PORÓWNANIE WYNIKÓW OZNACZEŃ BŁONNIKA POKARMOWEGO W PREPARATACH WYSOKOBŁONNIKOWYCH WYBRANYMI METODAMI ENZYMATYCZNYMI (angielski).pdf

N auka P rzyroda T echnologie

2007

Tom 1

Zeszyt 2

Dział: Nauki o Żywności i Żywieniu

ISSN 1897-7820 http://www.npt.up-poznan.net/tom1/zeszyt2/art_36.pdf

J ACEK A NIOŁA 1 , M AŁGORZATA P ACZKOWSKA 2

Department of Human Nutrition and Hygiene

August Cieszkowski Agricultural University of Poznań

Department of Nutritional Value of Food

The National Food and Nutrition Institute in Warsaw

A COMPARISON OF TWO ENZYMATIC METHODS

FOR THE ANALYSIS OF DIETARY FIBER

IN HIGH-FIBER PREPARATIONS

Summary. The aim of the study was to compare results of dietary fiber content determinations in

seven high-fiber preparations produced from different waste products, using two enzymatic meth-

ods, most commonly applied in Poland, i.e. according to Asp and AOAC. The results of dietary

fiber determinations obtained by the AOAC method were lower than those obtained according to

Asp: by 5.4% for insoluble fiber, by 11.8% – for soluble fiber and by 7.5% for total dietary fiber.

Additionally, a higher accuracy of determinations was shown, expressed in mean values of coeffi-

cients of variation, for AOAC method results. Differences in results of dietary fiber determina-

tions indicate the need to unify the method of determination of this component for the purpose of

certification and nutritional profiles.

Key words: high-fiber preparations, dietary fiber, determination, methods, comparision

Introduction

In recent years interest in new sources of dietary fiber (DF) has been constantly

growing, while on the other hand new methods of its determination are being devel-

oped. In view of the fact that different laboratories use different methods of determina-

tion for this component, the results concerning its contents may vary considerably.

The main category of methods proposed to analyse DF employs selective extraction

of non-fiber materials and gravimetric determination of the residue as fiber. The most

popular and recommended is the enzymatic digestion approach (R AVINDRAN and

P ALMER 1990, H ASIK et AL . 1997).

Scientific communities associated with dietary fiber research within AOAC IN-

TERNATIONAL have been the leaders in bringing consensus to the dietary fiber defini-

Anioła J., Paczkowska M., 2007. A comparison of two enzymatic methods for the analysis of dietary fiber in high-

-fiber preparations. Nauka Przyr. Technol. 1, 2, #36.

tion and method validation for over a quarter of a century. The consensus definition and

subsequent methodology have served as the basis for regulations worldwide with regard

to dietary fiber labelling and health claims (Official... 2004).

The enzymatic gravimetric method for the determination of total dietary fiber (TDF)

content developed by AOAC (Official... 2000) is at present used as a reference method

in many countries worldwide, especially the USA. It consists in the enzymatic digestion

of protein and available carbohydrates from a fat-free sample and gravimetric determi-

nation of the residue, including protein and ash contents. Such an approach results in the

need to perform a bigger number of replications, which increases the required time and

cost of determinations. Moreover, the relatively high cost of reagents needs also to be

taken into consideration.

In Poland an older enzymatic method according to Asp et al. (1983) is still being

used much more frequently. This method does not require so many replications during

determinations and makes it possible to use cheaper reagents, and for these reasons it is

recommended by the respective Polish Standard.

The aim of the study was to compare results of determinations of dietary fiber con-

tent in high-fiber preparations, using the above mentioned enzymatic methods, i.e. ac-

cording to Asp and AOAC.

Materials and methods

Experimental material consisted of six high-fiber preparations by Microstructure in

Warszawa, produced at the turn of 2004 and 2005, with mean particle size of approx.

100 μm; they were wheat bran (PS), cocoa husks (KA), sugar beet pulp (BC), apple

pomace (JA), black chokeberry pomace (AR) and black currant pomace (CP). Addition-

ally, analyses were performed on maize preparation (KU) – dry corncobs of mixed

different maize cultivars, obtained from the Swadzim Agricultural Experimental Station

of the Agricultural University of Poznań, ground using the same method as the other

preparations in case of the above mentioned producer.

Contents of soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and total die-

tary fiber (TDF), calculated from the sum of the above, were assayed using enzymatic

methods: by A SP et AL . (1983), following the Polish Standard (PN-A-79011-15 1998)

and by AOAC (Official... 2000), based on the methods of P ROSKY et AL . (1984, 1985).

Determinations by the enzymatic method according to Asp were performed at the

food analysis laboratory at the Department of Human Nutrition and Hygiene, the Agri-

cultural University of Poznań, using the following enzymes: NOVOZYMES Termamyl

120L, MERCK 1.07185 Pepsin, SIGMA P-1750 Pancreatin 4xUSP.

