Comparison of free fatty acid composition between low-fat and full-fat goat milk cheeses stored for 3 months under refrigeration

doi:10.4236/ojas.2011.12003

Paper Menu >>

Journal Menu >>

Vol.1, No.2, 17-23 (2011) Open Journal of Animal Sciences

doi:10.4236/ojas.2011.12003

Comparison of free fatty acid composition between

low-fat and full-fat goat milk cheeses stored for 3

months under refrigeration

W ass im No uira1, Young W. Park1*, Zehra Guler2, Thomas Terrill1

1Georgia Small Ruminant Research & Extension Center, Fort Valley State University, Fort Valley, USA;

2Department of Food Engineering, Mustafa Kemal University, Antakya, Turkey; parky@fvsu.edu

Received 17 May 2011, revised 12 June 2011, accepted 20 June 2011.

ABSTRACT

Differences i n free fatty acid (FFA) co mpositions

between low-fat (LF) a nd ful l-fa t ( FF: whol e m ilk)

goat chees es were ev aluated d uring 3 mon ths at

4˚C refriger ation. T he t wo types of che eses were

manufactured using a bulk milk from the mixed

herd of Saanen, Alpine, and Nubian goat bree ds.

LF cheeses were made using LF milk after

cream separation. FFAs of all cheeses were ex-

tracted in diisoprophyl ether using polypropyl-

ene chromatography column, and FFA concen-

trations were quantified using a gas chromato-

graph equipped with a fused silica capillary

column. Moisture, fat, protein contents (%) and

pH of fresh LF and FF cheeses were: 55.1, 52.3;

1.30, 25.6; 35.7, 22.5; 5.40, 5.42, respectively.

The FFA contents (mg/g cheese) of fresh FF and

LF cheeses prior to storage treatments for C4:0,

C6:0, C8:0, C10:0, C12:0, C14:0, C16:0, C18:0,

C18:1, and C18:2 were: 0. 020, 0.0 72; 0. 070, 0. 035;

0.061, 0.055; 0.181, 0.167; 0.073, 0.047; 0.174,

0.112; 0.579, 0.152; 0.308, 0.202; 0.521, 0.174;

and 0.057, 0.026, respectively. The respective

FFA to total fatty acid ratios for 0, 1 and 3

months aged FF and LF cheeses were 8.44, 12.4;

6.31, 16.91; 12.03, 14.19. The LF cheeses gener-

ated more FFA than FF cheeses, while actual

FFA content in FF cheese was significantly

higher than in LF cheese. The FFA contents of

LF cheese at 0, 1 and 3 months storage were

48.0, 96.8 and 36.4% of those of FF cheese, re-

spectively. It was concluded LF cheese gener-

ated higher amount of FFA than FF cheese, al-

though total FFA content was significantly

(P<0.05) lower in LF cheese than in FF chees e.

Keywords: Low Fat; Full Fat; Goat Milk Cheese;

Storage, Free Fatty Acid, Lipolysis

1. INTRODUCTION

Dietary fat has been implicated with coronary heart

diseases, atherosclerosis, diabetes and other health pro-

blems. Consumption of reduced or low fat dairy prod-

ucts has been increasingly popular among health-con-

scientious consumers in recent years [1].

Fat reduction, however, presents a challenging prob-

lem because fat is important for texture and flavor of

dairy products such as cheeses [2,3]. Fat reduction in

hard and semi-hard cheeses results in undesirable rub-

bery texture, lack of flavor, and/or presence of

off-flavors [3,4]. Reduced-fat (RF) and low-fat (LF)

cheeses which possess the characteristics of traditional

full-fat (FF) cheeses have been in demand [5]. Many

manufacturing procedures, therefore, have been sug-

gested and investigated to maximize sensory quality of

RF cheeses [6-8].

A myriad of biochemical and physical changes can

occur in goat milk cheeses after manufacture due to rip-

ening and degradation of nutrients in the products [9-11].

