CN108982883A - A kind of prediction Fresh-cut Lettuce shelf life model - Google Patents

Abstract

The present invention provides a kind of prediction Fresh-cut Lettuce shelf life models to be utilized by studying the variation that the vitamin C of Fresh-cut Lettuce and chlorophyll content occur with the extension of storage time at different temperaturesArrheniusEquation respectively models vitamin C and chlorophyll, and obtaining shelf life forecasting model is chlorophyll content shelf life forecasting model: SL_chlo=ln(C/C₀)/(- 1.16 × 10¹⁴×e^{(- 83100/8.314T)})；Vitamin C content shelf life forecasting model: SL_Vc=ln(V/V₀)/(- 2.39 × 10¹⁵×e^{(- 90300/8.314T)})；With the shelf life measured value at a temperature of 283K, separately verify the accuracy of the prediction model, by comparing the predicted value and relative error of two kinds of shelf life models, show that characterized by vitamin C, index models, can the shelf life preferably to Fresh-cut Lettuce in 0 ~ 20 DEG C of temperature range carry out real-time monitoring.

Description

Translated fromChinese

一种预测鲜切生菜货架期模型A model for predicting the shelf life of fresh-cut lettuce

技术领域technical field

本发明涉及一种预测鲜切蔬菜货架期模型，尤其是一种预测鲜切生菜货架期的模型。The invention relates to a model for predicting the shelf life of fresh-cut vegetables, in particular to a model for predicting the shelf life of fresh-cut lettuce.

背景技术Background technique

生菜又称叶用莴苣，是一种营养丰富的绿叶蔬菜，由于生菜中富含维生素、碳水化合物和矿物质等营养物质，常作为蔬菜沙拉食用。然而，鲜切产品的退化速度比未加工的原料快得多，主要是由于最小加工方法（去皮、切片、切块、切碎等）所造成的损害，如组织软化、切割表面褐变，降低营养价值，存在异味和微生物腐败，在贮藏过程中通常会缩短鲜切果蔬的货架期。近年来，鲜切产品的需求量迅速增长，但货架期的限制仍然是鲜切果蔬产业进一步发展的最大障碍。因此，本文通过货架期模型预测鲜切蔬菜流通中品质变化，对其货架期进行实时监测，具有一定的实用价值。Lettuce, also known as leaf lettuce, is a nutritious green leafy vegetable. Because lettuce is rich in nutrients such as vitamins, carbohydrates and minerals, it is often eaten as a vegetable salad. However, fresh-cut products degrade much faster than unprocessed raw materials, mainly due to damage caused by minimal processing methods (peeling, slicing, dicing, chopping, etc.), such as tissue softening, browning of cut surfaces, Reduced nutritional value, presence of off-flavors and microbial spoilage during storage often shorten the shelf life of fresh-cut fruits and vegetables. In recent years, the demand for fresh-cut products has grown rapidly, but the limitation of shelf life is still the biggest obstacle to the further development of the fresh-cut fruit and vegetable industry. Therefore, it is of practical value to use the shelf life model to predict the quality changes of fresh-cut vegetables in circulation and to monitor their shelf life in real time.

维生素C和叶绿素是蔬菜非常重要的两个营养指标，在贮藏过程中随着贮藏时间的延长，其营养成分会发生很大的变化，可依据其品质指标的含量判定其货架期。目前以温度为基础的预测模型是食品货架期预测最常用的一种方法，其中常用的方法是Arrhenius方程，该方程可以反映速率常数与温度之间的关系，可以用来描述品质衰变动力学。国内关于鲜切生菜在不同条件下的品质变化研究颇多，但对鲜切生菜在物流过程中以维生素C和叶绿素等为特征指标而建立的货架期预测模型的报道很少，缺少一种比较准确的预测货架期的方法。本文通过对鲜切生菜的维生素C和叶绿素在不同贮藏温度下变化规律的研究，利用Arrhenius方程分别对维生素C和叶绿素进行建模，通过比较两个模型的预测值和相对误差，从而得到一种更为准确的鲜切生菜货架期模型。Vitamin C and chlorophyll are two very important nutritional indicators of vegetables. During storage, as the storage time prolongs, their nutritional components will change greatly. The shelf life can be determined according to the content of their quality indicators. At present, the temperature-based prediction model is the most commonly used method for food shelf life prediction. The commonly used method is theArrhenius equation, which can reflect the relationship between the rate constant and temperature, and can be used to describe the quality decay kinetics. There are many domestic studies on the quality change of fresh-cut lettuce under different conditions, but there are few reports on the shelf-life prediction model established by using vitamin C and chlorophyll as characteristic indicators in the logistics process of fresh-cut lettuce, and there is a lack of a comparison. Accurate method for predicting shelf life. In this paper, through the study of the change law of vitamin C and chlorophyll of fresh-cut lettuce under different storage temperatures, theArrhenius equation was used to model vitamin C and chlorophyll respectively. By comparing the predicted values and relative errors of the two models, a kind of A more accurate shelf-life model for fresh-cut lettuce.

