0139–3006/$ 20.00 © 2010 Akadémiai Kiadó, Budapest

Acta Alimentaria, Vol. 39 (1), pp. 35–47 (2010)DOI: 10.1556/AAlim.39.2010.1.4

FRUIT QUALITY AND COMPOSITION OF HUNGARIAN BRED WALNUT CULTIVARS

G. BUJDOSÓac*, M. TÓTH-MARKUSb, H.G. DAOODb, N. ADÁNYIb and P. SZENTIVÁNYIa

a Research Institute for Fruitgrowing and Ornamentals, H-1223 Budapest, Park u. 2. Hungaryb Central Food Research Institute, H-1022 Budapest, Herman Ottó u. 15. Hungary

c Department of Pomology Faculty of Horticultural Science, Corvinus University of Budapest, H-1118 Budapest, Villányi út 29–43. Hungary

(Received: 18 June 2008; accepted: 4 March 2009)

Eight registered Hungarian walnut cultivars were tested for composition and sensory properties. The samples were collected at the Experimental Fields of the Research Institute for Fruitgrowing and Ornamentals in Érd-Elvira major. Proximate composition, fatty acids, minerals (P, Na, Ca, Mg, Ca, Fe and Se), polyphenols and vitamins (C, E) were determined in four consecutive years 2003–2006. The tested cultivars have an oil content, which falls within the upper range of the literature values. Polyphenols, iron and selenium contents are also high while the values for potassium and phosphorus are in the lower part of the given range. In our case, the crop years make a larger difference in the composition than the cultivars. Tiszacsécsi 83 is the only cultivar slightly differing from the others in lower mineral and protein content.

Keywords: walnut, fruit quality, breeding, composition, organoleptic, Hungary

As opposed to, e.g. the apple cultivar Jonathan grown all over the world, there are not any “global walnut cultivars” as walnut cannot adapt to climate conditions different from those of the breeding. This is the reason why regional breeding is important. The systematic and organized breeding of walnut started in Hungary in the 1950s. This work began under SZENTIVÁNYI’s (2006a) leadership who mainly studied the Carpathian race, starting out by landscape selection. This work resulted in three registered cultivars (Alsószentiváni 117, Milotai 10, Tiszacsécsi 83).

The landscape selection was succeeded by cross-breeding in the 1970s. For male trees SZENTIVÁNYI (2006a) chose the American cultivar Pedro, which has good genetic characteristics like “lateral bearing” and a light coloured kernel. Some of the most important aims of our breeding work were: late leafi ng out, higher ratio of “lateral bearing”. Among the hybrids of Milotai 10 and Alsószentiváni 117 we selected fi ve to apply for registration. In 2003, the National Institute for Agricultural Quality Control registered fi ve hybrids [Milotai kései (former hybrid number Milotai 10-9), Milotai bőtermő (former hybrid number Milotai 10-14), Milotai intenzív (former hybrid number: Milotai 10-37), Bonifác (former hybrid number Alsószentiváni 117-15) and Alsószentiváni kései (former hybrid number Alsószentiváni 117-31)] from among our candidates on the National List (SZENTIVÁNYI, 1998, 2006b, 2006c).

* To whom correspondence should be addressed.Phone: +36 1 3621596; fax: +36 1 3621573; e-mail: geza.bujdoso@uni-corvinus.hu

BUJDOSÓ et al.: QUALITY AND COMPOSITION OF WALNUT

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The weight of walnut kernel amounts to 38–50 percent of that of the whole nut. It is an excellent, high energy nutritive; 100 g of walnut is equivalent to 630 kcal. The largest part of the kernel is made up of lipids and proteins. Besides, walnut is a good source of vitamin E, folic acid, calcium, iron, magnesium and potassium. It has a very favourable fatty acid composition. The advantageous physiological effect of walnut consumption has been proven by several studies (FELDMAN, 2002; FDA 2004). The most important components of walnut according to the literature data are summarized in Table 1.

