Evaluation of denaturing gradient gel electrophoresis (DGGE) used to describe structure of bacterial communities in Istrian cheese

Denaturing gradient gel electrophoresis (DGGE) is a powerful method used to study structure of bacterial communities, without cultivation, based on the diversity of the genes coding for ribosomal RNA. However, the results are strongly dependent on the respective target region of the used primer systems. Therefore, three primer pairs that amplify different variable regions of the 16S rRNA gene (V1, V3 and V6 to V8) were tested in order to investigate the bacterial diversity existent in Istrian cheese. We found that primer set extremely influenced DGGE analysis. V3 primers were most efficient when 15 cheese associated isolates were resolved by DGGE. However, for Istrian cheese analysis, the best separation and highest number of bands in DGGE patterns were noticed for V6 to V8 primer pairs.Key words: Denaturing gradient gel electrophoresis, bacterial communities, Istrian cheese

Autohtoni sojevi roda Lactobacillus izolirani iz Istarskog sira kao potencijalne starter kulture

Istrian ewe’s milk cheese is an autochthonous product that is manufactured for generations on small family farms in the Croatian peninsula Istria. Traditional Istrian cheese is made from unpasteurized ewe’s milk, without the addition of starter cultures. Consequently, the specific flavour and texture of the Istrian cheese is owed to metabolic processes of indigenous microflora of which Lactobacillus species play pivotal role. Characterisation and selection of indigenous lactobacilli may result in the potential use of selected strains as starter, bioprotective or even probiotic cultures. This study focuses on potential use of Lactobacillus plantarum and Lactobacillus casei isolated from traditional Istrian cheese as starter cultures, by using methods that determine their proteolytic, lipolytic, antimicrobial and haemolytic potential, as well as their ability of acidification, autoaggregation and survival in simulated gastrointestinal conditions. Our results indicated that from 12 representative strains most revealed a low or moderate proteolytic activity as well as absence of lipolytic and haemolytic activities. From 12 strains, 5 of them showed a medium to strong acidification ability and lowered the pH of milk below 5.00 after 24 hours of incubation. Furthermore, almost all isolates exhibited antimicrobial activity against Serratia marcescens, and lowest number of isolates showed antimicrobial activity against Staphylococcus aureus and Listeria innocua. The studied Lactobacillus strains revealed high survival rate in a simulated oral cavity and duodenum conditions, while the survival ability in a simulated gastric conditions was much lower. Ability to aggregate was low for all tested strains, after 3 hours and after 5 hours of incubation.Tradicionalni Istarski sir proizvodi se od nepasteriziranog ovčjeg mlijeka, bez dodatka starter kultura. Prema tome, specifična aroma i tekstura Istarskog sira pripisuje se, uz ostale faktore, metaboličkim procesima autohtone mikroflore od kojih vrste roda Lactobacillus imaju ključnu ulogu. Karakterizacija i izbor autohtonih sojeva laktobacila može dovesti do potencijalnog korištenje odabranih sojeva kao starter, zaštitnih ili probiotičkih kultura. U ovom istraživanju željeli smo istražiti tehnološki i probiotički potencijal sojeva Lactobacillus plantarum i Lactobacillus casei izoliranih iz tradicionalnog Istarskog sira pomoću metoda koje određuju njihov proteolitički, kazeinolitički, lipolitički, antimikrobni i hemolitički potencijal, kao i njihovu sposobnost zakiseljavanja, autoagregacije i preživljavanja u simuliranim gastrointestinalnim uvjetima. Svih 12 reprezentativnih sojeva pokazuju nisku do umjerenu proteolitičku aktivnost te odsutnost lipolitičke i hemolitičke aktivnosti. Od 12 sojeva, 5 je pokazalo jaku sposobnost zakiseljavanja, spuštajući pH mlijeka ispod 5,00 nakon 24 sati inkubacije. Nadalje, gotovo svi izolati pokazuju antimikrobno djelovanje u odnosu na vrstu Serratia marcescens te slabo antimikrobno djelovanje u odnosu na Staphylococcus aureus i Listeria innocua. Istraživani sojevi pokazali su visoku prosječnu stopu preživljavanja u simuliranim uvjetima usne šupljine i dvanaesnika, dok je prosječna stopa preživljavanja u simuliranim želučanim uvjetima bila znatno niža. Nakon 5 sati inkubacije, autoagregacijska sposobnost svih istraživanih sojeva bila je niska