发明内容Contents of the invention

本发明的目的是提供一种预测鲜切生菜货架期的方法，维生素C和叶绿素是蔬菜最重要的两个营养指标，本发明以维生素C和叶绿素为特征指标，通过Arrhenius方程建立货架期模型，通过比较两个模型的预测值和相对误差，从而找到一种更为准确的货架期预测模型，更好地检测鲜切生菜在流通过程中的品质变化情况，更有效地评估流通过程中的营养变化情况以及货架期终点。The purpose of the present invention is to provide a method for predicting the shelf life of fresh-cut lettuce. Vitamin C and chlorophyll are the two most important nutritional indicators of vegetables. The present invention uses vitamin C and chlorophyll as characteristic indicators, and establishes a shelf life model through theArrhenius equation. By comparing the predicted values and relative errors of the two models, a more accurate shelf-life prediction model can be found, which can better detect the quality changes of fresh-cut lettuce in the circulation process, and more effectively evaluate the nutrition in the circulation process Changes and end of shelf life.

本发明通过以下技术步骤来实现：The present invention is realized through the following technical steps:

（1）挑选大小均一、颜色鲜亮、脆嫩、无腐烂虫害的生菜，将挑选好的生菜用酒精消毒的菜刀将整颗生菜切成3~5cm的小段，在自来水中浸泡5 min后，捞出沥干，于通风阴凉处晾晒1 h；(1) Select lettuce that is uniform in size, bright in color, crisp and tender, and free from rotten insects. Use an alcohol-sterilized kitchen knife to cut the whole lettuce into small pieces of 3 to 5 cm. Soak it in tap water for 5 minutes. Drain and dry in a cool and ventilated place for 1 hour;

（2）将鲜切生菜盛放在塑料托盘中并用保鲜膜包裹，每盒80 g左右，分别放入273、278、288、293 K恒温箱内贮藏，试验初期分别隔3 d、3 d、1.5 d、1 d、0.5 d测试一次，末期则依据品质变化情况调整频率。每个指标均进行2~3次平行实验，以确保实验数据稳定可用，最后计算平均值及标准差。(2) Put fresh-cut lettuce in plastic trays and wrap them with plastic wrap, about 80 g per box, and store them in incubators at 273, 278, 288, and 293 K, respectively. Test once every 1.5 d, 1 d, and 0.5 d, and adjust the frequency at the end according to the quality change. For each indicator, 2 to 3 parallel experiments were carried out to ensure that the experimental data was stable and available, and finally the average value and standard deviation were calculated.

（3）建立维生素C和叶绿素随着贮藏温度变化的动力学模型。分别用零级和一级化学反应动力学模型对不同贮藏温度的维生素C和叶绿素进行回归分析，确定一级动力学更适合反映鲜切生菜维生素和叶绿素等品质指标的变化规律，并且一级动力学方程的决定系数R²均大于0.95，具有较高的拟合精度。(3) Establish the dynamic model of vitamin C and chlorophyll with storage temperature. The zero-order and first-order chemical reaction kinetic models were used to perform regression analysis on vitamin C and chlorophyll at different storage temperatures. The coefficient of determination R² of the scientific equations is greater than 0.95, which has a high fitting accuracy.