Table 1. Composition of walnut according to literature (calculated to 100 g air dry kernel)

Component Unit SZENTIVÁNYI.(1976)

CHARLOT

et al.(1996)

GERMAIN

et al.(1999)

SOUCI

et al.(2000)

avg from–to

Water g 4–8 3.7±0.5 4.38 3.30–7.18

Protein g 13–25 18.3±1.6 11–19.6 14.4 13.6–15.6

Lipid g 45–72 65.6±2.9 51–69 62.5 56–68.1

Available carbohydrate (calculated) g 4–10 10–15 10.6

Total fi bre g 6.4±0.6 4.6–7.5 6.14

Minerals g 1.9±0.3 1.98 1.65–2.4

Potassium mg 440 ~ 500 440–700 544 440–700

Magnesium mg ~ 100 92–178 129 92–144

Calcium mg 110 ~ 100 41–100 87 60–100

Iron mg 2.1 ~ 3 2–3.1 2.5 2–3.1

Selenium μg 5.5

Phosphorous mg 600 ~ 350 310–510 409 310–510

Vitamin B1 mg 0.48 0.2–0.4 0.34 0.2–0.44

Vitamin B2 mg 0.13 0.06–0.16 0.12 0.06–0.16

Vitamin B6 mg 0.7–1 0.87 0.74–1

Vitamin E mg 27–45 6.0

Vitamin C mg 3 0.2–4 2.6

Vitamin A μg 21 (=70 NE) 3–13 8 3–13

Carotenoid μg 48 18–78

Polyphenol GAE mg 450–550

SZENTIVÁNYI (1958, 1976) published a lot of data on the composition of Hungarian walnuts, but data on newly bred cultivars are available in Hungarian, only (TÓTHNÉ MARKUS, 2006).

According to RUGGERI and co-workers (1998), the protein and lipid content of the walnut cultivars studied show great variability. The relative standard deviation of protein content was more than 20%. The authors concluded that the composition of walnut, especially fatty acids, depends on cultivar, climate and primarily provenance. As for the concentration of various sugars, the main component is sucrose (2%) and, to a lesser extent, glucose (0.8%).

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LAVEDRINE and co-workers (1997) studied the vitamin E content by HPLC as affected by geographical origin, cultivar and storage. Research by AMARAL and his group (2005) suggests that besides genetic factors the environmental ones also affect vitamin E content. Gamma-tocopherol was dominant, while delta- and alpha-tocopherols were present in cca. 10 times lower concentration. And while alpha-tocopherol shows the greatest vitamin activity, gamma-tocopherol is assumed to have an anti-infl ammatory effect higher than the alpha isomer. The latter is a more potent radical scavenger against nitrogen dioxide. KORNSTEINER and co-workers (2006) report 12.4–32.8 mg β- plus γ-tocopherol/100 g walnut oil, and 1020–2052 mg total phenolics expressed as gallic acid equivalent (GAE)/100 g fresh weight. ANDERSON and co-workers (2001) described 16 mg GAE/g walnut, while PEREIRA and his group (2008) has found 4 to 6 times more phenolics, which was explained by the different extraction method. The high polyphenol content is very healthy for its antioxidative, cancer preventive effect. At the same time polyphenols also help to prevent the oxidation of PUFA (FUKUDA et al., 2003).

Some published data for fatty acid composition of walnut are found in Table 2.

Table 2. Percentage fatty acids of walnut in literature

Fatty acid GARCIA et al.(1994)

LOPEZ et al. (1995)

CHARLOT et al. (1996)

GERMAIN et al. (1999)

ZWARTS et al.(1999)

C16:0 6.6–7.8 6–7.45 7.5±0.8 6.2–8.7 6.7–8.7

C18:0 1.7–2.2 2.23–2.81 2.5±0.3 2.2–3.6 1.5–2.5

C18:1 15.8–27 12.7–16.9 14.0±2.6 13.1–20.8 13.8–33

C18:2 51.8–61.5 58.7–63.5 60.9±3.5 52.4–64.2 49.3–62.3

C18:3 10–18.5 13.2–14.4 13.8±2.1 10.8–17.9 8–15.4

Research by GREVE and co-workers (1992) demonstrated that the polyunsaturated fatty acid (PUFA) content in walnut oil is determined by maturity, environment, genotype and draught stress. During ripening the ratio of PUFA was increasing until the recommended date of harvest. The PUFA level was infl uenced primarily by the degree of maturity, and to a lesser extent by the lack of irrigation (stress). With lower irrigation rate the PUFA concentration signifi cantly decreased in “Chico” walnuts. ZWARTS and his team (1999) studied the fatty acid composition of New Zealand walnuts. Storing the shelled walnut in commercial conditions for 4.5 months, the fatty acid composition underwent minor changes but the decrease of the PUFA profi le was not signifi cant in each and every cultivar studied.

1. Materials and methods

1.1. Samples studied

Cultivars Milotai 10, Milotai intenzív, Milotai kései (4 years), Milotai bőtermő (2 years), Alsószentiváni 117 (4 years), Bonifác (3 years), Alsószentiváni kései (4 years), Tiszacsécsi 83 (2 years) were investigated. The samples of registered cultivars were collected at the Experimental Fields of Research Institute for Fruitgrowing and Ornamentals in Érd-Elvira major.

