76 research outputs found
Paška skuta
No full textPaški sir je hrvatski najpoznatiji tvrdi ovčji sir, koji se proizvodi već dugi niz godina na
otoku Pagu i danas je jedan od najpoznatijih i najcjenjenijih sireva u svijetu.
Kao glavni nusproizvod proizvodnje sira, pa tako i paškog, nastaje sirutka, čiji sastav i
svojstva ovise o tehnologiji proizvodnje, dodacima i o kakvoći upotrijebljenog mlijeka.
U sirutku tijekom proizvodnje sira prelazi oko 50% suhe tvari mlijeka, a njezin najveći
udio čini laktoza (≈70%). Nakon laktoze po zastupljenosti dolaze sirutkini proteini (β-
laktoglobulin, α-laktalbumin, albumini krvnog seruma (BSA), imunoglobulini, proteoze i
peptoni), mliječna mast i mineralne tvari. Iz sirutke se dodatnim postupkom proizvodnje dobiva
skuta, odnosno albuminski sir koji pripada skupini svježih sireva. Skuta je bogata sirutkinim
proteinima koji su lako probavljivi i imaju visok stupanj iskoristivosti u organizmu.
Kvaliteta ovčjeg mlijeka korištenog za proizvodnju paškog sira u pokusnim uvjetima je,
izuzev pH vrijednosti, odgovarala kvaliteti propisanoj Pravilnikom o kakvoći svježeg sirovog
mlijeka (2000.) i standardima mlijeka paških ovaca koje su navodili drugi autori u literaturi. Iz
sirutke dobivene u proizvodnji paškog sira proizvedena je paška skuta za potrebe ovog rada.
Analize su provedene u Referentnom laboratoriju Zavoda za mljekarstvo, referentnim i
standardnim metodama.
Prosječni udio vode i suhe tvari paške skute iznosio je 49,91% odnosno 50,09%.
Prosječni udio mliječne masti u paškoj skuti je iznosio 37,19%, a udio mliječne masti u suhoj
tvari 74,23 %. Prosječni udio proteina iznosio je 11,71%, a pH vrijednost 6,39.
Izračunati randman u proizvodnji skute je iznosio prosječno 7,10 kg skute dobivenih iz
100 kg sirutke.Paški sir (the Pag Cheese) is the most famous Croatian sheep cheese, which has been
produced on the Island of Pag for ages and presently is one of the most renowned and praised
cheeses in the world.
Whey is the main by-product of any cheese production, and therefore also of the Pag
Cheese. Its composition and characteristics depend on the production technology, additives and
the quality of the raw milk.
During the production process, whey retains around 50% of the milk dry matter, while
its greatest part is lactose (70%). Besides lactose, other whey components are whey proteins (β-
lactoglobulins, α-lactalbumins, blood serum albumins, immunoglobulins, proteoses and
peptones), milk fat and mineral substances. Whey is further used in the production of skuta
(whey cheese), an albumin cheese that belongs to the group of cottage cheeses. Whey cheese is
rich in whey proteins that are easily digestible and have a high degree of usability in the
organism.
The quality of ovine milk used in the production of Pag Cheese in experimental
conditions, apart from the pH value, was in accordance with the Ordinance on the Quality of
Fresh Raw Milk (2000) and the milk standards of the Pag sheep stated by other authors in the
literature. Whey obtained from the production of Pag Cheese was used in the production of
whey cheese analysed in this paper. The analyses were conducted using reference standard
methods in the Reference Laboratory of the Department of Dairy Science.
The average ratio of water and dry matter in the Pag Whey Cheese was 49,91% and
50,09%, respectively. The average content of milk fat in the Pag Whey Cheese was 37,19% and
the content of milk fat in dry matter was 74,23%. The average protein content was 11,71% and
the pH value was 6,39.
The calculated yield in the production of whey cheese was average 7,10 kg of whey
cheese obtained from 100 kg of whey
The Impact of the replacement of a part of NaCl with KCl on the chemical composition and rheological properties of Škripavac cheese
No full textNatrij iz hrane utječe na mehanizam regulacije krvnog tlaka, a time i na zdravlje
krvožilnog sustava čovjeka. Kako se sir smatra jednim od značajnijih izvora natrija, u mnogim
istraživanjima koriste se zamjenske mineralne soli kao što je primjerice KCl kako bi se
reducirao udio natrija u siru, a da sir zadrži potrebnu slanost i ostala važna svojstva. Neupitno
je da NaCl koji se u sir dodaje postupkom soljenja u proizvodnji sira izravno utječe na mnoge
značajne karakteristike sira kao što su njegov sastav i reološka svojstava. Međutim, sir
škripavac karakterizira nizak udio soli (oko 1%), pa je za pretpostaviti da zamjena dijela NaCl
s KCl neće imati negativan utjecaj na njegov kemijski sastav i reološka svojstva. Cilj rada je
bio utvrditi utjecaj zamjene dijela NaCl s KCl na kemijski sastav i reološka svojstva sira
škripavca.