Positive correlations have been found between lipolyzed

flavor, fat acidity and short chain free fatty acid contents

[6,8,12]. The flavor intensity of Kasar cheese, a hard

cheese, was closely related to C4 - C10 free fatty acids

[13]. The presence of large amounts of free fatty acids

(FFA) can facilitate the rate of lipid oxidation, and free

fatty acids oxidize slightly greater rate than esterified to

glycerol. Even-numbered fatty acids from butyric to

lauric accounted for the major contribution to rancid

flavor [11,14]. Flavor deterioration from lipid oxidation

(reaction of milk lipids with oxygen) and/or lipolysis in

dairy products creates serious problems in storage stabil-

ity of the products [8,11,15,16].

The amount of FFA accumulated during ripening may

be an overall measure of lipolysis, and is quite variable

W. Nouira et al. / Open Journal of Animal Sciences 1 (2011) 17-23

depending on the type of cheese, lactic and secondary

starters, rennet type used, ripening time, and manufac-

turing methods and other factors [10,12,17]. The in-

digenous milk lipase, rennet preparation and microbes

entered intentionally or unintentionally during cheese

processing and ripening are primarily responsible for the

extent of lipolysis [12,17].

Although the effect of storage on levels of free fatty

acids in low-fat and reduced-fat dairy cow products have

been studied extensively, there is little information on

such dairy goat products with respect to effect of storage,

free fatty acid concentration and extent of lipolysis.

Therefore, the objectives of this study were to: 1) deter-

mine free fatty acid (FFA) concentrations of low-fat (LF)

and full-fat (FF) goat milk cheeses stored for three

months under refrigeration, and 2) compare FFA con-

tents between the two types of goat milk cheeses as well

as between different storage periods in relation to lipoly-

sis of the products.

2. MATERIALS AND METHODS

2.1. Preparation of Goat Milk

Goat milk used in this study was the bulk tank milk

collected from the milking goat herd consisted of Saanen,

Alpine and Nubian breeds at the Georgia Small Rumi-

nant Research and Extension Center, Fort Valley State

University, Fort valley, GA, USA. All goats were ma-

chine milked, and the experimental milks were pasteur-

ized at 63˚C (145˚F) for 30 minutes before manufacture

of the FF and LF experimental goat milk cheeses.

2.2. Manufacture of Low-Fat (LF) and Full-Fat

(FF) Goat Milk Cheeses

Three batches of LF and 3 batches of FF semi-soft

Cheddar-type caprine cheeses were manufactured at the

University dairy plant, according to the modified proce-

dures of Kosikowski [18] and Le Jaouen [19]. After pas-

teurization, the whole (FF) milk was cooled to 32˚C in a

227 L cheese vat. Lyophilized mesophilic direct vat set

starter culture (R704, 50 units, Chr. Hansen, Inc., Mil-

waukee, WI) and single strength rennet (10.6 mL of

rennet per 100 L milk; Chymax; Chr. Hansen, Inc., Mil-

waukee, WI) were added to the milk and then allowed to

coagulate for 30 minutes. The curd was cut using 1.6 cm

wire knives and allowed to heal for 10 minutes. The

temperature was gradually raised to 39˚C over 30 min-

utes and the curd was cooked for 45 minutes, assuring

for a firm curd. After draining whey, curds were salted at

a rate of 2.5% of original milk weight and placed

into150 × 150 mm cylindrical plastic molds and pressed

at 40 psi overnight at room temperature in a vertical

cheese press (Pneumatic Press, Kusel Equip. Co., Wa-

tertown, WI). Cheeses were removed from the molds

and vacuum packed in plastic pouches (FreshPak 500

vacuum pouches, Koch Supply, Kansas City, MO) using

a vacuum packager (Koch Ultravac 250, Koch Supply,

Kansas City, MO).

For LF cheese manufacture, cream was separated

from the pasteurized whole goat milk by a cream sepa-

rator (Model 17584, Clair Co., Althofen, Austria), and

then the LF cheese was made from the low-fat milk ac-

cording to the same procedure used for FF cheese.

