Quantitative sensory evaluation method for flavor characteristics of fragrant rapeseed oil

Abstract

The invention provides a quantitative sensory evaluation method for flavor characteristics of fragrant rapeseed oil. The quantitative sensory evaluation method comprises the following steps: establishing an evaluation group and training, performing flavor recognition training on an evaluator, and unifying an evaluation standard by using a standard reference sample; constructing a sensory evaluation index system of the fragrant rapeseed oil; performing intensity scoring on the key flavor indexes; and calculating the comprehensive score of the flavor of the strong-flavor rapeseed oil by using a comprehensive score formula. According to the method, the gain flavor and the benefit reducing flavor of the fragrant rapeseed oil are subjected to hedging calculation through a formula, so that the pleasure of consumers is reflected more truly. A quantitative description analysis method is adopted, a comprehensive score formula is combined, sensory experience is converted into a numerical value of 0-100, and a product quality grading standard is established. A positive index which can best represent a Maillard reaction product of the fragrant rapeseed oil and a negative index which can best represent processing defects are selected, and double experience of smell and taste is covered. And in combination with a radar map, the flavor weakness of the product can be identified at a glance.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a quantitative sensory evaluation method for the flavor characteristics of aromatic rapeseed oil. Background Technology

[0002] With the upgrading of consumption, "fragrant rapeseed oil" with a unique and rich aroma is increasingly favored by consumers. At present, the national standard GB / T 1536-2021 "Rapeseed Oil" mainly specifies the physicochemical indicators such as acid value and peroxide value, but in terms of sensory evaluation, it only has qualitative descriptions such as "has the inherent aroma and taste of rapeseed oil and has no off-odors", and lacks quantitative evaluation standards for the "fragrant" flavor characteristics.

[0003] However, existing sensory evaluations often rely on the subjective preferences of the evaluators and lack a detailed deconstruction of specific flavor dimensions. The main problems are: (1) lack of a balance mechanism between positive and negative indicators: existing evaluations often only focus on "fragrance" and ignore the negative flavors such as "vegetable green taste" (insufficient blanching) or "bitter almond taste / spicy taste" (glucosinolate degradation products) caused by improper processing control, which reduce the overall quality; (2) lack of quantitative formulas: there is a lack of a scientific algorithm to convert the scores of multiple sensory dimensions into a single comprehensive evaluation index, making it difficult to conduct horizontal quality comparisons between different batches of products. Referring to existing technologies, either the focus is on statistical scoring ratios or on complex fuzzy clustering algorithms. For daily quality inspection of enterprises, this invention provides a quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a quantitative sensory evaluation method for the flavor characteristics of aromatic rapeseed oil, thus solving the problems mentioned in the background. This invention uses a formula to offset the gain and loss flavors of aromatic rapeseed oil, more accurately reflecting consumer satisfaction. Employing Quantitative Descriptive Analysis (QDA) combined with the comprehensive scoring formula designed in this invention, sensory experiences are converted into numerical values ​​from 0 to 100, facilitating the establishment of product quality grading standards. Positive indicators best representing Maillard reaction products of aromatic rapeseed oil and negative indicators representing processing defects are selected, covering both olfactory and gustatory experiences. Combined with radar charts, flavor weaknesses of the product can be identified at a glance.

[0005] To achieve the above objectives, the present invention provides a quantitative sensory evaluation method for the flavor characteristics of aromatic rapeseed oil, comprising the following steps:

[0006] S1. Establish an evaluation team and provide training: Establish a sensory evaluation team, train evaluators in flavor identification, and use standard reference samples to unify evaluation standards.

[0007] S2. Construct a sensory evaluation index system for aromatic rapeseed oil. Based on the flavor wheel theory, screen out the key flavor indicators of aromatic rapeseed oil and divide the key flavor indicators into two categories: positive gain indicators and negative loss indicators.

[0008] S3. Conduct quantitative descriptive analysis, with evaluators assessing the samples to be tested and scoring the intensity of key flavor indicators.

[0009] S4. Calculate the overall flavor score. Calculate the overall flavor score S of the fragrant rapeseed oil using the overall score formula. The overall score formula is used to calculate the net flavor value. Subtract the total intensity of the defective flavor from the total intensity of the pleasant flavor and normalize to a score of 100.

[0010] Furthermore, the sensory evaluation team consists of 8-12 people, and the standard reference samples include roasted sesame seeds and peanuts to represent nutty aroma, and raw rapeseed oil to represent fresh vegetable flavor. The flavor recognition training is conducted in accordance with GB / T 1536-2021 and the standard for food sensory analysis methods.

