Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
2007
Volume 10
Issue 4
Topic:
Food Science and Technology
ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Jasińska M. , Mituniewicz-Małek A. 2007. TECHNOLOGICAL USEFULNESS OF KEFIR CULTURES OF THE CANADIAN ROSELL INSTITUTE INC. MANUFACTURE FOR KEFIR PRODUCTION FROM GOAT’S MILK, EJPAU 10(4), #30.
Available Online: http://www.ejpau.media.pl/volume10/issue4/art-30.html

TECHNOLOGICAL USEFULNESS OF KEFIR CULTURES OF THE CANADIAN ROSELL INSTITUTE INC. MANUFACTURE FOR KEFIR PRODUCTION FROM GOAT’S MILK

Małgorzata Jasińska, Anna Mituniewicz-Małek
Department of Dairy Technology and Food Storage, West Pomeranian University of Technology, Szczecin, Poland

 

ABSTRACT

Technological usefulness was examined of three kefir cultures (A, B and C) of the Canadian Rosell Institute Inc. for kefir production from goat’s milk. Culture A was composed of micro-organisms of genus Lactococcus, Leuconostoc and Lactobacillus and yeasts Saccharomyces florentinus. The other two cultures contained such a microflora as culture A, except for no yeasts in culture B and yeasts Kluyveromyces fragilis replacing yeasts Saccharomyces florentinus in culture C. Within the framework of research work, experimental kefirs were subjected to sensory evaluation and physicochemical analysis with respect to their titratable acidity, pH, and amine nitrogen and acetate aldehyde, ethyl alcohol (ethanol) contents. Basing on the carried out examination, it was found that kefir cultures of the Canadian Rosell Institute Inc. manufacture applied, in particular culture C, showed a great usefulness for kefir production from goat’s milk, since all experimental kefirs obtained were characterised by very good appearance and desired consistency during the whole study period. In addition, only slightly detectable goaty flavour as well as the largest content of acetate aldehyde was found in the product obtained using culture C.

Key words: goat’s milk, kefir cultures, kefir.

INTRODUCTION

In Poland, a basic raw material used for production of cultured dairy beverages has been cow’s milk until recently. At present, other animal species milk is appropriated for that purpose more and more frequently, including also the goat’s milk, which is one of economically important milk types produced in the world, apart from the cow’s milk. The use of goat’s milk for production of fermented milk favours preservation, and even enlargement, of its nutritive, dietary as well as therapeutic values [15, 18].

Cultured dairy beverages (yoghurt, kefir, etc.) obtained from goat’s milk differ in many respects from their homologues from cow’s milk, which in consequence is responsible for the fact that their specific organoleptic attributes are not always accepted by the Polish consumer. According to Kehagias et al. [7] and Wszołek [21], the quality of cultured dairy beverages from goat’s milk may be made attractive through choosing appropriate micro-organism strains.

In connection with the above, the objective of the study was to evaluate the usefulness of lyophilised kefir cultures of the Canadian Rosell Institute Inc. manufacture for production of kefir from goat’s milk, the more so as in the previous own research [4] the kefir from cow’s milk obtained using the same cultures was characterized by highly desirable qualitative attributes during two-weeks of cold storage.

MATERIAL

The subject of research work was the kefir from goat’s milk produced under laboratory conditions using thermostatic method at the Department of Dairy Technology of the Agricultural University in Szczecin. The raw material for its production was pasteurised goat’s milk (85°C·20 min-1) purchased at the beginning of November 2007 in a private farm “Kozi Gródek” in Wołczkowo near Szczecin.

For production of the kefir being the study material, three lyophilised kefir cultures (A, B and C) were used of the Canadian Rosell Institute Inc. manufacture, the Polish vendor of which is LESSIK Company from Warsaw. The composition of microflora of the afore-going cultures is presented in Table 1.