Sir škripavac proizveo se u pilot pogonu Zavoda za mljekarstvo. Ukupno 60 kg mlijeka
podijelilo se na tri podjednake mase po 20 kg u pet ponavljanja. U svakom ponavljanju
proizvedena su tri sira škripavca različitog udjela natrija kako slijedi: 100% NaCl (kontrolna
grupa), sir škripavac sniženog sadržaja natrija zamjenom 50% NaCl s KCl, sir škripavac
sniženog sadržaja natrija zamjenom 75% NaCl s KCl. Analize sira provedene su standardnim
metodama, a obuhvatile su određivanje sadržaja masti, proteina, suhe tvari, soli, natrija i kalija
te pH vrijednost i aktivitet vode. Za mjerenje teksture koristio se teksturni analizator (TA Plus
Lloyd Instruments) na kojem su se utvrdila slijedeća reološka svojstva: čvrstoća, lomljivost,
deformacija u točki loma, adhezivnost i kohezivnost.
Utvrđeno je da nema značajnih razlika u fizikalnom-kemijskom sastavu sira škripavca
kada je dio NaCl zamijenjen s KCl, osim za vrijednost pH koja se povećala za 0,1 (P<0,001),
dok se sadržaj natrija značajno (P<0,001) smanjio kada se dio NaCl zamijenio s KCl. Nije došlo
do značajnih promjena u reološkim svojstvima sira uslijed zamjene dijela NaCl s KCl, osim za
kohezivnost koja je bila veća (P = 0,099) u siru koji je proizveden s 50% NaCl i 50% KCl.
Koeficijenti korelacija između reoloških svojstava i fizikalnog-kemijskog sastava sira
škripavca pokazali su da lomljivost, deformacija u točci loma i gumenost sira rastu kao
posljedica porasta suhe tvari, a što podrazumijeva i veći udio masti i proteina u siru. Svojstvo
škripavosti posljedica je činjenice da sir škripavac ima specifičnu gumenu strukturu, pri čemu
je utvrđena visoka i negativna korelacija između gumenosti i sadržaja vode u bezmasnoj tvari
sira (P<0,05; r = -0,704).Sodium from food affects the mechanism of blood pressure regulation, and thus the
health of the human cardiovascular system. As cheese is considered one of the most important
sources of sodium, many studies use substitute mineral salts such as KCl to reduce the sodium
content of the cheese while maintaining the required salinity and the other cheese properties.
There is no doubt that NaCl added to cheese in the salting process during cheese production
directly affects many significant characteristics of the cheese such as its composition and rheological
properties. However, Škripavac cheese is characterized by a low salt content (about 1%),
so it is to be assumed that replacing part of NaCl with KCl will not have a negative impact on
its chemical composition and rheological properties. The aim of this paper is to determine the
impact of the replacement of a part of NaCl with KCl on the chemical composition and rheological
properties of škripavac cheese.
Škripavac cheese will be produced in the pilot plant of the Department of Dairy Science.
A total of 60 kg of milk was divided into three equal masses of 20 kg in five batches.In each
iteration, three Škripavac cheeses with different sodium contents were produced as follows:
100% NaCl (control group), Škripavac cheese with reduced sodium content by replacing 50%
NaCl with KCl, Škripavac cheese with reduced sodium content by replacing 75% NaCl with
KCl. Cheese analyses were included determination of fat, protein, dry matter, salt, sodium and
potassium content and pH and water activity.A texture analyser (TA Plus Lloyd Instruments)
was used to measure the texture, on which the following rheological properties were determined:
strength, brittleness, fracture point deformation, adhesiveness and cohesiveness.
It was found that there are no significant differences in the physico-chemical composition
of the hard cheese when part of the NaCl is replaced by KCl, except for the pH value which
increased by 0.1 (P <0.001), while sodium content decreased significantly (P <0.001) when part
of NaCl was replaced by KCl. There were no significant changes in the rheological properties
of the cheese due to the replacement of part of NaCl with KCl, except for the cohesiveness
which was higher (P = 0.099) in the cheese produced with 50% NaCl and 50% KCl.
The correlation coefficients between the rheological properties and the chemical-physical
composition of the Škripavac cheese showed that fracture, deformation at the breaking
point, and gumminess of the cheese increase as a result of the increase in dry matter, which
means higher fat and protein content in cheese. The squeaking property of Škripavac cheese is
a consequence of the fact that Škripavac cheese has a specific rubber structure which was in a
high and negative correlation with water content in the fat-free solids of cheese (P <0.05; r = -
0.704)
Adulteration of ewe and goat cheeses on the market of Republic of Croatia
No full textSirevi od kozjeg/ovčjeg mlijeka smatraju se patvorenim ukoliko se dokaže prisutnost od minimalno 1% udjela kravljeg mlijeka. Stoga je cilj ovog rada utvrditi pojavnost patvorenja ovčjih i kozjih sireva na tržištu Republike Hrvatske.
Metoda dokazivanja patvorenja obuhvaćala je izolaciju kazeina iz sira (n=25), izoelektrično fokusiranje γ2 i γ3-kazeina dobivenih hidrolizom β-kazeina djelovanjem plazmina kao referentnu metodu, te detekciju i kvantitativno određivanje γ-kazeina kravljeg, kozjeg i ovčjeg mlijeka metodom dezintometrije. Rezultati za svaki pojedini uzorak sira uspoređeni su s deklaracijom i unešeni u tablicu kako bi se dokazala eventualna prisutnost patvorenih ovčjih i kozjih sireva na tržištu Republike Hrvatske. Metoda izoelektričnog fokusiranja, koja se primjenjuje kao referentna za ovakve vrste analiza, pokazala se prikladnom za detekciju kravljeg mlijeka u ovčjim i kozjim sirevima. Rezultati ovog rada utvrdili su patvorenje kod 24% uzoraka sira sa tržišta Republike Hrvatske, odnosno udio kravljeg mlijeka u patvorenim sirevima bio je u rasponu 2% do 18%.Cheeses made from goat/ewe's milk are considered to be adulterated if more than 1% of cow's milk is added. Therefore, the aim of this thesis was to determine the possible adulteration of goat and ewe's cheeses with cow's milk on the market of the Republic of Croatia.
