Uticaj sastava i termičkog tretmana mleka na distribuciju proteina u proizvodnji kajmaka i svojstva formirane pokožice

Kajmak is a Serbian autochthonous dairy product which is usually manufactured by the traditional production procedure. Kajmak is characterized by specific composition and unique properties and can be classified into the group of delicious dairy products, which takes place between cheese and butter. However, significant differences in the production conditions often result in a very large variations of the kajmak composition and quality, which prevent its widespread and organized appearance on the market. The process of kajmak formation can be divided into hot and cold phases. In the hot phase, due to the surface activity of proteins and fats, as well as the intense water evaporation, the formation of the initial skin layer occurs, which represents the base and the top layer of the final product (kajmak). In the cold phase, initial skin is being enriched by milk fat, resulting in the formation of the lower layer of the kajmak. Heat treatment of milk, which is present in the kajmak production, results in the significant changes in milk protein complex, such as the denaturation of whey proteins, formation of milk protein coaggregates as well as reaction of denatured whey proteins and milk fat globule membrane (MFGM). Due to the strong surface activity, milk fat globule and proteins diffuse to the top layer of milk and concentrate at the air-milk interface. Casein, due to its micellar form, has minor affinity for hydrophobic surfaces compared with individual components of casein micelles or casein preparations. Native whey proteins are globular and hence shows a little surface activity. However, milk heat treatment at temperatures between 70°C to 75°C cause denaturation of whey proteins as well as modification of their secondary and tertiary structure. These modifications cause changes in their functional properties, which result in the increasing of surface activity, altered interfacial rheology, emulsion and foaming properties and others. Environmental conditions represent an important factor in the overall kajmak production. During the process of the initial skin and kajmak formation, milk is continuously being cooled and permanently is in contact with the surrounding air. During the cooling process there is high energy exchange, i.e. the process of heat flux exchange from the hot milk to the surrounding air. At same time, there is the evaporation of water from milk. The aim of this research was detailed investigation of the kajmak forming mechanisms, as well as factors that influence the composition and properties of this specific dairy product...Kajmak je srpski autohtoni mlečni proizvod koji se prevashodno izraĎuje u domaćoj radinosti. Odlikuje se specifičnim sastavom i senzornim svojstvima, na osnovu kojih se može svrstati u grupu delikatesnih mlečnih proizvoda, koji se nalaze izmeĎu sireva i maslaca. MeĎutim, izrazita raznolikost uslova u kojima se proizvodi rezultira u izrazito velikom variranju sastava i kvaliteta kajmaka, koja onemogućavaju njegov organizovan i širi nastup na tržištu. Proces formiranja kajmaka može se podeliti na toplu i hladnu fazu. U toploj fazi, usled površinske aktivnosti masti i proteina, kao i intenzivnog isparavanja vode, dolazi do formiranja početne pokožice, koja predstavlja osnovu i gornji sloj kajmaka, dok u hladnoj fazi dolazi do obogaćivanja pokožice mlečnom mašću, pri čemu se formira donji sloj kajmaka. Termički tretman mleka zastupljen u proizvodnji kajmaka rezultuje izraženim promenama na proteinskom kompleksu mleka, pri čemu dolazi do denaturacije proteina surutke, stvaranja koagregata proteina mleka kao i reakcije denaturisanih proteina surutke sa proteinima iz adsorpcionog sloja globula mlečne masti (MFGM). Usled površinske aktivnosti masti i proteina vrelog mleka dolazi do njihove difuzije i koncentrisanja u graničnom sloju mleko-vazduh. Kazeini se u mleku nalaze u micelarnoj formi i kao takvi pokazuju mali afinitet prema hidrofobnim površinama. Nativni proteini surutke su globularni i sporije se adsorbuju. MeĎutim, nakon termičkog tretmana, na temperaturama od 70 do 75°C, proteini surutke denaturišu, pri čemu dolazi do modifikacije sekunadarne i tercijarne konformacije molekula ovih proteina. Ove modifikacije uzrokuju promene njihovih funkcionalnih svojstava, koje se ogledaju u povećanoj površinskoj aktivnosti, izmenjenoj meĎupovršinskoj reologiji, emulzionim i penivim svojstvima i dr. Ambijentalni uslovi u kojima se izvodi proces formiranja kajmaka predstavljaju značajan faktor u proizvodnji kajmaka. U toku procesa formiranja pokožice i kajmaka mleko se neprekidno hladi i permanentno je u kontaktu sa okolnim vazduhom. U toku procesa hlaĎenja dolazi do razmene energije, odnosno, procesa predaje toplotnog fluksa sa strane vrelog mleka vazduhu, uz istovremeno isparavanje vode iz mleka. Istraživanja obuhvaćena ovim radom imaju za cilj detaljnije sagledavanje mehanizama formiranja kajmaka, kao i faktora koji utiču na sastav i svojstva proizvoda, a sve u funkciji stvaranja šire naučne osnove u poznavanju postupka formiranja ovog specifičnog mlečnog proizvoda..