[0011] Furthermore, the number of key flavor indicators is six, and the positive gain indicators include:

[0012] Nutty: The aroma is similar to roasted peanuts, sesame seeds, or walnuts; Oily: The rich, full-bodied aroma of oils; Woody: The deep aroma is similar to dry wood or roasted plant fibers.

[0013] Furthermore, the negative loss indicators include:

[0014] Vegetable flavor: similar to grass or raw bean smell; spicy flavor: a stinging sensation in the nasal cavity or mouth; bitter almond flavor: a distinct bitter taste with a sweet aftertaste or a bittersweet feeling.

[0015] Furthermore, the following scoring scale is established in S3:

[0016] Using a 0-5 scale, 0 points: undetectable; 1 point: slight; 3 points: moderate; 5 points: very strong.

[0017] Furthermore, S3 also includes data validity cleaning: statistically analyzing the scores of each indicator, calculating the coefficient of variation (CV), removing outlier evaluator data with CV > 20%, and taking the average of the remaining valid data as the final score of that indicator.

[0018] Furthermore, the comprehensive score formula is as follows:

[0019]

[0020] in:

[0021] P includes nuts, oils, and woody fragrance: The average score range of the positive indicators by the evaluation group is 0 - 5 points;

[0022] N includes vegetable green, spicy, and bitter almond: The average score range of the negative indicators by the evaluation group is 0 - 5 points;

[0023] S is the comprehensive flavor score;

[0024] α is the aroma enhancement coefficient, and the value of α is 1.2;

[0025] β is the off - flavor tolerance coefficient, and the value of β is 0.8.

[0026] Furthermore, the theoretical maximum positive contribution value of the comprehensive score formula is 15.0 points.

[0027] Furthermore, the interpretation of the calculation result of the flavor comprehensive score S is as follows:

[0028] S > 60: High - quality strong - flavored rapeseed oil, with positive flavor dominant.

[0029] 0 < S ≤ 60: Qualified / ordinary strong - flavored rapeseed oil. ​​​​​​​​​​​​​​​​​​​​​​ Figure 2 These are the types of flavor compounds detected by GCMS under different processing methods in the embodiments of the present invention;

[0037] Figure 3 This is a top view of the GC-IMS signal strength in an embodiment of the present invention;

[0038] Figure 4 This is an electronic nose radar diagram from an embodiment of the present invention. Detailed Implementation

[0039] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0040] Please see Figures 1 to 4 The present invention provides the following technical solution: a quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil. This method establishes a net flavor evaluation model, which breaks through the limitation of traditional sensory evaluation that only makes additions. Through formulas, the "gain flavors" (nutts, oils, woody aromas) and "loss flavors" (vegetable greens, spiciness, bitter almonds) of fragrant rapeseed oil are offset and calculated, so as to more realistically reflect the consumer's pleasure.

[0041] Example 1:

[0042] rapeseed oil after high-pressure wet heat treatment

[0043] 1. Evaluation process: Rapeseed oil was obtained by pressurizing, adding 5% water, steaming at 140℃ for 20 minutes, and stir-frying for 20 minutes. Ten evaluators tasted and scored the oil.

[0044] 2. Indicator Score:

[0045] Positive: Nutty (5), Oily (4), Woody (4).

[0046] Negative: Vegetable flavor (1), spicy flavor (1), bitter almond flavor (2).

[0047] 3. Calculate the overall score:

[0048]

[0049] 4. Conclusion: This sample has a prominent nutty aroma and very little off-odor, and belongs to high-quality, fragrant rapeseed oil.

[0050] Example 2:

[0051] Traditional steamed and stir-fried rapeseed oil

[0052] 1. Evaluation process: Rapeseed oil was obtained by adding 5% water, steaming at 160℃ for 20 minutes, and stir-frying for 30 minutes. Ten evaluators tasted and scored the oil.

[0053] 2. Indicator Score:

[0054] Positive: Nutty (4), Oily (3), Woody (3).

[0055] Negative: Vegetable flavor (2), spicy flavor (1), bitter almond flavor (1).

[0056] 3. Calculate the overall score:

[0057]

[0058] 4. Conclusion: The sample has a prominent nutty aroma, but the oily and woody aromas are not prominent, and the vegetable flavor is slightly obvious. It belongs to ordinary strong-aroma rapeseed oil.

[0059] Example 3:

[0060] Directly fried rapeseed oil

[0061] 1. Evaluation process: Rapeseed oil was obtained by stir-frying at 160℃ for 30 minutes. Ten evaluators tasted and scored the oil.

[0062] 2. Indicator Score:

[0063] Positive notes: nutty (2), oily (3), woody (1).

[0064] Negative: Vegetable flavor (3), spicy flavor (3), bitter almond flavor (2).