（4） 根据鲜切生菜在273 K、278 K、288 K、293 K下贮藏过程中的叶绿素和维生素C的变化规律，以1/T为横坐标，以lnk为纵坐标，进行线性回归，由于叶绿素和维生素C一级动力学模型速率k均为负数，因此本试验以ln（-k）为纵坐标进行拟合，从而求得指前因子A₀、活化能E_a等货架期预测模型参数。(4) According to the changes of chlorophyll and vitamin C in fresh-cut lettuce during storage at 273 K, 278 K, 288 K, and 293K , linear regression was performed with 1/T as the abscissa and lnk as the ordinate , since the ratek of the first-order kinetic model of chlorophyll and vitamin C is negative, so this experiment uses ln(-k ) as the ordinate to fit, so as to obtain the pre-exponential factor A₀ , activation energy E_a and other shelf-life predictions Model parameters.

（5） 由此得到维生素C和叶绿素的货架期预测模型为：(5) The shelf life prediction model of vitamin C and chlorophyll is obtained as follows:

维生素C含量货架期预测模型：SL_chlo=ln(C/C₀)/（-1.16×10¹⁴×e^{（-83100/8.314T）}）；Shelf life prediction model for vitamin C content: SL_chlo =ln(C/C₀ )/(-1.16×10¹⁴ ×e^{(-83100/8.314T)} );

叶绿素含量货架期预测模型：SL_chlo= ln(V/V₀)/（-2.39×10¹⁵×e^{（-90300/8.314T）}）；Chlorophyll content shelf life prediction model:SL_chlo = ln(V/V₀ )/(-2.39×10¹⁵ ×e^{(-90300/8.314T)} );

式中SL_chlo、SL_vc分别叶绿素和维生素C的货架期，C₀、V₀、C、V分别为叶绿素和维生素C的初始含量和贮藏第t d时的测量值。In the formula,SL_chlo ,SL_vc are the shelf life of chlorophyll and vitamin C respectively, andC₀ ,V₀ ,C ,V are the initial content of chlorophyll and vitamin C and the measured values at td of storage, respectively.

（6）对建立的货架期预测模型进行验证和评价：选取样品在10℃（283 K）条件下的货架期实测值，验证该预测模型的准确性。以维生素C和叶绿素损失20%时的状态为鲜切生菜货架期终点，通过比较实测值与预测值来验证模型SL_chlo和SL_vc的准确性，结果如表3所示。由表3可知货架期模型SL_vc和SL_chlo的相对误差分别为4.44%和8.89%，均在10%以内，可以被接受。与货架期预测模型SL_chlo相比，货架期模型SL_vc的相对误差更小，预测值更准确，说明以维生素C为特征指标建立的货架期模型优于以叶绿素为特征指标建立的货架期模型。(6) Verify and evaluate the established shelf life prediction model: Select the measured value of the shelf life of the sample at 10°C (283 K) to verify the accuracy of the prediction model. Taking the state of vitamin C and chlorophyll loss of 20% as the end point of the shelf life of fresh-cut lettuce, the accuracy of the models SL_chlo and SL_vc was verified by comparing the measured and predicted values. The results are shown in Table 3. It can be seen from Table 3 that the relative errors of the shelf life models SL_vc and SL_chlo are 4.44% and 8.89%, respectively, both within 10% and acceptable. Compared with the shelf-life prediction model SL_chlo , the relative error of the shelf-life model SL_vc is smaller and the prediction value is more accurate, indicating that the shelf-life model established with vitamin C as the characteristic index is better than the shelf-life model established with chlorophyll as the characteristic index .

本发明具体的实施步骤如下：Concrete implementation steps of the present invention are as follows:

(1) 挑选大小均一、色泽鲜艳、脆嫩、无腐烂虫害的生菜；(1) Choose lettuce that is uniform in size, bright in color, crisp and tender, and free from rot and pests;

(2)鲜切生菜经处理后，立即用保鲜膜包装好放在恒温箱内贮藏，不定期对维生素C和叶绿素(2) After the fresh-cut lettuce is processed, immediately pack it with plastic wrap and store it in an incubator.