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1.2. Chemicals

As otherwise not stated, analytical grade chemicals were used (Reanal, Hungary). Folin-Ciocalteu phenol reagent and n-heptane p. a. (Merck), boron trifl uoride methanol solution 14% (Sigma, Inc.).

1.3. Determination of water content

Water content was measured according to MSZ ISO (1992) at 103 °C at atmospheric pressure.

1.4. Determination of ash

Ash was measured according to MSZ EN (1995a) starting from 5 grams of walnut.

1.5. Determination of protein

Protein was measured from the defatted residue after Soxhlet extraction by automatic Kjelfoss device according to MSZ (1980a), using an N factor of 5.30.

1.6. Determination of oil content

Oil content was extracted according to MSZ EN ISO (2000), Part 1. The solvent was removed in rotary vacuum evaporator.

1.7. Determination of raw fi bre

Raw fi bre was measured according to MSZ (1981).

1.8. Total carbohydrate

Total carbohydrate is calculated = 100-(ash+water+protein+fat+raw fi bre) (SOUCI et al., 2000).

1.9. Measurement of total polyphenolics

Polyphenolics were extracted from ground, defatted walnuts. One g of fat-free walnut was shaken for 4 h in 25 ml 80% ethyl alcohol, and fi ltered. Colour reaction with Folin-Ciocalteu reagent was performed according to MSZ (1980b) in an appropriate dilution and given as gallic acid equivalent (GAE).

1.10. Determination of phosphorous

Phosphorous was measured as phosphate by spectrophotometry after ashing, according to Hungarian Standard MSZ EN (1995b)

1.11. Determination of metals

Sodium, potassium, calcium, magnesium, iron and selenium were determined with atomic absorption spectrometry (AAS) according to A.O.A.C. (1990). Sample preparation: digestion with HNO3-HClO4-H2SO4 (30-1-5) acid mixture. Measurement: Solaar M5 AA spectrometer (Thermo Elemental). Measurement conditions are summarized in Table 3.

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Table 3. Parameters of AAS measurement

Element Measurement technique Wavelength (nm) Slit width (nm)

Potassium fl ame-emission 766.5 0.5

Sodium fl ame-emission 589.0 0.5

Calcium fl ame 422.7 0.5

Magnesium fl ame 285.2 0.5

Selenium hydride generator, fl ame 196.0 0.5

Iron fl ame-STAT 248.3 0.2

1.12. Determination of vitamins

1.12.1. Vitamin E. One gram ground walnut was saponifi ed with 5 ml 30% KOH/MeOH, 20 ml MeOH, and 0.5 g ascorbic acid added, and boiled for 35 min on a sand bath. After cooling 15 ml water containing 20% sodium chloride and 40 ml of n-hexane were added to sample. Tocopherols were separated in upper phase after a short shaking with a separating funnel. Another 40 ml of hexane was added to lower phase and the separation was repeated. The lower phase was removed and the two upper phases united into a separating funnel, washed twice with distilled water and fi ltered through dry sodium sulphate. Filtrate was evaporated in Rotadest and re-dissolved in 5 ml of HPLC grade hexane.

HPLC conditions: column: Nucleosil 10 μm, 250×4.6; eluent: n-hexane-abs. ethanol, 99.6:0.4;

fl ow rate: 1.2 ml min-1; detection: fl uorescence, Ex-295 nm, Em-320 nm; vitamin E was given as α- and γ- tocopherols.

1.12.2. Vitamin C. Two grams of walnut were homogenized in a mortar and 20 ml of 3% metaphosphoric acid added. The mixture was transferred into Erlenmeyer fl ask and shaken for 15 min. Samples were fi ltered on a paper. Before injection it was further cleaned in 0.45 μm fi lter.

HPLC conditions: column: Nucleosil 100, 5 μm, 250×4.6; eluent: 970 ml 0.01 M KH2PO4 – 30 ml methanol – 0.5 ml TBA-OH; pH = 2.8; fl ow rate: 1 ml min–1; detection: UV 244 nm.

1.13. Determination of fatty acid composition

Fatty acids were analysed from the oil extracted according to 1.6. by gas chromatography of methyl esters of fatty acids according to TÓTH-MARKUS and SASS-KISS (1993). Oils were stored in deep freezer until analysis for a very short time.