Table 1. Microflora composition of kefir cultures used for production of kefir from goat’s milk

Goat milk attributes

Value

Dry matter [%]

13.20

Total protein [%]

4.10

Fat [%]

4.70

Thickness [g·cm-3]

1.029

Titratable acidity [°SH]

9.10

The goat’s milk appropriated for production of experimental kefirs, in the amount of 15 dm3, was heated to 22°C and separated into three equal batches according to production technology instruction [20]. Thereafter, each batch of the raw material (5 dm3) was inoculated with 5% supplement of the leaven obtained from kefir culture A, B or C. The milk prepared this way was poured out into individual containers, 200 cm3 each, and subjected to acidification process (22°C/12 – 14 h), followed by maturation process (8°C/12–14 h). The produced kefir was transferred into a cooling chamber with 5°C (±1°) and stored for three weeks. Samples for analyses were collected after cold storage day 1, 3, 7, 14 and 21 in the amount of 1 dm3 (5 kefir containers, 200 cm3 each) per each batch. Within the framework of research work, 150 beakers of experimental kefirs were produced and evaluated, including 50 beakers of kefir made using the leaven received from kefir culture A, 50 beakers of kefir made using the leaven received from kefir culture B, and 50 beakers of kefir made using the leaven received from kefir culture C.

RESEARCH METHODS

The experimental kefirs were subjected to sensory evaluation and physicochemical analysis.
Sensory evaluation was performed by a test panel of 2-4 persons, adequately trained and verified in respect of sensory sensitivity, taking into consideration such discriminants as: appearance, taste, aroma and consistency, according to a 5-point scale broadened with half-point scores [1].On the other hand, the physicochemical analysis of experimental kefirs included determination of: titratable aciditity in °SH [3], active acidity (pH) using a pH-meter [23], amine nitrogen content in trichloroacetic acid extract with the Pope and Stevens method [5], acetate aldehyde content by diffusion method with hydrazon hydrochloride in Conway cells [11], and ethyl alcohol (ethanol) content with titrimetic method after its oxidation to acetic acid [3].

In addition, in the goat’s milk being a raw material for production of experimental kefirs were determined: dry matter content according to the Fleischmann’s formula [23], fat content by the Gerber’s method Gerbera [3], total protein content by the Kjeldahl’s method [23], and their thickness with areometric method [23] and titratable acidity in °SH [3].

All determinations were made in 3 replicates and the obtained results were subjected to statistical analysis. The significance of differences in the levels of chemical indicators was estimated by the t-Student’s or Cochran-Cox’s test at significance level α = 0.05.

RESULTS

Results of the analysis of goat’s milk that was a raw material for production of experimental kefirs are presented in Table 2. The milk contained 13.2% dry matter, including 4.1% protein and 4.7% fat, on the average.

The results of performed consumer assessment of the experimental dairy beverages are illustrated in Table 3, basing on which it was showed that the kefir produced using kefir cultures of the Canadian Rosell Institute Inc. were characterised by a very good appearance, as no whey leakage was observed in any sample examined during three weeks of storage. On the other hand, the remaining sensory evaluation discriminants (taste, aroma and consistency) in the experimental kefirs were shaped depending on the type of applied kefir culture, although differences occurring between them were inconsiderable (Table 3). According to the test panel, the fact that in the product obtained using kefir culture C a goaty flavour was only slightly detectable, as opposed to other experimental products (with kefir culture A or B), is worthy of particular attention. In case of aroma, in all evaluated products no goaty aroma was found, which is typical for products made of goats’ milk, with the highest score for that discriminant being received by the kefir with culture B. Moreover, it should be stressed that kefirs produced with kefir culture A, B or C were characterized by desirable consistency during the whole study period, receiving the same high scores.

Table 2. Properties of goat’s milk used for kefir production

Kefir culture

Microflora composition

A

Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. lactis var. diacetylactis, Lactococcus lactis ssp. cremoris, Leuconostoc mesenteroides ssp. cremoris, Lactobacillus plantarum, Lactobacillus casei and yeasts Saccharomyces florentinus

B

Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. lactis var. diacetylactis, Lactococcus lactis ssp. cremoris, Leuconostoc mesenteroides ssp. cremoris, Lactobacillus plantarum, Lactobacillus casei

C

Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. lactis var. diacetylactis, Lactococcus lactis ssp. cremoris, Leuconostoc mesenteroides ssp. cremoris, Lactobacillus plantarum, Lactobacillus casei and yeasts Kluyveromyces fragilis (former Saccharomyces fragilis)

Table 3. Results of sensory evaluation of the kefir from goat’s milk produced using kefir cultures A, B and C during cold storage

