Examination of coagulation kinetics and rheological properties of fermented milk products: influence of starter culture, milk fat content and addition of inulin

Reološka svojstva gruša su osnovni parametri kakvoće fermentiranih mliječnih napitaka. Na teksturalna svojstva fermentiranog mliječnog napitka utječe čitav niz činioca poput upotrijebljene starter kulture, sastava mlijeka, početne viskoznosti mlijeka, kinetike fermentacije (intenziteta pada pH vrijednosti), toplinskog tretmana mlijeka prije fermentacije, provedene homogenizacije itd. Svrha ovog rada bila je ispitati utjecaj tri činioca na kinetiku grušanja i reološka svojstva fermentiranog mliječnog napitka: udjela mliječne masti u mlijeku, upotrijebljene starter kulture i dodatka jakog bifidogenog prebiotika inulina. Rezultati rada pokazali su da sva tri faktora imaju utjecaj na kinetiku fermentacije i koagulacije, te teksturu gotovih proizvoda. Najveći utjecaj starter kulture je dobro poznat, a najinteresantniji je utjecaj dodatka inulina na povećanje konzistencije probiotičkih uzoraka priređenih od punomasnog mlijekaRheological properties of curd of fermented milk products are one of the basic factors of their overal quality. The textural (rheological) properties of fermented dairy products depend on the many different factors such as starter culture, milk composition, initial viscosity of milk, fermentation kinetics (intensity of pH value decrease), heat treatment of milk, homogenization etc. The aim of this paper was to examine the influence of three factors to coagulation kinetics and rheological properties of fermented milk product: milk fat content, starter culture and addition of inulin (a strong bifidogenic prebiotic). Results of this work indicated that all three factors have influence on fermentation and coagulation kinetics, as well as to textural quality of fermented milk products. The greatest influence of starter culture is well known, while the influence of inulin addition on consistency of probiotic samples increase was found to be the most interesting

Rheological properties of goats and cow\u27s acidophilus milk during storage

Cilj rada bio je usporediti reološke osobine gruševa kozjeg i kravljeg acidofilnog mlijeka uz dodatke, te ispitati neke fizikalne i reološke promjene tijekom njihovog skladištenja. Ispitivani su i utjecaji dodatka koncentrata voćnog soka jabuke na stabilnost gruša tijekom skladištenja, kao i njihov utjecaj na održivost proizvoda. Reološke osobine i pH vrijednost gruševa određivane su odmah nakon fermentacije, te poslije 3,6i9 dana skladištenja. Dodatkom obranog mlijeka u prahu povećavala se vrijednost koeficijenta konzistencije u kozjem i kravljem acidofilnom mlijeku. Skladištenjem uzoraka vrijednost koeficijenta konzistencije se povećavala do šestog dana skladištenja, a zatim se smanjivala osobito u kozjem acidofilnom mlijeku. U uzorcima priređenim s koncentratom soka jabuke vidno su bile izražene inhibicije tijekom fermentacije i koagulacije. Unatoč inhibicijama tijekom fermentacije i koagulacije dobiveni gruševi uzoraka priređenih sli 2% koncentrata soka jabuke su visoke kvalitete. Obzirom na pH vrijednosti izmjerene tijekom skladištenja, primijećeno je da koncentrat voćnog soka jabuke djeluje djelomično konzervirajuće na dobivene proizvode.The aim of this paper was to compare rheological properties of goat\u27s and cow\u27s acidophilus milk curds and also to determine physical and rheological changes during storage. The influence of apple juice concentrate addition on the shelf life and curd stability during storage was determined. Rheological properties and pH values of prepared curds were measured after the fermentation and after 3, 6 and 9 days of storage. With addition of skimmed milk powder the consistency coefficient value in goat\u27s and cow\u27s acidophilus milk increased until the sixth day of storage. After that consistency coefficient value was decreased, especially of goat acidophilus milk. Samples prepared with apple juice concentrate showed inhibitions during the fermentation and coagulation. In spite of inhibitions during the fermentation and coagulation, the obtained curds, prepared with 1 and 2per cent of apple juice concentrate, showed high quality. On the basis of pH values measured during the storage, it was noticed that the apple juice concentrate had a partly conservative effect on products

Comparation of instrumental and sensory methods in fermented milk beverages texture quality analysis