In turn, the AOAC determinations were performed at the laboratory of the Depart-

ment of Nutritional Value of Food, the National Food and Nutrition Institute in Warsaw,

Poland, using analytical reagents: SIGMA TDF-100A Dietary Fiber, Total kit.

All determinations were performed using TECATOR FiberTec System E analyser,

with TECATOR Filter-Crucibles 30 ml, Por. 2 (40-90 µm), after preliminary sample

grinding in a TECATOR 1093-001 Cyclotec Sample Mill.

Anioła J., Paczkowska M., 2007. A comparison of two enzymatic methods for the analysis of dietary fiber in high-

-fiber preparations. Nauka Przyr. Technol. 1, 2, #36.

Detailed procedures for the above mentioned determinations were published earlier

by other authors (B ORYCKA and B ORYCKI 1999, G RONOWSKA -S ENGER et AL . 1992,

H ASIK et AL . 1997).

Analytical determinations were performed in at least four independent replications

and the results were given as mean and SD in terms of dry matter of preparations. One-

way analysis of variance (ANOVA) followed with Scheffe’s test was used to determine

the significance of mean differences, using the Statistica 6.0 computer program.

Coefficients of variation of results obtained for individual preparations and fiber

fractions were applied as a measure of precision for the applied methods:

V (%) = SD / mean × 100.

Results and discussion

Results of IDF, SDF and TDF content determinations in the analysed preparations

obtained using both methods are presented in Table 1. Next to means from four replica-

tions, also standard deviations and coefficients of variation of results were given (in

brackets). Different letter superscripts (a, b) were used to denote respective means of

results obtained by different analytical methods, differing statistically at significance

level p < 0.05 (Scheffe’s test).

The analysed preparations exhibited a high, but varied TDF content, the mean of

which ranged from 49.7% (PS) to 83.2% (KU) according to Asp, at a much lower share

of the soluble fraction in relation to the insoluble fraction.

A comparison of the results obtained using different methods showed distinct and in

most cases statistically significant differences in dietary fiber content in the analysed

preparations. Results of dietary fiber content determinations following the AOAC

methodology were lower than those obtained according to Asp: on average by 5.4% for

IDF, 11.8% for SDF and by 7.5% for TDF.

Additionally, a markedly higher precision of determinations was shown, as manifested

by the mean values of coefficients of variation of results, in case of determinations ob-

tained by the AOAC method at the National Food and Nutrition Institute in Warsaw.

On the basis of determination results for the seven analyzed preparations the follow-

ing dependencies were established, presented by linear regression formulas:

IDF (AOAC) = 0.827 × IDF (Asp) + 7.834,

SDF (AOAC) = 0.598 × SDF (Asp) + 1.436,

TDF (AOAC) = 0.974 × TDF (Asp) – 3.603.

In spite of the relatively high coefficients of linear correlation and significance lev-

els (Table 1) obtained for the given dependencies, in view of the high differences in the

presented results, especially for SDF determinations, the application of the above for-

mulas may not be recommended for the estimation of dietary fiber determination results

using the AOAC method on the basis of results obtained according to Asp.

Anioła J., Paczkowska M., 2007. A comparison of two enzymatic methods for the analysis of dietary fiber in high-

-fiber preparations. Nauka Przyr. Technol. 1, 2, #36.

Table 1. Results of IDF, SDF and TDF determinations using two enzymatic methods in high-fiber

preparations (mean ± SD, V (%) and difference (%), g/100 g; detailed description given in the text)

Tabela 1. Wyniki oznaczeń IDF, SDF i TDF dwoma metodami enzymatycznymi w preparatach

wysokobłonnikowych (średnia ± SD, V (%) oraz różnica (%), g/100 g; szczegółowy opis w tekście)

DF fraction

IDF

SDF

TDF

Method

preparation

percent-

age

differ-

ence

percent-

age

differ-

ence

percent-

age

differ-

ence

Asp

AOAC

Asp

AOAC

Asp

AOAC

49.69 b

± 1.42

(2.85%)

44.85 a

± 0.12

(0.26%)

–9.7

3.47 b

± 0.28

(8.21%)

1.86 a

± 0.06

(2.98%)

–46.5

53.16 b

± 1.51

(2.85%)

46.70 a

± 0.16

(0.33%)

–12.1

88.86 b

± 2.22

(2.49%)

79.84 a

± 0.22

(0.27%)

–10.2

0.84

± 0.08

(9.88%)

0.58

± 0.16

(27.45%)

–30.6

89.70 b

± 2.19

(2.44%)

80.42 a

± 0.27

(0.34%)

–10.3

60.42 b

± 0.76

(1.25%)

54.37 a

± 0.11

(0.20%)

–10.0

11.21 b

± 0.75

(6.73%)

9.18 a

± 0.13

(1.42%)

–18.1

71.63 b

± 0.54

(0.75%)

63.55 a

± 0.10

(0.16%)

–11.3

61.88 a

± 0.82

(1.33%)

70.90 b

± 0.25

(0.35%)