2.3. Experimental Design

The experiment was conducted in a 2 × 3 × 3 factorial

arrangement. Two types (LF and FF) of goat milk

cheeses were manufactured in three batches, and the

experimental caprine cheeses were stored for 3 different

storage (aging) periods (0, 1 and 3 months).

All treated cheese samples were analyzed for basic

chemical compositions, pH, acid degree value (ADV)

and free fatty acid and total fatty acid concentrations to

determine the differences in the parameters between the

two types of caprine milk cheeses.

2.4. Chemical Analysis

2.4.1. Analyses of Basic Nutrient Composition

Percents of fat, protein, ash and total solids contents

were analyzed according to the procedures of A. O. A. C.

[20] and Richardson [21].

2.4.2. pH Analysi s

A 10 g cheese sample and 20 ml deionized water were

homogenized in a Waring blender (Waring Products, Inc.,

New Hartford, CT). The pH of the cheeses were deter-

mined using an Accumet model pH meter (No. 910;

Fisher Scientific, Pittsburgh, PA).

2.4.3. Acid Degr ee Value (ADV)

The ADV refers to measure of the amount of free fatty

acids present in a fat sample, which is a quantitative in-

dex of hydrolytic lipolysis in dairy products. ADV was

determined by the Standard Methods for the Examina-

tion of Dairy Products [21]. Approximately 10 g of sam-

ple were grated, homogenized, and placed into a Bab-

cock cheese bottle for fat extraction; 1 ml of the final

extracted fat was titrated against the standard alcoholic

0.02N KOH solution. Calculation of ADV was per-

formed using the following formula:



ml KOH for sampleml KOH for blank N100

ADV= Weight of fatg



where N = normality of KOH solution in methanol.

W. Nouira et al. / Open Journal of Animal Sciences 1 (2011) 17-23

1919

2.4.4. Extraction of Free Fatty Acids in Cheese

Samples

Extraction of free fatty acids (FFA) was performed

using the modified procedures of Deeth et al. [22]. A 1.5

g cheese sample was shredded and placed in a

screw-capped test tube, and the internal standard (5 mL)

C5 and C17 in diethyl ether, 0.3 mL 4 N H2SO4, 2.5 g

Na2SO4, and hexane (5 mL) were added to the tube. The

tube mixture was shaken for 1 min using a vortex mixer.

Samples were allowed to stand for two hours. Then lipid

extract was applied to a polypropylene column (Biorad,

Los Angeles, CA, USA), which was conditioned with 5

mL hexane/diethyl ether (1:1, v/v) and the extract passed

through the column a second time. This was followed by

2x5 mL hexane/diethyl ether (1:1, v/v) to remove all

triacylglycerols. FFAs were eluted with 2 mL diisopro-

pyl ether containing 6% formic acid (Merck, Darmstadt,

Germany) and centrifuged at 2000 × g for 5 min. A 2 mL

aliquot of the supernatant was used for gas chroma-

tographic analysis. For each sample, two extractions of

FFAs were carried out, and two chromatographic injec-

tions made for each extract.

2.4.5. Quantification of Free Fatty Acids in Cheeses

FFA concentrations of cheese samples were quantified

using a gas chromatograph (17A-GC, Shimadzu Co.,

Japan) equipped with a fused silica capillary column

(DB-FFAP; 30 m × 0.25 mm i.d. × 0.25 μm, Agilent

Technologies, Wilmington, DE). Injector and detector

temperature were 250 and 280˚C, respectively. Oven

temperature was programmed from 50˚C to 230˚C at a

rate of 5˚C per minute, with initial and final hold times

of 5 and 20 min, respectively, and run time was 61 min-

utes. The injection mode was splittless for 1 min, and the

injection volume was 2 µL, with helium as carrier gas

for 1 mL/min. Analyses were carried out in triplicate.

2.4.6. Extraction and Quantification of Total Fatty

Acids (TFA) in Cheeses

The extraction and quantification of all fatty acids

were performed using fatty acids methyl esters (FAME)

according to A. O. C. S. procedure [23] with some modi-

fications.