The influence of milk composition and heat treatment on the distribution of proteins in kajmak production and properties of the formed skin layer

Kajmak je srpski autohtoni mlečni proizvod koji se prevashodno izraĎuje u domaćoj radinosti. Odlikuje se specifičnim sastavom i senzornim svojstvima, na osnovu kojih se može svrstati u grupu delikatesnih mlečnih proizvoda, koji se nalaze izmeĎu sireva i maslaca. MeĎutim, izrazita raznolikost uslova u kojima se proizvodi rezultira u izrazito velikom variranju sastava i kvaliteta kajmaka, koja onemogućavaju njegov organizovan i širi nastup na tržištu. Proces formiranja kajmaka može se podeliti na toplu i hladnu fazu. U toploj fazi, usled površinske aktivnosti masti i proteina, kao i intenzivnog isparavanja vode, dolazi do formiranja početne pokožice, koja predstavlja osnovu i gornji sloj kajmaka, dok u hladnoj fazi dolazi do obogaćivanja pokožice mlečnom mašću, pri čemu se formira donji sloj kajmaka. Termički tretman mleka zastupljen u proizvodnji kajmaka rezultuje izraženim promenama na proteinskom kompleksu mleka, pri čemu dolazi do denaturacije proteina surutke, stvaranja koagregata proteina mleka kao i reakcije denaturisanih proteina surutke sa proteinima iz adsorpcionog sloja globula mlečne masti (MFGM). Usled površinske aktivnosti masti i proteina vrelog mleka dolazi do njihove difuzije i koncentrisanja u graničnom sloju mleko-vazduh. Kazeini se u mleku nalaze u micelarnoj formi i kao takvi pokazuju mali afinitet prema hidrofobnim površinama. Nativni proteini surutke su globularni i sporije se adsorbuju. MeĎutim, nakon termičkog tretmana, na temperaturama od 70 do 75°C, proteini surutke denaturišu, pri čemu dolazi do modifikacije sekunadarne i tercijarne konformacije molekula ovih proteina. Ove modifikacije uzrokuju promene njihovih funkcionalnih svojstava, koje se ogledaju u povećanoj površinskoj aktivnosti, izmenjenoj meĎupovršinskoj reologiji, emulzionim i penivim svojstvima i dr. Ambijentalni uslovi u kojima se izvodi proces formiranja kajmaka predstavljaju značajan faktor u proizvodnji kajmaka. U toku procesa formiranja pokožice i kajmaka mleko se neprekidno hladi i permanentno je u kontaktu sa okolnim vazduhom. U toku procesa hlaĎenja dolazi do razmene energije, odnosno, procesa predaje toplotnog fluksa sa strane vrelog mleka vazduhu, uz istovremeno isparavanje vode iz mleka. Istraživanja obuhvaćena ovim radom imaju za cilj detaljnije sagledavanje mehanizama formiranja kajmaka, kao i faktora koji utiču na sastav i svojstva proizvoda, a sve u funkciji stvaranja šire naučne osnove u poznavanju postupka formiranja ovog specifičnog mlečnog proizvoda...Kajmak is a Serbian autochthonous dairy product which is usually manufactured by the traditional production procedure. Kajmak is characterized by specific composition and unique properties and can be classified into the group of delicious dairy products, which takes place between cheese and butter. However, significant differences in the production conditions often result in a very large variations of the kajmak composition and quality, which prevent its widespread and organized appearance on the market. The process of kajmak formation can be divided into hot and cold phases. In the hot phase, due to the surface activity of proteins and fats, as well as the intense water evaporation, the formation of the initial skin layer occurs, which represents the base and the top layer of the final product (kajmak). In the cold phase, initial skin is being enriched by milk fat, resulting in the formation of the lower layer of the kajmak. Heat treatment of milk, which is present in the kajmak production, results in the significant changes in milk protein complex, such as the denaturation of whey proteins, formation of milk protein coaggregates as well as reaction of denatured whey proteins and milk fat globule membrane (MFGM). Due to the strong surface activity, milk fat globule and proteins diffuse to the top layer of milk and concentrate at the air-milk interface. Casein, due to its micellar form, has minor affinity for hydrophobic surfaces compared with individual components of casein micelles or casein preparations. Native whey proteins are globular and hence shows a little surface activity. However, milk heat treatment at temperatures between 70°C to 75°C cause denaturation of whey proteins as well as modification of their secondary and tertiary structure. These modifications cause changes in their functional properties, which result in the increasing of surface activity, altered interfacial rheology, emulsion and foaming properties and others. Environmental conditions represent an important factor in the overall kajmak production. During the process of the initial skin and kajmak formation, milk is continuously being cooled and permanently is in contact with the surrounding air. During the cooling process there is high energy exchange, i.e. the process of heat flux exchange from the hot milk to the surrounding air. At same time, there is the evaporation of water from milk. The aim of this research was detailed investigation of the kajmak forming mechanisms, as well as factors that influence the composition and properties of this specific dairy product..

