CN115097085B

CN115097085B - Apple fruit brittleness grading method

Info

Publication number: CN115097085B
Application number: CN202210826211.5A
Authority: CN
Inventors: 杨惠娟; 张波; 苏秋方; 杨亚州; 赵政阳
Original assignee: Northwest A&F University
Current assignee: Northwest A&F University
Priority date: 2022-07-14
Filing date: 2022-07-14
Publication date: 2023-04-18
Anticipated expiration: 2042-07-14
Also published as: CN115097085A

Abstract

The invention belongs to the technical field of food, and particularly relates to an apple fruit brittleness grading method, which comprises the following steps: preparing fresh apples, and taking samples for later use; the samples were compression tested using a texture testing probe: the parameters are set as the speed before, during and after pressing is 0.5-1.5mm/s, the compression degree is 40-80%, and the trigger force is 10N; and testing indexes which can be tested by the texture analyzer, selecting indexes with good correlation with the apple sense brittleness as final evaluation indexes, and formulating apple fruit brittleness grading standards. The method utilizes the texture analyzer to carry out quantitative grading on the apple fruit brittleness, is more convenient, objective and accurate than the traditional sensory evaluation method, can avoid subjective influence generated by sensory detection as much as possible, and can be used in the fields of apple fruit brittleness breeding, fruit grading and the like.

Description

Apple fruit brittleness grading method

Technical Field

The invention belongs to the technical field of food, and particularly relates to an apple brittleness grading method.

Background

The apple belongs to the genus Malus of Maloideae of Rosaceae. Apple cultivation in China has a long history and a wide planting area. The national apple cultivation area 191.18 ten thousand hm in 2020 ² The yield 4050.10 ten thousand t, the global percentage is nearly half. The texture of fruits, including hardness and crispness, is an important indicator of quality evaluation as it represents the internal texture and mouthfeel of the fruit, and determines consumer choice and market competitiveness of the fruit. Fruit firmness reflects the firmness of the fruit, while fruit brittleness is not simply equivalent to firmness, which is a perceived and audible composite perception of the force and sound action that a person produces during chewing of the flesh.

The evaluation method of the fruit brittleness mainly comprises sensory evaluation and instrumental evaluation. The sensory evaluation is mainly based on the comprehensive feeling of a trained panel examiner when tasting the fruits, and then the evaluation and scoring are carried out, although the method has the advantages of simplicity, convenience, no limitation of time and place and no need of complex instruments, the results are easily affected by subjective consciousness and professional degree of the panel examiner, and the reliability and the authenticity of the data are difficult to guarantee, time and labor are consumed. At present, the method is mostly adopted in apple grading standards to evaluate the fruit brittleness. The instrument evaluation mainly uses an instrument to carry out quantitative evaluation on the fruit brittleness, and is more and more favored by the researchers due to the characteristics of rapidness, accuracy, time saving, labor saving and the like. However, the instrumental evaluation is too mechanical, often deviating from the sensory evaluation, and at the same time, there is a lack of establishment of a classification standard for apple fruit crispness.

In the prior art, mechanical test and acoustic test are the most commonly used methods for evaluating fruit brittleness, and mainly compression and puncture tests are performed by using a texture analyzer. Dividing the fruit into 4 parts of fruit top, fruit sunny side, fruit shady side and fruit shoulder before measurement; under the compression test, firstly taking cylindrical pulp samples from all parts of the fruit, and then vertically compressing the cylindrical pulp samples to a preset degree by using a probe larger than the pulp samples; the puncture test is to cut off the peel of the predicted part, vertically align the test probe to the test part, and apply pressure until the probe reaches the specified part; the fruit brittleness is characterized by recording the mechanical parameters and the acoustic parameters of the sample in the compression or puncture process.

However, the measurement result of the brittleness of the apple fruit by the mechanical test in the above conventional test method is greatly influenced by the hardness of the fruit, and the two show a high correlation, which is deviated from the texture characteristics of the apple fruit because the brittleness of the apple variety with a high hardness of the fruit is not necessarily high. The acoustic test has high requirements on test equipment and environment, the measurement precision is influenced, and meanwhile, the classification standard of apple fruit brittleness is lacked, so that the defects of the acoustic test and the acoustic test greatly limit the quality identification of filial generation and the quality classification of picked fruits in the apple breeding process. Therefore, it is required to develop a method for classifying outdated crispness of apples with high accuracy.

Disclosure of Invention

In order to solve the technical problems, the invention provides an apple brittleness grading method.

