Effect of inulin on the growth and survival of Bifidobacterium longum BB536 in fermented goat’s and cow’s milk

Fermentirani mliječni napitci proizvedeni su od standardiziranoga kozjega i kravljeg mlijeka (2,9 % mliječne masti) uz dodatak 3 % obranog mlijeka u prahu (kontrolni uzorci), ili uz dodatak 2 % inulina i 1 % obranog mlijeka u prahu (eksperimentalni uzorci). Fermentacija uzoraka provedena je pri 40 °C uporabom termofilne jogurtne kulture YC-380 i probiotičke kulture Bifidobacterium longum BB536. Kod svih je uzoraka poželjna kiselost (pH oko 4,5) postignuta za oko 5,5 h. Broj živih stanica probiotičke kulture (logN/mL) porastao je tijekom fermentacije podjednako za sve uzorke (oko 1,4 logaritamske jedinice), osim za uzorak kravljeg mlijeka obogaćenog inulinom u kojem je porast bifidobakterija bio najveći (oko 1,7 logaritamske jedinice). Tijekom trajanja fermentacije nešto brži pad pH-vrijednosti uočen je kod uzoraka od kozjeg mlijeka u odnosu na kravlje. Na kraju fermentacije između ispitivanih uzoraka nije bilo statistički značajne razlike u pH-vrijednostima (P>0,05), bez obzira na vrstu mlijeka ili dodatak inulina. Tijekom 30 dana čuvanja fermentiranih napitaka pri temperaturi hladionika (oko 6 °C) nešto niže pH-vrijednosti zabilježene su kod uzoraka kravljeg mlijeka u odnosu na kozje, osobito kod kravljeg mlijeka obogaćenog inulinom. Do petnaestog dana čuvanja u svim uzorcima uočen je porast broja živih stanica probiotičkih bakterija, dok je od 20. do 30. dana zabilježen njihov pad za oko 0,5 logaritamske jedinice. U kozjem mlijeku bilo je nešto slabije preživljavanje bifidobakterija nego u kravljem. Broj bifidobakterija u uzorcima obogaćenim inulinom zadnji dan čuvanja u odnosu na kontrolne uzorke bio je veći za oko 0,3 logaritamske jedinice, bez obzira na vrstu mlijeka. U svim uzorcima nakon 30 dana čuvanja u hladioniku osigurana je preporučena koncentracija bifidobakterija na osnovi koje se istraživani fermentirani napitci ubrajaju u probiotičke.Fermented dairy products were made from standardized goat and cow milk (2.9 % milk fat) with addition of 3 % skimmed milk powder (control samples), or with addition of 2 % inulin and 1 % skimmed milk powder (experimental samples). Fermentation of samples was carried out at 40 °C by thermophilic yoghurt culture YC-380 and probiotic culture Bifidobacterium longum BB536. Desired acidity (pH around 4.5) was achieved in all samples in about 5.5 h. Viable count of probiotic strain (logN/m) increased for all samples for on average 1.4 logarithmic units except for the sample of cow’s milk supplemented with inulin, which exhibited the highest growth of bifidobacteria for approximately 1.7 logarithmic units. During fermentation somewhat faster decrease of pH-value was observed in goat milk samples compared to cow milk samples. At the end of fermentation there was no statistically significant difference (P>0.05) in pH-values regardless of milk origin or inulin addition. During thirty days of fermented drink storage at lower temperature (about 6 °C), slightly lower pH-values were observed in cow milk samples compared to goat milk, especially in cow milk enriched with inulin. During storage, until the 15th day, an increase in the number of viable count of probiotic bacteria was observed in all samples, while from 20th to 30th day a decrease of 0.5 logarithmic units of the same parameter was recorded. In goat milk their survival was somewhat smaller compared to cow milk. The number of bifidobacteria in samples supplemented with inulin on the last day of storage, compared to control samples, was higher for 0.3 logarithmic units, regardless of the milk origin. After thirty days of refrigerated storage, recommended concentration of bifidobacteria was insured in all samples, thus directly implying that these fermented drinks can be included in probiotics

Application of immunoassay for the detection of cow milk in goat milk

Kozje mlijeko zbog svog sastava danas zauzima sve više mjesto u proizvodnji posebnih i traženih mliječnih proizvoda. S obzirom na količinu i različitu cijenu često se kozjem mlijeku dodaje kravlje mlijeko. Za brzo odvajanje kozjeg mlijeka od kravljeg mlijeka danas služe imunološke i elektroforetske metode. Jedna od imunoloških metoda je i radijalna imunodifuzija koja se primjenjuje upotrebom CV-TESTA (Levieux, 1977.) Mlijeko za analizu stavlja se u sloj agara koji sadržava antiserum svojstven za kravlje mlijeko. Mjerenjem difuzije koja nastaje poznatom imunološkom reakcijom s antiserumom i uz pomoć referentne krivulje dolazi se do proporcionalne količine dodanog kravljeg mlijeka u analiziranom uzorku. Primjenom CV-TESTA u rutinskoj analizi može se u kratku vremenu otkriti patvorenje kozjeg mlijeka, a samim tim omogućuje se upotreba čistoga kozjeg mlijeka za proizvodnju specifičnih i visoko vrijednih traženih mliječnih proizvoda.Got milk takes now-a-days important place in production of specific and looked for dairy products owing to its composition. On account of its quantity and different price goat milk is often adulterated with cow milk. For quick detection and quantification of cow milk in goat milk immunoassays and electrophoretic methods are used. Radial immunodiffusion is one of immunoassyas applying CV Test (Levi eux, 1977). Milk sample is put in agar layer containing specific antiserum for cow milk. Measuring the difussion developed owing to known immunologic reaction with antiserum by means of reference curve it is possible to achieve the added proportion of cow milk quantities in analyzed milk samples. Applying CV Test in routine analysis enables quick detection of goat milk adulteration and, by that very fact, the use of pure goat milk in processing is of specific worth and asked for dairy products