Total fatty acid compositions were determined by us-

ing a gas chromatograph (17A-GC, Shimadzu Co., Japan)

equipped with a fused silica capillary column (60 m

length × 0.25 mm i.d. × 0.2 μm; SP 2380, Supelco Inc.,

Bellfonate, PA) with a flame ionization detector (FID).

Oven temperature was programmed from 50˚C to 250˚C

at a rate of 4˚C /min, with initial and final hold times of

2 and 10 min. Injector and detector temperatures were

220 and 250˚C, respectively. The injection mode was

split injection, and injection volume was one µL. The

carrier gas was helium at a rate of 2 mL/min.

2.5. Statistical Analysis

The experimental data were analyzed for analysis of

variance, correlation coefficients and Duncan’s multiple

mean comparison as described by Steel and Torrie [24].

All data for unbalanced data were also analyzed by the

general liner models procedure of SAS program [25].

3. RESULTS AND DIS CUSSION

Basic nutrient compositions of experimental LF and

FF goat milk and their respective cheeses are shown in

Tab le 1 . The respective fat contents (%) of LF and FF

goat milk were 0.41 and 3.66, while those of LF and FF

cheeses were 1.30 and 25.6, indicating substantial dif-

ferences (P < 0.01) in fat contents in LF and FF milk and

cheeses. The protein contents of LF and FF milk were

slightly different, whereas those of LF and FF cheeses

were significantly (P < 0.01) different because fat was

removed in the LF cheese which had more dense protein

matrix than FF cheese.

When the acid degree values (ADV) were tested for

the experimental cheeses, LF cheese regardless of the

storage treatment did not have any detectable levels of

ADV due to the original very low contents of fat in the

cheeses (Table 2). However, the FF goat cheese showed

continuous increase in ADV as the storage period ad-

vanced from 0 month to 3 months, indicating that no

detectable lipolysis occurred in LF cheese while gradual

increase in lipolysis occurred in FF cheese (Table 2).

However, there were no differences in pH values be-

tween the FF and LF cheeses, nor between 0, 1 and 3

moths storage periods as shown in (Table 2). In a previ-

ous report, pH of hard type goat cheeses were increased

as the aging time advanced up to 6 months due to the

formation of NH3 by catabolism of cheese proteins [16].

The FFA profiles of both FF and LF cheeses are

shown in Ta bl e 3. Among all the detected free fatty ac-

ids, only C6:0, C10:0 and C12:0 showed significant (P <

0.05) differences between the two cheeses during the 3

months storage period. The FF cheese contained the

highest concentration of all these three free fatty acids

after 3 months storage, indicating that FF cheese showed

greater lipolysis evidenced by higher FFA level (Tables

2 and 3). All other free fatty acids except these 3 fatty

acids did not show any statistically significant differ-

ences between treatments, even if a few values appeared

to be a little high but not different due to the higher

variations in concentration between samples. It was also

observed that the relative abundance of FFA after 3

months refrigerated aging of FF goat cheese in the de-

scending order of our cheese samples were: C18:0,

W. Nouira et al. / Open Journal of Animal Sciences 1 (2011) 17-23

Table 1. Basic composition (%) of LF and FF goat milk and their respective cheeses.

Total solids Fat Protein Ash

X SD X SD X SD X SD

Milk

9.72b

0.92

0.41b

0.07

3.32a

0.09

0.53b

0.09

FF 11.72a 1.52 3.66a0.08 3.22a0.11 0.69a 0.01

Cheese

44.9a

2.87

1.30b

0.58

35.7a

2.33

5.21a

0.93

FF 47.7a 1.46 25.6a0.48 22.5b1.34 3.70b 0.29

X is mean, and SD is standard deviation values. a,b Means with different superscripts within same columns are significantly different P < 0.01 or 0.05). The

differences for fat and protein contents between FF and LF milk and cheese groups are significant at P < 0.01. The mean comparisons are made separately for

milk samples and for cheese samples within the same columns.

Table 2. Summary of mean pH and ADV of FF and LF goat milk cheeses during 3 months refrigerated storage.