The invention aims to provide an apple fruit brittleness grading method, which comprises the following steps:

preparing fresh apples, and taking samples for later use;

the samples were compression tested using a texture tester test probe P50: the parameters are set to be that the speed before, during and after pressing is 0.5-1.5mm/s, the compression degree is 40-80%, and the trigger force is 10N;

and testing indexes representing the apple brittleness by using a texture analyzer, selecting indexes with good correlation with the apple sense brittleness as final evaluation indexes, and formulating apple fruit brittleness grading standards.

Preferably, in the method for grading the brittleness of apple fruits, the sample is in the shape of a cylinder with the diameter of 1cm and the height of 1 cm.

Preferably, the apple fruit brittleness grading method is characterized in that the speed before pressing, the speed during pressing and the speed after pressing are all 1.0mm/s, the compression degree is 80%, and the trigger force is 10N.

Preferably, in the apple fruit brittleness grading method, indexes for characterizing apple brittleness through texture testing include Fractrubability, N.Peaks, distance1, young's module, drop slope and Drop Off, and specific meanings of the indexes are shown in Table 1.

TABLE 1 TPA test index definition and semantic description thereof

Preferably, in the method for classifying apple fruit brittleness, n.peaks is used as a final evaluation index for classifying apple fruit brittleness.

Preferably, in the method for classifying the apple fruit brittleness, the apple fruit brittleness classification standard is as follows:

grade 2, no brittleness, corresponding N.Peaks value of 28.56-32.02;

grade 4, low brittleness, corresponding N.Peaks value of 40.73-42.30;

grade 6, medium crisp, corresponding N.Peaks value is 46.40-47.90;

grade 8, high friability, corresponding n.peaks number of 53.88-58.70.

Compared with the prior art, the invention has the following beneficial effects:

on the premise of optimizing the apple fruit brittleness determination method based on the texture analyzer, the invention grades the fruit brittleness of different apple varieties, provides accurate data support for the description of the apple variety fruit characteristics, greatly improves the reliability and repeatability of the fruit quality characteristics, and can be popularized to common mass consumers, field production operation and application to the determination and grading of the fruit brittleness in apple crossbreeding. And data support is provided for quality identification of filial generation and quality grading of picked fruits in the breeding process of the apples.

Drawings

FIG. 1 is a graph of the change in TPA texture index of a fruit at different compression rates and compression set;

wherein the light gray is 40%, the middle gray is 60%, and the dark gray is 80%;

FIG. 2 is a schematic diagram of the peak difference during compression;

wherein, the texture map of the A,2 grade brittleness fruits in the compression process; and B, texture atlas of 8-grade crisp fruits in the compression process.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention to be implemented, the present invention will be further described with reference to the following specific embodiments and accompanying drawings.

In the description of the present invention, reagents used are commercially available and methods used are all conventional in the art, unless otherwise specified.

Example 1 TPA (TA. XT2i type texture analyzer (Stable Micro System, UK)) test parameter optimization of apple fruit texture

The test method comprises the following steps: preparing fresh apples for later use; cutting a cylindrical sample with the diameter of 1cm and the height of 1cm by using a sampler; compression testing was performed using TPA test probe P50; the parameters are set as the speed before, during and after pressing is 0.5mm/s, or 1.0mm/s, or 1.5mm/s, the compression degree is 40%, 60% and 80%, and the trigger force is 10N. 6 indexes related to the fruit texture, which can be obtained in a compression process pressure-deformation chart, are counted by texture analyzer software, and are Hardness (Hardness), brittleness 1 (Fractrurability), elasticity (Springes), cohesiveness (Cohesiveness), chewiness (Chewiness) and recoverability (Resilience). The specific meanings of each index are shown in Table 2.

TABLE 2 TPA test index definition and semantic description thereof

In order to analyze the influence of the compression speed and the compression deformation on the texture of the apple fruits, analysis of variance is carried out on the apple fruits, and the result shows that the compression deformation has extremely remarkable influence on hardness, elasticity, cohesiveness, chewiness and resilience and has no remarkable influence on brittleness 1; the compression speed had no significant effect on other fruit texture indicators except cohesiveness and chewiness (table 3).

TABLE 3 impact of compression speed and compression set on the TPA texture index of fruit

Note: * And indicates significant differences at 0.05 and 0.01 levels, respectively.

