in µg / mL; A 目标 This indicates the peak area of ​​the target object.

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