Study On The Preparation Conditions Of Whey Fermentation Broth

Whey fermented foods have received increasing attention from researchers and the market in recent years.Fermentation of whey with lactic acid bacteria and yeast not only increases the flavor of the product,improves the nutritional system,but also enhances the probiotic effect.In this paper,we developed a whey fermented beverage with high nutritional value and good flavor and investigated the whole engineering process.The fermentation broth,fermentation substrate and whey protein hydrolase species were studied,and the fermentation conditions of whey fermentation broth were optimized.The lactic acid bacteria addition amount and fermentation time in the two fermentation processes were also studied.The effect of fermentation temperature on the quality of whey fermentation broth,the specific experimental process and results are as follows:1)Determination of whey fermentation strains and fermentation substrates:whey fermentation broth was prepared from three lactic acid bacteria(Lactobacillus rhamnosus LV108,S treptococcus thermophilus grx02,and Lactobacillus helveticus LH100-3).Based on whey fermentation liquid characteristics and sensory flavor quality,Lactobacillus rhamnosus LV108 was selected as lactic acid bacteria fermentation strain.Then seven kinds of yeast(Kluyveromyces marxianus ATCC 8651/CCRC20540;Kluyveromyces lactis ATCC10689;Hansennula anomala 2.296;Saccharomyces cerevisiae ATCC9080/2.346/M05)with Lactobacillus rhamnosus LV108 were mixed to prepare whey fermentation broth.After studied the quality of the fermentation broth,Kluyveromyces marxianus CCRC20540 was selected as the fermentation yeast.At the same time,the effects of six whey powders(PILI,WPC72,D90,Wangxin,White Bird,and Argentina)on the quality of whey fermentation broth were researched.Among them,the whey fermentation broth prepared by whey powder(PILI)had a sensory score of up to 82 and a soluble solid content of 3.21%,which is in line with the requirement of preparing whey fermentation liquid with good sensory and high clarity.In order to determine the whey protease,the proteolytic rate of papain,flavor protease,neutral protease,alkaline protease,pepsin at different pH conditions were studied,and the bitterness value of the corresponding enzymatic hydrolysate was tasted and evaluated.Results showed that the enzymatic hydrolysis of papain reached at 21.4%,while the bitterness was the lowest,at 1.25.Therefore,papain was selected as the whey protein hydrolase of this experiment.2)Determination of primary fermentation conditions.The two different fermentation modes of Lactococcus lactis were examined:inoculating Lactococcus lactis at the first place or later in the following.The content of diacetyl and acetaldehyde was determined by o-phenvlenediamine method.Results showed that inoculating Lactococcus lactis in the first had higher diacetyl and acetaldehyde content.On this basis,fermentation of three strains of Lactococcus lactis MW0030,MWO039 and MWO040,and four groups of mixed bacteria(MWO030:MWO039=1:1,MW0030:MW0040=1:1,1-6MW0039:MW0040=1:1,MWO030:MW0039:MW0040=1:1:1)were explored.Results showed that when the fermentation strain of Lactococcus lactis was MWO039:MW0040=1:1(v/v).the content of diacetyl and acetaldehyde in the fermentation broth was the highest,reaching 12.03 mg/L and 8.21 mg/L.respectively.Next,the fermentation time,fermentation temperature,and Lactococcus lactis inoculation amount were determined by single factor test to be 32 h,32 ? and 2.0%,respectively.The fermentation process was optimized by response surface experiment.Results showed that when the dosage of Lactococcus lactis was 2.09%,the fermentation time was 31.6 h.and temperature was 34?,the flavor of fermented milk was the best,and the content of diacetyl was 15.24mg/L.while acetaldehyde content was 12.07 mg/L.3)Determination of secondary fermentation conditions.The fermentation broth obtained from Lactococcus lactis was used as a substrate,and five kinds(1.Lactobacillus thamnosus LV108 single strain fermentation;2.Kluyveromyces marxianus CCRC20540 single strain fermentation;3.simultaneous Lactobacillus rhamnosus LV108 mixed fermentation with Kluyveromyces marxianus CCRC20540;4.inoculating Lactobacillus rhamnosus LV108 single-fermentation fermentation,then inoculating Kluyveromyces marxianus CCRC20540 mixed fermentation;5.inoculating Kluyvero,myces marxianus CCRC20540 single-fermentation fermentation,then inoculating Lactobacillus rhamnosus LV108 mixed fermentation)second fermentation methods were carried out to prepare whey fermentation broth.Through comparing the clarification of the whey fermentation broth,the determination of flavor substances and the vitamin B,it was determined that the fermentation broth prepared by fermentation method 3 had the most flavor compounds,the soluble solid content was 3.46%,and the vitamin B content was VB1 of 1.08 mg/L,VB2 of 0.53 mg/L,VB 6 of 5.31 mg/L respectively.The fermentation time,fermentation temperature,lactic acid bacteria inoculum and yeast inoculum volume were determined by single factor test to be 72 h,30?,1.5%and 0.01%,respectively.The hybrid fermentation process was optimized by orthogonal experiment.The fermentation conditions were optimized and finally determined with fermentation time 72 h,fermentation temperature 30?,lactic acid bacteria inoculum volume 1.5%,and yeast inoculum volume 0.1%.4)Determination of fermentation characteristics,nutritional value,probiotic ability and flavor substances of whey fermentation broth.The whey fermentation broth has an aciditv of 84.85°T,an alcohol content of 0.47%,a solid content of 3.32%,a turbidity of 38.9 NTU,and a high clarity of the fermentation broth,which is beneficial to the sensory quality of the whey fermentation broth.The final product contains vitamin B 7.18mg/L,and six kinds of essential amino acids with the total content is 398mg/100mL.Total antioxidant capacity is 9.51U/mL and ACEI 67.54%.In addition,the organic acid content is:malic acid 0.47 mg/mL.lactic acid 2.43 mg/mL.acetic acid 0.88 mg/mL.citric acid 0.16 mg/mL.and succinic acid 0.63 mg/mL.The main components of flavor substances are six kinds of alcohols(ethanol,isoamyl alcohol.isobutanol,phenylethyl alcohol,tetradecyl alcohol,and 2-cis-9-octadecenyloxyl),accounting for 36.89%.The esters accounted for 16.01%(ethyl acetate,ethyl lactate,ethyl stearate,ethyl octanoate,ethyl decanoate and isoamyl acetate),and 12 kinds of acids(acetic acid,lactic acid.octanoic acid,butyric acid,lauric acid,palmitic acid,heptadecanoic acid,enoic acid,pentadecanoic acid,10-octadecenoic acid,benzoic acid,and Z-7-hexadecenoic acid)accounted for 29.52%.