The sampling method involved isolation of casein from cheese (n=25), using the reference method of isoelectric focusing of γ2 and γ3-casein obtained from β-casein which is hydrolysed by plasmin, and detection and quantification of γ-casein from cow's milk by the method of densitometry. The obtianded results for each sample of cheese were compared with the product declaration in order to prove the possible presence of adulterated goat and ewe's cheese with cow's milk on the market of the Republic of Croatia. The isoelectric focusing method, which is used as a reference method for this type of analysis was suitable for detection of cow's milk in cheeses produced from goat's or ewe's milk. The results of this thesis showed that 24% of cheese samples from the market of Republic of Croatia were adulterated, with addition of cow's milk in range from 2% to 18%
Clostridium tyrobutyricum in milk and late blowing of cheese
No full textKasno nadimanje sira je česta mana tvrdih sireva u mljekarskoj industriji. Ovu manu
sira možemo prepoznati po šupljinama, atipičnim rupicama i po većem broju otvora koji su
razasuti u sirnome tijestu. Osim toga, možemo ga prepoznati i po žilavome sirnome tijestu,
bljutavome okusu i neugodnom mirisu. Još jedna od opasnosti kod sireva sa kasnim
nadimanjem je često površinsko pucanje kroz čije se pukotine otvara put drugim štetnim
bakterijama i plijesnima, u unutrašnjost sira, čime se kvarenje još više pojačava i ubrzava.
Glavni uzročnik kasnog nadimanja sira je gram pozitivna bakterija Clostridium tyrobutyricum
koja najčešće dolazi iz tla ili silaže. Ona provodi maslačno-kiselu fermentaciju, gdje iz laktata
nastaju maslačna kiselina, ugljikov dioksid i vodik. Time dolazi do stvaranja plina koji uzrokuje
stvaranje rupica i pukotina u sirnome tijestu. Osim bakterije C. tyrobutyricum, kasno
nadimanje sira mogu uzrokovati i ostale Clostridium vrste: C. butyricum, C. beijerinckii i C.
sporogenes. One spadaju u termorezistentnu skupinu bakterija koje preživljavaju standardnu
temperaturu pasterizacije (63 °C). Stoga se tijekom procesa proizvodnje sira dodaje enzim
lizozim radi prevencije pogreške nadimanja. Lizozim se proizvodi iz bjelanjka jajeta, može
uzrokovati alergijske reakcije pa ga pri deklariranju na listi sastojaka sira potrebno istaknuti
masnim slovima.Late blowing of cheese is a cheese fault of hard cheeses that frequently occurs in the
dairy industry. This defect can be identified by cavities, atypical holes, and an increased
number of openings scattered throughout the cheese mass. Additionally, it can be recognized
by a tough cheese texture, bland taste, and unpleasant odor. Another danger with late
blooming cheeses is that they often develop surface cracks, which provide pathways for other
harmful bacteria and moulds to penetrate into the interior of the cheese, thereby intensifying
and accelerating spoilage. The primary cause of late blowing in cheese is the gram-positive
bacterium Clostridium tyrobutyricum, which usually originates from soil or silage. This
bacterium produces butyric acid, carbon dioxide, and hydrogen from lactate. This results in
gas formation, causing holes and cracks in the cheese mass. Besides C. tyrobutyricum, other
Clostridium species such as C. butyricum, C. beijerinckii, and C. sporogenes can also cause late
blowing of cheese. These bacteria belong to the thermoresistant group, surviving the usual
pasteurization temperatures. Therefore, during cheese production, the enzyme lysozyme is
added to prevent this defect. Lysozyme is produced from egg white, so it needs to be
highlighted in bold letters in the list of cheese ingredients, as it can cause allergic reactions
The influence of milk standardization on Škripavac cheese yield
No full textSir je jedna od temeljnih namirnica u ljudskoj prehrani, pri tome je u interesu svakog obiteljskog poljoprivrednog gospodarstva koje se bavi proizvodnjom sira povećati njegovu prodaju. Gotovo 80% troškova proizvodnje sira čini cijena mlijeka. Randman sira se definira kao broj utrošenih kg mlijeka za proizvodnju jednog kg sira ili broj kg sira proizvedenog od 100 kg mlijeka. Randman sira ponajprije ovisi o sadržaju masti i proteina u mlijeku za sirenje. U proizvodnji sira sadržaj masti i proteina u industrijskim uvjetima prerade u pravilu se standardizira na optimalan omjer 1 : 0,9 kako bi povećali iskoristivost navedenih sastojaka u sir. S obzirom da se mlijeko za sirenje u tradicionalnoj proizvodnji ne standardizira, pretpostavka je da bi se standardizacijom mlijeka za sirenje moglo učinkovitije iskoristiti masti i proteini mlijeka za sirenje te samim time postići bolji randman. Stoga je cilj ovog rada utvrditi utjecaj postupka standardizacije mlijeka na kemijski sastav sirutke i sira škripavca te randman sira škripavca. Također se želi utvrditi da li uobičajni postupci standardizacije mlijeka u tradicionalnom sirarstvu mogu povećati učinak iskorištavanja masti i proteina, a da pri tom kemijski sastav sira ostaje unutar granica koje se navode u literaturi.