Mikrobiološka analiza unutarnjeg i vanjskog zraka farme svinja u Slavoniji

Due to a large concentration of animals living in a relatively small area, air on pig farms can be contaminated by microorganisms which can have an adverse effect on animal and human health. To determine the microbiological air quality on a pig farm in Slavonia, as well as the differences in the microbiological air quality at different distances from the farm, air was sampled at five locations at the farm (nursery room, finishing rooms 1 and 2, service room, gestation room) and four locations at a distance of 1.5, 5, 10 and 15 m from the farm in July 2019. At each location, temperature and relative humidity were measured and air for microbiological analysis was collected in quadruplicates (n=36) by impaction method. The total aerobic mesophilic bacteria (AMB), as well as yeast and mould counts were determined on blood agar and Sabouraud dextrose agar, respectively, and expressed as CFU/m3. The AMB counts in all five farm locations, as well as the yeast and mould counts in nursery and finishing room 1 exceeded the reference values of 1.05x103 CFU/m3 for AMB and 4.1x102 CFU/m3 for yeasts and moulds. Overall, the AMB load was significantly higher (P0.05). In addition, the abundance of airborne AMB and yeasts and moulds decreased as the distance from the farm increased.Zbog velike koncentracije životinja u relativno malom prostoru, zrak na farmama svinja može biti kontaminiran mikroorganizmima koji mogu štetno utjecati na zdravlje životinja i ljudi. Kako bi se odredila mikrobiološka kvaliteta zraka unutar farme svinja u Slavoniji te mikrobiološka kvaliteta vanjskog zraka s porastom udaljenosti od farme, prikupljeni su uzorci zraka na pet lokacija unutar farme (uzgajalište, tovilište 1, tovilište 2, pripustilište i čekalište) te na četiri lokacije udaljene 1,5, 5, 10 i 15 m od farme tijekom srpnja 2019. Na svakoj lokaciji izmjerene su temperatura i relativna vlažnost te su uzeti uzorci zraka metodom impakcije u četiri ponavljanja (n=36). Ukupan broj aerobnih mezofilnih bakterija (AMB) određen je na krvnom agaru, dok je ukupan broj kvasaca i plijesni određen na Sabouraud dekstroznom agaru. Dobivene vrijednosti izražene su kao CFU/m3. Broj AMB u zraku na svih pet lokacija unutar farme te broj kvasaca i plijesni u uzgajalištu i tovilištu 1 bili su viši od dozvoljenih referentnih vrijednosti od 1,05x103 CFU/m3 za AMB i 4,1x102 CFU/m3 za kvasce i plijesni. Broj AMB u zraku nastambi bio je značajno veći (P0,05) u broju. Nadalje, broj AMB te kvasaca i plijesni u zraku smanjivao se s povećanjem udaljenosti od zgrade farme

THE ROLE OF GUT MICROBIOTA ON MAINTAINING HEALTH OF PIGS

Stabilna crijevna mikrobiota utječe na mnogo načina na održavanje ili poboljšanje zdravlja svinja. Dosadašnja istraživanja su pokazala pozitivan utjecaj crijevne mikrobiote u iskoristivosti hranjivih tvari, poboljšanju morfoloških i fizioloških svojstava gastrointestinalnog (GI) trakta, u sprječavanju prodora patogenih vrsta, a također mikroorganizmi probavila imaju važnu imunološku ulogu. Osim korisnih i poželjnih bakterijskih vrsta, crijevna mikrobiota svinja može uključivati patogene poput Salmonella spp., Clostridia spp. i patogenih sojeva E. coli. U slučaju narušene ravnoteže prirodno prisutnih mikrobnih zajednica, ovi patogeni mogu uzrokovati bolesti svinja te posljedično gubitke u proizvodnji. U prošlosti su za osiguranje stabilne mikrobiote GI trakta preventivno korišteni antibiotici, no od kada je prepoznata štetnost takve prakse sve više se koriste probiotici, prebiotici te različiti aditivi. Za takav pristup, potrebno je poznavati sastav i brojnost mikrobnih zajednica prisutnih u GI traktu svinja kao i identificirati ključne mikroorganizme u prevenciji infekcija i održavanju zdravlja domaćina. Zbog toga je u fokusu znanstvenog interesa definirati i detaljno karakterizirati crijevnu mikrobiotu zdravih jedinki, istražiti međusobne mikrobne interakcije, kao i interakcije s domaćinom, te različite načine osiguravanja stabilne crijevne mikrobiote kako bi se održala vitalnost i zdravlje životinja.Stable gut microbiota may influence the health and wellbeing of pigs. Results of up-to-date studies have shown a positive effect of gut microbiota on feed efficiency, improvement of morphological and physiological characteristics of gastrointestinal (GI) tract, prevention of breach of pathogenic species, as well as a positive role in immunology. However, besides beneficial bacterial species, gut microbiota of pigs can include pathogens such as Salmonella spp., Clostridia spp. and pathogenic strains of E. coli. When the balance of naturally present microbial communities is disturbed, these pathogens can cause illness of pigs, causing production losses. Antibiotics were used in the past for ensuring a stable gut microbiota, but since damaging effects of such practice were recognized, alternative methods have been considered, such as the use of probiotics and prebiotics. For this approach, it is necessary to know the composition and abundance of microbial communities in GI tract of healthy pigs, as well as to identify the most important microorganisms that have a role in the prevention of infection and maintaining the wellbeing of the host. Therefore, many studies have been focused on defining and detailed characterization of gut microbiota of healthy individuals, to study interactions between microbes as well as microbial interactions with the host. Also, different approaches have been considered to ensure a stable gut microbiota to maintain vitality and health of animals