[0065] 3. Calculate the overall score:

[0066]

[0067] 4. Conclusion: The negative flavor intensity of this sample is slightly heavy, with excessive vegetable and spicy tastes. Fortunately, the oily taste is quite obvious, and the sensory quality is barely positive.

[0068] Example 4:

[0069] Screw-pressed rapeseed oil

[0070] 1. Evaluation process: Rapeseed oil was obtained by cold pressing of raw materials. Ten evaluators tasted and scored the oil.

[0071] 2. Indicator Score:

[0072] Positive notes: nutty (2), oily (1), woody (1).

[0073] Negative: Vegetable flavor (4), spicy flavor (4), bitter almond flavor (2).

[0074] 3. Calculate the overall score:

[0075]

[0076] 4. Conclusion: The negative score of this sample indicates that the intensity of its negative flavor far exceeds that of its positive flavor. The vegetable and spicy flavors are too strong, which may be due to insufficient roasting temperature or raw material problems. The sensory quality is that of non-fragrant rapeseed oil.

[0077] This embodiment also provides verification of the above method:

[0078] 1. GC-MS Verification

[0079] GC-MS detection: Weigh 5g of rapeseed oil into a 20mL headspace vial and add 10μL of 0.816g / mL internal standard 2-methyl-3-heptanone. Adsorb the DVB / CAR / PDMS extraction material for 30min, then desorb at the GC injection port for 5min. Repeat three times for each sample. Chromatographic conditions: DB-WAX (30 m × 0.32 mm × 0.25 µm); Temperature program: 40℃ for 2min, increase to 200℃ at 4℃ / min, hold for 2min, then increase to 230℃ at 5℃ / min; Helium flow rate 1.3ml / min, injection port temperature 250℃, splitless injection mode. Mass spectrometry conditions: Electron energy 70eV; Ion source temperature 230℃; Transfer line temperature 250℃; Quadrupole temperature 150℃; Mass scan range m / z 40~350. Qualitative analysis: GC-MS raw data were matched with the NIST17 spectral library for qualitative analysis. Quantitative analysis: The internal standard method was used for quantification.

[0080] The results are as follows Figure 1 and Figure 2 As shown, the types and contents of flavor compounds in rapeseed oil treated with high pressure and wet heat are higher than those in the other three categories, which is consistent with the results calculated from the comprehensive flavor score.

[0081] 2. GC-IMS Verification

[0082] Take 1 mL of rapeseed oil and place it in a 20 mL headspace bottle.

[0083] Headspace injection conditions: headspace incubation temperature 80℃; incubation time 15 min; incubation rotation speed 500 r / min; injection volume 500 µL; headspace injection needle temperature 85℃.

[0084] GC conditions: MXT-5 column; column temperature 60℃; carrier gas N2 (purity > 99.999%); chromatographic run time 30 min; carrier gas flow rate gradient set to an initial flow rate of 1 mL / min, linearly increasing to 2 mL / min within 2 min, linearly increasing to 100 mL / min within 20 min, and linearly increasing to 100 mL / min within 30 min.

[0085] IMS conditions: drift tube temperature 45℃; drift gas N2 (purity > 99.999%); drift gas flow rate 150 mL / min.

[0086] The results are as follows Figure 3 As shown, the types of flavor compounds in rapeseed oil treated by high-pressure wet heat and traditional steaming and frying are significantly higher than those treated by other methods, which is consistent with the results calculated by the comprehensive flavor score formula.

[0087] 3. Electronic nose verification

[0088] Gas sampling: Weigh 5g of rapeseed oil into a 50mL sample bottle, seal it with sealing film, and equilibrate at room temperature for 5 minutes before electronic nose detection. The heating oven temperature is 60℃, the stirring speed is 500r / min, and each sample bottle is heated for 10 minutes. Detection parameters: gas washing time 180s, zeroing time 5s, sample preparation 5s; headspace sampling is used, injection time 120s, flow rate 0.4L / min, and three parallel tests are performed.