Sample
type

Qualitative
discriminant

Kefir culture A

Kefir culture B

Kefir culture C

storage time (days)

  1  

3

7

14

21

1

3

7

14

21

1

3

7

14

21

Appearance

5

5

5

5

5

5

5

5

5

5

5

5

5

5

5

Taste

4 ♥

3.92 ♥

4.33 ♣

4.33 ♣

3.63 ●

4.19 ●

4.33 ●

3.92 ♣

4.33 ♣

4.25 ●

4.5 ♣

4.08 ♣

4.17 ♣

4.83 ♣

4.63 ♣

Aroma

4

4.08

4.25

4.33

3.69

4.13

4.42

4.33

4.33

3.88

4.25

3.67

3.83

4

3.56

Consistency

4.5

4.83

4.75

4.83

4.81

4.5

4.92

4.67

4.92

4.88

4.5

4.83

4.5

4.83

4.81

♥ distinct goaty flavour
● goaty flavour
♣ slightly goaty flavour

The first physicochemical indicator analyzed in the kefir produced from goat’s milk was titratable acidity, the value of which was shaped depending on the type of applied inoculation as well as on the time of cold storage (Fig. 1). During the whole study period (three weeks), the acidity of experimental kefirs ranged from 36.80°SH to 40°SH. The largest acidity fluctuations during three weeks of the study period were found in the kefir produced using kefir culture C, whereas the smallest in case of that with kefir culture A. However, the performed statistical analysis allowed for stating that differences in the acidity of experimental kefirs were statistically non-significant (Table 4).

Table 4. Results of statistical analysis of the chemical indicators of kefir produced using kefir cultures A, B and C during cold storage

Reference sample

Statistical measure

Compared sample

acidity

amine nitrogen

acetate aldehyde

ethyl alcohol

kefir culture
B

kefir culture
C

kefir culture
B

kefir culture
C

kefir culture
B

kefir culture
C

kefir culture
B

kefir culture
C

Kefir culture A

Test

Cochran-Cox

t-Student

t-Student

Cochran-Cox

Cochran-Cox

t-Student

t-Student

Cochran-Cox

t/C

0.624

0.520

0.881

0.633

7.859

5.052

0.761

1.493

tα/Cα

2.145

2.048

2.048

2.145

2.145

2.048

2.048

2.145

Inference

-

-

-

-

+

+

-

-

Kefir culture B

Test

 

Cochran-Cox

 

Cochran-Cox

 

Cochran-Cox

 

t-Student

t/C

 

0.061

 

0.081

 

13.818

 

0.755

tα/Cα

 

2.145

 

2.145

 

2.145

 

2.048

Inference

 

-

 

-

 

+

 

-

As opposed to titratable acidity, the active acidity (pH) of analysed kefirs was even less diverse, both in relation to the type of applied culture and the time of storage (Fig. 2). During three weeks of the study period, the lowest pH values were found in general in the sample that was produced using kefir culture A (4.22-4.52), whereas the largest in the sample with kefir culture B (4.30-4.56). Furthermore, its should be stressed that in the last period of cold storage an increase in pH occurred in all examined kefirs, which after 21 days was larger by 0.3 unit in the sample with kefir culture A, by 0.22 unit in the sample with kefir culture B, and by 0.27 unit in the sample with kefir culture C, when compared with its initial value (after 1 day).

Fig. 1. Results of statistical analysis of the chemical indicators of kefir produced using kefir cultures A, B and C during cold storage

Fig. 2. Effect of kefir cultures A, B and C on the pH of kefir made of goat’s milk during cold storage

Subsequently, the content of amine nitrogen was determined in the kefir being experimental samples. The largest differences in the content of that nitrogen form were observed in the initial and the final storage period (Fig. 3); that is, after 1 day of the study period the amount of amine nitrogen was the largest in the kefir produced using kefir culture A (30.8 mg·100 g-1), whereas the smallest in that with kefir culture C (21.7 mg·100 g-1). On the other hand, after the last day of cold storage the largest amine nitrogen content was characteristic of the kefir obtained using kefir culture C (36.17 mg·100 g-1), whereas the lowest one of that obtained with kefir culture A (25.90 mg·100 g-1). The performed statistical analysis of amine nitrogen content in the kefir from goat’s milk showed no significant effect of the type of applied kefir culture on the shaping of that indicator (Table 4).

