The Stability And Prediction Model Of Near Infrared Spectroscopy For Lycium Ruthenicum Murr Beverage Fermented With Lactic Acid Bacteria

Lycium ruthenicum Murr are a rich source of functional active substances,including anthocyanins,proanthocyanidins,phenols,and flavonoids.They contain the highest content of anthocyanins among all berries,earning them the nickname"king of anthocyanins".However,the instability of anthocyanins poses a challenge for processing Lycium ruthenicum Murr.This article explores the production process of fermented beverages using Lactobacillus casei to prepare Lycium ruthenicum Murr lactic acid bacteria.Developed a comprehensive protection technology and established a near-infrared spectroscopy rapid detection model to analyze the main components in the fermented beverage of Lycium ruthenicum Murr lactic acid bacteria.The main research content and results are as follows:（1）The production process for Lycium ruthenicum Murr lactic acid bacteria fermented beverage was optimized as follows.Firstly,enzymatic hydrolysis conditions were determined:adding 1 g/L of pectinase and cellulase,hydrolyzing at 37℃for 3.5 hours.Secondly,a strain of Lactobacillus casei with high retention rate of anthocyanins was screened as the fermentation strain,and the culture medium was optimized:30 g·L^-1 skim milk powder,70 g·L^-1glucose and80 g·L^-1 juice of Lycium ruthenicum Murr.Finally,the optimal fermentation conditions were obtained:solid-liquid ratio of 1:30（g:m L）,inoculation rate of 3%,fermentation temperature of37℃,fermentation time of 15 hours,and total acid content of approximately 3.5 g/L at the end of fermentation.Lactic acid bacteria fermentation significantly improved the stability of anthocyanins.By optimizing the sterilization parameters,a sterilization intensity of 85℃for 25minutes was determined.（2）The degradation kinetics of functional ingredients during sterilization in Lycium ruthenicum Murr lactic acid bacteria fermented beverage were studied,and a comprehensive protection technology was developed.The degradation behavior of functional ingredients and color during storage of Lycium ruthenicum Murr lactic acid bacteria fermented beverage at different temperatures were investigated.The degradation of anthocyanins,proanthocyanidins,total phenols,and total flavonoids followed first-order kinetics,while color degradation followed zero-order kinetics.A comprehensive protection technology was developed by controlling environmental factors and adding protective agents:the beverage was kept in the dark and the oxygen content was controlled below 0.5 mg/L,and 0.05%tea polyphenols were added as a protective agent.This process increased the anthocyanin content by 18.2%,proanthocyanidin content by 11.7%,total phenols content by 9.4%,and total flavonoids content by 7.6%,while reducing color difference by 19.7%.The degradation kinetics and storage experiments verified the enhanced stability of the beverage due to light avoidance,deoxygenation,and addition of protective agents.The comprehensive protection technology effectively improved the stability of functional ingredients during processing and storage of the beverage.（3）Established a shelf life prediction model for fermented beverages using Lycium ruthenicum Murr lactic acid bacteria and verified the accuracy of the model through actual storage experiments.During accelerated storage for 90 days at temperatures ranging from 40℃to 60℃,the degradation kinetics of sensory attributes,functional ingredient contents,microbial indicators,centrifugal precipitate rate,particle size,and Zeta potential were studied.Selected anthocyanins,Zeta potential,and centrifugal precipitate rate indicators with high correlation（R²>0.90）to sensory difference to construct the shelf life model.Compared the actual and predicted shelf lives at temperatures of 40℃,50℃,and 60℃,and found that the error between the actual and predicted shelf lives was less than 10%for all three temperatures when using the centrifugal precipitate rate as the indicator.Based on the shelf life prediction model:SS=1.52×exp「t（kbT）/hexp（（-0.23 T-23.15）/（RT））」+0.36 constructed using the centrifugal precipitate rate as the indicator,estimated the shelf life of fermented beverages using Lycium ruthenicum Murr lactic acid bacteria under normal temperature conditions of 25℃to be 236days.Moreover,when the beverage was stored at 40℃and normal temperature（about 25℃）for 180 days,the error between the predicted and actual centrifugal precipitate rate was less than 1%,indicating that the shelf life prediction model had good accuracy.（4）A near-infrared spectroscopy PLS prediction model was established for the content of anthocyanins,proanthocyanidins,total phenols,total flavonoids,and total acids in Lycium ruthenicum Murr lactic acid bacteria fermented beverage.Through optimization of 9preprocessing methods and 10 band combinations,the prediction models for anthocyanins,proanthocyanidins,and total acids had Rc² and Rp² greater than 0.9,RPD>2.5,indicating excellent prediction capabilities with reliable and robust results.The prediction models for total phenols and total flavonoids had Rc² and Rp² greater than 0.8,RPD>2.5,indicating good prediction capabilities that met the needs of rapid detection,with reliable and robust results.The prediction performance of 30 samples not included in the modeling was evaluated by Levene’s test and T-test.The results showed the mean absolute errors（MAE）of the predicted values and true values of anthocyanins,procyanidins,total phenols,total flavonoids and total acids were 7.42 mg/L,3.49 mg/L,0.04 g/L,0.09 g/L and 0.24 g/L,respectively.No significant difference between predicted values and measured values.The model had good generalization and reproducibility,and the established calibration model can be used for practical detection.Fourier transform near-infrared spectroscopy combined with chemometrics is a simple,fast,and reliable method for determining the content of anthocyanins,proanthocyanidins,total phenols,total flavonoids,and total acids in Lycium ruthenicum Murr lactic acid bacteria fermented beverage.