Tekstura gruša fermentiranih mliječnih napitaka jedan je od osnovnih činioca njihove ukupne kakvoće. Fermentirani mliječni napici imaju svojstva tečenja karakteristična za tiksotropni (pseudoplastični) tip tekućina. Ujedno su to viskoelastični sustavi, jer imaju sposobnost obnavljanja teksture nakon prestanka djelovanja sile koja je bila uzrokom deformacije. Opis teksture takvog sustava zahtijeva kompleksnu analizu većeg broja svojstava. Cilj istraživanja bio je što potpunije opisati teksturu fermentiranih mlijčnih napitaka. Pri tome su kao osnovna svojstva teksture uzeti struktura, čvrstoća (konzistencija) i stabilnost gruša. Primijenjen je model opisa ta tri parametra na osnovi eksperimentalnih podataka. Rezultati dobiveni modelom uspoređeni su s rezultatima senzorskog ocjenjivanja. Modelom je ispitan utjecaj udjela mliječne masti i dodatka obranog mlijeka u prahu na kakvoću teksture acidofilnog mlijeka. Pokazalo se da je primjenom modela na osnovi instrumentalnih i senzorskih ispitivanja, moguće detaljno i objektivno definirati kakvoću teksture fermentiranih mliječnih napitaka. Istraživanje je pokazalo visoku korelaciju između rezultata instrumentalnih i senzorskih ispitivanja (r = 0,8975). Rezultati mjerenja pokazali su značajan utjecaj na teksturu oba promatrana činioca: udjela mliječne masti i dodatka obranog mlijeka u prahu. Uzorci s višim udjelima mliječne masti imali su bolju teksturu u odnosu na uzorke s nižim udjelima mliječne masti. Dodavanjem većeg udjela obranog mlijeka u prahu poboljšavala se tekstura svih ispitivanih uzoraka. Primijenjenim modelom određeni su optimalni udjeli dodatka obranog mlijeka u prahu u sprezi s odabranim udjelima mliječne masti.The texture of the curd of fermented dairy products is one of the primary factors of their overall quality. The flow properties of fermented dairy products have characteristic of thixotropic (pseudoplastic) type of liquids. At the same time, these products are viscoelastic systems, i.e. they are capable of texture renewal after applied deformation. Complex analysis of some of the properties is essentional for the system description . The aim of the present work was to completely describe the texture of fermented milk beverages . Three basic parameters were taken into consideration: structure, hardness (consistency) and stability of the curd. The description model of these three parameters was applied on the basis of the experimental results obteined. Results obtained by present model were compared with the results of sensory analysis. Influence of milk fat content and skimmed milk powder addition on acidophilus milk texture quality was also examined using this model. It was shawn that, by using this model – on the basis of instrumental and sensory analyses, a complete and objective determination of texture quality of the fermented milk beverages can be obtained. High degree of correlation between instrumental and sensory results (r =0.8975) is obtained results of this work indicated that both factors (milk fat content and skimmed milk powder addition) had an influence on texture quality. Samples with higher milk fat content had a better texture properties in comparsion with low fat content samples. Texture of all examined samples was improved by increasing skimmed milk powder content. Optimal amounts of skimmed milk powder addition with regard to milk fat content, in milk, is determined using the proposed model

