Interaction of Brine Concentration, Brine Temperature, and Presalting on Salt Penetration in Ragusano Cheese

Article · June 2006with132 Reads
DOI: 10.3168/jds.S0022-0302(06)72211-1 · Source: PubMed
Abstract
Thirty-one 3.6-kg blocks of Ragusano cheese were made on each of 6 different days (in different weeks) starting with a different batch of milk on each day. On d 1, 3, and 5, the cheeses were not presalted and on d 2, 4, and 6, all cheeses were presalted (PS). One of the 31 blocks of cheese was selected at random for analysis before brine salting (i.e., on d 0). The remaining 30 blocks were randomly divided into 2 groups of 15 blocks each; one group was placed in 18% brine (18%B) and the other group was placed in saturated brine (SB). For the 15 blocks within each of the 2 brine concentrations (BC), 5 blocks were placed in a brine tank at 12 degrees C, 5 at 15 degrees C, and 5 at 18 degrees C, and submerged for 24 d. The research objective was to determine the combined impacts (i.e., interactions) of PS the curd before stretching, BC (SB vs. 18%B), and brine temperature (BT; 12, 15, and 18 degrees C) on salt uptake, moisture content, and yield of Ragusano cheese. Although BC, BT, and PS each had their own separate impacts on salt uptake, there was little interaction of these effects on salt uptake when they were used in combination. The PS most quickly delivered salt to the interior of the cheese and was the most effective approach to salting for controlling early gas formation. There were strong separate impacts of BC, BT, and PS on cheese moisture content, moisture loss, and net weight loss, with BC having the largest separate impact on these parameters. Reducing BT reduced salt content and increased moisture, but the effects were small. The more important effect of reduced BT was to reduce growth of gas forming bacteria. The 18%B produced higher moisture, and less moisture and weight loss than SB. The effect of interactions of BC, BT, and PS on moisture loss and net weight loss were small. To achieve the maximum benefit from the various approaches to salting for controlling early gas formation in Ragusano cheese, PS combined with slightly lower BT (i.e., 15 degrees C instead of 18 degrees C) should be used. Although using 18%B instead of SB did increase salt uptake, the point at which improved salt uptake occurred due to use of 18%B did not provide benefit in prevention of early gas formation, as reported separately. However, use of 18%B instead of SB provided a 9.98% increase in cheese yield due to reduced moisture loss during brining; this would be very attractive to cheese makers. The increase in yield needs to be balanced against the risk of growth of undesirable bacteria in the 18%B and the creation of another cheese quality defect.
17 Figures
J. Dairy Sci. 89:JDS 5494 Take L160
American Dairy Science Association, 2006.
Interaction of Brine Concentration, Brine Temperature, and Presalting
on Salt Penetration in Ragusano Cheese
1
C. Melilli,* D. M. Barbano,†
2
M. Caccamo,* L. Tuminello,* S. Carpino,* and G. Licitra*‡
*CoRFiLaC, Regione Siciliana, 97100 Ragusa, Italy
†Northeast Dairy Food Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853
‡Dipartimento di Scienze Agronomiche, Agrochimiche e delle Produzioni Animali, Catania University, 95100 Catania, Italy
ABSTRACT
Thirty-one 3.6-kg blocks of Ragusano cheese were
made on each of 6 different days (in different weeks)
starting with a different batch of milk on each day. On
d 1, 3, and 5, the cheeses were not presalted and on d
2, 4, and 6, all cheeses were presalted (PS). One of the
31 blocks of cheese was selected at random for analysis
before brine salting (i.e., on d 0). The remaining 30
blocks were randomly divided into 2 groups of 15 blocks
each; one group was placed in 18% brine (18%B) and
the other group was placed in saturated brine (SB). For
the 15 blocks within each of the 2 brine concentrations
(BC), 5 blocks were placed in a brine tank at 12°C, 5
at 15°C,and5at18°C, and submerged for 24 d. The
research objective was to determine the combined im-
pacts (i.e., interactions) of PS the curd before stretching,
BC (SB vs. 18%B), and brine temperature (BT; 12, 15,
and 18°C) on salt uptake, moisture content, and yield
of Ragusano cheese. Although BC, BT, and PS each had
their own separate impacts on salt uptake, there was
little interaction of these effects on salt uptake when
they were used in combination. The PS most quickly
delivered salt to the interior of the cheese and was the
most effective approach to salting for controlling early
gas formation. There were strong separate impacts of
BC, BT, and PS on cheese moisture content, moisture
loss, and net weight loss, with BC having the largest
separate impact on these parameters. Reducing BT re-
duced salt content and increased moisture, but the ef-
fects were small. The more important effect of reduced
BT was to reduce growth of gas forming bacteria. The
18%B produced higher moisture, and less moisture and
weight loss than SB. The effect of interactions of BC,
Received July 18, 2005.
Accepted October 12, 2005.
1
Use of names, names of ingredients, and identification of specific
models of equipment is for scientific clarity and does not constitute
any endorsement of product by authors, Cornell University, the
Northeast Dairy Foods Research Center, CoRFiLaC, and Diparti-
mento di Scienze Agronomiche, Agrochimiche e delle Produzioni Ani-
mali, Catania University.
2
Corresponding author: dmb37@cornell.edu
1
BT, and PS on moisture loss and net weight loss were
small. To achieve the maximum benefit from the vari-
ous approaches to salting for controlling early gas for-
mation in Ragusano cheese, PS combined with slightly
lower BT (i.e., 15°C instead of 18°C) should be used.
Although using 18%B instead of SB did increase salt
uptake, the point at which improved salt uptake oc-
curred due to use of 18%B did not provide benefit in
prevention of early gas formation, as reported sepa-
rately. However, use of 18%B instead of SB provided a
9.98% increase in cheese yield due to reduced moisture
loss during brining; this would be very attractive to
cheese makers. The increase in yield needs to be bal-
anced against the risk of growth of undesirable bacteria
in the 18%B and the creation of another cheese qual-
ity defect.
Key words: brine, salt penetration, cheese yield
INTRODUCTION
Ragusano cheese is a brine-salted, pasta-filata raw
milk cheese that is aged for 6 to 9 mo and is produced
on farms in Eastern Sicily. Lactic acid is produced by
natural milk microflora and desirable microflora from
the surface of traditional wooden cheese vats (Licitra et
al., 1998). The first 3 to 8 d of brine salting of Ragusano
cheese is done on the farms and is followed by brine
salting at an aging center. Typically, saturated brines
(18°C) are used at both locations. When salt uptake by
cheese during brining is too slow, early gas formation
and off-flavor development occur due to the growth of
undesirable bacteria. The level of undesirable bacteria
is dependent on their initial level in the milk (Choisy
et al. 1987). Their growth is favored by slow acid produc-
tion during cheese making (Choisy et al., 1987), slow
salt penetration, and high temperature during brining.
Resmini et al. (1974) found that salt uptake in Parmi-
giano-Reggiano cheese was faster when nonsaturated
brine (approximately 16%) was used for the first 5 to 6
d of brining followed by saturated brine (SB) until 24
d. A study on Ragusano cheese (Melilli et al., 2003a)
demonstrated that use of 18% brine (18%B) instead of
SB (i.e., about 26% wt/wt) for the first 8 d of 24 d of brine
MELILLI ET AL.2
salting increased the rate of salt uptake, compared with
24 d in SB, in agreement with the results of Resmini
et al. (1974) for a nonpasta-filata cheese. The cheese in
18%B at 18°C achieved the same salt content in 12 d
as cheese in SB for 24 d at 18°C. The increased rate of
salt uptake with 18%B compared with SB was related
to the impact of lower brine concentration (BC)onthe
moisture content and porosity of the cheese near the
surface of the block (Melilli et al., 2003a). Brine with
higher salt content causes a rapid loss of moisture from
cheese near the surface of the block. Moisture loss
causes shrinkage of the cheese structure and decreases
porosity, which impedes moisture movement out and
salt movement into the block (Melilli et al., 2003a,
2005). The use of 18% salt brine for the first 8 d delayed
the moisture loss and cheese shrinkage at the exterior
of the block and allowed more rapid salt penetration
(Melilli et al., 2003a). Melilli et al. (2005) calculated
the decrease in porosity at the exterior 1-mm portion
of the block that was 50.8 and 29.2% for cheeses that
had been in SB vs. 18%B at 12 d, respectively. Even
though the reduction in weight loss when using an
18%B makes a positive impact on cheese yield and the
rate of salt penetration into the block, Melilli et al.
(2004b) demonstrated that reducing BC did not have
any impact on coliform count and had minimal impact
on reducing early gas production in Ragusano cheese.
A second approach to more quickly increase salt in the
interior of Ragusano cheese was by presalting the curd
before stretching. Melilli et al. (2003a) showed that pre-
salted (PS) cheeses prior to brining contained 60% of
the final salt content in the center of the block as that
achieved in 24 d of saturated salt brining with no pre-
salting (NPS). Presalting did not change the rate of
salt uptake from 18%B or SB (Melilli et al., 2003a) or
moisture loss, but presalting the curd with 2% added
salt before stretching reduced the coliform count in the
cheese by 1.41 log and made a major reduction in early
gas formation (Melilli et al., 2004b). Although presalt-
ing delivers about 2.5 to 3% salt in the water phase
immediately to the center of the blocks of cheese (Melilli
et al., 2003a), the large reduction in early gas formation
in Ragusano cheese due to PS reported by Melilli et al.
(2004b) was caused by the interaction of the tempera-
ture (about 48°C), the low pH (about 5.2 to 5.3), and
the PS during stretching and the ability of these condi-
tions to kill gas-forming bacteria.
Brine temperature (BT) influences salt uptake dur-
ing brining. Geurts et al. (1974) showed for Gouda
cheese that salt diffusion at 20°C was higher by about
40 to 50% than at 12.5°C. Turhan and Kaletunc
¸
(1992)
found that for White cheese, a semihard pickled cheese
(Caric
´
, 1993), the salt penetration was slower with de-
creasing BT because of decreased salt diffusivity. Mel-
Journal of Dairy Science Vol. 89 No. 2, 2006
illi et al. (2003b) determined that salt uptake in Ragu-
sano cheese increased with increasing BT from 12 to
24°C, but at brine temperatures higher than 18°Ca
stimulation of early gas production was noted, even
though the salt uptake by the cheese was faster. Reduc-
ing brine temperature from 18 to 12°C made a larger
reduction in early gas formation in cheeses that were
not presalted (from 6.8 to 1.8% gas holes, respectively)
than in cheeses that were presalted (from 1.9 to 0.5%
gas holes, respectively; Melilli et al., 2004b).