进行测定；to measure;

(3)建立维生素C和叶绿素随着贮藏温度变化的动力学模型；(3) Establish a kinetic model of vitamin C and chlorophyll as the storage temperature changes;

(4)建立零级和一级化学反应动力学的参数，选取更适合表现生菜各指标品质变化规律；(4) Establish the parameters of the zero-order and first-order chemical reaction kinetics, and select the parameters that are more suitable for expressing the quality changes of lettuce indicators;

(5)运用Origin 8.6软件进行线性和非线性拟合，得到不同温度下TBA值的速率常数k、决定系数R²和∑R²进行比较，最后求出TBA值的速率常数A₀活化能E_a；(5) Use Origin 8.6 software to perform linear and nonlinear fittings to obtain the rate constant^k , coefficient of determination R2 and^ΣR2 of TBA values at different temperatures for comparison, and finally obtain the rate constant_A0 activation energy E of TBA values_a ;

(6)以维生素C和叶绿素为特征指标建立货架期预测模型；(6) Establish a shelf life prediction model with vitamin C and chlorophyll as characteristic indicators;

叶绿素含量货架期预测模型：SL_chlo=ln(C/C₀)/（-1.16×10¹⁴×e^{（-83100/8.314T）}）；Chlorophyll content shelf life prediction model: SL_chlo =ln(C/C₀ )/(-1.16×10¹⁴ ×e^{(-83100/8.314T)} );

维生素C含量货架期预测模型：SL_Vc=ln(V/V₀)/（-2.39×10¹⁵×e^{（-90300/8.314T）}）；Shelf life prediction model for vitamin C content: SL_Vc =ln(V/V₀ )/(-2.39×10¹⁵ ×e^{(-90300/8.314T)} );

式中SL_chlo、SL_vc分别叶绿素和维生素C的货架期，C₀、V₀、C、V分别为叶绿素和维生素C的初始含量和贮藏第t d时的测量值；In the formula,SL_chlo ,SL_vc are the shelf life of chlorophyll and vitamin C respectively, andC₀ ,V₀ ,C ,V are the initial content of chlorophyll and vitamin C and the measured values at td of storage, respectively;

(7)在283K温度下鲜切生菜的维生素C和叶绿素变化情况来预测和验证货架期模型的准确性。(7) Changes of vitamin C and chlorophyll in fresh-cut lettuce at 283K to predict and verify the accuracy of the shelf-life model.

本发明的货架期模型可以更准确地对0~20℃温度范围内鲜切生菜的货架期进行实时监测。更好地检测鲜切生菜在流通过程中的品质变化情况，更有效地评估流通过程中的营养变化情况以及货架期终点。The shelf life model of the invention can more accurately monitor the shelf life of fresh-cut lettuce in the temperature range of 0-20°C in real time. Better detection of quality changes of fresh-cut lettuce during circulation, more effective assessment of nutritional changes during circulation and end of shelf life.

具体实施方式Detailed ways

挑选大小均一、颜色鲜亮、脆嫩、无腐烂虫害的生菜，将挑选好的生菜用酒精消毒的菜刀将整颗生菜切成3~5cm的小段，在自来水中浸泡5 min后，捞出沥干，于通风阴凉处晾晒1 h。 Select lettuce with uniform size, bright color, crisp tenderness, and no rot and pests. Cut the selected lettuce into 3~5cm pieces with an alcohol-sterilized kitchen knife, soak in tap water for 5 minutes, remove and drain , and dry in a cool and ventilated place for 1 hour.

将鲜切生菜盛放在塑料托盘中并用保鲜膜包裹，每盒80 g左右，分别放入273、278、288、293 K恒温箱内贮藏，试验初期分别隔3 d、3 d、1.5 d、1 d、0.5 d测试一次，末期则依据品质变化情况调整频率。每个指标均进行2~3次平行实验，以确保实验数据稳定可用，最后计算平均值及标准差。Fresh-cut lettuces were placed in plastic trays and wrapped with plastic wrap, about 80 g per box, and stored in 273, 278, 288, and 293 K incubators, respectively. Test once every 1 day and 0.5 days, and adjust the frequency according to the quality change at the end. For each indicator, 2 to 3 parallel experiments were carried out to ensure that the experimental data was stable and available, and finally the average value and standard deviation were calculated.