El impacto de las especias a la microflora natural de la “kora” de la carne de carnero durante el proceso tecnológico de la producción

Tradicijski hrvatski suhomesnati proizvod, kaštradina, proizvodi se od ovčjeg ili kozjeg mesa, najčešće isluženih ovaca ili muških kastrata. Sastav prirodne mikroflore svakog tradicijskog proizvoda je specifičan i ima važnu ulogu u razvoju tipičnih senzorskih svojstava samog proizvoda. Za poboljšanje senzorskih karakteristika dodaju se začini koji, osim što doprinose aromi samog proizvoda, imaju i antimikrobno djelovanje. Cilj ovog rada bio je istražiti utjecaj dodanih začina (češnjak, ružmarin i lovor) na prirodnu mikrofloru „kore“ kaštradine. Istraživanjem je bilo obuhvaćeno 20 trupova ovaca pasmine travnička pramenka. Nakon 24-satnog hlađenja trupovi su rasječeni na polovice, a sa svake polovice je odvojen but s potkoljenicom i plećka sa podlatkicom. Preostali dio trupa se naziva „kora“. Primijenjene su dvije varijante soljenja mesa: soljenje solju, te soljenje komercijalnom smjesom soli i prirodnih začina (češnjak, lovor i ružmarin). Uzorci „kore“ kaštradine su uzimani prvog (sirovina), sedmog (nakon faze soljenja) te četrnaestog dana (nakon zrenja) tehnološkog procesa proizvodnje. Istraživane su slijedeće skupine mikroorganizama: ukupne aerobne mezofilne bakterije, bakterije mliječne kiseline, enterokoki, mikrokoki, kvasci i plijesni, Staphylococcus aureus, enterobakterije, koliformi, Escherichia coli, Salmonella spp., Listeria spp. i sulfitreducirajuće klostridije. Istraživani uzorci „kore“ kaštradine, bez obzira na tehnologiju proizvodnje bili su mikrobiološki ispravni. Dodani začini su negativno utjecali na prosječni broj koliforma i ukupnih aerobnih mezofilnih bakterija. S obzirom kako u uzorcima „kore“ kaštradine nisu dokazani patogeni (Escherichia coli, Salmonella spp., Listeria spp.) nije se mogao utvrditi utjecaj začina na njih.The traditional Croatian dry-cured meat product, kastradina, is produced from mutton, most often the meat of old ewes or wethers. The composition of natural microflora of each traditional product is specific and plays an important role in the development of its typical sensory characteristics. Spices, that, in addition to contributing to the aroma of the product itself, also have antimicrobial properties, are added to improve the sensory characteristics. The aim of this study was to examine the effect of added spices (garlic, rosemary and laurel) on the natural microflora of the “kora” of kastradina. The study was carried out on 20 carcasses of Travnik Pramenka sheep. After 24-hours of cooling, the carcasses were first cut in halves, upon which the haunch and the shoulder were separated from the half. The remaining part of the carcass is called “kora”. Two types of meat salting were applied: salting using sea salt and salting using the commercial mixture of salt and natural spices (garlic, laurel and rosemary). The “kora” of kastradina was sampled on the 1st (raw meat), 7th (after the salting phase) and 14th (dry product) day of the technological production process. The following groups of microorganisms were examined: total aerobic mesophilic bacteria, lactic acid bacteria, enterococci, micrococci, yeasts and moulds, Staphylococcus aureus, enterobacteria, coliforms, Escherichia coli, Salmonella spp., Listeria spp., and sulfite-reducing clostridia. The examined samples "kora" of kastradina (Escherichia coli, Salmonella