Brine-salted cheeses generally lose weight during
brining, even though they are taking up salt. Geurts
et al. (1974, 1980) reported that the net weight loss from
cheese during brining is due to moisture loss. Melilli et
al. (2003a) reported an 11.3% weight loss from 3.5 kg
blocks of brine salted Ragusano cheese and the shrink-
age of block size was estimated to be 10.4%. This was
consistent with a report of 14% shrinkage for Gouda
cheese reported by Payne and Morison (1999). Shrink-
age does not occur uniformly within the block and
Geurts et al. (1980) estimated that the exterior portion
of a block might shrink by as much as 30%. Shrinkage
of the exterior portion of the block changes the micro-
structure near the block surface forming a barrier layer
very early (i.e., first 24 to 48 h) in the brining process
(Melilli et al., 2005). However, surface shrinkage does
contribute to the typical shape of the Ragusano blocks
of cheese by converting the flat-sided rectangular block
with 90° angles on the edges into a block that has
rounded edges and corners. The rounding of the block
shape at the edges is caused by the faster rate of mois-
ture loss at the edges and corners of the block compared
with the moisture loss from the flat center faces of the
rectangular block. The surface barrier layer influences
salt uptake during the remainder of the brining process.
Weight loss during brining reduces cheese yield; there-
fore, it would be desirable to optimize cheese-making
and brining conditions to provide maximum reduction
in early gas formation while maintaining the highest
possible cheese yield. The objective of this research was
to determine the combined impact (i.e., interactions) of
PS the curd before stretching, BC (saturated vs. 18%
salt brine), and BT (12, 15, and 18°C) on salt uptake,
moisture content, and yield of Ragusano cheese.
MATERIALS AND METHODS
Experimental Design and Statistical Analyses
Thirty-one 3.6-kg blocks of Ragusano cheese were
made on each of 6 different days (in different weeks)
starting with a different batch of milk on each day. On
d 1, 3, and 5, the cheeses were not presalted and on d
2, 4, and 6 all cheeses were presalted. One of the 31
blocks of cheese was selected at random for analysis
SALT PENETRATION DURING BRINE SALTING 3
before brine salting (i.e., d 0). The remaining 30 blocks
were randomly divided into 2 groups of 15 blocks each;
one group was placed in 18%B and the other group was
placed in SB. For the 15 blocks within each of the 2
BC, 5 blocks were placed in a brine tank at 12°C, 5
at 15°C, and 5 at 18°C. Cheese blocks were sampled
immediately before brine salting (d 0) and after 1, 4, 8,
16, and 24 d of brine salting.
Data were analyzed using the GLM procedure of SAS
(version 8, 1999; SAS Institute, Inc., Cary, NC). Weight
of the blocks of cheese, pH, moisture, salt, and salt in
moisture content were determined at 0, 1, 4, 8, 16, and
24 d of brining. Because time of brining was treated as
a continuous variable in the ANOVA model, the linear
and quadratic terms for time would be correlated. Dis-
tortion of the ANOVA by multicollinearity of these
terms in the model was minimized by centering the time
of brining data using a mathematical transformation
(Glantz and Slinker, 2001). The time was transformed
as follows: time = d of brining [(last testing day first
testing day)/2]. This transformation made the data set
orthogonal with respect to time.
Cheese Making
Six cheese makings were done from February to
March 2003. Milk produced by Brown Swiss, Holstein,
and mixed-breed cows from 3 farms, from both milkings
(morning and evening) was commingled and trans-
ported to the CoRFiLaC pilot plant ([Au: location?]).
The raw whole milk (1,300 L) was heated in a plate-
and-frame heat exchanger to 35°C and pumped directly
into 7 traditional wooden cheese vats and Ragusano
cheese was manufactured using the procedures de-
scribed by Melilli et al. (2003a,b). The milled curd was
weighed and divided into 31 batches of 4 kg of curd
each. Three cheese makers stretched 31 batches of curd
to produce 31 blocks of cheese (15.2 × 15.2 × 15.2 cm)
that weighed approximately 3.6 kg after stretching. On
3 different days of cheese making, the cheese makers
stretched 31 NPS cheeses and, during another 3 days,
the cheese makers stretched 31 PS cheeses, following
the procedures of Melilli et al. (2003a,b). On cheese-
making d 2, 4, and 6, the curd to make all 31 blocks of
cheese was presalted at a rate of 2% added salt and
each block was stretched in 10 L of hot brine (4.5% salt,
wt/vol) to minimize salt loss during stretching (Melilli
et al., 2003a). The average temperature and pH of the
curd during stretching were about 48°C and 5.30.
Each 3.6-kg block of cheese was marked with a letter
(treatment) and a number (sampling day) so that the
cheese could be correctly identified in the brine tank.
After forming the blocks, 1 of the 31 blocks was sampled
and analyzed before brining. The initial SB used in this
Journal of Dairy Science Vol. 89 No. 2, 2006
experiment was one that had been used for many years
in a commercial Ragusano cheese-aging center. Old SB
was used because it contained a normal calcium and
lactate content, and had a pH of about 5.2, which would
avoid the defect of cheese-rind softening, the loss of the
deep yellow color, and stickiness (Geurts et al., 1972)
that can occur with a new brine that contains no calcium
and has high pH. The 18%B solution was prepared
from some of the SB by diluting with water to reach a
concentration of 18% salt (wt/vol). The pH of the 18%
brine was adjusted by directly adding lactic acid to
achieve the same pH (approximately 5.20) as the satu-
rated brine. The brines were prepared 15 d before the
experiment and placed in tanks in controlled tempera-
ture rooms to equilibrate before the beginning of the
experiment. Furthermore, during this 15-d period be-
fore initiation of the study, blocks of regular Ragusano
cheese were placed into each brine to equilibrate the
calcium content. The ratio of the volume of brine to
volume of experimental blocks of cheese was kept at 5
or greater (Zorrilla and Rubiolo, 1991) so that the ratio
of the volume of brine to cheese would not limit salt
uptake during the experiment. The blocks were kept
submerged for 24 d. During the 24 d of brining the
blocks of cheese were turned daily and the salinity of
the brine was checked 4 times/d with a hydrometer
and adjusted to maintain either saturation or 18% salt
concentration during each day as needed.
Milk for Cheese Making
Milk samples were collected, randomly, from 1 of the
7 vats, at 35°C, and they were tested for fat, crude
protein, and lactose content using an infrared milk ana-
lyzer (AOAC, 2000; method number 33.2.31; 972.16),
for SCC using a Fossomatic cell counter (AOAC, 2000;
method number 17.13.01; 978.26), for the titratable
acidity, and pH. The average raw whole milk used in
3 cheese-making sessions had an acidity of 0.13 g lactic
acid/100 mL and a pH of 6.70 at 35°C. The average fat,
CP, and lactose content were 3.26, 3.27, and 4.70%
respectively, with an average SCC of 400,000 cells/mL.
Sampling and Analysis of Cheese
Each experimental block (15.2 × 15.2 × 15.2 cm) of
Ragusano cheese, on each sampling day, was weighed
and divided in 4 portions (P1, P2, P3, and P4) using
a meat slicer (model 601003, Electrolux, Zanussi Italia
s.p.a, Pordenone, Italy), as described by Melilli et al.
(2003a,b). The exterior portion (P1) represented all 6
faces of the block (approximately 0.6-cm thick); after
removal of the P1 portion, the P2 portion was removed
(approximately 1-cm thick) from all 6 faces of the block.
MELILLI ET AL.4
The P3 portion (approximately 1-cm thick) was removed
next, leaving a cube of about 10 × 10 × 10 cm as the
central portion (P4) of the cheese block. Cheeses were
sampled at 0 time (before brining), 1, 4, 8, 16, and 24
d of brining. Each portion (P1, P2, P3, and P4) was
weighed, cut into cubes, and grated. Moisture content
was determined by drying a 3-g sample in a forced air
oven at 100°C for 24 h (AOAC, 2000, method number
33.2.44; 990.20), salt content by the Volhard method
(AOAC, 2000, method number 33.7.1; 935.43), and the
pH with a gel-filled electrode (model: HA405-DXK-S8/
120, Mettler Toledo Process Analytical Inc., Wilming-
ton, MA).
RESULTS
Total Weight and Moisture Loss, and Total Moisture
and Salt Uptake During Brining
All of the 3.6-kg blocks lost between 190 to 500 g in
24 d of brining (Table 1). The weight of each block of
cheese is presented in Table 1 and the salt content of
each block of cheese will be presented later in the paper.
Using these weights, researchers that are in interested
in mathematical modeling of factors influencing salt
movement in cheese will have access to the data. There
was an impact (P < 0.01) of BC on mean total weight
loss during brining (Table 2). Cheeses kept in saturated
brine for 24 d lost more (P < 0.01) weight than the
cheeses in 18%B (Table 2, Figure 1). There was a sig-
nificant linear (t) and quadratic (t × t) effect of time on
total weight loss, and a significant interaction of time
(linear and quadratic) with BC (Table 2, Figure 1) with
a slower rate of weight loss for the 18%B than the SB
cheeses with time of brining. Cheeses kept in a SB for
24 d had higher least square mean total weight loss
than cheeses kept at 18%B (Table 3). The second largest
impact on total weight loss was due to BT (Table 2).
The cheeses that were kept at higher BT (18°C) for 24
d lost more (P < 0.01) weight than the cheeses at lower
BT (Table 2, Figure 2). The cheeses kept at 18°C for
24 d had higher least squares mean weight loss than
cheeses kept at 12°C (197 vs. 167 g; Table 3) and a
faster rate of weight loss over time (t × BT interaction;
Table 2, Figure 2). Even though there was no direct
effect of PS on weight loss, there was an interaction
(P = 0.03) of PS × BC. The cheese that was PS and held
in 18%B lost less total weight, whereas PS cheeses in
SB lost slightly more total weight (Table 3). There was
no interaction (P > 0.05) of BC and BT or 3-way interac-
tion of BC, BT, and PS on total weight loss (Table 2).