Dodatkom obranog mlijeka u prahu (OMUP) nije uvjetovana bolja iskoristivost mliječne masti i proteina kako se očekivalo, no randman sira značajno se povećao (P < 0,05). S druge strane standardizacija obiranjem dijela vrhnja uzrokovala je bolju iskoristivost mliječne masti, no iskoristivost proteina bila je manja, što je zajedno uvjetovalo sniženi randman (P=0,08). Standardizacija mlijeka dodatkom OMUP može dati ekonomsku korist u proizvodnji tradicionalnih sireva, dok standardizacija obiranjem može imati utjecaj na sniženi randman sira, vjerojatno zbog mehaničkog tretmana mlijeka za sirenje separacijom koja se u tradicionalnoj proizvodnji sira u pravilu ne koristi.Cheese is one of the fundamental foods in the human diet, thus it is in the interest of every agricultural family which produce cheese to increase its sales. Almost 80% of the expense of cheese production is the price of milk. The yield of cheese is defined as the number of utilized milk for the production of one kg of cheese, or the number of kg of cheese produced from 100 kg of milk. The yield of cheese notably depends on the contents of fat and proteins in the cheesemilk. In cheese production, the contents of fat and proteins in industrial conditions of processing are usually standardized to an optimal ratio of 1:0.9, in order to increase the recovery of the aforementioned ingredients in the cheese. Since the milk used to make cheese in traditional production is not standardized, it is presumed that standardization of cheesemilk in this type of production, the fat and proteins of the milk used to make cheese could be more efficiently recovered and yield percentage could be achieved by doing so. Thus, the goal of this thesis is to determine the influence of the standardization procedure of cheesemilk, to the chemical composition of whey and Škripavac cheese, as well as the yield efficiency. It also wants to determine if the usual procedures of milk standardization in traditional cheese-making can increase the efficiency of recovery of fat and proteins while keeping the chemical composition of the cheese within the average borders mentioned in the literature.
By adding skimmed milk powder (SMP) the increased recovery of milk fat and proteins was not determined as had been expected, but the yield of cheese increased significantly (P>0.05). On the other hand, standardization through skimming part of the cream caused an increase in the recovery of milk fat, but the recovery of proteins decreased, which together caused the decrease of yield (P=0.08). The standardization of milk by adding SMP could provide an economic advantage in traditional cheese producing, while standardization through skimming could have a negative effect on the cheese yield, probably due to the mechanical treatment of the milk through separation, which is not usually used in traditional production of cheese
Effect of sheep's milk composition on proteolytic and textural changes during ripening of Brač cheese
No full textBrački sir je punomasni, tvrdi ovčji sir te se kao i većina hrvatskih tradicijskih sireva
proizvodi od sirovog ovčjeg mlijeka, o čijem sastavu i sposobnosti zgrušavanja u najvećoj
mjeri ovisi i njegova kakvoća.
Stoga je cilj ovog istraživanja bio utvrditi: kemijski sastav, fizikalna svojstva i
higijensku kvalitetu sirovog ovčjeg mlijeka, proteolitičke i teksturne promjene bračkog sira
tijekom zrenja te povezanost navedenih promjena sa sastavom mlijeka.
Istraživanje je provedeno na 60 sireva proizvedenih u 15 proizvodnih šarži. Analiza
kemijskog sastava, fizikalnih svojstava i higijenske kvalitete mlijeka te kemijskog sastava
sira je provedena standardnim metodama. Sposobnost sinereze sirnog gruša je utvrđena
centrifugiranjem i izražena je kao udio otpuštene sirutke u odnosu na ukupnu masu
uzorka. Tvrdoća sirnog gruša je utvrđena pomoću cilindrične sonde i teksturnog
analizatora prema uputama proizvođača. Proteolitičke promjene tijekom zrenja bračkog
sira su utvrđene standardnim metodama dok su njegove teksturne značajke utvrđene
metodom analize teksturnog profila.
Provedenim istraživanjem je utvrđeno da je s povećanjem omjera kazeina i
mliječne masti u ovčjem mlijeku značajno (P<0,01) povećana lomljivost i čvrstoća bračkih
sireva dok se vrijednosti WSN (% TN), TCA-SN (% TN), ukupnih slobodnih aminokiselina,
Iγ/β i Iα nisu značajnije mijenjale. Statistički značajno (P<0,01) najveća vrijednost lomljivosti
i čvrstoće je utvrđena u bračkim sirevima proizvedenim od mlijeka s koncentracijom uree
u rasponu od 25,01 do 35,00 mg/100 g dok su vrijednosti teksturnih pokazatelja ispod
odnosno iznad navedenog raspona bile gotovo podjednake. Sirevi proizvedeni od mlijeka
s koncentracijom uree manjom od 25,00 mg/100 ml su imali značajno (P<0,05) najveću
vrijednost Iγ/β te utvrđenu sekundarnu proteolitičku aktivnost. Nastavak povećanja
koncentracije uree iznad 25,01 mg/100 ml u ovčjem mlijeku je značajno (P<0,05) smanjio
vrijednost navedenih pokazatelja u bračkom siru. Povećanje broja somatskih stanica u
ovčjem mlijeku je značajno (P<0,05) smanjilo vrijednosti Iα ali nije utjecalo na vrijednosti
Iγ/β u bračkom siru. Značajno (P<0,01; P<0,05) najveću lomljivost i čvrstoću ali i intenzitet
sekundarne proteolitičke aktivnosti je utvrđen u sirevima proizvedenim od mlijeka s brojem
somatskih stanica iznad 501.000/ml.