spp., Listeria spp.), were microbiologically correct, regardless of the production technology. Added spices had a negative effect on the average number of coliforms and the total aerobic mesophilic bacteria. Since no pathogens were detected in any of the samples of the “kora” of kastradina, it was not possible to determine the effect of spices on pathogens.Das traditionelle kroatische Dauerfleischprodukt Kaštradina wird aus Schaf- oder Ziegenfleisch hergestellt, am häufigsten von ausgedienten Schafen oder männlichen Kastraten. Die Zusammensetzung der Mikroflora eines jeden traditionellen Produkts ist spezifisch und spielt bei der Entfaltung der typischen sensorischen Eigenschaften des Produkts eine bedeutende Rolle. Um die sensorischen Eigenschaften zu verbessern, werden Gewürze zugegeben, die nicht nur das Aroma des Produkts verbessern, sondern auch über eine antimikrobielle Wirkung verfügen. Ziel dieser Arbeit war es, die Auswirkung der Gewürze (Knoblauch, Rosmarin und Lorbeer) auf die natürliche Mikroflora der Kaštradina-„Rinde“ zu untersuchen. Die Untersuchung umfasste 20 Schafsrümpfe der Sorte Travnička pramenka. Nachdem die Rümpfe 24 Stunden gekühlt wurden, wurden sie in Hälften eingeteilt. Von jeder Hälfte wurden die Haxe mit der Keule und das Schulterblatt mit der Haxe abgetrennt. Der restliche Rumpfteil wird „Rinde“ genannt. Es wurden zwei Pökelungsverfahren angewendet: die Pökelung mit Salz und die Pökelung mit einer kommerziellen Mischung aus Salz und natürlichen Gewürzen (Knoblauch, Lorbeer und Rosmarin). Proben der „Rinde“ wurden am ersten Tag (Rohstoff), am siebten (nach der Pökelungsphase) und am vierzehnten Tag (nach der Reifung) des technologischen Herstellungsprozesses genommen. Die Proben wurden auf folgende Gruppen von Mikroorganismen untersucht: Gesamtanteil der aeroben mesophilen Bakterien, Milchsäurebakterien, Enterokokken und Mykrokokken, Hefen und Pilze, Staphylococus aureus, Enterobakterien, coliforme Bakterien, Escherichia coli, Salmonella spp., Listeria spp. und sulfitreduzierende Clostridien. Die Proben der „Rinde“ waren, ungeachtet der Herstellungstechnologie, mikrobiologisch einwandfrei. Die zugesetzten Gewürze haben sich negativ auf die durchschnittliche Anzahl der coliformen Bakterien und auf den Gesamtanteil der aeroben mesophilen Bakterien ausgewirkt. Da in den Proben der Kaštradine-„Rinde“ keine pathogenen Bakterien nachgewiesen wurden (Escherichia coli, Salmonella spp., Listeria spp.), konnte die Auswirkung der Gewürze auf diese Bakterien nicht untersucht werden.In Croazia c’è un prodotto della tradizione gastronomica chiamato kaštradina che viene fatto essiccando le carni della pecora o del maschio castrato. La composizione della microflora naturale di ogni singolo prodotto tipico è specifica e gioca un ruolo importante nello sviluppo delle proprietà sensoriali tipiche del prodotto in sé. Per migliorare le caratteristiche sensoriali si aggiungono spezie che, oltre ad aromatizzare il prodotto, svolgono anche un’azione antimicrobica. Questo studio aveva lo scopo d’indagare l’impatto delle spezie aggiunte (aglio, rosmarino e alloro) sulla microflora naturale della “kora” della kaštradina. Lo studio ha coinvolto 20 carcasse di ovini di razza pramenka di Travnik. Dopo un raffreddamento durato 24 ore, le carcasse sono state tagliate in due mezzane, e da ogni mezzana sono stati messi da parte il cosciotto con lo stinco e la spalla sino al gomito. La parte