Salt present in the blocks due to PS was not counted
as part of salt uptake from brine, but is considered later
in the salt content of the cheese. Total salt uptake from
brine was influenced (P < 0.01) by BC, but not directly
Journal of Dairy Science Vol. 89 No. 2, 2006
by BT and PS (Table 2). The least squares mean total
salt uptake (Table 3) was higher for 18%B cheeses than
for the SB cheeses, and there was an interaction (P =
0.01) of BC with time (linear and quadratic) of brining
(Table 2, Figure 3). The overall least squares mean
uptake of salt from brine was not influenced by presalt-
ing the cheese before brining (Table 3), but there was
aBC× PS interaction (Table 2; P = 0.01). The PS cheeses
in SB took up slightly more salt, whereas the PS cheeses
in 18%B took up slightly less salt (Table 3), than the
corresponding NPS cheeses.
There was an effect of BC (P < 0.01) on loss of total
moisture (Table 2). Least squares mean moisture loss
was higher for cheeses in SB (Table 3). Loss of moisture
increased with time of brining (Figure 4), and there
was an interaction of BC with time (linear and qua-
dratic terms) of brining (Table 2, Figure 4). There was
a difference in moisture loss even after1dofbrining
and the difference got progressively larger with increas-
ing time of brining (Figure 4). More than 50% of the
moisture loss occurred during the first 8 d of brining,
as reported in previous studies (Melilli et al., 2003a,b).
There was no impact detected (P > 0.05) of BT and PS
on total moisture loss (Table 2).
Salt and Moisture Concentration in the Cheese
During Brining
Percentage salt in the cheese was primarily influ-
enced (P < 0.01) by PS (Tables 2 and 4, Figure 5). Pre-
salting produced a higher salt content both initially
and throughout 24 d of brining (Table 3, Figure 5). All
cheeses increased in salt concentration with time of
brining (Table 4). Brine concentration and its interac-
tion with the quadratic term for time of brining was
significant (P = 0.01), with cheeses left 24 d in 18%B
having higher salt content than cheeses in SB (Tables
2 and 4, Figure 6). The interaction between BC and PS
had an effect (Table 2; P = 0.01) on salt concentration
in the cheese. Without PS, the salt content of the cheese
in 24 d was higher (i.e., 2.50 vs. 2.09%) for cheese in
18%B (Table 3). When the cheese was PS there was
very little influence (3.00 vs. 3.14%) on the least squares
mean total salt concentration (Table 3). However, PS
increased (71 vs. 67 g; Table 3) the least squares mean
total uptake of salt of the cheeses in SB (BC × PS inter-
action; Table 2) whereas it decreased (79 vs. 84 g; Table
3) the least squares mean total salt uptake in 18%B.
In spite of this small difference in salt uptake, the direct
effect of PS on final percentage salt was large (Table
4), particularly in the P4 portion. Thus, PS had a larger
impact on final salt percentage in SB cheeses than in
18%B cheeses.
SALT PENETRATION DURING BRINE SALTING 5
Table 1. Weight (g) in 24 d of brining time, for portions P1, P2, P3, and P4 of each treatment
1
Presalted cheeses Nonpresalted cheeses
Total Original Total Original
Day P1 P2 P3 P4 weight weight P1 P2 P3 P4 weight weight
Saturated brine at 12°C
0 748 1,117 791 1,066 3,722 3,727 695 955 792 1,123 3,565 3,571
1 887 1,066 744 951 3,648 3,732 807 984 707 986 3,484 3,574
4 945 1,029 683 846 3,503 3,687 928 971 657 851 3,407 3,592
8 958 1,022 647 754 3,381 3,639 955 971 615 748 3,289 3,545
16 977 1,071 652 669 3,370 3,729 878 980 609 690 3,157 3,498
24 1,016 1,039 639 626 3,319 3,740 962 1,007 592 599 3,160 3,595
18% Brine at 12°C
0 748 1,117 791 1,066 3,722 3,727 695 955 792 1,123 3,565 3,571
1 866 1,069 747 969 3,651 3,705 816 998 705 946 3,465 3,522
4 935 1,077 705 859 3,576 3,689 915 1,016 665 838 3,435 3,552
8 909 1,098 703 828 3,538 3,683 932 1,052 665 791 3,441 3,597
16 941 1,105 713 767 3,525 3,719 869 1,055 668 748 3,340 3,530
24 932 1,117 714 739 3,503 3,695 929 1,089 666 665 3,349 3,601
Saturated brine at 15°C
0 748 1,117 791 1,066 3,722 3,727 695 955 792 1,123 3,565 3,571
1 868 1,049 745 985 3,648 3,745 801 987 717 995 3,500 3,595
4 935 998 667 871 3,471 3,664 906 946 643 873 3,367 3,549
8 963 1,025 641 779 3,407 3,696 938 951 614 791 3,295 3,563
16 939 1,068 649 683 3,339 3,722 839 1,013 633 723 3,209 3,591
24 972 1,051 637 606 3,266 3,714 926 989 580 585 3,079 3,531
18% Brine at 15°C
0 748 1,117 791 1,066 3,722 3,727 695 955 792 1,123 3,565 3,571
1 859 1,061 752 977 3,649 3,710 823 987 712 989 3,511 3,572
4 938 1,049 699 888 3,574 3,708 913 998 657 850 3,418 3,549
8 954 1,074 700 809 3,537 3,690 921 1,013 636 769 3,339 3,507
16 975 1,099 703 747 3,524 3,735 889 1,059 651 736 3,335 3,543
24 943 1,134 714 723 3,514 3,757 897 1,070 649 647 3,263 3,547
Saturated brine at 18°C
0 748 1,117 791 1,066 3,722 3,727 695 955 792 1,123 3,565 3,571
1 855 1,025 731 969 3,580 3,677 779 958 705 1,013 3,455 3,550
4 935 1,020 682 892 3,529 3,751 879 944 645 877 3,345 3,556
8 927 1,034 647 774 3,382 3,690 907 952 611 801 3,270 3,545
16 908 1,070 647 697 3,321 3,734 797 1,009 623 753 3,182 3,569
24 897 1,114 612 613 3,236 3,700 839 1,001 587 630 3,058 3,561
18% Brine at 18°C
0 748 1,117 791 1,066 3,722 3,727 695 955 792 1,123 3,565 3,571
1 851 1,061 751 975 3,638 3,708 797 971 699 983 3,450 3,522
4 913 1,049 697 919 3,577 3,725 899 987 653 871 3,409 3,555
8 917 1,100 695 843 3,555 3,744 910 1,010 636 797 3,353 3,539
16 913 1,131 701 746 3,491 3,733 786 1,059 670 1,059 3,575 3,549
24 833 1,140 724 764 3,461 3,725 843 1,076 663 682 3,263 3,591
1
Treatments: presalting the curd (presalted vs. not presalted), brine concentration (saturated brine vs.
18% brine), and brine temperature (12, 15, and 18°C). P1, P2, P3, and P4 represent portions of the cheese
block from exterior surface (P1) to interior core (P4).
Percentage moisture in the cheese was influenced the
most (P < 0.01) by BC and by its interaction with time
(linear and quadratic) of brining (Table 2, Figure 7).
Percentage moisture was higher for 18%B cheeses than
for SB cheeses (Figure 7) and this influenced cheese
yield (i.e., smaller weight loss). The effect of BT was
also significant (P < 0.01) and its interaction with the
linear term for time of brining (P = 0.05). Cheeses left
24 d in brine at 18°C had a lower moisture percent
than the cheeses left 24 d at lower brine temperatures
Journal of Dairy Science Vol. 89 No. 2, 2006
(Tables 2 and 3, Figure 8). Fat and protein content
(data not shown) of the cheeses in this study changed
in concentration on a wet basis in an inverse relation-
ship with moisture content of the cheese.
Moisture, Salt, and pH Variation Within
Blocks During Brining
Moisture. There was an impact of BC on moisture
content of cheese in all portions within the block, but the
MELILLI ET AL.6
Table 2. Sums of the squares (Type III SS) and probability values (in parentheses) for the ANOVA of the
impact of treatments
1
on the total weight loss, total moisture loss, salt uptake, and percentage salt and
moisture of Ragusano cheese over 24 d of brining
Total
Total weight Total salt moisture Salt Moisture
Factors
2
df loss (g) uptake (g) loss (g) (%) (%)
Whole plot
BC 1 316,102* 8,102* 285,179* 4.46* 89.00*
(<0.01) (<0.01) (<0.01) (0.01) (<0.01)
BT 2 39,234* 67 10,342 0.11 18.87*
(<0.01) (0.67) (0.07) (0.50) (<0.01)
PS 1 91 14 175 32.71* 1.71*
(0.57) (0.69) (0.72) (<0.01) (0.01)
BC × PS 1 2,091* 959* NS 1.10* 3.83*
(0.03) (0.01) (0.01) (0.01)
BC × BT × PS 7 1,489 467 8,919 0.44 0.48
(0.94) (0.67) (0.41) (0.69) (1.00)
Subplot
t 1 2,568,107* 415,512* 5,049,611* 399.20* 1,971,65*
(<0.01) (<0.01) (<0.01) (<0.01) (<0.01)
t × BC 1 215,100* 1,772* 201,369* NS 75.02*
(<0.01) (0.01) (<0.01) (<0.01)
t × BT 2 9,418* NS NS NS 5.80*
(0.01) NS (0.05)
t × t 1 251,740* 40,854* 495,420* 34.33* 211.85*
(<0.01) (<0.01) (<0.01) (<0.01) (<0.01)
(t × t) × BC 1 15,413* 1,497* 12,612* 1.42* 5.10*
(<0.01) (0.01) (0.01) (0.01) (0.02)
Error 198 165,184 189.19
Error 200 23,221 246,862
Error 201 22.51
R
2
0.96 0.95 0.96 0.96 0.93
1
Treatments: presalting the curd (presalted vs. not presalted), brine concentration (saturated brine vs.
18% brine), and brine temperature (12, 15, and 18°C). P1, P2, P3, and P4 represent portions of the cheese
block from exterior surface (P1) to interior core (P4).
2
Factors: BC = brine concentration; BT = brine temperature; PS = presalting; t = time.