0 month 1 month 3 month

FF LF FF LF FF LF

X SD X SD X SD X SD X SD X SD

pH 5.40a 0.01 5.42a 0.01 5.43a 0.01 5.43a 0.02 5.28a 0.0 5.48a 0.02

ADV 0.70a 0.08 0.0 - 1.06 b 0.05 0.0 - 1.34bc 0.07 0.0 -

X is mean; SD is standard deviation; a,b,c Means with different superscript within same row is different (P < 0.05)

Table 3. Comparison of mean free fatty acid concentration (mg/g cheese) of full-fat (FF) with low-fat (LF) goat milk cheeses aged

for 3 months under refrigeration.

0 month 1 month 3 month

FFA FF LF FF LF FF LF

C4:0 0.0202a 0.072a 0.0104a 0.0325a 0.0524a 0.034a

C6:0 0.0701ab 0.0353b 0.0497ab 0.0565ab 0.2153a 0.0925ab

C8:0 0.0609a 0.0551a 0.0575a 0.0411a 0.1222a 0.0638a

C10:0 0.1805b 0.1066b 0.1620b 0.1007b 0.4706a 0.1253b

C12:0 0.0729b 0.0474b 0.0649b 0.0558b 0.2511a 0.0501b

C14:0 0.1744a 0.1119a 0.1575a 0.1173a 0.2231a 0.1492a

C16:0 0.5794a 0.1520a 0.3839a 0.1451a 0.5113a 0.2401a

C18:0 0.3076a 0.2022a 0.1892a 0.1540a 0.7423a 0.1111a

C18:1 0.5211a 0.1740a 0.3332a 0.6455a 0.4816a 0.2332a

C18:2 0.0572a 0.0255a 0.0875a 0.1000a 0.2744a 0.1175a

Total FFA 2.0443b 0.982d 1.4957bc 1.4485bc 3.3443a 1.2168c

Total fatty acids 24.226ab 7.917c 23.719ab 8.568c 27.798a 8.574c

FFA/TFA ratio 8.44 12.4 6.31 16.9 12.03 14.2

a,b,c,d Means with different superscripts in same row are different (P < 0.05 or P < 0.01). All FFA values are means of 3 batches of cheeses, and each batch

samples were analyzed in duplicates.

C16:0, C18:1, C10:0, C12:0. C14:0, and C6:0 acid. At-

taie and Richter [26] reported that aging time greatly

influenced levels of volatile FFA in goat Cheddar cheese

for the first 3 months, then remained relatively un-

W. Nouira et al. / Open Journal of Animal Sciences 1 (2011) 17-23

2121

changed for the rest of the 6 months aging period. They

also observed the descending order of the relative abun-

dance of FFA in their goat Cheddar cheese were: C10:0,

C12:0, C8:0, C6:0 and C4:0 acid, which may not be di-

rectly comparable to our results, since they determined

the concentrations of volatile fatty acids (C4:0 to C12:0).

With respect to total FFA and total fatty acid (TFA)

concentrations, the respective levels of the FF goat milk

cheese for the 0, 1 and 3 months aging were: 2.04, 24.2;

1.50, 23.7; 3.34, 27.8, whereas the LF cheese of the cor-

responding aging periods were 0.982, 7.917; 1.449,

8.568; 1.217, 8.574, respectively. These results also

clearly show that the LF cheese contained considerably

lower levels of FFA and TFA, compared to the FF cheese

(Tab le 3). Total FFA concentrations of FF and LF goat

cheeses after 3 months refrigerated storage increased

from 2.044 to 3.344, and 0.982 to 1.217 mg/g cheese,

respectively. These results indicate that some increase

(1.30 mg/g cheese) in lipolysis occurred in FF goat milk

cheese, but very minimal change (0.235 mg/g cheese)

occurred in LF goat cheese during the 3 months experi-

mental storage period. These FFA concentrations are

reflected with the results of ADV values shown in Table

2. Positive correlations were found between lipolyzed

flavor, fat acidity, and short-chain FFA contents [6,11,17]

Even-numbered fatty acids, from butyric to lauric acid,

in milk and dairy products account for the major contri-

bution to rancid flavor [11,14].