FIG. 1 is a graph showing the change of texture indexes of TPA fruit at different compression speeds and compression deformation amounts, and the change of the texture indexes of TPA fruit at different compression speeds and deformation amounts shows that the hardness value increases with the increase of the compression deformation amount without significant difference at each compression speed; the brittleness 1 value has no difference under different compression speeds and compression deformation amounts; three texture indexes of elasticity, cohesiveness and recoverability are all reduced along with the increase of the compression deformation amount; when the compression set is 40%, the fruit chewiness is highest without difference between compression speeds, and at 60% compression set, the fruit chewiness is lowest. The chewiness and cohesiveness are significantly affected by two factors, the compression set and the compression speed, and when the compression set is 60% and 80%, the fruit cohesiveness and chewiness are at the compression speed of 1mm/s, with the lowest values (fig. 1), which is probably due to the chewiness value being the product of the hardness value, the elasticity value and the cohesiveness value. The influence of the compression speed and the compression deformation on the fruit texture index is comprehensively considered, the compression speed is determined to be 1mm/s, and the compression deformation 80 percent is a TPA test parameter of the apple fruit texture.

Example 2 establishment of apple fruit brittleness determination method

A texture analyzer is selected to carry out a compression experiment to measure the brittleness of the apple fruits, and the measuring method comprises the following steps: preparing fresh apples for later use; cutting a cylindrical sample with the diameter of 1cm and the height of 1cm by using a sampler; compression testing was performed using TPA test probe P50; the parameters are set to be that the speed before, during and after pressing is 1.0mm/s, the compression degree is 80 percent, and the trigger force is 10N. And (3) counting each index in the pressure-deformation map in the compression process by using the software (Exponent) of the instrument, wherein the meaning of each index is shown in the table 1.

The SPSS software is used for analyzing the correlation between the fruit brittleness 1 and the hardness to find that the fruit brittleness 1 and the hardness have extremely obvious positive correlation (R = 0.91), however, the real brittleness and hardness of the apple fruit do not all show the correlation, the result that the brittleness 1 cannot accurately reflect the apple fruit brittleness in the TPA measurement result is shown, and the TPA test index needs to be further deeply dug. Through the correlation analysis of indexes (brittleness 2-6) which can represent brittleness and are newly excavated, brittleness 1 and hardness, the fruit hardness shows extremely obvious correlation with other texture indexes except for no obvious correlation with brittleness 2 and brittleness 3, and correlation coefficients with brittleness 1, brittleness 4 and brittleness 6 are respectively as high as 0.905, 0.828 and 0.832, which shows that the hardness has great influence on the brittleness indexes; the two indexes of brittleness 4 and brittleness 5 show similar correlation modes with the hardness, wherein the correlation coefficient of brittleness 4 and brittleness 1 is 0.844; the brittleness 1 has no significant correlation with the brittleness 2 only, the brittleness 6 has no significant correlation with the brittleness 3 only, and has significant correlation with other texture indexes, the brittleness 1 and the brittleness 6 have better correlation, and the correlation coefficient is 0.865; the two indexes of brittleness 2 and brittleness 3 are special, brittleness 2 only has a significant negative correlation with brittleness 6, brittleness 3 only has a significant negative correlation with brittleness 1, and has no significant correlation with other texture indexes, which shows that the two indexes of brittleness 2 and brittleness 3 are relatively independent and are slightly influenced by other texture indexes (table 4).

The fruit hardness and the several brittleness indexes have different degrees of correlation, which indicates that the information reflected by the indexes has some overlap and can be subjected to dimensionality reduction treatment. The measurement results of the hardness and 6 brittleness indexes are subjected to principal component analysis, the vector load coefficient and variance contribution rate of each principal component factor are shown in table 5, the cumulative contribution rate of the two principal components is 76.619%, the characteristic value of the 1 st principal component is 4.424, the contribution rate is 55.305%, the brittleness index mainly comprises 2, 4, 5 and 6, the most critical role of the four indexes in fruit brittleness evaluation is shown, meanwhile, the definition of the four indexes on a quality composition spectrum is related to the up-and-down fluctuation of a curve, the calculation is complex, and the comprehensive role of stress and strain in the compression process of apple pulp is reflected. The characteristic value of the No. 2 main component is 1.705, the contribution rate is 21.314%, the brittleness is mainly 1, the brittleness is 3 and the hardness is mainly included, the single action of stress or strain of apple pulp in the compression process is reflected, and the indexes are shown to have important contribution to fruit brittleness evaluation.

TABLE 4 correlation between fruit crispness indices

Note: * And represent significant correlations at the 0.05 and 0.01 levels (two-sided), respectively.