*Statistically significant (P < 0.05).
magnitude of the impact of BC on moisture decreased
greatly from portions P1 to P4 (Table 5). Overall, the
impact of BC produced the largest effect on moisture
Figure 1. Impact of brine concentration, 18% brine () vs. satu-
rated brine (), on total weight loss (g) in Ragusano cheese at 0, 1,
4, 8, 16, and 24 d of brining.
Journal of Dairy Science Vol. 89 No. 2, 2006
content in P1, followed by BT, and then by PS. In portion
P1, the 18%B cheeses had higher (P < 0.01) moisture
than the SB cheeses (Figure 9, Table 6). There was also
a significant (P < 0.01) interaction of BC with time
(linear and quadratic) with the 24-d-old cheeses in
18%B having higher moisture content in the P1 portion
(approximately 34%) than the cheeses held in the SB
(approximately 27%; Figure 9). Final moisture content
of the P1 portion reached in 24 d of brining in the cheese
left in 18%B was nearly achieved in 4 d of brining,
whereas the cheese in SB continued to lose a large
amount of moisture after d 4 (Figure 9). Higher mois-
ture content would be expected to maintain higher po-
rosity of the exterior (P1) portion of the cheese at 18%B
and permit faster salt uptake. There was an effect (P
< 0.01) of BT on moisture content in P1 (Table 5), with
least squares mean moisture content higher for the
cheeses kept 24 d at 12 and 15°C than those kept at
18°C (Figure 10, Table 6). There was a significant linear
interaction of BT with time (P = 0.04; Table 5, Figure
SALT PENETRATION DURING BRINE SALTING 7
Table 3. Least squares mean values of the total weight loss, total moisture loss, and salt (uptake and
percentage) and moisture percentage for presalted and not presalted cheeses at 2 brine concentrations (18%
vs. saturated), and 3 brining temperatures (12, 15, and 18°C) over 24 d of brining
Total Total Total
weight salt moisture
loss uptake loss Salt Moisture
Variable (g) (g) (g) (%) (%)
Presalting 181
a
75
a
256
a
3.07
a
40.55
a
No presalting 182
a
75
a
258
a
2.30
b
40.73
a
LSD NS NS NS 0.09 NS
Saturated brine 228
a
69
b
301
a
2.55
b
39.91
b
18% Brine 136
b
81
a
213
b
2.82
a
41.37
a
LSD 7.75 2.89 9.43 0.09 0.26
Saturated brine
Presalting 230
a
71
a
304
a
3.00
a
39.69
b
No presalting 225
b
67
b
298
a
2.09
b
40.13
a
18% brine
Presalting 132
b
79
b
209
a
3.14
a
41.41
a
No presalting 140
a
84
a
218
a
2.50
b
41.32
a
12°C 167
c
75
a
249
a
2.65
a
40.94
a
15°C 182
b
75
a
257
a
2.69
a
40.66
a
18°C 197
a
76
a
266
a
2.71
a
40.32
b
LSD 9.49 NS NS NS 0.32
a–c
Means within salting method, brine concentration, and brine temperature within a column not sharing
the same superscript are different (P < 0.05).
10), with moisture difference among the BT getting
large [Au: getting large? Increasing?] with time of
brining. There was a trend for higher moisture content
of the P1 portion (P = 0.01) for the PS cheeses, but the
size of this impact (Figure 11) was small compared with
the BC effect (Table 6, Figure 9).
Cheese in portion P2, left 24 d in 18%B, (Figure 9)
decreased in moisture with time of brining but the
change with time was more linear than quadratic com-
pared with the change in P1 (Table 5). There was a (P
< 0.01) linear interaction of time × BC in portion P2
(Table 5, Figure 9), with cheeses kept for 24 d in 18%B
maintaining higher moisture content (approximately
Figure 2. Impact of the interaction time by brine temperature:
12°C(), 15°C(), and 18°C() on total weight loss (g) in Ragusano
cheese at 0, 1, 4, 8, 16, and 24 d of brining.
Journal of Dairy Science Vol. 89 No. 2, 2006
37%) than the cheeses left in the SB (approximately
34%). This would produce higher porosity in the 18%B
cheeses than in the SB cheeses. There was a significant
effect (P < 0.01) of BT (Table 5), showing that at lower
BT, the P2 portion of the cheeses maintained higher
moisture content at the end of 24 d of brining (36.3 vs.
35%; Figure 10). There was also a significant interac-
tion of BT with the time of brining (P = 0.04; Figure
10, Table 5). In general, the absolute magnitude of the
difference in moisture in P2 due to BT was smaller than
Figure 3. Impact of brine concentration, 18% brine () vs. satu-
rated brine (), on total salt uptake (g) in Ragusano cheese at 0, 1,
4, 8, 16, and 24 d of brining.
MELILLI ET AL.8
Figure 4. Impact of brine concentration, 18% brine () vs. satu-
rated brine (), on total moisture loss (g) in Ragusano cheese at 0,
1, 4, 8, 16, and 24 d of brining.
in P1 (Figure 10). The effect of the PS on the moisture
content of the P2 and P3 portions was significant (Table
5) with PS cheese having lower least squares mean
moisture (P < 0.01; Table 6). The 2-way interaction (PS
× BC) was significant (P < 0.01) with PS having no
impact on least squares mean moisture within portion
in 18%B (41.18 vs. 41.23%), but in contrast, producing
lower moisture in cheeses kept in SB (39.97 vs. 40.68%;
Table 6). The PS cheeses may have had a slightly more
porous structure (i.e., more moisture) at the exterior 1
mm of the surface of the block early in brining, as re-
ported by Melilli et al. (2005), which allowed more mois-
ture to exit from the P2 and P3 portions for the PS
blocks vs. blocks that were not PS and then placed in
SB. Similar impacts of BC, BT, and PS on moisture
observed in P1 were also seen in portions P3 and P4, but
the absolute magnitude of the differences in moisture
became smaller in the interior portion of the blocks
(Tables 5 and 6, Figures 9, 10, and 11).
Salt. There were both linear and quadratic effects of
time on salt content of the cheeses in all portions (Table
7, Figures 12, 13, 14), with salt content increasing with
time of brining. The PS had the largest effect (P < 0.01)
on the salt content in all the portions (P1, P2, P3, and
P4; Table 7), with a higher salt content in all portions for
the PS cheeses (Figure 12, Table 8). The key difference
produced by PS was that the all PS cheeses started at
time 0 with about 1% salt content in all portions (Figure
12). The goal of PS was to deliver a moderate amount
of salt to the center of the block of cheese at time 0 with
the goal of reducing early gas production by undesirable
bacteria. Presalting made a large reduction in gas pro-
duction and these results have been reported separately
(Melilli et al., 2004b). Overall, the rate of increase in
percentage salt content with time of brining was not
Journal of Dairy Science Vol. 89 No. 2, 2006
strongly influenced by PS, when the difference in initial
salt content was considered (Figure 12). The second
largest impact of a main experimental treatment on
salt content within the block of cheese was due to BC
(Table 7) with cheeses in 18%B achieving a higher least
squares mean salt content in all portions (Table 8) and
by the end of 24 d (Figure 13) than the cheeses in SB.
There was a small impact (P = 0.01) of BT on overall
salt content in portions P3 and P4 (Tables 7 and 8 and
Figure 14). This was consistent with a previous report
(Melilli et al., 2003b) that the higher the BT tempera-
ture, the higher the salt content (Figure 14). However,
although the impact of BT was significant, the absolute
differences in salt content (over this small range of
temperature) were not large. This does not mean BT is
not important because lower BT can reduce the rate at
which undesirable gas producing organisms cause gas
defects (Melilli et al., 2004b). From a practical point of
view, keeping the BT slightly lower (e.g., 15 instead of
18°C) has the advantage of not decreasing salt uptake
very much (Figure 14), but may make an important
contribution to reducing gas production by undesirable
microflora, as reported by Melilli et al. (2004b).
Salt in Moisture. The impact of PS on salt in mois-
ture was significant (P < 0.01) in all portions (Table 9),
showing that PS cheeses had a higher salt in moisture
content than cheeses that were NPS (Table 10, Figure
15). Cheeses that were PS contained about 2.25% salt
in moisture in all portions (Figure 15) before being
placed in brine, whereas cheeses that were NPS con-
tained about 0.2% salt in moisture. Salt in moisture in
the P1 portion became very high (about 8 to 10%) within
24 h (Figure 15) after the start of brining and this is
at least part of the reason why gas holes are not seen
near the surface of the cheese. Looking specifically at
each portion of the block, in P1 there was a significant
effect of BC (P < 0.01; Table 9), with cheeses kept in
SB achieving a higher salt in moisture content in P1
(Figure 16, Table 10). The 2 treatments (SB vs. 18%B)
were about the same with respect to salt in moisture
until 8 d in the P1 portion and then they diverged
(Figure 16) as the P1 portion of the cheese in SB contin-
ued to increase in salt in moisture. Even though the
salt in moisture was similar in the P1 portions of cheese
in SB and 18%B until8dofbrining (Figure 16), the
moisture content of the P1 portions were very different
(Figure 9), with the cheeses in 18%B having a much
higher moisture and much more porous structure (i.e.,
less barrier to salt penetration) than the cheeses in SB.