In light of total FFA to total fatty acids (TFA) ratios of

both FF and LF cheeses, LF cheese showed relatively

higher ratio than that of FF cheese. However, the actual

increase in FFA content of LF cheese was much smaller

than that of FF cheese, simply because LF cheese con-

tained substantially lower fat content than FF cheese

(Ta b l es 1 and 3; Figure 1). Figure 1 demonstrates that

total fatty acid concentrations of FF cheeses were sub-

stantially higher than those of LF cheeses, regardless of

storage times. The figure also shows that the differences

in concentration (mg/g cheese) between FFA and TFA

are much greater in FF cheese than LF cheese through-

out the storage periods. The relatively greater FFA/TFA

ratio in LF cheese compared to that in FF cheese can be

attributed to the disrupted fat globule membranes of LF

cheese which can have a greater chance of exposure to

lipolytic enzymes by cream separation as well as cheese

processing and storage. The origin of enzymes responsi-

ble for lipolysis in cheese include the indigenous milk

lipase (lipoprotein lipase: LPL), rennet preparation, and

microbes that develop during cheese ripening either in-

tentionally (starter bacteria and specific molds or yeasts)

or unintentionally (nonstarter acid bacteria and adventi-

tious molds or yeasts) that should not be present at sig-

nificant numbers [12,17,27]. The LPL activity, although

lower in goat than in cow milk, is more bound to the fat

globules and better correlated to spontaneous lipolysis in

goat milk [28]. On the other hand, the undisrupted fats

without cream separation in FF cheese would have less

exposure to the lipase enzymes, resulting in less chance

of lipolysis in the FF cheese. Although the milk was

pasteurized before cream separation, there would be

chances of the intentional and unintentional microbial

lipases activities during processing and storage

of our experimental goat cheeses.

Reports also have shown that lipolysis of milk and

dairy products can occur by three different sources: 1)

induced lipolysis, 2) spontaneous lipolysis and 3) micro-

bial lipolysis [11,29]. Induced lipolysis is influenced by

several factors, such as processing factors including agi-

tation, separation, pumping, mixing, foaming, presence

of air, homogenization, activation by temperature

changes, freezing and thawing, storage and processing

[11,29,30]. Spontaneous lipolysis can occur through two

main factors, such as milk processing factors, and milk-

ing animal factors including stage of lactation, feed,

season, breed, mastitis, milk and fat yield, and physio-

logical factors. Microbial lipolysis is caused by many

microorganisms that contaminate dairy products. These

organisms produce lipase which develop rancid flavor.

The psychrotrophic bacteria are most common sources

of these lipases [11]. Bacterial lipases are different from

milk lipases, are not inactivated by pasteurization, and

can attack the intact fat globules in milk [12,27,30].

Since LF cheese manufacture after cream separation in

this study could be prone to be involved in these three

types of lipolysis, higher lipid hydrolysis might have

been occurred in the LF cheeses, causing a higher pro-

portional increase of FFAs in LF cheeses even though

the FFA amount was small.

Concentration (mg/ g cheese)

0mon-LF0 mon-FF1 m on-LF1 mon-FF3 mon-LF3 mon-FF

Total FFA

Total FA

Figure 1. Comparison of levels (mg/g cheese) of total free

fatty acids (FFA) and total fatty acids (TFA) between LF and

FF goat milk cheeses for 3 months refrigerated storage [Dif-

ferences between LF and FF cheeses were significant (P <

0.01)].

W. Nouira et al. / Open Journal of Animal Sciences 1 (2011) 17-23

4. CONCLUSIONS

The profiles of free fatty acid compositions of the 0 to 3

months aged FF and LF caprine cheeses revealed that FF

cheeses contained higher levels of all types of free fatty

acids, except for the butyric acid in the initial cheeses.

