Ethanol Extract From Morus Alba L.Leaves:Optimization Of The Extraction Process And Its Application In Chilled Pork Preservation

Mulberry(Morus alba L),a treasure all over the body,whose leaves is a kind of edible and medicinal natural material.Frosted mulberry leaf was the batter one which contains a variety of bioactive components,such as flavonoids,polyphenols,and polysaccharides,with antioxidant,hypoglycemic and antibacterial activities.These biological activities give it potential for use in the food and drug industry.Chilled pork is popular as the advantages of high safety,rich nutritional value,and sensory comfort.However,chilled pork is in 4?environments from production to market,which is more likely to deteriorate than frozen meat.Therefore,it is very important to develop a healthy,efficient,economic,and environmental protection preservative.The ethanol extraction process from mulberry leaf was optimized by the response surface method.The bioactivities including antibacterial,antioxidant,hypoglycemic activities,and?-amylase inhibitory activity were evaluated of ethanol extracts and its petroleum ether fraction,ethyl acetate fraction,and n-butanol fraction.To select the safe and economical samples for preservation of chilled pork,analytic hierarchy process(AHP)was used to evaluate four kinds of extracts comprehensively.The main contents of this paper are as follows:(1)Taking the extraction yield of flavonoids as the response value,the effects of ethanol concentration,extraction time,solid-liquid ratio,and extraction temperature on the yield were investigated.According to the single factor experimental results,the experiment was designed by response surface method in four factors-three levels by using Design-Expert software.After linear fitting and response surface analysis,the optimal extraction conditions were obtained as follows:extraction temperature of70.85?,ethanol concentration of 39.3%,extraction time of 120.18 min,and solid-liquid ratio of 1:34.64(g:m L)with the theoretical yield of flavonoids50.33mg/g.To verify the accuracy of the prediction model,the optimal parameters were modified.Three experiments were repeated under the optimal conditions,and the experimental values were basically consistent with the predicted values,indicating that the model could predict the actual extraction of flavonoids from mulberry leaves.(2)The results showed that all the samples of ethanol extract(MLF),petroleum ether fraction(MLF_p),ethyl acetate fraction(MLF_e),and n-butanol fraction(MLF_b)had antibacterial activities against Staphylococcus aureus,Bacillus pumilus,and Bacillus subtilis.By comparing the minimum inhibitory concentration(MIC)values of MLF,MLF_b,MLF_e and MLF_b of mulberry leaves to S.aureus,B.pumilus,B.subtilis and E.coli,it can be determined that MLF_e has the strongest antibacterial activity.The IC₅₀/EC₅₀ of ABTS⁺free radical scavenging ability,DPPH free radical scavenging ability,and total reducing power of the four samples were compared which was in the order of MLF_e>MLF_b>MLF>MLF_p.The inhibitory activity of?-amylase was in the order of MLF_b>MLF_e>MLF>MLF_p.All these results illustrated that the effective components extracted by various extractants were different.MLF_bwas more conducive to the extraction of hypoglycemic components from MLFe,followed by MLF,and MLFp.The hemolysis test showed that there was no hemolysis in the concentration of 0.005-1 mg/m L of ethanol extract,which indicated that the ethanol extract of mulberry leaves was safe in food and medicine industry.(3)The extraction yield(reciprocal of yield),antibacterial activity(MIC),antioxidant activity(IC₅₀/EC₅₀)and?-amylase inhibitory activity(IC₅₀)were taken as indexes to evaluate the four samples comprehensively by the analytic hierarchy process.Through the establishment of mathematical model,the weight coefficients were calculated and analyzed.Finally,the comprehensive score was calculated,and the ethyl acetate,with the lowest score,was the best sample followed by the ethanol extract.The ethanol extract was selected as the raw material of meat preservation for economic and the complicated composition reason.(4)The pH,TBARS value,TVB-N value,and colony number of the meat samples was measured of the chilled pork samples.Combined with sensory evaluation,the results showed that MLF had good preservation performance,positively correlated with the concentration,which could extend the storage period to 9 days.According to the bioactivity of MLF,this paper explored its application in the preservation of chilled pork,provided a new raw material for natural preservatives,and provided a new idea for the development and application of mulberry products.