residua della carcassa, usata per fare la kaštradina, in gergo di chiama “kora”. La salagione della carne è stata eseguita secondo due modalità: la prima con il sale, la seconda con una miscela in commercio che comprende sia il sale, sia alcune spezie naturali (aglio, alloro e rosmarino). I campioni di “kora” sono stati prelevati il primo giorno (materia prima), il settimo giorno (dopo la fase della salagione) ed il quattordicesimo giorno (dopo la stagionatura) del processo tecnologico di produzione della kaštradina. L’analisi ha riguardato i seguenti gruppi di microrganismi: batteri aerobi mesofili totali, batteri dell’acido lattico, enterococchi, micrococchi, lieviti e muffe, Staphylococus aureus, enterobatteri, coliformi, Escherichia coli, Salmonella spp., Listeria spp. e clostridi solfito riduttori. I campioni esaminati di “kora”, a prescindere dal processo tecnologico adottato, sono risultati microbiologicamente idonei. Le spezie aggiunte hanno avuto un impatto negativo sul numero medio di coliformi e di batteri aerobi mesofili totali. Poiché sui campioni di “kora” utilizzata per fare la kaštradina non sono stati rinvenuti microrganismi patogeni (Escherichia coli, Salmonella spp., Listeria spp.,) non è stato possibile accertare l’impatto su di essi.El producto cárnico crudo-curado tradicional croata, la carne de carnero, se produce de la carne de oveja o de cabra, generalmente de ovejas viejas o carneros castrados. La composición de la microflora natural de cada producto tradicional es específica y tiene una función importante en el desarrollo de las características sensoriales del producto. Para la mejora de las características sensoriales se añaden las especias que, además de contribuir al aroma del producto, también son antimicrobianas. El fin de este trabajo fue investigar la influencia de las especias añadidas (el ajo, el romero y el laurel) sobre la microflora natural de la “kora” de la carne de carnero. La investigación incluyó 20 canales de las ovejas de la raza pramenka de Travnik. Después de 24 horas las canales fueron cortadas en medias canales, y de cada media canal fueron divididos el muslo con el jarrete y la paleta con el antebrazo. El resto de la canal se llama la “kora”. Fueron aplicadas dos variantes del salazón de carne: el salazón por la sal y el salazón por la mezcla comercial de la sal y de las especias naturales (el ajo, el romero y el laurel). Las muestras de la “kora” fueron tomadas el primer (la materia prima), el séptimo (después de la fase de salazón) y el día catorce (después de la maduración) del proceso tecnológico de la producción. Fueron investigados siguientes grupos de microorganismos: bacterias mesófilas aerobias totales, bacterias del ácido láctico, bacterias mesófilas aerobias totales, bacterias del ácido láctico, enterococos, micrococos, levaduras y mohos, Staphylococcus aureus, enterobacterias, coliformes, Escherichia coli, Salmonella spp., Listeria spp. y clostridios reductores de sulfito. Las muestras investigadas de la carne de carnero, a pesar de la tecnología de la producción, fueron microbiológicamente seguras. Las especias añadidas afectaron negativamente el número total de los coliformes y de las bacterias mesófilas aerobias totales. Visto que en las muestras de la carne de carnero no fueron encontrados los patógenos (Escherichia coli, Salmonella spp., Listeria spp.), no fue posible determinar el impacto de las especias sobre ellos