The total FFA contents of LF cheese were 48.0, 96.8 and

36.4 % of FF cheeses for 0, 1 and 3 months aging, indi-

cating that the 1 month aged cheeses contained higher

FFA than the 0 and 3 month stored ones. The LF cheese

revealed more proportional increase in FFA compared to

the FF cheese, although the actual amount of FFA in LF

cheese was much lower than that in FF cheese. This re-

sult may account for the higher lipolytic enzyme activi-

ties in LF cheese by the indigenous milk enzymes, or

microbial enzymes of intentional and unintentional mi-

croorganisms which can have a greater access to the dis-

rupted fat globule membranes by cream separation and

subsequent cheese processing and storage. Further stud-

ies may be necessary to ascertain what exact sources or

mechanisms are involved in the elevation of FFA in LF

caprine cheeses in order to prevent the increased lipoly-

sis which may deteriorate the quality of low-fat goat milk

cheeses.

5. ACKNOWLEDGEMENTS

This study was supported by USDA 1890 Capacity Building Grant,

Award No. 2007-38814-18518. The authors greatly appreciate Mr.

Schauston Miller and Carlton Green for collection of goat milk and

processing, and Ms. Ruby Ragan for her assistance in cheese manufac-

ture. Dr. Zehra Güler was supported by the Scientific and Technological

Research Council of Turkey, with 2219-postdoctoral research fellow-

ships (TÜBİTAK-TURKEY, 2008) for a visiting scientist at Fort Valley

State University, Fort Valley, GA, USA.

REFERENCES

[1] Thayer, A.M. (1992) Food Additives. Chemical Engi-

neering News, 70, 26.doi:10.1021/cen-v070n024.p026

[2] Jameson, G.W. (1990) Cheese with less fat. Australian

Journal of Dairy Technology, 11, 93.

[3] Mistry, V.V. (2001) Low fat cheese technology. Interna-

tional Dairy Journal, 11 , 413-422.

doi:10.1016/S0958-6946(01)00077-2

[4] Olson, N.F. and Johnson, M.E. (1990) Light cheese prod-

ucts: characteristics and economics. Food Technology, 44,

93-96.

[5] Honer, C. (January 1993). Second thoughts. Dairy Field.

Skokie.

[6] Drake, M.A., Herrett, W., Boylston, T.D. and Swanson,

B.G. (1995) Sensory evaluation of reduced fat cheeses.

Journal of Food Science, 60, 898-901.

doi:10.1111/j.1365-2621.1995.tb06256.x

[7] Ashfield, M.A., Ma, L., Drake, M.A., Barbosa-Canovas,

G.V. and Swanson, B.G. (1997) Rheology of full-fat and

low-fat Cheddar cheeses as related to type of fat mimetic.

[8] Carunchia Whetstine, M.E., Karagul-Yuceer, Y., Avsar, Y.

and Drake, M.A. (2003) Identification and quantification

of character aroma components in fresh Chevre-style

goat cheese. Journal of Food Science, 68, 2441-2447.

doi:10.1111/j.1365-2621.2003.tb07043.x

[9] Fox, P.F. (1989) Proteolysis during cheese manufacture

and ripening. Journal of Dairy Science, 72, 1379-1400.

doi:10.3168/jds.S0022-0302(89)79246-8

[10] McSweeney, P. and Sousa, M. (2000). Biochemical path-

ways for the production of flavor compounds in cheese

during ripening: A review. Lait, 80, 293-324.

doi:10.1051/lait:2000127

[11] Park, Y.W. (2001) Proteolysis and lipolysis of goat milk

cheese. Journal of Dairy Science, 84 (E. Suppl.),

E84-E92.

[12] Velez, M.A., Perotti, M.C., Wolf, I.V., Hynes, E.R. and

Zalazar, C.A. (2010) Influence of milk pretreatment on

production of free fatty acids and volatile compounds in

hard cheeses: Heat treatment and mechanical agitation.