Prevencija urogenitalnih infekcija oralnim unosom probiotičkih laktobacila

In general, lactobacilli are nonpathogenic part of the normal urogenital microflora and have been recognized as a barrier against colonization of unwanted (pathogen) microflora. The results of many in vitro studies suggest following mechanisms of probiotic lactobacilli action in urogenital tract: adhesion to urogenital cells, competition with pathogens for adhesive sites, production of biosurfactants, co-aggregation with pathogens, production of antimicrobial substances (organic acids, hydrogen peroxide and bacteriocins) and stimulation of immune system. From 80 different lactobacilli species isolated from human or animal intestinal and urogenital tract, only few lactobacilli strains possess optimal properties to be effective as probiotic therapeutics against infections in the urogenital tract. Combination of Lactobacillus rhamnosus GR-1 and Lactobacillus fermentum RC-14 was proposed as the best one for epithelial vaginal cells colonization and inhibition of uropathogens adhesion. The results of a number of clinical studies confirmed beneficial role of oral lactobacilli. However, the most of commercially available Lactobacillus strains, which are ordinary used in fermented dairy products, are seriously limited in protection of urogenital tract when they are ingested orally.Laktobacili su dio standardne nepatogene normalne urogenitalne mikroflore, koji djeluju kao barijera protiv kolonizacije nepoželjne (patogene) mikroflore. Prema rezultatima mnogih in vitro studija probiotički laktobacili u urogenitalnom traktu mogu djelovati putem sljedećih mehanizama: adhezija na stanice urogenitalnog trakta, natjecanje s patogenima za adhezivna mjesta, produkcija biosurfaktanata, koagregacija s patogenima, produkcija antimikrobnih supstancija (organske kiseline, vodikov peroksid i bakteriocini) i stimulacija imunološkog sustava. U urogenitalnom traktu samo nekoliko sojeva laktobacila, od 80 sojeva laktobacila koji su izolirani iz probavnog i urogenitalnog trakta, ima terapijska svojstva. U kolonizaciji epitelnih stanica vagine i sprječavanja adhezije patogena najuspješnijom se pokazala kombinacija bakterija Lactobacillus rhamnosus GR-1 i Lactobacillus fermentum RC-14. Rezultati niza kliničkih studija potvrdili su blagotvorni učinak oralnog unosa probiotičkih laktobacila. Međutim, najveći broj komercijalno dostupnih Lactobacillus sojeva, koji se uobičajeno koriste za fermentacije u mljekarskoj industriji, ukoliko se unesu oralno imaju limitirano zaštitno djelovanje u urogenitalnom traktu

Alteration of fatty acids content during cow\u27s and goat\u27s milk fermentation with ABT-2 culture

Cilj rada bio je ispitati utjecaj fermentacije kozjeg i kravljeg mlijeka ABT- 2 kulturom na promjenu udjela pojedinačnih masnih kiselina u kozjem i kravljem mlijeku. Svrha rada bila je utvrditi povećanje udjela pojedinačnih kratko (SCFA - short chain fatty acids) i srednje (MCFA - middle chain fatty acids) lančanih masnih kiselina tijekom fermentacije kozjeg i kravljeg mlijeka. Hipoteza u radu bila je da veći udjeli SCFA i MCFA tijekom fermentacije ABT-2 kulturom nastaju u kozjem nego u kravljem mlijeku. Rezultati rada pokazali su da se fermentacijski procesi brže odvijaju u kozjem mlijeku u usporedbi s kravljim. Statistički značajno veći broj stanica probiotičkih bakterija Bifidobacterium spp. i Lactobacillus acidophilus La zabilježen je tijekom fermentacije kozjeg mlijeka, uz istodobno brže padanje pH vrijednosti kozjeg mlijeka u odnosu na kravlje. Uslijed fermentativne aktivnosti bifidobakterija iz ABT-2 kulture povećavao se udio SCFA i MCFA u obje vrste mlijeka. Međutim, značajno veći udio mjerenih SCFA i MCFA nastao je fermentacijom kozjeg mlijeka.In this paper, changes in composition and contents of each fatty acid during fermentation with ABT-2 culture were examined. The objective of this study was to determinate the increase of short (SCFA) and medium (MCFA) chain fatty acids in goat\u27s and cow\u27s milk during fermentation with ABT-2 culture. The hypothesis of this study was that higher contents of SCFA and MCFA are produced in goat\u27s milk in comparison with cow\u27s milk, during fermentation with ABT-2 culture. Obtained results have shown that fermentation process in goat\u27s milk is faster than in cow\u27s milk. The number of viable cells of probiotic bacteria Lactobacillus acidophilus La-5 and Bifidobacterium spp. was statistically greater in goat\u27s milk than in cow\u27s milk; consequently, pH value decreased more obviously in goat\u27s milk than in cow\u27s milk during whole fermentation process. Increase of SCFA and MCFA contents during fermentation was noted in both types of milk due to activity of bifidobacteria derived from ABT-2 culture. However, considerably higher amounts of examined SCFA and MCFA were produced in goat\u27s milk than in cow\u27s milk

The effect of natural antioxidants on the oxidative stability of pumpkin seed oil