建立维生素C和叶绿素随着贮藏温度变化的动力学模型。分别用零级和一级化学反应动力学模型对不同贮藏温度的维生素C和叶绿素进行回归分析，确定一级动力学更适合反映鲜切生菜维生素和叶绿素等品质指标的变化规律，并且一级动力学方程的决定系数R²均大于0.95，具有较高的拟合精度。相关参数见表1。A dynamic model of vitamin C and chlorophyll changes with storage temperature was established. The zero-order and first-order chemical reaction kinetic models were used to perform regression analysis on vitamin C and chlorophyll at different storage temperatures. The coefficient of determination R² of the scientific equations is greater than 0.95, which has a high fitting accuracy. The relevant parameters are shown in Table 1.

表1零级和一级动力学反应速率常数k及决定系数R²Table 1 Zero-order and first-order kinetic reaction rate constantk and coefficient of determinationR²

（4） 根据鲜切生菜在273 K、278 K、288 K、293 K下贮藏过程中的叶绿素和维生素C的变化规律，以1/T为横坐标，以lnk为纵坐标，进行线性回归，由于叶绿素和维生素C一级动力学模型速率k均为负数，因此本试验以ln（-k）为纵坐标进行拟合，从而求得指前因子A₀、活化能E_a等货架期预测模型参数，如表2所示。(4) According to the changes of chlorophyll and vitamin C in fresh-cut lettuce during storage at 273 K, 278 K, 288 K, and 293K , linear regression was performed with 1/T as the abscissa and lnk as the ordinate , since the ratek of the first-order kinetic model of chlorophyll and vitamin C is negative, so this experiment uses ln(-k ) as the ordinate to fit, so as to obtain the pre-exponential factor A₀ , activation energy E_a and other shelf-life predictions The model parameters are shown in Table 2.

表2品质指标货架期预测模型参数Table 2 Parameters of quality index shelf life prediction model

（5） 由此得到维生素C和叶绿素的货架期预测模型为： (5) The shelf life prediction model of vitamin C and chlorophyll is obtained as follows:

维生素C含量货架期预测模型：Vitamin C content shelf life prediction model:

SL_Vc=ln(V/V₀)/（-2.39×10¹⁵×e^{（-90300/8.314T）}）；SL_Vc = ln(V/V₀ )/(-2.39×10¹⁵ ×e^{(-90300/8.314T)} );

叶绿素含量货架期预测模型：Chlorophyll content shelf life prediction model:

SL_chlo=ln(C/C₀)/（-1.16×10¹⁴×e^{（-83100/8.314T）}）；SL_chlo = ln(C/C₀ )/(-1.16×10¹⁴ ×e^{(-83100/8.314T)} );

式中SL_chlo、SL_vc分别叶绿素和维生素C的货架期，C₀、V₀、C、V分别为叶绿素和维生素C的初始含量和贮藏第t d时的测量值。In the formula,SL_chlo ,SL_vc are the shelf life of chlorophyll and vitamin C respectively, andC₀ ,V₀ ,C ,V are the initial content of chlorophyll and vitamin C and the measured values at td of storage, respectively.

（6）对建立的货架期预测模型进行验证和评价：选取样品在10℃（283 K）条件下的货架期实测值，验证该预测模型的准确性。以维生素C和叶绿素损失20%时的状态为鲜切生菜货架期终点，通过比较实测值与预测值来验证模型SL_chlo和SL_vc的准确性，结果如表3所示。由表3可知货架期模型SL_vc和SL_chlo的相对误差分别为4.44%和8.89%，均在10%以内，可以被接受。与货架期预测模型SL_chlo相比，货架期模型SL_vc的相对误差更小，预测值更准确，说明以维生素C为特征指标建立的货架期模型优于以叶绿素为特征指标建立的货架期模型。(6) Verify and evaluate the established shelf life prediction model: Select the measured value of the shelf life of the sample at 10°C (283 K) to verify the accuracy of the prediction model. Taking the state of vitamin C and chlorophyll loss of 20% as the end point of the shelf life of fresh-cut lettuce, the accuracy of the models SL_chlo and SL_vc was verified by comparing the measured and predicted values. The results are shown in Table 3. It can be seen from Table 3 that the relative errors of the shelf life models SL_vc and SL_chlo are 4.44% and 8.89%, respectively, both within 10% and acceptable. Compared with the shelf-life prediction model SL_chlo , the relative error of the shelf-life model SL_vc is smaller and the prediction value is more accurate, indicating that the shelf-life model established with vitamin C as the characteristic index is better than the shelf-life model established with chlorophyll as the characteristic index .