Effect of Soil Tillage Practices on Dynamic of Bacterial Communities in Soil

Several studies have indicated that intensive tillage has notable effect on properties of the soil microbiota that may influence numerous important soils functions, e.g. mobilization of nutrients or change of the overall emission rates of greenhouse gases. Therefore, the aim of our study was to investigate dynamic of microbial communities in soil planted with soybean under different tillage systems. Moreover, abundance of populations harboring the nitrous- oxide reductase gene (nosZ) as an indicator for potential shift s in N2O emission rates was studied. The study was established at chernozem soil of Northern Baranja region in Republic of Croatia as completely randomized block design of four replicate plots for each tillage system in three years experiment. The soil was managed as followed: CT - conventional tillage (moldboard ploughing at 25-30 cm depth), DH - multiple discs harrowing (10-15 cm depth), and NT – no-tillage system. Soil samples were collected in summer and autumn in year 2003. Our results suggested that the reduction of tillage had no effects on the bacterial community structure. This might be a result of the very dry climatic conditions at the investigated site and /or a result of plant species effect (soybean). Slight effects of the tillage management became visible at least when samples were taken in autumn for microbes harboring the N2O reductase gene, indicating that there might be shift s in denitrification pattern in response to changes in tillage practice

Prediction of mycotoxigenic molds incidence on agricultural crops

Sinteza mikotoksina odvija se u specifičnim okolišnim uvjetima od kojih se temperatura, vlaga i CO2 navode kao ključni čimbenici za produkciju mikotoksina. Klimatske promjene te sve češći vremenski ekstremi značajno mijenjaju te čimbenike pa se posljedično narušavaju poznati obrasci kontaminacije plijesnima i sinteze mikotoksina na poljoprivrednim kulturama. Međutim, smatra se da će promjene povezane s kontaminacijom mikotoksikogenim plijesnima biti regionalne i usko u vezi s pojedinim vrstama plijesni, jer svaka vrsta ima svoje optimalne okolišne uvjete za rast i stvaranje toksičnih metabolita. Predviđa se da bi aflatoksini mogli postati učestali kontaminanti žitarica u Europi, a u tropskim predjelima moguće je izumiranje aflatoksikogenih plijesni zbog visokih temperatura. Za mikotoksikogene plijesni koje produciraju okratoksine, kao i za predstavnike roda Fusarium, također će biti izmijenjeni obrasci rasprostranjenosti i produkcije mikotoksina. Posebno zabrinjava porast prisutnosti plijesni F. graminearum, F. poae i F. langsethiae na žitaricama u sjevernoj i srednjoj Europi te posljedično kontaminacija tih usjeva deoksinivalenolom te T-2 i HT-2 toksinima. Pojavnost F. verticillioides i kontaminacija kukuruza fumonizinima bit će još više izražena na području južne Europe, kao i kontaminacija vina okratoksinima od plijesni A. carbonarius. S obzirom na očigledne klimatske promjene i posljedice koje one ostavljaju, nužna su daljnja istraživanja koja bi omogućila uspješno osmišljavanje strategija za prevenciju kontaminacije usjeva mikotoksinima u budućnosti.Mycotoxin synthesis takes place in specific environmental conditions, where temperature, humidity, and CO2 are considered the key factors in mycotoxin production. Due to climate change and increasingly frequent weather extremes those factors significantly change, hence, the previously established patterns of mold contamination and mycotoxin synthesis in agricultural crops are disrupted. However, the changes in mycotoxigenic mold contamination are expected to have a regional character, closely dependent on individual mold species, as each species grows and synthesizes toxic metabolites at optimal environmental conditions. Aflatoxins are predicted to become frequent grain contaminants in Europe, whilst the aflatoxigenic molds could go extinct in the tropics due to high temperatures. Also, the distribution and mycotoxins synthesis patterns of mycotoxigenic molds that produce ochratoxins and the members of the Fusarium genus will be modified. The increased presence of the molds F. graminearum, F. poae, and F. langsethiae on grains in northern and central Europe and the consequent contamination of these crops with deoxynivalenol and T-2 and HT-2 toxins are particularly concerning. The occurrence of F. verticillioides and maize contamination with fumonisins will be even more pronounced in southern Europe, as well as the contamination of wine with ochratoxins produced by A. carbonarius. Given climate change and its consequences, further research is necessary to design strategies for preventing crop contamination with mycotoxins in the future