Rezultati ovog istraživanja pokazuju da je kakvoća sirovog ovčjeg mlijeka jedan od
ključnih čimbenika koji utječu na tijek razgradnje parakazeinske strukture bračkog sira kao
temeljnog biokemijskog procesa koji mijenja njegove teksturne značajke.Introduction
Brač cheese is produced from raw sheep milk and its quality is mainly affected by
the composition of milk as in most of Croatian traditional cheeses. If good hygiene is
practised during milking of healthy sheep, wholeness and intact levels of milk constituents
(especially casein) are retained. In the coagulation process of milk, casein forms the
continuous and hard para-casein matrix which in relation to the other milk constituents
mostly occludes the milk fat. Hard para-casein matrix also keeps its functional properties
during syneresis process and represents basic substrate for proteolytic enzyme activity
during process of cheese ripening. Proteolytic changes during cheese ripening are
fundamental process which plays a vital role in development of characteristics of cheese
texture. Therefore, the motivation for this study is to evaluate effect of raw sheep milk
composition on textural curd characteristics and intensity of proteolytic and textural
changes during the ripening of Brač cheese.
Hypothesis and aims of the research
The hypothesis of the research is that raw sheep milk composition has effect on
curd syneresis and texture. The present research also aimed to assess the hypothesis
that proteolytic and textural changes during ripening of brač cheese depends on raw
sheep milk composition. Because casein network in cheese influence its mechanical
behaviour, it can be hypothesized that intensity of proteolysis in brač cheese changes its
textural characteristics during ripening.
The objective of this research is to determine:
• physicochemical composition and hygienic quality of raw sheep milk,
• texture and syneresis characteristics of curd as indicators of sheep milk
coagulation ability,
• effect of sheep milk composition on texture, syneresis ability and whey expulsion
of curd at four different times of coagulation,
• chemical, textural and proteolytic changes in Brač cheese during ripening,
• relationship between sheep milk composition and textural, proteolytic and
composition changes of Brač cheese during ripening,
• relationship between proteolytic pattern and texture of Brač cheese.
Materials and methods
The research was conducted on a family farms in the area of Pražnice and
Supetar on the Brač island. Milk samples were collected twice a month throughout the
different lactation periods (Supetar – 125 and Pražnice – 75 days in milking). Raw milk
samples were collected into a laboratory bottles, transported in a portable refrigerator to a
laboratory and stored at 4⁰ C until its coagulation within the next 24 hours. The milk
samples intended for physicochemical analysis were filled in 100 ml capacity polyethylene
laboratory bottles, preserved with azidiol and sent to the Reference Laboratory for Milk
and Dairy Products at the Faculty of Agriculture in Zagreb. Raw sheep milk was analysed
for fat, protein, casein, lactose, dry matter, solids-non-fat, urea, total and ionic calcium
content as well as somatic cell counts, total number of bacteria and acidity.
Milk was poured in a laboratory beaker and warmed in water bath at 32⁰ C. After
rennet addition milk was immediately transferred into eight glass beakers and conical
bottom centrifuge tubes. A hundred milliliters of milk for curd preparation was added in
each of eight glass beakers. Furthermore a thirty grams of milk for syneresis test was
weighed in each of sixteen centrifuge tubes. Each analysis was done in duplicate. Milk
samples were placed in water bath at 25°C and allowed to coagulate for 30, 45, 60 and 75
minutes in laboratory under climatized conditions at same temperature. Strength of
obtained curd in glass beakers were measured by texture analyser (Lloyd instruments,
model TA Plus) equipped with a 500 N load cell (model XLC -0500-A1) and cylindrical
probe (model FG/CY3, 12,5 mm in diameter). Syneresis was measured by centrifuging
the curd at 5000 RPM for 15 min. After centrifugation the free water was separated,
weighed and expressed as percentage of the total weight of milk (30 g).
Fifteen batches of Brač cheese were produced with four cheeses in each batch.
The cheeses were periodically sampled after 0, 30, 60, 90 and 120 days. Using a drill,
cheese samples (about 20 g) were taken from the lateral side of each cheese in order to
determine chemical composition and proteolytic changes of cheese during ripening period
of four months. Cheese samples for texture measurement were taken by cork borer
parallel to the direction of pressing of cheese between the edge of the top and bottom
surface. Cheese cores were cut into cylindrical samples (diameter=17 mm; height=25
mm). One part of the cheese, with core, was cut at a depth of 1 cm which was nearest the
surface, and was then replaced in the hole in the cheese. The hole was coated with
cheese wax, covered with plastic mash and finally sealed with cheese wax before the
cheese was replaced in the ripening room. Cheese were analysed for content of fat,
protein, dry matter and salt as well as pH value. Proteolysis in cheese was monitored by
polyacrylamide gel electrophoresis and determining content of water soluble nitrogen
(WSN) as a percentage of total nitrogen (% TN), trichloroacetic acid-soluble nitrogen
(TCA-SN) as a percentage of total nitrogen as well as free amino acid (as g of leucine/100
g dry matter). The texture profile analysis (TPA) was carried out using the texture
analyser (Lloyd instruments, model TA Plus). The textural characteristics of Brač cheese
were analysed for hardness 1, strain at hardnes 1, fracturability, strain at fracture,
hardness 2, adhesiveness, cohesiveness and springiness.