Production and characteristics of kajmak

Kajmak je tradicionalni mliječni proizvod specifičnog sastava i senzorskih svojstava. Svi parametri procesa proizvodnje, zrenja, sastava i senzorskih svojstava ovog specifičnog mliječnog proizvoda u okviru su odgovarajućih parametara srodnih mliječnih proizvoda: sireva i maslaca. Proizvodnja kajmaka je danas zastupljena u seoskim domaćinstvima i zasniva se na tradicionalnom postupku. Tradicionalan način izrade kajmaka nije pogodan za industrijsku proizvodnju. Kajmak dobiven tradicionalnim postupkom, od proizvođača do proizvođača veoma je neujednačene kvalitete. Radi standardizacije proizvodnje i svojstava kajmaka, neophodno je njegovu proizvodnju prilagoditi i prenijeti u industrijske uvjete. Time bi bila omogućena bolja prodaja kajmaka na domaćem i stranom tržištu. U radu je predstavljen postupak industrijske proizvodnje kajmaka koji je razvijen u kompaniji «Polimark» na osnovi zaštićene tehnologije. Tehnološki postupak osigurava dobivanje proizvoda visoke i standardne kvalitete, koji po svim karakteristikama odgovara kajmaku dobivenom tradicionalnim postupkom. Postupak industrijske proizvodnje kajmaka obuhvaća i sve procese tradicionalne proizvodnje, ali je način sprovođenja prilagođen kako bi bili zadovoljeni zahtjevi suvremenog načina rada u industrijskim uvjetima. Postupak pruža niz prednosti u odnosu na tradicionalni način izrade, a jedna od prednosti je višestruko skraćenje vremena proizvodnje, bakteriološka ispravnost proizvoda, standardizacija postupka i dobivenog proizvoda, industrijski način rada i široke mogućnosti u korištenju preostalog mlijeka.Traditional method of kajmak production is, due to the numerous steps, inappropriate for industrial production scale. Traditionally produced kajmak differs greatly from producer to producer in composition and quality. To standardize production scale and characteristics of kajmak, it is necessary to adapt its production steps to industrial scale. That would result in better selling in domestic and foreign market. Procedure of industrial kajmak production presented in this paper was developed in company «Polimark», based on patented technology. Technological procedure enables production of standardized, high quality product, which fully matches characteristics of traditionally produced kajmak. All processes involved in traditional production are included in presented technology, but their application is modified in order to follow the principles which are usually used in industrial production scale. Presented procedure has a number of advantages compared to traditional production, such as: great decrease in production time, high microbiological product quality, industrial process design and a wide range of possibilities in utilization of remained milk