Seguridad microbiológica de la sal común en el mercado

Kako je sol sastojak većine prehrambenih proizvoda, odličan konzervans, a najvećim dijelom začin za dosoljavanje gotovo svakog jela, cilj istraživanja ovog rada bio je ustanoviti mikrobiološku ispravnost kuhinjske soli plasirane na hrvatsko tržište. Mikrobiološke analize provedene su na deset uzoraka soli različitih domaćih i stranih proizvođača, a uzorkovani su u maloprodaji. Uzorci soli su prema nacionalnim mikrobiološkim kriterijima za hranu pretraženi na ukupni broj aerobnih mezofilnih bakterija i ukupni broj plijesni. Niti jedan pretraženi uzorak morske, kamene soli, himalajske soli i cvijeta soli nije bio sukladan propisanim kriterijima.Since salt is the main ingredient of most food products, excellent conservative properties, and most of all, the spice for adding to almost every kind of food, the aim of this study was to establish the microbiological safety of kitchen salt on the Croatian market. Microbiological analyzes were carried out on ten samples of salt various domestic and foreign producers, sampled in retail. Samples of salt were tested according to national microbiological criteria for the total number of aerobic mesophilic bacteria, and the total number of moulds. Not a single analyzed sample of sea salt, rock salt, Himalayan salt and flower of salt was consistent with the prescribed criteria.Da Salz der Hauptbestandteil der meisten Lebensmittelprodukte ist, ausgezeichnete konservierende Eigenschaften besitzt und vor allem als Gewürz verwendet wird, das fast allen Arten von Lebensmitteln zugegeben wird, bestand das Ziel dieser Studie darin, die mikrobiologische Sicherheit von Kochsalz auf dem kroatischen Markt zu ermitteln. Mikrobiologische Analysen wurden an 10 Salzproben verschiedener in- und ausländischer Hersteller durchgeführt, die im Einzelhandel gesammelt wurden. Die Salzproben wurden nach nationalen mikrobiologischen Kriterien auf die Gesamtzahl der aeroben mesophilen Bakterien und die Gesamtzahl der Schimmelpilze getestet. Keine der analysierten Proben von Meersalz, Steinsalz, Himalaya-Salz und Salzblume entsprach den vorgeschriebenen Kriterien.Poiché il sale da cucina è presente nella maggior parte dei prodotti alimentari, è un ottimo conservante e viene usato per insaporire quasi ogni pietanza, questo studio aveva come obiettivo quello di accertare l’idoneità microbiologica del sale da cucina in commercio in Croazia. L’analisi microbiologica ha riguardato dieci di campioni di sale di differenti produttori nazionali e stranieri. Il procedimento di campionatura è avvenuto nei punti vendita al dettaglio. Secondo i criteri microbiologici nazionali per gli alimenti, l’analisi ha accertato il numero complessivo di batteri mesofili aerobici e il numero complessivo di muffe nei campioni di sale esaminati. Neanche uno dei campioni di sale marino, salgemma, sale himalayano e fior di sale presi in considerazione è risultato conforme ai criteri prescritti.Dado que la sal es el ingrediente en la mayoría de los productos alimenticios, un conservante excelente y, sobre todo, la especie para casi cada tipo de comida, el fin de este trabajo fue determinar la seguridad microbiológica de la sal común en el mercado croata. Los análisis microbiológicos fueron hechos en 10 muestras de sal de diferentes productores, tanto nacionales como extranjeros, y las muestras fueron tomadas en la venta al por menor. Las muestras fueron analizadas de acuerdo con los criterios microbiológicos nacionales para la comida para determinar el número total de las bacterias aerobias mesófilas y de número total de los moldes. Ninguna de las muestras de la sal marina, sal triturada, sal del Himalaya ni la flor de sal fue de acuerdo con los criterios prescritos

Utjecaj inkubacijske temperature i koncentracije aflatoksina M1 u mlijeku na larve račića Artemia salina

Temperature-dose relationships with aflatoxin M1 (AFM1) were studied using the brine shrimp Artemia salina larvae as an biological indicator in the temperature range from 20 °C to 40 °C. Increase in the incubation temperature resulted in sensitivity increase by the brine shrimp to AFM1. Optimum sensitivity occured at 30 °C. Positive results were obtained at 0.18 μg AFM1 x L-1 of whole pasteurized milk with a mortality of over 15%. Greater than 90 % mortality occurred at dose levels of 0.9 μg AFM1 x L-1 and above. The test can be conducted during 30-60 hours.Proučavani su utjecaji inkubacijske temperature i koncentracije aflatoksina M1 (AFM1) na larve račića Artemia salina kao biologijskog indikatora u temperaturnom rasponu od 20 °C do 40 °C. Povišenje temperature inkubacije uzrokovalo je povećanu osjetljivost račića na AFM1. Optimalna osjetljivost očitovala se pri 30 °C. Pozitivni rezultati dobiveni su pri koncentraciji AFM1 0,18 μ g x L-1 pasteriziranog mlijeka uz izraženu smrtnost višu od 15 %. Smrtnost viša od 90 % očitovala se pri koncentracijama AFM1 0,9 μ g x L-1 i višim. Test se može provesti u tijeku 30-60 sati

Proteolitički soj Lactococcus lactis i lipolitički soj Enterococcus durans, izolirani iz tradicionalnog sira i upotrijebljeni kao funkcionalne mesne starter kulture