Descriptive statistics, analysis of variance (ANOVA) using a GLM procedure,
pairwise comparisons of mean values with Fisher’s LSD test, Pearson's correlation
coefficients and linear regression analysis were performed with SPSS (version 21).
Results and conclusions
The results showed that composition of sheep milk had a greater effect on curd
syneresis ability in comparision to its strength. Casein and fat content, casein to fat ratio
as well as urea concentration in sheep milk had no significant effect on curd strength.
Increasing of casein and fat content in sheep milk significantly (P<0.01; P<0.05) reduced
syneresis ability of curd while increasing casein to fat ratio significantly (P<0.01) enhanced
its syneresis ability. Enhanced curd strength and its syneresis ability were significantly
affected by increase of total (P<0.01; P<0.05) and ionic calcium (P<0.01) in sheep milk.
The increase of urea concentration in sheep milk had no significant effect on curd strength
but obtained curd showed significant reduction (P<0.01) in syneresis ability. Somatic cell
count in sheep milk significantly (P<0.05) affected curd strength but did not affect its
syneresis ability.
The increase of casein content in sheep milk significantly (P<0.01; P<0.05)
reduced the extent of secondary proteolysis in Brač cheese. The level of β-casein and its
ripening index were significantly (P<0.01; P<0.05) affected by increase of casein content
in sheep milk. The levels of the rest of caseins in Brač cheese did not show statistically
significant differences due to the increase of casein content in sheep milk. The research
showed that increase of casein content in sheep milk had significant effect (P<0.01;
P<0.05) on hardness 1 and hardness 2, fracturability and springiness of Brač cheese
while changes in adhesiveness, cohesiveness as well as strain at fracture and hardness 1
did not show statistically significant differences.
The content of TCA-SN (%TN) in Brač cheese was significantly (P<0.01) reduced
as a result of an increase of milk fat in sheep milk. The increase of the aforementioned
parameter in sheep milk also reduced the content of free amino acid and WSN (% TN) in
Brač cheese but without statistical significances. The increase of milk fat in sheep milk
significantly (P<0.05) reduced level of γ-caseins in Brač cheese while the levels of the rest
of caseins in Brač cheese did not show statistically significant differences. The
fracturability, hardness 1 and hardness 2 of Brač cheese significantly (P<0.01) decreased
with increase of milk fat in sheep milk. On the other hand, adhesiveness, cohesiveness as
well as strain at fracture and hardness 1 of Brač cheese were not affected by fat content
in sheep milk.
The extend of secondary proteolysis in Brač cheese was not changed regardless
of casein to fat ratio in sheep milk. The increase of casein to fat ratio in sheep milk caused
a significant increase in levels of β and γ-caseins in Brač cheese. Although level of αs1casein
in Brač cheese did not undergo statistically significant changes, level of αs1-I-
casein was significantly modified with increase of casein to fat ratio in sheep milk. The
fracturability, hardness 1 and hardness 2 of Brač cheese significantly (P<0.01) increased
as a result of an increase of casein to fat ratio in sheep milk. Increase of casein to fat ratio
significantly (P<0.05) affected strain at fracture of Brač cheese but did not affect its
adhesiveness, cohesiveness, springiness and strain at hardness 1.
The increase of urea concentration in sheep milk significantly (P<0.01) modified
levels of β-caseins but did not affect content of the rest of caseins in Brač cheese. The
extent of secondary proteolysis in Brač cheese was significantly (P<0.05) affected by the
increase of urea concentration in sheep milk. The fracturability, hardness 1 and hardness
2 of Brač cheese were significantly (P<0.01) modified with increase of urea concentration
in sheep milk. However, no significant differences were found between urea concentration
in sheep milk and adhesiveness, cohesiveness, springiness as well as strain at fracture
and hardness 1.
Extend of secondary proteolysis in Brač cheese were significantly (P<0.01;
P<0.05) affected by increase of somatic cell count in sheep milk. The levels of α and βcasein
significantly (P<0.05) increased with increasing somatic cell count in sheep milk
while changes in γ and αs1-I caseins did not show statistically significant differences. The
increase of somatic cell count content in sheep milk significantly increased fracturability
(P<0.05) and hardness 2 (P<0.01) as well as significantly reduced adhesiveness (P<0.01)
in Brač cheese. Changes in strain at fracture and hardness 1 as well as springiness were
also significantly (P<0.01; P<0.05) affected by increase of somatic cell count in sheep
milk. There were no significant differences in hardness 1 and cohesiveness in Brač
cheese due to increase of somatic cell count in sheep milk.
The content of TCA-SN (%TN) in Brač cheese was significantly (P<0.01) reduced
as a result of advancement of lactation. The stage of lactation had no significant effect
both on the content of free amino acid and WSN (% TN) in Brač cheese. The level of βcasein
in Brač cheese was significantly (P<0.05) reduced in Brač cheese with
advancement of lactation. The levels of the rest of caseins in Brač cheese did not show
significant differences due to stage of lactation. With advancement of lactation, the
cheeses became significantly (P<0.01) softer. The major consequences were a significant
(P<0.01) increase of fracturability, hardness 1 and hardness 2 with stage of lactation. The
other texture parameters were not affected by stage of lactation.