The more porous structure (particularly in P1) of the
cheese in 18%B allowed more uptake of salt (Table 3,
Figure 3) and higher salt in moisture (PS × BC interac-
tion; Table 9) in the interior (P2, P3, and P4) portions
with time of brining (Figure 16), which was the opposite
SALT PENETRATION DURING BRINE SALTING 9
Table 4. Salt (%) in 24 d of brining time, for portions P1, P2, P3, and P4
1
of each treatment
Presalted cheeses Nonpresalted cheeses
Day P1 P2 P3 P4 P1 P2 P3 P4
Saturated brine at 12°C
0 1.03 1.02 1.00 1.00 0.07 0.10 0.10 0.11
1 3.71 1.46 0.99 0.96 3.08 0.51 0.11 0.06
4 4.72 2.45 1.29 0.95 3.96 1.68 0.52 0.12
8 5.51 3.69 2.00 1.12 4.79 2.81 1.08 0.35
16 6.05 4.81 3.12 1.87 5.12 3.65 2.18 0.91
24 6.22 5.15 3.77 2.37 6.18 5.16 3.45 1.83
18% Brine at 12°C
0 1.03 1.02 1.00 1.00 0.07 0.10 0.10 0.11
1 3.76 1.40 0.92 0.97 3.18 0.53 0.11 0.04
4 5.19 2.79 1.47 0.98 4.81 2.12 0.59 0.14
8 5.20 4.38 2.65 1.40 5.66 3.63 1.53 0.37
16 6.26 5.16 3.57 1.92 6.23 4.91 3.20 1.36
24 6.51 5.67 4.47 2.84 6.27 5.22 3.58 1.81
Saturated brine at 15°C
0 1.03 1.02 1.00 1.00 0.07 0.10 0.10 0.11
1 3.54 1.42 0.94 0.88 2.77 0.51 0.15 0.78
4 4.19 2.52 1.37 1.00 3.72 1.57 0.42 0.09
8 5.60 3.69 2.29 1.23 4.40 2.50 1.17 0.27
16 5.89 4.83 3.40 1.96 5.64 4.34 2.74 1.18
24 6.88 5.98 4.71 3.03 5.47 4.51 3.08 1.62
18% Brine at 15°C
0 1.03 1.02 1.00 1.00 0.07 0.10 0.10 0.11
1 3.84 1.46 0.90 0.90 3.13 0.55 0.11 0.08
4 4.71 3.19 1.55 1.00 5.05 2.47 0.77 0.21
8 5.73 4.14 2.58 1.34 5.59 3.64 1.71 0.45
16 6.27 5.21 3.87 2.26 6.03 4.94 3.27 1.44
24 6.52 5.79 4.67 3.14 6.31 5.45 4.07 2.29
Saturated brine at 18°C
0 1.03 1.02 1.00 1.00 0.07 0.10 0.10 0.11
1 3.60 1.50 1.05 1.07 2.56 0.52 0.11 0.05
4 4.43 2.84 1.51 0.97 3.96 1.99 0.65 0.11
8 5.41 3.94 2.43 1.34 4.30 2.68 1.30 0.46
16 5.91 5.01 3.68 2.23 5.06 4.15 2.69 1.13
24 6.28 5.45 4.90 3.46 4.94 4.35 3.04 1.73
18% Brine at 18°C
0 1.03 1.02 1.00 1.00 0.07 0.10 0.10 0.11
1 3.80 1.64 1.06 1.02 3.36 0.76 0.12 0.08
4 4.69 3.29 1.71 0.97 4.84 2.49 0.84 0.19
8 5.45 4.14 2.54 1.26 5.52 3.78 1.94 0.53
16 6.20 5.30 4.05 2.37 5.93 5.08 3.75 5.08
24 6.39 5.84 5.00 3.61 5.69 4.99 3.81 2.16
1
Portions P1, P2, P3, and P4 represent portions of the cheese block from exterior surface (P1) to interior
core (P4).
of P1 portion in SB (Figure 16). Thus, the combination
of PS plus lower BC produced a higher salt in moisture
content in the interior portions (Figures 15 and 16),
particularly during the first 8 d. The P4 portion of the
PS cheeses at d 0 had about the same salt in moisture
content as a cheese that had been in SB for 16 d without
PS. Higher salt in moisture content during the early
stages of brine salting, particularly when brine temper-
ature is >18°C, should help control early gas production
(Melilli et al., 2003b). The main effect of BT in P1 was
not significant (P = 0.59; Tables 9 and 10); the salt in
moisture content for all brine temperatures 24 d of
Journal of Dairy Science Vol. 89 No. 2, 2006
brining (Figure 17) was about 18%. However, BT did
have a consistent influence (P 0.05; Tables 9 and 10)
on salt in moisture in the P2, P3, and P4 portions with
cheeses at lower BT achieving lower salt in moisture
(Figure 17) after 24 d of brining, but the magnitude of
the impact of BT on salt in moisture was very small
compared with the impact of PS and BC. This is consis-
tent with the previous report of Melilli et al. (2003b).
Decreasing BT increases the viscosity of the water
phase (Walstra et al., 1999) and this would tend to
have more impact in the interior portions of the cheese
because the salt taken up from the brine has a longer
MELILLI ET AL.10
Figure 5. Impact of presalting, presalted () vs. not presalted
(), on total salt content (%) in Ragusano cheese at 0, 1, 4, 8, 16,
and 24 d of brining.
distance to travel through a more viscous water phase.
This is also consistent with the increasing type III sum
of squares for the BT going from P1 to P4 (Table 9) and
the interaction of t × BT for portions P3 and P4 observed
in the present study. Salt in moisture content can in-
fluence gas production by undesirable microflora (Mel-
illi et al., 2004b), proteolysis and lipolysis (Melilli et
al., 2004a), growth of desirable microflora, and pH
changes in cheese produced by desirable lactic acid-
producing bacteria.
pH. The impact of all treatments (i.e., PS, BC, and
BT) on cheese pH both initially and during time of
storage was very small (usually <0.1 pH units). Gener-
ally, if all has gone well in cheese making, the typical
pH of the cheese should be achieved before PS and the
pasta-filata step in Ragusano cheese making (Licitra
et al., 1998). The R
2
for the ANOVA models were low
(Table 11) and the absolute impacts of the treatment
Figure 6. Impact of brine concentration, 18% brine () vs. satu-
rated brine (), on total salt content (%) in Ragusano cheese at 0, 1,
4, 8, 16, and 24 d of brining.
Journal of Dairy Science Vol. 89 No. 2, 2006
Figure 7. Impact of brine concentration, 18% brine () vs. satu-
rated brine (), on total moisture content (%) in Ragusano cheese at
0, 1, 4, 8, 16, and 24 d of brining.
parameters on cheese pH were small (Table 12). In the
present study, the pH of the curd at stretching was
about 5.1 to 5.3, thus the acid development by the
starter culture was completed before PS. The largest
impact on pH of the main effects was in the P1 portion
with PS cheese in 18%B held at the lowest temperature
(i.e., 12°C) having the highest pH, but the differences
were small (generally <0.05 pH units). Although there
was an effect (P < 0.02) of time of brining on pH of the
P1, P2, and P3 portions (Table 11), it explained only a
very small amount of the total variation in pH
among treatments.
DISCUSSION
Factors Influencing Salt Uptake During Brining
Salt content of cheese influences both rate of growth
and type of microbial populations (both desirable and
undesirable) that are present in cheese. In brine-salted
cheeses salt diffuses slowly into the cheese and probably
Figure 8. Impact of the interaction time by brine temperature:
12°C(), 15°C(), and 18°C() on total moisture content (g) in
Ragusano cheese at 0, 1, 4, 8, 16, and 24 d of brining.
SALT PENETRATION DURING BRINE SALTING 11
Table 5. Sums of the squares (Type III SS) and probability values for the ANOVA of the impact of treatments
1
on moisture content of cheese portions (P1, P2, P3, and P4) of Ragusano cheese at 0, 1, 4, 8, 16, and 24 d
of brining
Factors
2
df P1 P2 P3 P4 Analyzed as Error term
Whole plot
BC 1 702.09* 84.18* 5.19* 1.00* Category BC × BT × PS
(<0.01) (<0.01) (0.01) (0.01)
BT 2 84.63* 28.31* 5.58* 3.50* Category BC × BT × PS
(<0.01) (<0.01) (0.01) (0.01)
PS 1 7.48* 7.85* 4.28* 3.47* Category BC × BT × PS
(0.01) (0.01) (0.01) (0.01)
BC × PS 1 NS 6.10* 3.39* 2.25* Interaction BC × BT × PS
(0.01) (0.01) (0.01)
BC × BT × PS 7 5.10 1.22 0.15 0.39 Whole plot error Model error
(0.99) (0.98) (1.00) (1.00)
t 1 2,492.50* 2,694.80* 1,426.16* 466.35* Continuous Model error
(<0.01) (<0.01) (<0.01) (0.01)
t × BC 1 275.21* 80.52* 7.71* NS Interaction Model error
(<0.01) (<0.01) (0.01)
t × BT 2 27.78* 7.01* NS NS Interaction Model error
(0.04) (0.04)
t × t 1 967.06* 317.19* 24.09* 3.85* Continuous Model error
(<0.01) (<0.01) (<0.01) (0.04)
(t × t) × BC 1 78.28* NS NS NS Interaction Model error
(< 0.01)
Error 198
Error 199 205.55
Error 201 190.40
Error 202 185.19
R
2
0.86 0.94 0.89 0.72
1
Treatments: presalting the curd (presalted vs. not presalted), brine concentration (saturated brine vs.
18% brine), and brine temperature (12, 15, and 18°C). P1, P2, P3, and P4 represent portions of the cheese
block from exterior surface (P1) to interior core (P4).
2
Factors: BC = brine concentration; BT = brine temperature; PS = presalting; t = time.
*Statistically significant (P < 0.05).
does not reach an inhibitory concentration in the inte-
rior until starter growth has ceased (Fox et al., 2000).
Salt content also can influence partitioning of proteins
Figure 9. The impact of saturated brine (SB) vs. 18% brine (18%B)
during 24 d of brining time on moisture content in portions P1 (,
), P2 (, ), P3 (, ), and P4 (, ); P1, P2, P3, and P4 represent
portions of the cheese block from exterior surface (P1) to interior core
(P4). Filled symbols are cheeses in SB and open symbols are the
cheeses in 18%B.
Journal of Dairy Science Vol. 89 No. 2, 2006
and enzymes between the casein matrix and the water
phase of cheese. Enzymatic reactions (e.g., proteolysis,
lipolysis, oxidation, decarboxylation, deamination) that
contribute to flavor development during cheese aging
can be influenced by salt content. Mature brine contains
solutes other than NaCl, such as lactate, calcium, and
free fatty acids. The SB used in the present study were
mature brines and the 18%B were made from the SB by
water dilution and then were pH- and calcium-adjusted
before use in the experiment. During the first day of
brine salting, the cheese may take up solutes other than
NaCl from the brine into the exterior portion of the
cheese. Melilli et al. (2004a) demonstrated this for the
uptake of butyric acid from brine by Ragusano cheese.