Fig. 3. Effect of kefir cultures A, B and C on the content of amine nitrogen in the kefir made from goat’s milk during cold storage

Thereafter, the content of flavour and aromatic compounds (acetate aldehyde and ethyl alcohol) was determined in the experimental material, the level of which was shaped depending of the type of applied kefir culture and the time of storage (Fig. 4, Fig. 5).

In case of acetate aldehyde, definitely largest amount of that compound, for three weeks of the study period, was characteristic of the kefir produced using kefir culture C (0.572-0.826 mg·dm-3), whereas the smallest one of that produced with kefir culture B (0.207-0.313 mg·dm-3). On the other hand, in the sample produced with kefir culture A the level of analyzed compound ranged from 0.422 mg·dm-3 to 0.666 mg·dm-3. It was found that differences occurring in the content of acetate aldehyde in the examined kefirs were statistically significant (Table 4). It should be also mentioned that in the first week of cold storage a clear decrease in the amount of produced metabolite was observed in all experimental kefirs; that is, the content of acetate aldehyde in the sample produced using kefir culture C was lower by c. 35.4% after 7 days, in the sample with kefir culture A lower by c. 33.3%, whereas in the sample with kefir culture B lower by c. 32.8%, in relation to its content after 3 days of storage.

Fig. 4. Effect of kefir cultures A, B and C on the content of acetate aldehyde in the kefir made from goat’s milk during cold storage

Fig. 5. Effect of kefir cultures A, B and C on the content of ethyl alcohol in the kefir made from goat’s milk during cold storage

On the other hand, the concentration of ethyl alcohol (ethanol) in all experimental kefirs was insignificant, of the order of hundredths of one percent, during the whole study period. However, during three weeks of cold storage certain differences were observed between respective experimental samples in its concentration, with the largest found after 7 days of storage; that is, after the first week of study the lowest concentration of ethyl alcohol (ethanol) was characteristic of the kefir obtained using kefir culture C, being lower in relation to that of kefirs produced with kefir culture B and A, respectively by c. 52.7% and 50.3%. The performed statistical analysis showed that differences observed in ethyl alcohol (ethanol) content in the examined kefirs during three weeks of storage were not statistically significant (Table 4).

DISCUSSION

The goat milk is characterised by a very large inconstancy in its chemical composition during the lactation period, which results in differences in dry matter (d.m.) content of that raw material. According to reference data [2], depending on the period of lactation, the largest fluctuations among basic milk components are observed in fat content, 3.2% to 5.9%, while other components are more stabile (protein 2.9-3.9%, lactose 4.3-4.8%) [13]. In Poland, the mean content of basic goat milk components, taking into account the entire lactation period, is formed as follows: fat 2.25-5.52%, protein 2.58-4.15%, lactose 3.92-5.28%, ash 0.74-0.95%, dry matter 10.49-14.83% [10]. Depending on the period of lactation, its titratable acidity also changes, which according to Chrzanowska et al. [4], as well as to Wszołek [21], may range from 5.4°SH to 9.2°SH. In connection with the above, physicochemical attributes of the goat’s milk being a raw material for production of experimental kefirs fit into the range given in the cited literature.

It was showed in the course of carried out research work that kefirs from goat’s milk, which were produced using kefir cultures A, B or C of the Canadian Rosell Institute Inc. manufacture, were characterised by desired sensory attributes. During the whole storage time (three weeks), no whey leakage was observed in them, or a goaty aroma. The examined products had a desired thick consistency, which is frequently semi-liquid or even liquid in cultured beverages made of goat’s milk, which is not always accepted by the Polish consumer. Moreover, in case of using kefir culture C, a considerable decrease was observed in the intensity of goaty flavour. Sensory attributes of cultured beveraged from goat’s milk, including kefir, were also examined by Pieczonka and Pasionek [14]. The cited authors found, as opposed to the results obtained in the presented own study, that experimental kefir preserved a very good sensory quality only for 6 days of cold storage, since on the 9th day substantial defects were observed in it, namely the thinning and non-homogeneity of its consistency, less characteristic or slightly foul taste, as well as the appearance of goaty taste. It should be stresses however that raw material used by those authors for production of fermented milk was obtained in different time period (April and May), which could have been of a vital influence on the quality and shelf-life of the obtained kefirs.