TABLE 5 principal component factor vector load factor and variance contribution rate

Four indexes of brittleness 2, brittleness 4, brittleness 5 and brittleness 6 which have great contribution in the main component 1 and the brittleness of the sensory evaluation are selected for carrying out correlation analysis, and the fact that the brittleness and the brittleness 2 show extremely obvious positive correlation is found, the correlation coefficient is 0.781, and the three indexes of brittleness 4, brittleness 5 and brittleness 6 show obvious negative correlation (table 6). The information reflected by the brittleness 2 index is comprehensive and relatively independent, and is less influenced by other brittleness indexes; meanwhile, the composition has a large contribution in the 1 st main component and plays a more key role in fruit crispness evaluation; and the crispness correlation of the apple fruit crispness evaluation is good, and finally, the crispness 2 (N.peaks) can be determined to be used as an instrument measuring index for apple fruit crispness evaluation.

TABLE 6 correlation between sensory evaluation of fruit crispness and TPA-measured crispness index

Example 3 grading criteria for apple fruit crispness

The linear correlation between the sensory evaluation of the apple fruit brittleness and the instrument measurement index N.Peaks shows that the fruit brittleness can be graded and evaluated through the confidence interval of the N.Peaks index. As can be seen from Table 7, the overall trend of the crispness 2 value was gradually increasing with increasing sensory crispness scores, i.e., from less crispness to extreme crispness, in the fruit. The difference between sensory grade 4 crispness and sensory grade 2 crispness of the apple fruits is 11.23 at most in terms of average value; the difference between the grade 6 brittleness and the grade 4 brittleness is 5.63 at least; while the difference between the 8-grade brittleness and the 6-grade brittleness was centered at 9.14. The change of the fruit sense brittleness along with the instrumental index brittleness 2 is not a simple linear relation. The confidence interval of the brittleness 2 of the instrument measurement index corresponding to each sensory brittleness level is 28.56-32.02 (not brittle) and the interval size is 3.46;4 (low brittleness) is 40.73-42.30, and the interval size is 1.67;6 (medium brittleness) is 46.40-47.90, and the interval size is 1.50;8 (high brittleness) is 53.88-58.70, and the interval size is 4.82. The narrow interval of the 4-grade brittleness and the 6-grade brittleness suggests that the difference between the brittleness of the apples at the several grades is small and is not easy to distinguish, and the wide interval of the 2-grade brittleness and the 8-grade brittleness suggests that the measured index N.Peaks of an instrument is sensitive to the sensory brittleness of the non-crisp and extremely crisp two sides of the extremely crisp fruits, and the two are easy to distinguish. Meanwhile, the numerical values of all intervals are not overlapped, and the index N.Peaks can be further used for evaluating and grading the sensory brittleness of the apple fruits. Fig. 2 is a texture map of the grade 2 and 8 crispness fruits in the compression process, and the significant difference between the n.peaks indexes can be reflected more intuitively.

TABLE 7 different types of brittleness ratings

It should be noted that, when the present invention relates to a numerical range, it should be understood that two endpoints of each numerical range and any value between the two endpoints can be selected, and since the steps and methods adopted are the same as those in the embodiment, in order to prevent redundancy, the present invention describes a preferred embodiment. While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. The apple fruit brittleness grading method is characterized by comprising the following steps:

preparing fresh apples, and taking samples for later use; the sample shape is a cylinder with a diameter of 1cm and a height of 1 cm;

the samples were compression tested using a texture analyzer test probe: the parameters are set to be that the speed before, during and after pressing is 1.0mm/s, the compression degree is 80 percent, and the trigger force is 10N;

testing indexes representing the apple brittleness by a texture analyzer, selecting indexes with good correlation with the apple sense brittleness as final evaluation indexes, and formulating apple fruit brittleness grading standards;

indexes for characterizing apple brittleness by a texture analyzer test comprise Fractrubability, N. Peaks, distance1, young's module, drop slope and Drop Off;

wherein, fractrubability is defined as the first peak value of the sample in the first compression process, and the unit is g;

n, peaks is defined as the total number of fracture Peaks generated by the sample during the first compression;

distance1 is defined as the displacement of the sample deformed when the biological yield point occurs in the first compression process, and the unit is mm;

young's module is defined as the ratio of the first peak value to the corresponding displacement of the sample in the first compression process, and the unit is g/mm;

drop slope is defined as the slope of the falling peak of the sample after the biological yield point occurs during the first compression;

drop Off is defined as the mean of all falling peaks of the sample during the first compression in g;

taking N, peaks as a final evaluation index for apple fruit brittleness grading;

the apple fruit brittleness classification standard is as follows:

grade 2, no brittleness, and the corresponding N.Peaks value is 28.56-32.02;

grade 4, low brittleness, corresponding N, peaks number of 40.73-42.30;

grade 6, medium crisp, corresponding N.Peaks value is 46.40-47.90;

grade 8, high brittleness, corresponding n. Peaks number 53.88-58.70.