In cheeses where the curds are salted directly during
the cheese-making process and before block formation,
the salt content of the cheese is more uniform within
blocks than for brine-salted cheeses. During brine salt-
ing, large salt concentration gradients develop within
blocks of cheese (Guinee and Fox, 1986). In general,
the larger the block of cheese, the larger the gradient
MELILLI ET AL.12
Table 6. Least squares mean values of the percentage moisture of
cheese portions
1
(P1, P2, P3, and P4) of Ragusano cheese, for the
presalted and not presalted cheeses at 2 brine concentrations (18%
vs. saturated), and 3 brining temperatures (12,15, and 18°C) averaged
across 24 d of brining
Variable P1 P2 P3 P4
Presalting 35.04
a
40.57
b
43.19
b
44.69
a
No presalting 34.67
a
40.96
a
43.47
a
44.95
a
LSD NS 0.27 0.26 NS
Saturated brine 32.87
b
40.33
b
43.23
a
44.89
a
18% Brine 36.83
a
41.21
a
43.43
a
44.75
a
LSD 0.55 0.27 NS NS
Saturated brine
Presalting 33.02
a
39.97
b
42.97
b
44.66
a
No presalting 32.73
a
40.68
a
43.50
a
45.12
a
18% Brine
Presalting 37.06
a
41.18
a
43.41
a
44.73
a
No presalting 36.60
a
41.23
a
43.44
a
44.78
a
12°C 35.46
a
41.13
a
43.54
a
44.96
a
15°C 34.94
a
40.82
a
43.31
ab
44.84
a
18°C 34.16
b
40.35
b
43.15
b
44.65
a
LSD 0.67 0.33 0.32 NS
a,b
Means within salting method, brine concentration, and brine
temperature within a column not sharing the same superscript are
different (P < 0.05).
1
Portions P1, P2, P3, and P4 represent portions of the cheese block
from exterior surface (P1) to interior core (P4).
in salt content with high salt at the exterior and low
salt in the center.
Salt uptake during brine salting has been studied by
Geurts et al. (1974, 1980) for Gouda cheese and Resmini
et al. (1974) for Parmigiano-Reggiano cheese. The
cheese characteristics that influence rate of penetration
of salt during brine salting are: porosity of the cheese
(Geurts et al., 1974), tortuosity of the channels of water
within the structure (Geurts et al. 1974), the proportion
of the total water that is bound, the viscosity of the
Figure 10. The impact of brine temperature (BT) during 24 d of
brining time on moisture content in portions P1 (), P2 (), P3 (),
and P4 (); P1, P2, P3, and P4 represent portions of the cheese block
from exterior surface (P1) to interior core (P4). Dashed lines represent
cheese at 12°C BT; solid lines represent cheese at 15°C BT; and dotted
lines represent cheeses at 18°C BT.
Journal of Dairy Science Vol. 89 No. 2, 2006
Figure 11. The impact of presalting vs. not presalting during 24
d of brining time on moisture content in portions P1 (, ), P2 (,
), P3 (, ), and P4 (, ); P1, P2, P3, and P4 represent portions
of the cheese block from exterior surface (P1) to interior core (P4).
Filled symbols are not presalted cheeses and open symbols are the
presalted cheeses.
free water phase (Guo et al., 1997; Payne and Morison,
1999), and the interaction of sodium with the protein
matrix (Payne and Morison, 1999).
Many variables during cheese making and brining
can influence salt penetration through the structure of
cheese. Resmini et al. (1974) found that cheese placed
in brine that was not fully saturated took up salt at a
faster rate than cheese placed in SB. This was con-
firmed in Ragusano cheese by Melilli et al. (2003a) with
cheese taking up salt faster in 18%B than SB. The
moisture content of the cheeses differed greatly from
the inside to the exterior surface of the block, but the
cheese in 18%B had higher moisture at the exterior
surface producing a more porous structure and more
rapid salt penetration. During brining, cheese loses
moisture into the brine and this causes the moisture
content and porosity at the exterior surface of the block
to decrease and form a barrier layer with lower porosity
that impedes further salt penetration (Melilli et al.,
2003a). Melilli et al. (2005) characterized the barrier
layer in Ragusano cheese. In the 1-mm zone at the
surface of the cheese, the porosity of the cheese in SB
had decreased by about 36% after 4 d brining and by
50% at 12 d of brining, whereas cheese in 18%B had a
decrease in porosity of about 23% after 4 d and 28%
after 12 d of brining. Electron micrograph images pre-
sented in that study were consistent with these differ-
ences in porosity (Melilli et al., 2005). Moisture gradi-
ents from the surface to the interior of brine-salted
cheeses can be very large. The exterior 1 mm of the
block had a moisture content of 42% in cheese before
brining but was 28% after 12 d in 18%B, whereas the
moisture was only 20% after 12 d in SB, producing a
large difference in porosity (Melilli et al., 2005) and
shrinkage of the structure (Melilli et al., 2003a).
Shrinkage of the cheese structure takes place at the
SALT PENETRATION DURING BRINE SALTING 13
Table 7. Sums of the squares (Type III SS) and probability values for the ANOVA of the impact of treatments
1
on salt content of cheese portions (P1, P2, P3, and P4) of Ragusano cheese over 24 d of brining
Factor
2
df P1 P2 P3 P4 Analyzed as Error term
Whole plot
BC 1 8.48* 9.82* 5.26* 1.21* Category BC × BT × PS
(<0.01) (<0.01) (0.01) (0.01)
BT 2 1.11* 0.42 2.66* 2.00* Category BC × BT × PS
(0.04) (0.08) (0.01) (0.01)
PS 1 17.81* 26.34* 42.07* 10.68* Category BC × BT × PS
(<0.01) (<0.01) (<0.01) (<0.01)
BC × PS 1 3.47* 1.04* NS NS Interaction BC × BT × PS
(0.01) (0.01)
BC × BT × PS 7 0.61 0.31 0.94 0.63 Whole plot Model error
(0.99) (0.90) (0.19) (0.24) error
t 1 439.09* 571.40* 377.08* 113.93* Continuous Model error
(<0.01) (<0.01) (<0.01) (<0.01)
t × BC 1 NS 0.65* 1.83* 1.13* Interaction Model error
(0.03) (<0.01) (<0.01)
t × PS 1 NS 0.60* NS 0.50* Interaction Model error
(0.04) (0.01)
t × BT 2 NS NS 0.94* 1.43* Interaction Model error
(0.01) (<0.01)
t × BT × PS 2 NS NS NS 0.54* Interaction Model error
(0.02)
t × t 1 160.66* 67.60* 3.98* 3.01* Continuous Model error
(<0.01) (<0.01) (<0.01) (<0.01)
(t × t) × BC 1 NS 2.77* 1.12* NS Interaction Model error
(<0.01) (0.01)
(t × t) × PS 1 NS NS NS 0.27* Interaction Model error
(0.05)
Error 202 175.58
Error 199 27.74
Error 198 18.50
Error 195 13.31
R
2
0.79 0.96 0.96 0.92
1
Treatments: presalting the curd (presalted vs. not presalted), brine concentration (saturated brine vs.
18% brine), and brine temperature (12, 15, and 18°C). P1, P2, P3, and P4 represent portions of the cheese
block from exterior surface (P1) to interior core (P4).
2
Factors: BC = brine concentration; BT = brine temperature; PS = presalting; t = time.
*Statistically significant (P < 0.05).
exterior surface and has been reported by Payne and
Morison (1999) and Geurts et al. (1980).
Presalting of Ragusano cheese was explored as an
approach to achieve higher salt content in the interior
of brine-salted cheese early in the brining process with
the goal of reducing early gas formation. This approach
was used successfully in Ragusano cheese and delivered
60% of the salt to the center of a block at the beginning
of brine salting, without reducing the subsequent up-
take of salt during brine salting of the presalted cheese
(Melilli et al., 2003a). Presalting achieved about 2 to
2.5% salt in the water phase of the cheese, but this is
low compared with the concentration of salt in brines;
therefore, the presalting had very little impact on salt
uptake from 18%B or SB (Melilli et al., 2003a).
Turhan and Kaletunc
¸
(1992) reported that BT (4,
12.5, and 20°C) had a significant impact on salt penetra-
Journal of Dairy Science Vol. 89 No. 2, 2006
Figure 12. The impact of presalting vs. not presalting during 24
d of brining time on salt content (%) in portions P1 (, ), P2 (,
), P3 (, ), and P4 (, ); P1, P2, P3, and P4 represent portions
of the cheese block from exterior surface (P1) to interior core (P4).
Filled symbols are not presalted cheeses and open symbols are the
presalted cheeses in 18% brine.
MELILLI ET AL.14
Figure 13. The impact of saturated brine (SB) vs. 18% brine
(18%B) during 24 d of brining time on salt content (%) in portions
P1 (, ), P2 (, ), P3 (, ), and P4 (, ); P1, P2, P3, and P4
represent portions of the cheese block from exterior surface (P1) to
interior core (P4). Filled symbols are cheeses in SB and open symbols
are the cheeses in 18%B.
tion with lower BT producing slower salt penetration.
Resmini et al. (1974) found that blocks of Parmigiano-
Reggiano cheese absorbed more salt at higher brine
temperature (18 to 20°C) than at lower temperature
(12.5 to 13°C). Melilli et al. (2003b) reported that the
uptake of salt by Ragusano cheese was faster with in-
creasing (12 to 24°C) BT, but that the rate of change
of salt penetration as a function of increasing BT was
not linear across this range of temperatures. Viscosity
of the water phase is temperature dependent with lower
temperatures favoring higher viscosity (Walstra et al.,
1999) and this is consistent with slower salt penetration
at lower temperatures.
The slower rate of salt penetration at lower BT was
reported to be due to the increased viscosity of the water
phase of cheese with decreasing temperature (Melilli
Figure 14. The impact of brine temperature (BT) during 24 d of
brining time on salt content in portions P1 (), P2 (), P3 (), and
P4 (); P1, P2, P3, and P4 represent portions of the cheese block
from exterior surface (P1) to interior core (P4). Dashed lines represent
cheese at 12°C BT; solid lines represent cheese at 15°C BT; and dotted
lines represent cheeses at 18°C BT.