Journal of Dairy Science, 93, 4545-4554.

doi:10.3168/jds.2010-3352

[13] Guler, Z. (2005) Quantification of free fatty acids and

flavor characteristics of Kasar cheeses. Journal of Food

Lipids, 12, 209-221.

doi:10.1111/j.1745-4522.2005.00018.x

[14] Ha, J.K. and Lindsay, R.C. (1991) Contributions of cow,

sheep, and goat milks to characterizing branched-chain

fatty acid and phenolic flavors in varietal cheeses. Jour-

nal of Dairy Science, 74, 3267-3274.

doi:10.3168/jds.S0022-0302(91)78512-3

[15] Day, E.A. (1960) Autoxidation of milk lipids. Journal of

Dairy Science, 43, 1064.

doi:10.3168/jds.S0022-0302(60)90329-5

[16] Jin, Y.K. and Park, Y.W. (1995) Effects of aging time and

temperature on proteolysis of commercial goat cheeses in

the US. Journal of Dairy Science, 78, 2598-2608.

doi:10.3168/jds.S0022-0302(95)76888-6

[17] Collins, Y., McSweeney, P.L.H. and Wilkinson, M. (2003)

Lipolysis and free fatty acid catabolism in cheese: A re-

view of current knowledge. International Dairy Journal,

13, 841-846.doi:10.1016/S0958-6946(03)00109-2

[18] Kosikowski, F.V. (1977) Cheese and fermented milk

foods, 2nd Edition, Edwards Brothers, Inc., Ann Arbor,

437-440.

[19] Le Jaouen, J.-C. (1987) The fabrication of farmstead goat

cheese. Cheesemaker’s Journal,Ashfield,MA 01330, 45.

[20] AOAC. (1985) Official methods of analysis. 14th Edition,

The Association of Official Analytical Chemists, Wash-

ngton, D.C. No. 43.292. 7.001, 7.009, 7.006.

[21] Case, R.A., Bradley, R.L. Jr. and Williams, R.R. (1985)

Chemical and physical methods. In: Richardson, G.H. Ed.,

Standard Methods for the Examination of Dairy Prod-

ucts.15th Edition, American Public Health Association,

Washington, D.C., 327.

[22] Deeth, H.C., Fitz-Gerald, C.H. and Snow, A.J. (1983) A

GC method for the quantitative assay of free fatty acids.

New Zealand Journal of Science and Technology, 18,

13-20.

[23] AOCS. (1975) Official methods and recommended prac-

tices of the american oil chemists’ society. American Oil

Chemists’ Society, Champaign, No. 1, 3A and 6, 7-15.

[24] Steel, R.G.D. and Torrie, J.H. (1960) Principles and Pro-

W. Nouira et al. / Open Journal of Animal Sciences 1 (2011) 17-23

2323

cedures of statistics. McGraw-Hill, New York, 190.

[25] SAS Institute. (1999) User’s guide: statistics, 8th Edition.

SAS Institute, Inc., Cary.

[26] Attaie, R. and Richter, R.L. (1996) Formation of volatile

free fatty acids during ripening of Cheddar-like hard goat

cheese. Journal of Dairy Science, 79, 717-724.

doi:10.3168/jds.S0022-0302(96)76418-4

[27] Hickey, D.K., Kilcawley, K.N., Beresford, T.P. and Wil-

kinson, M.G. (2007) Lipolysis in cheddar cheese made

from raw, thermized, and pasteurized milks. Journal of

Dairy Science, 90, 47-56.

doi:10.3168/jds.S0022-0302(07)72607-3

[28] Chilliard, Y., Ferlay, A., Rouel, J. and Lamberet, G. (2003)

A review of nutritional and physiological factors affecting

goat milk lipid synthesis and lipolysis. Journal of Dairy

Science, 86, 1751-1770.

doi:10.3168/jds.S0022-0302(03)73761-8

[29] Deeth, H.C. and Fitz-Gerald, C.H. (1976) Lipolysis in

dairy products: A review. Australian Journal of Dairy

Technology, 31, 53-64.doi:10.1016/j.idairyj.2004.01.005

[30] Evers, J.M. (2004) The milkfat globule mem-

brane-Compositional and structural changes post secre-

tion by the mammary secretory cell. International Dairy

Journal, 14, 661-674.