The levels of αs1 and β-casein were significantly (P<0.01; P<0.05) reduced and the
levels of its degradation products were significantly (P<0.01) increased during the 120-day
maturation period of Brač cheese. The extend of secondary proteolysis in Brač cheese
significantly (P<0.01) increased by increasing of its ripening time. On the other hand, Brač
cheese became significantly (P<0.01) harder, less springy and less cohesive
Influence of salting method on the chemical composition, yield, rheological and sensory characteristics of Škripavac cheese
No full textLički škripavac je autohtoni proizvod Like i dijela Korduna kojeg karakterizira
škripavost tijekom žvakanja. U pokusu je standardnom tehnologijom proizveden škripavac uz
korištenje 40 kg mlijeka podijeljenog u dva podjednaka dijela. Sir je soljen na dva načina:
soljenjem sirnog zrna i soljenjem mlijeka. Sirevima su standardnim metodama utvrđeni
kemijski sastav, fizikalna, reološka i senzorska svojstva te izračunate vrijednosti randmana i
iskoristivosti masti i proteina. Istraživanjem je utvrđeno da sirevi soljeni u mlijeko zadržavaju
veću količinu vode (P <0,05), imaju značajno niži prosječan udio proteina (P<0,01) te nižu
pH vrijednost (P<0,001). Ovi su sirevi imali višu iskoristivost mliječne masti (P<0,05) te viši
stvarni (P<0,0001) i naravnati randman (P<0,01), višu elastičnost (P<0,05) i deformiranost u
točci loma (P<0,05), a nižu čvrstoću u drugoj kompresiji (P<0,05). Prosječan udio mliječne
masti, aktivitet vode, iskoristivost proteina i ostale vrijednosti teksture (čvrstoća 1, lomljivost,
kohezivnost i gumenost) nisu se značajno razlikovale, kao niti senzorne ocjene (P>0,05).Lički Škripavac cheese is autochthonous product of Lika and part of Kordun regions
which is characterized by squeaky sound made while chewing. In this study škripavac cheese
was produced by standard method using 40 kg of milk divided in two equal parts. Cheese was
salted using two methods: salting of curd and salting of milk. Physico-chemical, rheological,
and sensory properties of chesse were determined by standard methods while yield, fat and
protein usability were calculated. It was determined that cheeses salted in milk retain more
water (P <0,05) and have significantly less protein (P <0,01) and lower pH value (P <0,001).
These cheeses had higher milk fat usability (P <0,05) and higher average yield (P <0,01),
elasticity (P <0,05), and deformation (P <0,05) but lower hardness in second compression (P
<0,05). Average milk fat ratio, water activity, protein usability and textural profile
characteristics (hardness 1, fracturability, cohesiveness, gumminess) were not significantly
different which is also true for its sensory grades (P > 0,05)
Potential of using whey in production of alcoholic beverages
No full textU proizvodnji sira glavni nusproizvod je sirutka. Sirutka je veliki zagađivač okoliša budući da sadrži više od 6% organske tvari. Osim u proizvodnji albuminskih sireva, bioplina, laktoze i sirutke u prahu, sirutka kao sirovina se posljednjih desetak godina koristi i u proizvodnji raznih alkoholnih pića kao što je primjerice votka od sirutke. Pri tome, sastav sirutke može utjecati na sastav destilata i konačnu kvalitetu proizvoda. Cilj ovog rada bio je istražiti potencijal proizvodnje alkoholnog pića iz sirutke zaostale nakon proizvodnje istarske skute. U pokusnim uvjetima u mini sirani obiteljskog poljoprivrednog gospodarstva na području Istre proizvedene su 3 šarže istarske skute. Sirutka zaostala nakon proizvodnje istarske skute povrgnuta je fermentaciji u duplikatoru korištenjem kulture kvasaca Kluyveromyces marxianus subsp. marxianus. Za potrebe ovoga rada provedena je destilacija fermentirane sirutke, a uzorci su potom analizirani na Agronomskom fakultetu Sveučilišta u Zagrebu. Destilatu alkoholne jakosti 35% utvrđen je sastav, a dobiveni spojevi su: acetaldehid, metanol, n-propanol, i-butanol, n-butanol, 3-metil-1-ol, 2-metilbutan-1-ol te etil-laktat. Dobiveni destilat upućuje na to da postoji potencijal korištenja sirutke u proizvodnji alkohola. No, u budućnosti je potrebno provesti dodatna istraživanja u svrhu kontrole čimbenika proizvodnje i destilata, zbog mogućeg štetnog djelovanja pojedinih hlapivih spojeva na ljudsko zdravlje.In cheese production the main by-product is whey. Whey is a major polluter of the environment as it contains more than 6% organic matter. In addition to the production of albumin cheeses, biogas, lactose and whey powder, whey as a raw material has been used in the production of various alcoholic beverages such as whey vodka. The composition of the whey may affect the composition of the distillate and the final quality of the product. The aim of this study was to investigate the production potential of alcoholic beverages from whey left over from the production of Istrian skuta cheese. In experimental conditions, 3 batches of Istrian skuta cheese were produced in the mini cheese factory of a family farm in Istria. Whey left over from the production was fermented in a duplicator using a culture of the yeast Kluyveromyces marxianus subsp. marxianus. For the purposes of this work, fermented whey was distilled, and the samples were analyzed at the Faculty of Agriculture, University of Zagreb. The 35% alcoholic distillate was determined, and the obtained compounds were: acetaldehyde, methanol, n-propanol, i-butanol, n-butanol, 3-methyl-1-ol, 2-methylbutan-1-ol and ethyl lactate. The obtained distillate indicates that there is a potential use of whey in the production of alcohol. However, in the future it is necessary to conduct some more research in order to control the factors of production and distillates, due to the possible negative effects of some volatile compounds on human health
Clostridium tyrobutyricum in milk and late blowing of cheese
No full textKasno nadimanje sira je česta mana tvrdih sireva u mljekarskoj industriji. Ovu manu
sira možemo prepoznati po šupljinama, atipičnim rupicama i po većem broju otvora koji su
razasuti u sirnome tijestu. Osim toga, možemo ga prepoznati i po žilavome sirnome tijestu,
bljutavome okusu i neugodnom mirisu. Još jedna od opasnosti kod sireva sa kasnim
nadimanjem je često površinsko pucanje kroz čije se pukotine otvara put drugim štetnim
bakterijama i plijesnima, u unutrašnjost sira, čime se kvarenje još više pojačava i ubrzava.