14.6

17.89 b

± 0.66

(3.66%)

9.67 a

± 0.41

(4.26%)

–45.9

79.76

± 0.58

(0.72%)

80.57

± 0.19

(0.23%)

1.0

59.32

± 2.19

(3.70%)

56.58

± 0.07

(0.12%)

–4.6

10.19

± 0.89

(8.75%)

10.76

± 0.48

(4.46%)

5.6

69.51

± 1.74

(2.51%)

67.34

± 0.47

(0.70%)

–3.1

83.24 b

± 0.59

(0.70%)

77.49 a

± 0.51

(0.66%)

–6.9

1.86 a

± 0.15

(8.22%)

3.15 b

± 0.32

(10.27%)

69.1

85.10 b

± 0.59

(0.70%)

80.63 a

± 0.83

(1.03%)

–5.3

71.57 b

± 0.45

(0.63%)

63.71 a

± 0.34

(0.54%)

–11.0

8.51

± 1.36

(15.99%)

7.10

± 0.22

(3.04%)

–16.6

80.09 b

± 0.95

(1.19%)

70.81 a

± 0.54

(0.77%)

–11.6

Correlation

coefficient

r = 0.90 (p < 0.01)

–

r = 0.88 (p < 0.01)

r = 0.95 (p < 0.001)

–

V (%)

average

1.85 b

± 1.17

0.34 a

± 0.19

–

8.78

± 3.75

7.70

± 9.15

–

1.59 b

± 0.96

0.51 a

± 0.32

–

Percentage

difference

(average)

–

–5.4

–

–11.8

–

–7.5

It may not be excluded that such equations could be useful in case of homogenous

groups of products, e.g. grain or bran of different cereals, different assortments of bak-

ery products or different vegetables.

Anioła J., Paczkowska M., 2007. A comparison of two enzymatic methods for the analysis of dietary fiber in high-

-fiber preparations. Nauka Przyr. Technol. 1, 2, #36.

The presented results confirm analytical problems mentioned by B ORYCKA and

B ORYCKI (1999) in the determination of dietary fiber, as well as the incompatibility of

the applied methods.

Thus, the unification of methods to determine dietary fiber used nationally and their

adaptation to world standards, proposed earlier by G RONOWSKA -S ENGER et AL . (1992),

seems advisable, with the implementation of the AOAC method as obligatory method-

ology in the determination of dietary fiber in food being the most reasonable.

Conclusions

Statistically significant differences shown in the values of dietary fiber determina-

tion results were shown for the Asp and AOAC methods, with the results obtained using

the AOAC method being significantly lower.

Differences in the results of dietary fiber determinations obtained using different

methods indicate the need to unify the methodology of determining this component for

the needs of food composition tables and nutritional certification.

Acknowledgements

The study was financed by the Ministry of Science and Higher Education as re-

search project no. 2 PO6T 049 27.

References

A SP N.G., J OHANSSON C.G., H ALLMER H., S ILJESTRÖM M., 1983. Rapid enzymatic assay of in-

soluble and soluble dietary fiber. J. Agric. Food Chem. 31: 476-482.

B ORYCKA B., B ORYCKI J., 1999. Wybrane aspekty metodyki określania zawartości błonnika po-

karmowego. Pr. Inst. Lab. Bad. Przem. Spoż. 54: 111-122.

D EVRIES J.W., 2004. Dietary fiber: the influence of definition on analysis and regulation. J. Assoc.

Off. Anal. Chem. 87, 3: 682-706.

G RONOWSKA -S ENGER A., D RYWIEŃ M., N OWIERSKA B., 1992. Porównanie wybranych enzyma-

tycznych metod oznaczania błonnika pokarmowego w żywności. Rocz. PZH 43, 2: 187-192.

Hasik J., Dobrzańska A., Bartnikowska E., 1997. Rola włókna roślinnego w żywieniu człowieka.

Wyd. SGGW, Warszawa.

Official methods of analysis. 2000. Red. W. Horwitz. AOAC Intern. Gaithersburg, MD, USA.

PN-A-79011-15. 1998. Koncentraty spożywcze. Metody badań. Oznaczenia zawartości błonnika

pokarmowego.

P ROSKY L., A SP N.G, F URDA I., D E V RIES J.W, S CHWEIZER T.F., H ARLAND B.F., 1984. Determina-

tion of total dietary fiber in products, and total diets: interlaboratory study. J. Assoc. Off.

Anal. Chem. 67, 6: 1044-1052.

P ROSKY L., A SP N.G., F URDA I., D E V RIES J.W., S CHWEIZER , T.F., H ARLAND B.F., 1985. Determi-

nation of total dietary fiber in foods and food products: collaborative study. J. Assoc. Off.

Anal. Chem. 68, 4: 677-679.

R AVINDRAN G., P ALMER J.K., 1990. Comparison of four different methods for the analysis of

dietary fiber in winged bean seeds. J. Food Sci. 55, 1: 137-140.

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