Journal of Dairy Science Vol. 89 No. 2, 2006
Table 8. Least squares mean values of the percentage salt of cheese
portions (P1, P2, P3, and P4)
1
of Ragusano cheese, for the presalted
and not presalted cheeses at 2 brine concentrations (18% vs. satu-
rated), and 3 brining temperatures (12, 15, and 18°C) at 0, 1, 4, 8,
16, and 24 d of brining
Variable P1 P2 P3 P4
Presalting 4.57
a
3.34
a
2.35
a
1.57
a
No presalting 4.00
b
2.56
b
1.46
b
0.68
b
LSD 0.25 0.10 0.08 0.07
Saturated brine 4.09
b
2.75
b
1.76
b
1.07
b
18% Brine 4.48
a
3.15
a
2.05
a
1.17
a
LSD 0.25 0.10 0.08 0.07
Saturated brine
Presalting 4.50
a
3.21
a
2.25
a
1.53
a
No presalting 3.67
b
2.29
b
1.28
b
0.61
b
18% Brine
Presalting 4.65
a
3.47
a
2.45
a
1.61
a
No presalting 4.32
b
2.83
b
1.65
b
0.74
b
12°C 4.36
a
2.89
a
1.78
b
1.02
b
15°C 4.31
a
2.96
a
1.92
a
1.14
a
18°C 4.19
a
3.00
a
2.02
a
1.20
a
LSD NS NS 0.10 0.09
a,b
Means within salting method, brine concentration, and brine
temperature not sharing the same superscript within a column are
different (P < 0.05).
1
Portions P1, P2, P3, and P4 represent portions of the cheese block
from exterior surface (P1) to interior core (P4).
et al., 2003b). There also may be a movement of casein
from the protein matrix into solution in the water phase
of the cheese with decreasing BT due to reduced hy-
drophobic attractions among the caseins. Increased ca-
sein concentration in the water phase would also cause
increased viscosity and would increase resistance to
salt movement in the water phase. Guo et al. (1997)
reported that the protein content of the expressible se-
rum of Mozzarella increased with time of storage and
salt content from 3% to 10% CP over 10 d of storage at
4°C and this would be expected to increase the viscosity
of the water phase of cheese.
Interactions of Factors Influencing Salt Uptake
Typically, effects of PS, BC, and BT on the uptake
of salt from brine have been studied separately and
possible interactions of these factors are not well char-
acterized. Our study was designed to characterize the
interactions of these factors. Although presalting the
curd before brining was very effective at delivering a
starting salt in moisture of about 2.5% to all locations
within the block of cheese before brining (Figure 15),
PS did not produce any large differences in moisture
content (Table 6) and therefore had only a small impact
on cheese porosity and rate of salt uptake from brine
(Figure 12). This is consistent with previous reported
results on PS (Melilli et al., 2003a). The PS cheeses
achieved a desired final salt content sooner than
SALT PENETRATION DURING BRINE SALTING 15
Table 9. Sums of the squares (Type III SS) and probability values for the ANOVA of the impact of treatments
1
on salt in moisture content of cheese portions (P1, P2, P3, and P4) of Ragusano cheese over 24 d of brining
Factor
2
df P1 P2 P3 P4 Analyzed as Error term
Whole plot
BC 1 116.88* 39.53* 27.97* 6.98* Category BC × BT × PS
(<0.01) (<0.01) (0.01) (0.01)
BT 2 1.09 8.69* 19.92* 12.70* Category BC × BT × PS
(0.59) (0.01) (0.05) (0.01)
PS 1 134.03* 223.29* 228.05* 55.14* Category BC × BT × PS
(<0.01) (<0.01) (<0.01) (<0.01)
BC × PS 1 45.89* 12.18* NS NS Interaction BC × BT × PS
(0.01) (0.01)
BC × BT × PS 7 5.69 2.47 15.10* 3.87 Whole plot Model error
(0.99) (0.88) (0.01) (0.16) error
t 1 6,070.95* 4,969.71* 2,579.20* 671.92* Continuous Model error
(<0.01) (<0.01) (<0.01) (<0.01)
t × BC 1 130.53* NS 6.82* 6.70* Interaction Model error
(<0.01) (0.01) (<0.01)
t × BT 2 NS NS 8.00* 9.40* Interaction Model error
(0.01) (<0.01)
t × PS 1 NS NS 3.35* 5.47* Interaction Model error
(0.02) (0.01)
t × BT × PS 2 NS NS 4.92* 3.29* Interaction Model error
(0.02) (0.01)
t × BC × BT × PS 2 NS NS 8.13* NS Interaction Model error
(0.02)
t × t 1 1,619.07* 384.74* 10.50* 21.51* Continuous Model error
(<0.01) (<0.01) (<0.01) (<0.01)
(t × t) × BC 1 NS 19.61* 7.62* NS Interaction Model error
(<0.01) (0.01)
(t × t) × PS 1 NS NS NS 1.76* Interaction Model error
(0.03)
Error 201 1,337.18 211.11
Error 190 110.97
Error 195 70.06
R
2
0.87 0.97 0.96 0.93
1
Treatments: presalting the curd (presalted vs. not presalted), brine concentration (saturated brine vs.
18% brine), and brine temperature (12, 15, and 18°C). P1, P2, P3, and P4 represent portions of the cheese
block from exterior surface (P1) to interior core (P4).
2
Factors: BC = brine concentration; BT = brine temperature; PS = presalting; t = time.
*Statistically significant (P < 0.05).
cheeses that were not PS. No interaction effects of PS
with BT on moisture (Table 5), salt (Table 7), or salt
in moisture (Table 9) content of cheese were found.
However, interactions of PS with BC were observed.
The PS cheeses lost more weight and took up more salt
in SB, whereas the opposite was true in 18%B (Table
3). There was a small but significant effect of the inter-
action of BC and PS on total cheese moisture content
(Table 2), with PS cheeses having slightly lower mois-
ture content in SB than cheeses that were not PS (Table
3). This same effect of PS was not observed to the same
extent in the cheeses in 18%B (Table 3). The BC and
PS interaction was more apparent when the moisture
content by portion was observed (Tables 5 and 6) with
PS cheeses in SB having lower moisture than cheeses
that were not presalted, particularly in the interior (i.e.,
Journal of Dairy Science Vol. 89 No. 2, 2006
P2, P3) of the block (Table 6). The difference in salt
content and salt in moisture between the cheeses that
were PS and those that were not was much larger for
the P1 and P2 portions of cheeses in SB than in 18%B
(Tables 8 and 10). Although the BC, BT, and PS each
have their own impacts on salt uptake, there was not
much interaction of these effects when they were used
in combination.
Interactions of Factors Influencing Moisture
and Cheese Yield
During brine salting, blocks of cheese increase in
weight due to salt uptake and decrease in weight due
to moisture loss. In net, Ragusano cheese loses weight
during brine salting (Tables 2 and 3, Figure 1) so mois-
MELILLI ET AL.16
Table 10. Least squares mean values of the percentage salt in mois-
ture of cheese portions (P1, P2, P3, and P4)
1
of Ragusano cheese, for
the presalted and not presalted cheeses at 2 brine concentrations
(18% vs. saturated), and 3 brining temperatures (12, 15, and 18°C)
at 0, 1, 4, 8, 16, and 24 d of brining
Variable P1 P2 P3 P4
Presalting 13.99
a
8.74
a
5.66
a
3.58
a
No presalting 12.41
b
6.71
b
3.57
b
1.56
b
LSD 0.69 0.27 0.20 0.16
Saturated brine 13.70
a
7.41
b
4.31
b
2.44
b
18% Brine 12.70
b
8.05
a
4.92
a
2.69
a
LSD 0.69 0.27 0.20 0.16
Saturated brine
Presalting 14.95
a
8.66
a
5.49
a
3.48
a
No presalting 12.45
b
6.15
b
3.12
b
1.40
b
18% brine
Presalting 13.03
a
8.83
a
5.84
a
3.67
a
No presalting 12.37
b
7.27
b
4.01
b
1.71
b
12°C 13.10
a
7.47
b
4.29
c
2.32
b
15°C 13.24
a
7.75
a,b
4.65
b
2.61
a
18°C 13.26
a
7.96
a
4.91
a
2.77
a
LSD 0.85 0.34 0.25 0.20
a–c
Means within salting method, brine concentration, and brine
temperature not sharing the same superscript within a column are
different (P < 0.05).
1
Portions P1, P2, P3, and P4 represent portions of the cheese block
from exterior surface (P1) to interior core (P4).
ture loss is larger than salt uptake (Table 3); this has
a negative impact on cheese yield. There was an impact
of the interaction BC × PS on moisture content of the
P2, P3, and P4 portions of the block (Table 5), with PS
cheeses maintaining higher moisture in 18%B than in
SB (Table 6). This provides a larger volume of cheese
within each block that has a composition similar to
that in the center of block where the sensory quality is
considered the best. It would be desirable to select salt-
ing conditions that favor minimization of cheese yield
Figure 15. The impact of presalting vs. not presalting during 24
d of brining time on salt in moisture content (%) in portions P1 (,
), P2 (, ), P3 (, ), and P4 (, ); P1, P2, P3, and P4 represent
portions of the cheese block from exterior surface (P1) to interior core
(P4). Filled symbols are not presalted cheeses and open symbols are
the presalted cheeses in 18% brine.
Journal of Dairy Science Vol. 89 No. 2, 2006
Figure 16. The impact of saturated brine (SB) vs. 18% brine
(18%B) during 24 d of brining time on salt in moisture content (%)
in portions P1 (, ), P2 (, ), P3 (, ), and P4 (, ); P1, P2,
P3, and P4 represent portions of the cheese block from exterior surface
(P1) to interior core (P4). Filled symbols are cheeses in SB and open
symbols are the cheeses in 18%B.
loss during brining, while maximizing the combined
effect of these salting conditions to minimize the risk
of early gas production.
With respect to cheese yield, the impact of the combi-
nation of factors influencing salt uptake and salt con-
tent was quite dramatic. The common practice for man-
ufacture of Ragusano cheese using a BT of 18°CinSB
for 24 d with no PS produced a yield (i.e., weight) loss
of 14.13% in 3.6-kg blocks (calculated from data in Table
1) in 24 d. This represents a very large loss. Use of
the combination of PS and reduced BC allowed cheese
makers to achieve the same salt in moisture concentra-
tion in less than 24 d (Figures 15 and 16). Reduced BT
also reduces weight loss during brining (Table 3). The
combination of PS, a BT of 15°C, and 18%B for 8 d of
brining would deliver adequate salt into all portions of
Figure 17. The impact of brine temperature (BT) during 24 d of
brining time on salt in moisture content in portions P1 (), P2 (),
P3 (), and P4 (); P1, P2, P3, and P4 represent portions of the
cheese block from exterior surface (P1) to interior core (P4). Dashed
lines represent cheese at 12°C BT; solid lines represent cheese at
15°C BT; and dotted lines represent cheeses at 18°C BT.