Oksidacija lipida je prepoznata kao glavni problem u jestivim uljima, ona prouzrokuje važnu promjenu kemijskih, senzorskih i nutritivnih svojstava. U ovom radu istraživan je utjecaj prirodnih antioksidanasa (ekstrakt ružmarina Oxy’Less CS, ekstrakt zelenog čaja, ekstrakt nara 10) u udjelima od 0,04% i 0,1% na oksidacijsku stabilnost bučinog ulja i djevičanskog bučinog ulja. Oksidacijska stabilnost ulja, sa i bez dodanog prirodnog antioksidansa, ispitivana je primjenom Oven testa. Rezultati Oven testa prikazani su kao vrijednost peroksidnog broja (mmol O2 / kg) nakon određenog vremena držanja uzorka pri temperaturi od 63 °C, odnosno tijekom četiri dana trajanja testa. Rezultat istraživanja pokazuje da veću antioksidacijsku aktivnost ima ekstrakt ružmarina Oxy’Less CS kod obje koncentracije u odnosu na ekstrakt zelenog čaja i ekstrakt nara 10. Ispitivani prirodni antioksidansi dodani u udjelu 0,1% efikasnije štite ova ulja od oksidacije u odnosu na dodatak udjela 0,04%. Također, dodatkom prirodnih antioksidanasa postiže se veća uspješnost zaštite djevičanskog bučinog ulja od oksidacijskog kvarenja u odnosu na zaštitu bučinog ulja. Djevičansko bučino ulje pokazuje veću održivost ili stabilnost prema oksidacijskom kvarenju.Lipid oxidation has been recognised as the major problem affecting edible oils, as it is the cause of important deteriorative changes in their chemical, sensory and nutritional properties. This study researched the effect of natural antioxidants (rosemary extract Oxy’Less CS, green tea extract, pomegranate extract 10), in dosage of 0.04% and 0.1%, on the oxidative stability of pumpkin seed oil and virgin pumpkin seed oil. The oxidative stability of oil, with and without added natural antioxidant, was evaluated using the Oven test conditions. The results are expressed as peroxide number value (mmol O2 /kg) after keeping the sample for a certain period of time at temperature of 63°C, that is, within four days of the duration of the test. The result showed the highest antioxidant activity with rosemary extract Oxy’Less CS comparable to green tea extract and pomegranate extract 10 in both concentrations. Tested natural antioxidants added in dosage of 0.1% protect these oils from oxidation more effectively than dosage of 0.04%. Moreover, by adding natural antioxidants, the protection of virgin pumpkin seed oil from oxidative deterioration is increased comparable to the protection of pumpkin seed oil. Virgin pumpkin seed oil shows higher sustainability or stability to oxidative deterioration

Inhibitory effect of goat and cow milk fermented with Bifidobacterium longum bb-46 on growth of uropathogenic Candida albicans

Cilj ispitivanja bio je utvrditi antagonistički utjecaj kozjeg i kravljeg mlijeka fermentiranog probiotičkom bakterijom Bifidobacterium longum Bb- 46 na rast uropatogenog kvasca Candida albicans. Hipoteza u ovom radu bila je da fermentirano kozje mlijeko ima moguće jače inhibicijsko djelovanje na rast Candida albicans u usporedbi s fermentiranim kravljim mlijekom. Povrh toga, praćene su korelacije između stupnja inhibicije i određenih parametara mliječno kisele fermentacije (broj stanica Bifidobacterium longum Bb-46 i pH vrijednost). Rezultati istraživanja pokazali su da fermentirano kozje mlijeko značajno jače inhibira rast Candida albicans u odnosu na fermentirano kravlje mlijeko (P<0,05). Nije utvrđena nikakva korelacija stupnja inhibicije rasta Candida albicans s pH vrijednosti fermentiranog mlijeka i brojem živih stanica Bifidobacterium longum Bb-46 u fermentiranom kozjem i kravljem mlijeku.The study was carried out to determine the antagonistic influence of goat and cow milk fermented with Bifidobacterium longum Bb-46 on uropathogenic Candida albicans strain. The hypothesis of this study was that fermented goat milk could have possible stronger inhibitory effect on the growth of uropathogenic yeast Candida albicans than fermented cow milk. The correlation between the inhibitory effect and the time of fermentation (number of viable Bifidobacterium longum Bb-46 cells and pH of fermented milk) was also determined. The obtained results have shown considerably higher inhibitory effect of fermented goat milk on the growth of Candida albicans compared with fermented cow milk. There was no significant correlation between number of Bifidobacterium longum Bb-46 cells in fermented and the inhibitory effect; as well as between changes in pH during fermentation and inhibitory effect of fermented goat or cow milk