On the other hand, among evaluated physicochemical indicators statistically significant differences between respective experimental kefirs were found only in the content of acetate aldehyde, which definitely was the largest in the kefir produced with kefir culture C. According to the literature, in products obtained with participation of mesophilic strains, which also include kefir a small amount of acetate aldehyde is desired, as it smoothes out an irritant flavour of diacetyl [8, 9]. However, a characteristic component of kefir is ethyl alcohol (ethanol), the concentration of which may amount even to 1-2%. In the experimental samples, ethyl alcohol (ethanol) concentration was very low, which supposedly resulted from the fact that kefir for examination was produced using lyophilised kefir cultures, not with kefir fungi (kefir grains). As it is reported in the literature [12], kefir produced with kefir fungi (kefir grains) has a definitely higher concentration of ethyl alcohol (ethanol) than that produced with kefir leaven. However, according to Seiler [17] the content of ethyl alcohol (ethanol) in kefir depends of production conditions, speaking more precisely on the applied temperature of incubation and on whether mixing was applied during maturation process, or not. In connection with the above, in kefir produced with traditional method (without mixing) the content of ethanol ranges from 0.04 to 0.3 ml·100 ml-1, whereas in the mixed kefir from 0.8 to 1.3 ml·100 ml-1. Moreover, as reported by Tratnik et al. [19], according to many authors the content of ethanol is highly differentiated; that is, in the kefir produced in Germany its content is very low and ranges from 0.002 to 0.005 ml·100 ml-1, whereas in Eastern Europe from 0.01 to 0.04 ml·100 ml-1.

Summing up, it should be supposed that inconsiderable differences in the qualitative attributes and selected physicochemical indicators of experimental samples resulted from slightly different composition of the microflora (different species of yeasts or their lack) of respective kefir cultures used for production of experimental kefir. Furthermore, the fact that qualitative attributes of cultured dairy beverages, in particular those made of goat’s milk, may greatly depend, apart from raw material properties, on choosing for their production adequate kefir cultures is confirmed. This is corroborated by earlier research work of Kehagias et al. [7] who analyzed physicochemical properties of yoghurts made, among others, of goat’s milk according to the selection of appropriated leaven that, as proved, can improve their viscosity rather considerably. In addition, as reported by Wszołek [21], one can obtain yoghurt without a goat’s milk powder supplement with a viscosity comparable to that of yoghurts obtained from cow’s milk by using suitable kefir inoculations. Also according to Pijanowski [16], as well as to Ziajka and Dzwolak [22], the selection of appropriate kefir inoculation is of crucial importance for the formation of qualitative attributes of fermented milk.

The obtained study results indicate that the examined kefir inoculations A, B and C of the Canadian Rosell Institute Inc., in particular kefir culture C, can be recommended for production of kefir from goat’s milk.

CONCLUSIONS

  1. Kefir made from goat’s milk obtained using kefir cultures A, B and C was characterized by highly desirable sensory attributes during three weeks of cold storage. The applied kefir cultures affected to the highest degree the consistency and taste of produced kefir.

  2. Microflora of the applied kefir cultures A, B and C did not differ significantly in respect of acidifying ability, proteolytic activity and ethyl alcohol-producing capability.

  3. The kefir cultures used for production of kefir from goat’s milk differed significantly in the acetate aldehyde-producing ability, with its highest content being characteristic of the product made with kefir culture C.

  4. Experimental kefirs were characterized by a very low concentration of ethyl alcohol.

  5. The evaluated kefir cultures of the Canadian Rosell Institute Inc. manufacture, in particular kefir culture C, show great usefulness for production of kefir from goat’s milk.


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Accepted for print: 26.09.2007


Małgorzata Jasińska
Department of Dairy Technology and Food Storage,
West Pomeranian University of Technology, Szczecin, Poland
Papieża Pawła IV/3, 71-459 Szczecin, Poland

Anna Mituniewicz-Małek
Department of Dairy Technology and Food Storage,
West Pomeranian University of Technology, Szczecin, Poland
Papieża Pawła IV/3 71-459 Szczecin, Poland
email: aniamalek4@wp.pl

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