SALT PENETRATION DURING BRINE SALTING 17
Table 11. Sums of the squares (Type III SS) and probability values for the ANOVA of the impact of
treatments
1
on pH of cheese portions (P1, P2, P3, and P4) of Ragusano cheese over 24 d of brining
Factor
2
df P1 P2 P3 P4
3
Analyzed as Error term
Whole plot
BC 1 0.04* 0.01 0.01 Category BC × BT × PS
(0.01) (0.88) (0.11)
BT 2 0.07* 0.11 0.06* Category BC × BT × PS
(0.01) (0.01) (0.01)
PS 1 0.13* 0.15* 0.01 Category BC × BT × PS
(<0.01) (<0.01) (0.18)
BC × BT 2 0.01* NS NS Interaction BC × BT × PS
(0.01)
BT × PS 2 NS NS 0.03*
(0.01)
BC × BT × PS 7 0.01 0.01 0.03 Whole plot Model error
(0.99) (0.97) (0.99) error
t 1 0.03* 0.39* 0.42* Continuous Model error
(0.02) (<0.01) (<0.01)
t × PS 1 NS NS 0.08* Interaction Model error
(0.01)
(t × t) × PS 1 NS 0.06* NS Interaction Model error
(0.01)
Error 203 1.09
Error 201 1.48
Error 202 1.60
Error ————
R
2
0.21 0.32 0.28
1
Treatments: presalting the curd (presalted vs. not presalted), brine concentration (saturated brine vs.
18% brine), and brine temperature (12, 15, and 18°C). P1, P2, P3, and P4 represent portions of the cheese
block from exterior surface (P1) to interior core (P4).
2
Factors: BC = brine concentration; BT = brine temperature; PS = presalting; t = time.
3
Model not significant.
*Statistically significant (P < 0.05).
Table 12. Least squares mean values of the pH of cheese portions
1
(P1, P2, P3, and P4) of Ragusano cheese, for the presalted and not
presalted cheeses at 2 brine concentrations (18% vs. saturated), and
3 brining temperatures (12, 15, and 18°C) at 0, 1, 4, 8, 16, and 24 d
of brining
Variable P1 P2 P3 P4
2
Presalting 5.28
a
5.28
a
5.26
a
5.27
a
No presalting 5.23
b
5.23
b
5.24
a
5.26
a
LSD 0.02 0.02 NS NS
Saturated brine 5.24
b
5.26
a
5.26
a
5.27
a
18% Brine 5.27
a
5.26
a
5.25
a
5.27
a
LSD 0.02 NS NS NS
12°C 5.28
a
5.29
a
5.27
a
5.28
a
15°C 5.26
a
5.26
a
5.25
ab
5.27
a
18°C 5.24
b
5.23
b
5.23
b
5.26
a
LSD 0.02 0.03 0.03 NS
a,b
Means within salting method, brine concentration, and brine
temperature not sharing the same superscript within a column are
different (P < 0.05).
1
Portions P1, P2, P3, and P4 represent portions of the cheese block
from exterior surface (P1) to interior core (P4).
2
Model not significant.
Journal of Dairy Science Vol. 89 No. 2, 2006
cheese and reduce weight loss to 4.15% of the original
block weight. This would be a net yield increase of
9.98%, which is a very important economic opportunity
for cheese makers. Ragusano cheese blocks in the pres-
ent study were 3.6-kg cubic blocks, whereas the typical
commercial Ragusano cheese block is rectangular and
weighs about 15 kg (Licitra et al., 2000). Size and shape
of cheese blocks influences salt uptake, moisture loss,
and the nature of salt and moisture gradients that de-
velop within a block of cheese during brining (Guinee
and Fox, 1986). As block size increases, the percentage
of the total weight that is lost will be lower than the
14.13% for 3.6-kg blocks in SB, but consideration of
strategies to reduce cheese yield loss are still economi-
cally important in 15-kg blocks.
Combined Influence of PS, BC, and BT
for Controlling Early Gas Formation
Brine-salted cheeses have a lower moisture, harder
exterior layer (rind). Typically, there is a gradation of
cheese texture and flavor characteristics from the exte-
rior to the interior center of the block with the highest
MELILLI ET AL.18
quality cheese in the center (higher moisture and lower
salt). This gradient of composition changes very little
throughout the 6 to 9 mo of aging of the cheese (Licitra
et al., 2000). Thus, the composition in the center region
of the block is typical of the most desirable cheese and
the conditions that favor proper flavor development. If
moisture is too high, salt too low or too slow to penetrate
the interior portions of the cheese, and pH too high,
then there is a high probability of the development of
early gas defects in Ragusano cheese and other brine-
salted cheeses (Choisy et al., 1987; Kosikowski and Mis-
try, 1997). In traditional cheese making on farms the
technologies are simple (Licitra et al., 1998). First, good
milk quality combined with good cleaning and sanita-
tion of cheese-making equipment will keep the load
of undesirable gas producing organisms at low levels
(Choisy et al., 1987). Next, a proper rate and amount
of acid production by lactic acid bacteria to achieve a
target milling pH of about 5.2 in a normal length of time
allows the desirable lactic acid bacteria to predominate.
Once the cheese is milled, then PS, controlling BC, and
BT are the next factors that could be used to advantage
in a system to control undesirable gas formation in
cheese. Although not done traditionally in the manufac-
ture of Ragusano cheese and many other traditional
pasta-filata cheeses, adding part of the salt to the curd
before stretching in hot water is an approach that can
ensure that a significant amount of salt is present in the
interior portions of the blocks before early gas formation
can begin. Although the presence of the salt in the
interior of the cheese very early should be beneficial,
an unexpected benefit of PS was discovered in this ex-
periment and reported separately (Melilli et al., 2004b).
The interaction of the salt in the curd and stretching
water, combined with the temperature (about 48°C)
and pH (about 5.3) of the stretching step for Ragusano
cheese was much more effective at killing undesirable
gas-forming bacteria in the curd before brine salting
than was expected and produced a 1.4 log reduction in
coliform count in the cheese before brine salting (Melilli
et al., 2004b). This reduction in the initial load of unde-
sirable bacteria coupled with a salt in moisture content
throughout the cheese of about 2.5% at the beginning
of brine salting significantly reduced gas formation
compared with cheese that was not presalted. Although
in the present study, the lower BT actually makes a
minor reduction in salt penetration into cheese, the
benefit of lower BT in retarding the growth and gas
production by undesirable bacteria is more important
than the reduction in salt uptake. Reducing salt concen-
tration in brine from saturation to 18% NaCl increased
the rate of salt penetration into the block during brine
salting, but was not effective at delivering salt rapidly
into the interior of the block to control early gas forma-
Journal of Dairy Science Vol. 89 No. 2, 2006
tion. However, the use of 18% BC does have a very
beneficial impact on cheese yield by reducing moisture
loss even if it has little effectiveness by itself in reducing
early gas formation. While the 9.98% increase in cheese
yield due to higher moisture content when using 18%
BC would be very attractive to a cheese maker, the use
of 18%B may produce other risks to cheese quality and
should be considered very carefully. Maintaining brine
concentration at 18% NaCl instead of SB is more diffi-
cult to control and may produce additional risks to
cheese quality due to growth of undesirable bacteria in
the more dilute brine and result in contamination of
the cheese with bacteria that may produce off flavors.
First (and most importantly) farmstead cheese mak-
ers must maintain a high level of sanitation and keep
the count of undesirable bacteria in the milk low. After
improving raw milk quality, the most practical and safe
course of action to minimize early gas formation is to
add salt to curd (pH 5.2) to achieve about 30 to 50% of
the final salt content in the cheese curd before stretch-
ing and to use slightly lower brine temperature (e.g.,
15 instead of 18°C) during brining. When using PS, the
cheese will not have to remain in the brine as long as
the traditional approach (Melilli et al., 2003a). This
approach combined with good milk quality and proper
acid development during the cheese-making process
will reduce the probability of early gas development in
the cheese. These conditions will produce a traditional
cheese that still has a gradient of moisture content
and typical appearance but with greatly reduced risk
of early gas formation. Once the cheese has finished
brining (<24 d), then the temperature and time condi-
tions of aging will determine the rate of subsequent
proteolysis, lipolysis, and flavor development.
CONCLUSIONS
Although the BC, BT, and PS each had their own
separate impacts on salt uptake, there was little inter-
action of these effects on salt uptake when they were
used in combination. The PS most quickly and effec-
tively delivered salt to the interior of the cheese and
was the most effective salting approach to control early
gas formation. There were strong separate impacts of
BC, BT, and PS on cheese moisture content, moisture
loss, and net weight loss, with BC having the largest
separate impact on these parameters. Reducing BT re-
duced salt content and increased moisture, but the ef-
fects were small. The more important impact of reduced
BT was to reduce gas defects. The 18%B produced
higher moisture, and less moisture and weight loss than
SB. The effect of interactions of BC, BT, and PS on
moisture content, moisture loss, and net weight loss
were small. To achieve the maximum benefit from the
SALT PENETRATION DURING BRINE SALTING 19
various approaches to salting for controlling early gas
formation in Ragusano cheese, PS combined with
slightly lower BT (i.e., 15°C instead of 18°C) should be
used. Although using 18%B instead of SB did increase
salt uptake, the point at which improved salt uptake
occurred due to use of 18%B did not provide benefit in
prevention of early gas formation, as reported sepa-
rately. However, use of 18%B instead of SB provided a
9.98% increase in cheese yield due to reduced moisture
loss during brining and this would be very attractive
to cheese makers. The increase in yield needs to be
balanced against the risk of growth of undesirable bac-
teria in the 18%B and the creation of another cheese
quality defect.
ACKNOWLEDGMENTS
The authors thank Stefania La Terra, Giovanni Fa-
rina, Glenda Leto, Jessica Mallozzi, Mario Manenti,
Lucia Cascone, Stefania Cilia, Giovanni Marino, Gio-
vanni Tumino, Sebastiano Campo, Antonio Difalco, Gi-
useppe Schembari, Rosario Tumino, and Patrizia
Campo for their technical assistance in cheese manufac-
ture and cheese analysis. Financial support was pro-
vided by the Assessorato Agricoltura e Foreste della
Regione Siciliana, Palermo, Italy.
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