Postupak proizvodnje kajmaka tradicionalnog kvaliteta u uslovima industrijskog načina rada

Kajmak is our exclusive traditional dairy product. It is made on farms, as a home made product. Traditional procedure lasts about 24 h and it is not suitable in its original form for industrial application. Procedure of industrial kajmak production reviewed in this work was developed in company "Polimark", based on patented technology. Technological procedure enables production of standardized, high quality product, which fully match's the characteristics of traditionally produced kajmak. All processes involved in traditional production are also included in presented technology, but the way of their application is modified in order to follow the principles present in production on industrial scale. Presented procedure has a number of advantages compared to traditional production, such as: massive decrease in production time; high microbiological product quality; industrial process design; and wide range of possibilities in utilization of remained milk.Kajmak je naš ekskluzivni tradicionalni mlečni proizvod. Izrađuje se u seoskim domaćinstvima na tradicionalni način postupkom koji traje oko 24 h, a koji u svom izvornom obliku nije pogodan za industrijsku primenu. U radu je predstavljen postupak industrijske proizvodnje kajmaka koji je razvijen u kompaniji "Polimark" na osnovu zaštićene tehnologije. Tehnološki postupak obezbeđuje dobijanje proizvoda visokog i standardnog kvaliteta, koji se ni po čemu ne razlikuje od kajmaka dobijenog tradicionalnim postupkom. Svi procesi zastupljeni u postupku proizvodnje prisutni su i u tradicionalnoj proizvodnji, ali je način njihove primene korigovan kako bi se uvažili zahtevi savremenog načina rada u industrijskim uslovima. Postupak pruža niz prednosti u odnosu na tradicionalni način izrade. Izdvajaju se višestruko skraćenje vremena proizvodnje, bakteriološka ispravnost proizvoda industrijski način rada i široke mogućnosti u korišćenju preostalog mleka

Razvoj tehnologije niskomasnih sireva od ultrafiltriranog (UF) mlijeka

The production procedure of low fat cheeses produced from ultrafiltered milk (UF cheese) was developed in this study. The production procedure, that includes utilization of UF milk with 2 % of lactose, addition of 1.5 % inulin and salting with 2 % of mixed salt (NaCl/KCl in ratio 3:1) was defined based on the investigation that included the influence of coagulation parameters, different lactose content of UF milk, different inulin content, and different salt type and content on the properties of low fat UF cheeses. Presented production procedure enables the production of a product with satisfactory dietetic and functional properties. Reduced lactose content of UF milk contributes to stabilisation of pH value at an adequate level and achievement of acceptable texture properties of low fat UF cheeses. Defined inulin content (1.5 %) improved cheese texture, as well as its functional properties, enabling the cheese produced to be marked as a “good source of fibre”. Reduced sodium content, due to partial substitution of NaCl with KCl, also contributes to the improvement of dietetic properties of cheeses. Low fat UF cheeses, produced according to defined production procedure, were analysed during 8 weeks of ripening and storage periods. Composition, pH values and proteolytic pattern were typical for brined cheeses. Uniform microstructure and acceptable sensory properties, especially the texture, confirm the validity of the developed production procedure of low fat UF cheeses from UF milk.U radu je razvijen tehnološki postupak proizvodnje niskomasnih sireva od ultrafiltriranog (UF) mlijeka. Ispitivanjem utjecaja parametara koagulacije, različitog udjela laktoze, dodavanja različitog udjela inulina, kao i vrste i sadržaja soli na svojstva niskomasnih sireva od UF mlijeka, definiran je tehnološki postupak koji obuhvaća upotrebu UF mlijeka sa 2 % laktoze, dodavanje 1,5 % inulina i soljenje sa 2 % kombinirane soli (NaCl/KCl u omjeru 3:1). Takav postupak u potpunosti omogućava dobivanje proizvoda s dobrim dijetetskim i funkcionalnim svojstvima. Smanjen udjel laktoze u UF mlijeku doprinosi postizanju i zadržavanju pH vrijednosti na adekvatnoj razini, što rezultira prihvatljivim teksturalnim svojstvima niskomasnih sireva. Definirana količina inulina (1,5 %) poboljšava teksturalna, kao i funkcionalna svojstva sireva, što omogućava da se proizvod deklarira kao “dobar izvor vlakana”. Također, smanjen udjel natrija uslijed djelomične supstitucije NaCl sa KCl pridonosi poboljšanju dijetetskih svojstava sireva. Niskomasni sirevi od UF mlijeka, proizvedeni prema definiranom postupku proizvodnje, ispitivani su tijekom 2 mjeseca zrenja i skladištenja. Parametri sastava, pH vrijednosti i proteolize ukazuju na mali obujam promjena, tipično za sireve u salamuri. Ujednačena mikrostruktura i veoma dobra senzorska svojstava, osobito tekstura, potvrđuju validnost razvijenog postupka proizvodnje niskomasnih sireva od UF mlijeka