表3 283 K下鲜切生菜的实测值与预测值Table 3 Measured and predicted values of fresh-cut lettuce at 283 K

因此以维生素为特征指标建立起的货架期模型可以更准确地对0~20℃温度范围内鲜切生菜的货架期进行实时监测。Therefore, the shelf life model established with vitamins as characteristic indicators can more accurately monitor the shelf life of fresh-cut lettuce in the temperature range of 0-20 °C in real time.

Claims (5)

1. a kind of prediction Fresh-cut Lettuce shelf life model, it is characterised in that: store Fresh-cut Lettuce respectively at different temperatures, surveyVitamin C and chlorophyll have been determined with the changing rule of storage time, establish shelf life forecasting model；Specific step is as follows:

(1) uniform, bright in colour, tender and crisp, without insect pest of rotting the romaine lettuce of size is selected；

(2) Fresh-cut Lettuce after processing, is packaged to be placed in insulating box with preservative film and be stored immediately, irregularly to vitamin C andChlorophyll

It is measured；

(3) vitamin C and chlorophyll are established with the kinetic model of storage temperature fluctuation；

(4) parameter of zero level and level-one Chemical Kinetics is established, selection is more suitable for showing each index quality comparison rule of romaine lettuceRule；

(5) with 8.6 software of Origin carry out linear and nonlinear fitting, obtain the rate constants k of TBA value under different temperatures,Coefficient of determination R²With ∑ R²It is compared, finally finds out the rate constant A of TBA value₀Activation energy_a；

(6) the Index Establishment shelf life forecasting model characterized by vitamin C and chlorophyll；

Chlorophyll content shelf life forecasting model:

SL_chlo=ln(C/C₀)/(- 1.16 × 10¹⁴×e^{(- 83100/8.314T)})；

Vitamin C content shelf life forecasting model:

SL_Vc=ln(V/V₀)/(- 2.39 × 10¹⁵×e^{(- 90300/8.314T)})；

In formulaSL_chlo、SL_vcChlorophyll and ascorbic shelf life respectively,C₀、V₀、C、VRespectively chlorophyll and ascorbicMeasured value when initial content and storage t d；

(7) shelf life model is predicted and verified to the vitamin C of Fresh-cut Lettuce and chlorophyll situation of change at a temperature of 283KAccuracy.

2. a kind of prediction Fresh-cut Lettuce shelf life model as described in claim 1, it is characterised in that: romaine lettuce is impregnated through tap waterIt is dried into 1 h in ventilating and cooling place after processing, avoid its because temperature is excessively high, caused by overlong time Fresh-cut Lettuce lose it is originalNutritive value.

3. a kind of prediction Fresh-cut Lettuce shelf life model as described in claim 1, it is characterised in that: Fresh-cut Lettuce in 273,278,283,285K, the interior storage of 293 K insulating boxs, test initial stage is primary every 3 d, 3 d, 1.5 d, 1 d, 0.5 d test respectively,Latter stage then adjusts frequency according to quality comparison situation；Each index carries out 2 ~ 3 parallel laboratory tests, to ensure that experimental data is stablizedIt can use, finally calculate average value and standard deviation.

4. a kind of prediction Fresh-cut Lettuce shelf life model as described in claim 1, it is characterised in that: pass through corresponding quality energyGrade Functional Analysis determines that first order kinetics are more suitable for reflecting the changing rule of Fresh-cut Lettuce vitamin C and chlorophyll, and level-one is dynamicThe coefficient of determination R2 of mechanical equation is all larger than 0.95.

5. the shelf life forecasting model of Fresh-cut Lettuce as described in claim 1, it is characterised in that: with chlorophyll and vitamin CState when losing 20% is Fresh-cut Lettuce shelf life terminal, by shelf life model at a temperature of 283KSL_chloWithSL_vcPredicted valueIt is compared with relative error, obtaining one kind, more accurately prediction Fresh-cut Lettuce shelf life model is Vitamin C content shelf lifePrediction model:

SL_Vc=ln(V/V₀)/(- 2.39 × 10¹⁵×e^{(- 90300/8.314T)}),

In formulaSL_vcAscorbic shelf life respectively,V₀、VMeasurement when respectively ascorbic initial content and storage t dValue.