[0089] The electronic nose contains an array of 28 different metal oxide sensors. Each sensor responds to different atmospheric substances, as follows: S1 propane, smoke, etc.; S2 alcohol, smoke, isobutane, formaldehyde, etc.; S3 hydrogen; S4 sulfides; S5 ammonia, amines, etc.; S6 toluene, acetone, ethanol, hydrogen, etc.; S7 short-chain alkanes and flammable gases, etc.; S8 liquefied petroleum gas (LPG); S9 toluene, formaldehyde, benzene, alcohol, acetone, etc.; S10 hydrogen-containing gases; S11 alkanes, carbon monoxide, etc.; S12 LPG, methane, etc.; S13 short-chain alkanes; S14 methane, fuel gas, smoke, etc.; S15 ammonia, amines, etc.; S16 hydrogen sulfide; S17 hydrogen-containing substances; S18 aromatic hydrocarbons, aliphatic hydrocarbons. S19: Cyclic hydrocarbons, halogenated hydrocarbons, ethers, esters, glycol derivatives, acetonitrile, pyridine, phenol, etc.; S20: Alcohols, ketones, aldehydes, aromatic compounds, etc.; S21: Methane, biogas, natural gas, etc.; S22: Combustible gases, etc.; S23: Phenol, ketones, ethyl acetate, cyclohexanone, chlorobenzene, methylbenzene, ethers, etc.; S24: Alkanes, alkenes, liquefied petroleum gas, combustible gases, etc.; S25: Alkanes, alcohols, natural gas, smoke, etc.; S26: Some esters, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, cyclic hydrocarbons, halogenated hydrocarbons; S27: Smoke, cooking odors, etc.; S28: Methane, fuel gas, etc.

[0090] The test results are as follows. It is clear that the rapeseed oil treated with high pressure and wet heat has a better flavor than the other three types, followed by traditional steaming and frying, direct frying, and spiral cold pressing. This is consistent with the results calculated by the comprehensive flavor score formula.

[0091] This embodiment has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0092] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil, characterized in that, It includes the following steps: S1. Form an evaluation group and conduct training. Form a sensory evaluation group, train the evaluators on flavor recognition, and use standard reference samples to unify the evaluation criteria. S2. Construct a sensory evaluation index system for strongly fragrant rapeseed oil. Based on the flavor wheel theory, screen out the key flavor indicators of strongly fragrant rapeseed oil, and classify the key flavor indicators into two categories: positive gain indicators and negative loss indicators. S3. Implement quantitative descriptive analysis. The evaluators taste the test samples and score the intensity for the key flavor indicators. S4. Calculate the comprehensive flavor score. Use the comprehensive score formula to calculate the comprehensive flavor score S of strongly fragrant rapeseed oil. The comprehensive score formula is used to calculate the flavor net value, subtract the total intensity of defective flavors from the total intensity of pleasant flavors, and normalize it to a 100-point scale.

2. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 1, characterized in that: The number of people in the sensory evaluation group is 8 - 12. The standard reference samples include roasted sesame and peanuts representing nutty aroma, and lettuce seed grinding liquid representing green vegetable flavor. The flavor recognition training is carried out according to GB / T 1536 - 2021 and food sensory analysis method standards.

3. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 2, characterized in that: The number of the key flavor indicators is 6. The positive gain indicators include: Nutty flavor: aroma similar to roasted peanuts, sesame or walnuts; Greasy flavor: the mellow feeling unique to grease and strong fatty aroma; Woody flavor: deep aroma similar to dry wood and roasted plant fibers.

4. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 3, characterized in that, The negative loss indicators include: Green vegetable flavor: similar to the smell of grass and raw bean fishiness; Spiciness: the stinging feeling that stimulates the nasal cavity or oral cavity; Bitter almond flavor: obvious bitter aftertaste or bitterness.

5. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 1, characterized in that, In S3, the following scoring scale is established: Adopt a 0 - 5 scale. 0 points: not detected; 1 point: weak; 3 points: medium; 5 points: extremely strong.

6. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 5, characterized in that: In S3, it also includes data validity cleaning: count the scores of each indicator, calculate the coefficient of variation CV,剔除 the data of outlier evaluators with CV > 20%, and take the average value of the remaining valid data as the final score of this indicator.

7. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 1, characterized in that, The comprehensive score formula is: ； Where: P includes nutty, greasy, and woody flavors: respectively, the average score range of the evaluation group for positive indicators is 0 - 5 points; N includes green vegetable, spicy, and bitter almond flavors: respectively, the average score range of the evaluation group for negative indicators is 0 - 5 points; S is the comprehensive flavor score; α is the aroma enhancement coefficient, and the value of α is 1.2; β is the off-flavor tolerance coefficient, and the value of β is 0.

8.

8. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 7, characterized in that: The theoretical maximum positive contribution value of the comprehensive score formula is 15.0 points.

9. The quantitative sensory evaluation method for the flavor characteristics of fragrant rapeseed oil according to claim 7, characterized in that: The interpretation of the calculation result of the comprehensive flavor score S is: S > 60: High-quality strongly fragrant rapeseed oil, with positive flavors dominant; 0 < S ≤ 60: Qualified / ordinary strongly fragrant rapeseed oil; S < 0: Not strongly fragrant rapeseed oil, with negative flavors exceeding positive flavors and serious defects.

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