Mogućnosti primene Raman spektroskopije u ispitivanju mleka i proizvoda od mleka

Raman spectroscopy is a vibrational spectroscopic technique based on inelastic light scattering. This non-destructive, non-contact technique provides a number of qualitative and quantitative information about the different samples and has been applied in many fields of research. In combination with an optical microscope this method is ideal for testing of heterogeneous systems. The limitations of this technique include problems with fluorescence, but nowadays they are significantly reduced with developed instrumental solutions. Thanks to the numerous advantages (very weak signal lead, working with concentrated solutions, a wide range of sample types, etc.), Raman spectroscopy has great potential for application in the examination of milk and milk products.Raman spektroskopija je vibraciona spektroskopska tehnika koja se zasniva na neelastičnom rasejanju svetlosti. Ova nedestruktivna, bezkontaktna tehnika daje brojne kvalitativne i kvantitativne informacije o različitim uzorcima i našla je primenu u mnogim oblastima istraživanja. U kombinaciji sa optičkim mikroskopom idealna je za ispitivanje heterogenih sistema. Od početka primene, ograničenja ove tehnike tiču se problema sa fluorescencijom, koji su se razvojem instrumentalnih rešenja danas značajno smanjili. Zahvaljujući prednostima koje pruža (vrlo slab signal vode, rad sa koncentrovanim rastvorima, širok opseg tipova uzoraka i dr.), Raman spektroskopija ima vrlo veliki potencijal za primenu u ispitivanju mleka i proizvoda od mleka

Properties of low-fat ultra-filtered cheeses produced with probiotic bacteria

Probiotics are live microorganisms that in certain numbers may confer a health benefit on the host. Nowadays, there are many dairy products on the market, especially fermented milks, with probiotics, and their popularity is rising. The aim of this article was to investigate the viability of commercial probiotic bacteria (Lactobacillus acidophilus LAFTI(center dot)L10 i Bifidobacterium lactis LAFTI(center dot)B94, DSM, Netherland) as well as their influence on the changes of composition, pH, proteolysis, microbiological status and sensory properties of low-fat ultra-filtered (UF) cheeses within 2 months of ripening. Low-fat cast ultra-filtered (UF) cheeses were produced according to the defined production procedure by mixing UP milk protein powder, skim milk and cream, without (control cheese A) and with adjunct probiotic culture (cheese B). The compositional parameters (milk fat, proteins and dry-matter content), pH, proteolysis parameters (water soluble nitrogen, nitrogen soluble in 5% PTA, urea and SDS PAG electrophoresis), as well as the numbers of starters and probiotic bacteria, were determined during ripening. In addition, sensory evaluations of cheeses were performed throughout the ripening time. A significant influence of probiotic strains on the composition, pH and primary proteolysis of cheese during ripening was not found. The counts of commercial probiotic bacteria were maintained at high levels (> 10(7) cfug(-1)) during the overall ripening period, as a prerequisite of their therapeutic effects. The adjunct probiotic cultures enhanced the rate of secondary proteolysis, which was shown by the significantly higher levels of PTAN/TN of experimental compared to the control cheeses. The sensory evaluation showed that the overall aroma of low-fat cheeses was remarkably improved by the addition of the probiotic cultures used. Based on the results it can be concluded that the low-fat UF cheeses differ in good dietetic and functional properties as well as very acceptable sensory properties, and can be used as carriers of probiotics