Glavni uzročnik kasnog nadimanja sira je gram pozitivna bakterija Clostridium tyrobutyricum
koja najčešće dolazi iz tla ili silaže. Ona provodi maslačno-kiselu fermentaciju, gdje iz laktata
nastaju maslačna kiselina, ugljikov dioksid i vodik. Time dolazi do stvaranja plina koji uzrokuje
stvaranje rupica i pukotina u sirnome tijestu. Osim bakterije C. tyrobutyricum, kasno
nadimanje sira mogu uzrokovati i ostale Clostridium vrste: C. butyricum, C. beijerinckii i C.
sporogenes. One spadaju u termorezistentnu skupinu bakterija koje preživljavaju standardnu
temperaturu pasterizacije (63 °C). Stoga se tijekom procesa proizvodnje sira dodaje enzim
lizozim radi prevencije pogreške nadimanja. Lizozim se proizvodi iz bjelanjka jajeta, može
uzrokovati alergijske reakcije pa ga pri deklariranju na listi sastojaka sira potrebno istaknuti
masnim slovima.Late blowing of cheese is a cheese fault of hard cheeses that frequently occurs in the
dairy industry. This defect can be identified by cavities, atypical holes, and an increased
number of openings scattered throughout the cheese mass. Additionally, it can be recognized
by a tough cheese texture, bland taste, and unpleasant odor. Another danger with late
blooming cheeses is that they often develop surface cracks, which provide pathways for other
harmful bacteria and moulds to penetrate into the interior of the cheese, thereby intensifying
and accelerating spoilage. The primary cause of late blowing in cheese is the gram-positive
bacterium Clostridium tyrobutyricum, which usually originates from soil or silage. This
bacterium produces butyric acid, carbon dioxide, and hydrogen from lactate. This results in
gas formation, causing holes and cracks in the cheese mass. Besides C. tyrobutyricum, other
Clostridium species such as C. butyricum, C. beijerinckii, and C. sporogenes can also cause late
blowing of cheese. These bacteria belong to the thermoresistant group, surviving the usual
pasteurization temperatures. Therefore, during cheese production, the enzyme lysozyme is
added to prevent this defect. Lysozyme is produced from egg white, so it needs to be
highlighted in bold letters in the list of cheese ingredients, as it can cause allergic reactions
Implementation of HACCP in an approved low-capacity milk processing facility
No full textPravne strukture kojima se povodi zakonodavstvo na području sigurnosti hrane unutar Europske unije, nisu uvijek bile ujednačene. Neujednačenosti je dovela do brojnih trgovinsko pravnih problema. U svrhu pojednostavljenja trgovine te u svrhu zaštite zdravlja potrošača na području Europske unije, Europska komisija razvija jedinstveni sustav upravljanja svim procesima proizvodnje hrane, izuzevši primarnu proizvodnju. Primjenu sustava koji se temelji na analizi opasnosti i uspostavi kritičnih kontrolnih točaka (HACCP), u Republici Hrvatskoj od 31. srpnja 2006. godine, dužni su provoditi svi subjekti u poslovanju s hranom. Prilikom provedbe primjene sustava u objektima malog kapaciteta koji posluju s hranom, nerijetko dolazi do problema u implementaciji i provođenju HACCP-a zbog infrastrukturne manjkavosti takvih objekata u smislu broja prostorija, opreme i uređenosti objekta. Stoga je cilj ovoga rada prikazati način implementacije HACCP sustava u odobrenom objektu za preradu mlijeka malog kapaciteta. Način implementacije sustava opisani su na primjeru odobrene mljekare malog kapaciteta prerade mlijeka do 300 l na dan koristeći 12 koraka implementacije HACCP sustava te su opisane posebnosti predmetnog objekta malog kapaciteta sukladno uvjetima pravila o mjerama prilagodbe („Flexibility“).The legal structures underpinning/implementing food safety legislation within the European Union haven´t always been harmonized. The issue of this discrepancy has led to numerous trade and low problems. With hopes of simplifying trade and protecting the health of consumers in the European Union, the European Commission is developing a unified management system for all food production processes, apart from primary production. The implementation of such a system based on Hazard Analysis and Critical Control Points (HACCP) is obligatory for all food business operators in the Republic of Croatia since 31 July 2006. During the implementation of HACCP in food businesses in small scale dairy plants due to infrastructure problems (lack of optimal number of processing rooms, less level of equipment and other facilities) some problems could occur. Therefore, the purpose of this thesis is to demonstrate the possibilities of HACCP implementation in proved dairy plant of small capacity. In this thesis the implementation methods by presenting an example of dairy plant of low capacity which process up to 300 l of milk per day are described. Twelve steps of HACCP implementation were determined and specificities of small scale dairy plant were postulated according to the rules for the measurements of flexibility
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