Research background. As fermentation is an integral feature of both, dry sausage and cheese production, this has led to the evaluation of bacterial cultures Lactococcus lactis ssp. cremoris (LL8307) and Enterococcus durans (ED0207) originally isolated from artisanal Croatian hard type cheese to diversify the range of flavours of dry fermented sausages and to increase their microbiological safety. Both strains were chosen for their high or medium acidifying, proteolytic and/or lipolytic activity and bioprotective potential after step-by-step selection of wild isolates. Therefore, this study aims to evaluate the survival rate of selected starter cultures in wild boar meat sausages during the ripening period of 40 days at a local small-scale facility under artisanal conditions as well as their influence on sausage quality parameters. Experimental approach. Safety, biotechnological and probiotic properties of twenty-three enterococcal and lactococcal isolates of dairy origin were studied. Based on the results, two best candidates were selected and added to the meat batter during the artisanal wild boar meat sausage preparation where their survival rate, effect on physicochemical, microbiological and sensorial properties and histamine content were evaluated. Results and conclusions. As revealed by repetitive element-polymerase chain reaction (rep-PCR), native starter cultures survived up to 15 days of ripening and were either absent from (LL8307) or reduced by 80% (ED0207) in final products. The application of native starter cultures rapidly decreased pH (p<0.05), leading to the significantly lower load of E. coli, coliforms and Enterobacteriaceae in ready-to-eat sausages prepared by the addition of starter cultures (3.04-3.94 log CFU/g) than in the control (3.88-5.00 log CFU/g). Analysis of hedonic test data revealed that some of the sensory traits (odour, flavour, juiciness) of treatments with starter cultures were highly liked by the higher percentage of consumers. The results suggest that these starter cultures would represent a valuable tool to improve the homogeneity of artisanal manufacture and hygienic quality of fermented sausages and can be safely used for food application. Novelty and scientific contribution. This is the first study to explore in depth the biotechnological potential of bacterial cultures isolated from artisanal Croatian cheese as functional starter cultures for high-quality game meat sausage production.Pozadina istraživanja. S obzirom na to da se fermentacija podjednako koristi za dobivanje trajnih kobasica i tvrdih sireva, bakterijske kulture Lactococcus lactis ssp. cremoris (LL8307) i Enterococcus durans (ED0207) izolirane su iz tradicionalnih hrvatskih tvrdih sireva, te detaljno okarakterizirane radi postizanja palete okusa trajnih fermentiranih kobasica i povećanja njihove mikrobiološke sigurnosti. Oba soja su odabrana nakon postupne selekcije autohtonih izolata zbog njihove velike ili srednje velike sposobnosti zakiseljavanja, proteolitičke i/ili lipolitičke aktivnosti, te moguće biozaštitne uloge. Stoga je svrha ovog istraživanja bila procijeniti stopu preživljavanja odabranih starter kultura u kobasicama od mesa divlje svinje tijekom perioda zrenja od 40 dana pri tradicionalnim uvjetima proizvodnje, te ispitati njihov utjecaj na parametre kakvoće kobasica. Eksperimentalni pristup. Ispitana su sigurnosna, biotehnološka i probiotička svojstva dvadeset i triju izolata enterokoka i laktokoka podrijetlom iz hrvatskih tradicionalnih tvrdih sireva. Na osnovi dobivenih rezultata izabrana su dva najbolja kandidata, koja su dodana nadjevu kobasica od mesa divlje svinje, te je procijenjena stopa preživljavanja izolata, njihov utjecaj na fizikalno-kemijska, mikrobiološka i senzorska svojstva kobasica te udjel histamina. Rezultati i zaključci. Analizom ponavljajućih elemenata lančane reakcije polimerazom (rep-PCR) utvrđeno je da su autohtone starter kulture preživjele u kobasicama do 15 dana zrenja, a da ih nije bilo (soj LL8307) ili je njihov broj bio reduciran za 80 % (soj ED0207) u gotovim proizvodima. Primjena odabranih starter kultura brzo je smanjila pH-vrijednost kobasica (p<0,05) i znatno smanjila broj E. coli, koliforma i enterobakterija u gotovim proizvodima pripremljenim s dodatkom starter kultura (3,04-3,94 log CFU/g), u usporedbi s kontrolnim uzorkom (3,88-5,00 log CFU/g). Analiza rezultata hedonističkog testa otkrila je da su se neke od senzornih osobina (miris, okus, sočnost) kobasica proizvedenih s odabranim starter kulturama svidjele većem broju potrošača. Rezultati upućuju na zaključak da ove starter kulture mogu pridonijeti standardizaciji proizvodnje i poboljšanju higijenske ispravnosti tradicionalnih fermentiranih kobasica, te da se mogu sigurno primijeniti u proizvodnji hrane. Novina i znanstveni doprinos. Ovo je prva studija koja je detaljno istražila biotehnološki potencijal bakterijskih kultura izoliranih iz tradicionalnog hrvatskog sira i upotrijebljenih kao funkcionalne starter kulture u proizvodnji visokokvalitetnih kobasica od mesa divljači