Promene u sadržaju fenolnih jedinjenja u listovima suncokreta nakon inokulacije uzročnikom plamenjače

Two nearly isogenic lines of sunflower, resistant and susceptible to downy mildew, due to the presence/absence of the Pl6 gene, were used in this study. Inoculation with the suspension of Plasmopara halstedii zoospores, was done on the plants in the phase of first pair of leaves. In the samples taken from 2nd to 96th h after inoculation, content of phenolic compounds in methanolic extracts from frozen leaves were analyzed (UV-VIS and HPLC analysis). A constitutive level of phenolic compounds, as well as, their accumulation after the inoculation were higher in the susceptible than in the resistant isogenic line. Chlorogenic, ferulic acid and esculin had the highest contribution to the phenolic compound accumulation 24 h after the inoculation in the susceptible line, while only the chlorogenic acid and eculin accumulated in the resistant line. Also, there was a trend of scopoletin accumulation in the resistant line.U ovom radu korišćene su dve izogene linije suncokreta koje se razlikuju po prisustvu Pl6 gena za otpornost prema plamenjači. U fazi prvog para listova izvršena je inokulacija biljaka suspenzijom zoospora Plasmopara halstedii. U uzorcima uzetim od dva do 96 h nakon inokulacije, analiziran je sadržaj fenolnih jedinjenja u metanolnim ekstraktima iz zamrznutih listova suncokreta (UV-VIS i HPLC analiza). Konstitutivni nivo fenolnih jedinjenja, kao i njihova akumulacija nakon inokulacije su veći kod osetljive nego kod otporne izogene linije. Najveći doprinos akumulaciji fenolnih jedinjenja 24 h nakon inokulacije kod osetljive linije imaju hlorogena, ferulična kiselina i eskulin, a kod otporne linije hlorogena kiselina i eskulin. Kod otporne linije postoji trend akumulacije skopoletina

Ispitivanje kvaliteta kajmaka - hemijski, mikrobiološki i senzorni aspekt

Kajmak is autohthonous product, which is traditionally made like farmhouse fermented milk product by farmers. In such conditions of production, quality of kajmak is usually very variable and nonstandard. The aim of this paper was to research chemical composition, autohthonous microflora, microbiological and sensory quality of kajmak samples, which had been collected from green markets and supermarkets on Belgrade territory. Chemical composition and sensory quality of tested kajmak samples showed great difference, while according to microbiological analyses, not all samples were suitable for human consumption. Industrial production of kajmak, under controlled conditions and usage of starter cultures could be the solution for getting good standard quality of this dairy product. Also, this could lead to better marketing possibilities for domestic market and for export.Kajmak predstavlja autohtoni proizvod, čija je proizvodnja pretežno zastupljena u seoskim domaćinstvima i zasniva se na tradicionalnom postupku dobijanja. U takvim uslovima, proizvod je veoma neujednačenog i nestandardizovanog kvaliteta. Cilj rada je bio da se ispita hemijski sastav autohtona mikroflora i mikrobiološka ispravnost, kao i senzorne karakteristike uzoraka kajmaka koji se mogu naći u slobodnoj prodaji na teritoriji Beograda. U pogledu hemijskog sastava i senzornog kvaliteta svi ispitivani uzorci kajmaka pokazuju veliku raznolikost, dok u mikrobiološkom pogledu uzorci ne odgovaraju važećim normama Pravilnika, te kao takvi ne bi smeli da se stavljaju u promet. Rešenje pitanja standardizacije procesa proizvodnje i kvaliteta kajmaka moglo bi biti u industrijskoj proizvodnji koja bi dala proizvod dobrog standardnog kvaliteta. To bi omogućilo i veći plasman kajmaka kako na domaćem, tako i stranom tržištu