New Researches in Biotechnology - Facultatea de Biotehnologii ...

More documents

Recommendations

Info

Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 2011cheeses is related to Gouda type cheeses, there are some differences regarding toadded amount of starter, pH of grains and whey mixture before heating forHolandes cheese and prolonged pressing before brining of Krievijas cheese forintensification of lactic acid fermentation process.The samples of unripened cheese were packed in a polymer material film,and ripened for 60 days at 6 °C and 12 °C. Ripening temperature was chosentaking as a basis conclusions in research articles relating variability of microflora(6 °C), and the recommended ripening parameters (12 °C) for Krievijas andHolandes cheeses. The both ripening regimes help understand better the influenceof microflora on the quality of cheese, including the formation of sensoryproperties.Determination of the pH was performed to cheese samples, according toLVS ISO 5546:2010 ‘Caseins and caseinates – determination of the pH’, by usingpH-meter, 3520 pH Meter’-JENWAY (Barloworld Scientific Ltd., Essex, UK).Determination of water activity was performed for cheese samples, byusing Meter AquaLab LITE (Decagon Inc, USA). Samples for determination ofwater activity were measured with accuracy ± 0,015. Prior to sample analyzingcalibration of the equipment was performed by means of 0.5M KCl (Lot 932375,Decagon).Determination of Lactobacillus spp. was performed in analysed samples, accordingto LVS ISO 15214:1998 by using MRS agar media (Scharlau, Spain). Media wasprepared according to LVS CEN ISO/TS 11133-1:2009. Sample dilutions wereperformed according to LVS EN ISO 8261:2002 and ISO 6887-5:2010.Colony forming units of the lactic acid bacteria were determined by meansof ISO 15214:1998. The chosen parameters for cultivation of lactic acid bacteria inMRS agar were 72 hours at 37 °C, taking as a basis regimes recommended in thescientific literature (Coeuret et al., 2003).Identification of Lactobacillus spp. colonies was performed taking as a basisfermentation of carbohydrates by using API 50 CHL (BioMerieux, France). Theprogram APILAB Plus version 4.0 (BioMerieux) was used for identification of theisolated colonies up to species.Isolation of DNA was performed for most frequently identifiedrepresentatives of Lactobacillus spp. species - L.plantarum 1, L.curvatus, by usingPowerSoil DNA Isolation Kit (MO BIO Laboratories Inc.).Polymerase chain reaction analysis was performed for confirmation of theisolated Lactobacillus species. The obtained sequences were analyzed at StadenPackage 1.6.0. release (http://staden.sourceforge.net/) and compared to sequencesavailable in the data base BLAST (www.ncbi.nlm.nih.gov ).Data analyse was performed by using StatistiXL and Microsoft Excel programs.228
Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 20113. RESULTSIn the beginning of cheese ripening the concentration of starter lactic acidbacteria decreases rapidly, thus liberating space for multiplication of non-starterlactic acid bacteria.In the Tables 1, summarization about the lactic acid bacteria speciesisolated from Krievijas cheese is provided, as well as variability of species underthe influence of temperature and duration of ripening is given.In the beginning of ripening Krievijas cheese II presence of starter microflorawas detected and prevalence of L.curvatus until the 30 th ripening day attemperature 6 °C was observed. From a sample ripened for 45 days at temperature6 °C L.helveticus was isolated. Williams and Banks (1997) report on isolation ofL.helveticus from Cheddar cheese ripened for 6 – 9 months, considering thisspecies as non-starter lactic acid bacteria. During ripening of Krievijas cheese I andII at temperature 12 o C, a presence of L.plantarum 1 was detected.Table 2The changes of Lactobacillus spp. during Krievijas cheese ripeningRipeningat 6 o Cat 12 o Ctime, days Krievijas cheese I Krievijas cheese II Krievijas cheese I Krievijas cheese IILc.lactisLc.lactis subsp.lactis 1,Lc.lactis subsp.lactis 1, Lc.lactis subsp.lactisUnripened subsp.lactis 1, Lc.lactisL.curvatus 1, Lc.lactisL.curvatus subsp.lactis 2,subsp.lactis 2,L.curvatusL.curvatus15 daysLc.lactis subsp.lactis 2,L.curvatusL.plantarum 130 days L.curvatus45 daysL.curvatusL.helveticus L.curvatus L.plantarum S460 daysL.paracasei subsp.paracasei JCM 8133L.paracasei MH55,L.plantarum DSPV354TDNA fragment sequencing of most frequently identified L.plantarum 1 andL.curvatus revealed that nucleotide sequence of L.curvatus of ripened cheese for 60days at 6 °C conforms to the strain L.paracasei subsp.paracasei JCM 8133, but incheese ripened for 60 days at 12 °C – to the strain L.paracasei MH55. In their turn,the isolated L.plantarum 1 from cheese samples ripened for 45 and 60 days at 12°C conform to the strains L.plantarum S4 and L.plantarum DSPV 354Trespectively.API 50 CHL system applied for identification of Lactobacillusphenotypically showed satisfactory results when determining genus ofmicroorganisms. According to Tynkkynen (1999) and co-authors, its precision isconsiderably lower when identifying microorganisms up to species. This could beexplained by the fact that the system initially was intended for identification of229
Page 1 and 2:
UNIVERSITY OF AGRONOMICAL SCIENCES
Page 3 and 4:
Proceeding of the 4 rd Internationa
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Day 7Day 10Proceeding of the 4 rd I
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178: Proceeding of the 4 rd Internationa
Page 227: Proceeding of the 4 rd Internationa
show all

New Researches in Biotechnology - Facultatea de Biotehnologii ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?