1.14. Sensory investigations

We carried out organoleptic testing of the Hungarian walnut cultivars and candidates in each year from 2002 to 2007. The aim of the test was to fi nd out whether the given variety is more appealing in shell or in kernel. The fruit diameter was measured at the widest point of the fruit. The kernel ratio was calculated by dividing the weight of fruit by the weight of kernel. The market value of our cultivars and candidates was tested by Hungarian specialists. The samples were judged on a fi ve points scale. The market value’s properties were: skin colour, skin surface, kernel colour and taste (BUJDOSÓ et al., 2004, 2006).

40

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1.15. Statistics

All analyses were done at least in triplicate. Data are given as mean±standard deviation. When appropriate, data were analysed for signifi cant differences by Student’s t-test in Excel. Principal component analysis was performed using Minitab version 13,0. Sensory scores were evaluated by statistical method of SQ2 (sum of quadratic deviation) (MOOD & GRAYBILL, 1963).

2. Results and discussion

Compositional data were determined from walnuts collected between 2003 and 2006 in Érd-Elvira major. The average and standard deviation of the proximate composition, metals, vitamins and polyphenols of the cultivars, calculated to dry weight are summarised in Table 4.

According to Table 4, the oil content of the eight Hungarian cultivars tested falls within the upper range of literature values (Table 1) while potassium, calcium and phosphorous are at the lower end. Among minerals, iron is high as compared to the values listed in Table 1. The iron level is similar to that of beef liver usually recommended as a good source of iron. This is advantageous from a nutritional point of view.

Based on the selenium content measured, walnut belongs to medium level selenium sources, as the values are four to six times less than those measured in cereals. Nevertheless, the selenium content is much higher than the values reported by LAVEDRINE and co-workers (2000) and similar to the concentration published by SOUCI and co-workers (2000).

The amount of total polyphenols is three times higher than the value published by GERMAIN and co-workers (1999), but similar to the data published by MACFARLANE and co-workers (1988), KORSTEINER and co-workers (2006) and ANDERSON and co-workers (2001). As a tendency, the polyphenol content changed in opposite direction to oil content (Fig. 1).

The high standard deviation in vitamin values from year to year can be caused by diverse storage time and conditions, as the tocopherols act as a barrier of oil rancidity both in shelled walnut and in walnut oil.

The percent composition of fatty acids in the eight cultivars from 2003 to 2006 is listed in Table 5.

The cultivars have a rather similar fatty acid distribution. The measured values for Milotai 10 differ from those published by GREVE and co-workers (1992), who reported much lower polyunsaturated fatty acid content (55.6%). This is probably caused by the poor adaptation of walnut to different ecological conditions. Tiszacsécsi has slightly more linoleic acid (at the expense of oleic acid) but it differs signifi cantly only from Alsószentiváni 117 and Bonifác. The oleic acid content in all cultivars tested is higher than those reported by LOPEZ and co-workers (1995), CHARLOT and co-workers (1996) and GERMAIN and co-workers (1999).

According to GREVE and LABAVITCH (1985) the largest part of the oil in the walnut kernel accumulates from July to October. We studied the meteorological data for Érd-Elvira major. Figure 1 shows that there is a parallel trend in the average oil content of Milotai and Alsószentiváni cultivars and the average temperature from May until September in years 2003–2006. The content of polyunsaturated fatty acids in 100 g walnut oil was changing to the opposite direction.

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Tabl

e 4.

Com

posi

tion

of H

unga

rian

wal

nut c

ultiv

ars 2

003–

2006

(ave

rage

and

stan

dard

dev

iatio

n) in

100

g d

ry k

erne

l

Para

met

erU

nit

Als

ósze

ntiv

áni

117

Bon

ifác

Als

ósze

ntiv

áni

kése

iM

ilota

i10

Milo

tai i

nten

zív

Milo

tai k

ései

Milo

tai b

őter

mő

Tisz

acsé

csi

xSD

x

SDx

SDx

SDx

SDx

SDx

SDx

SD

Ash

g1.

87

±0.3

11.

99±0

.19

1.98

±0.2

31.

83±0

.26

2.00

±0.1

32.

00±0

.13

1.95

±0.3

81.

54±0

.03

Prot

ein

g14

.7

±1.4

15.6

±2.8

14.8

±0.9

15.4

±1.7

14.7

±1.8

16.5

±1.1

13.8

±2.4

11.2

±0.7

Raw

fi br

eg

0.75

±0

.41

0.77

±0.4

61.

02±0

.92

1.09

±0.4

61.

42±0

.37

1.07

±0.6

20.

98±0

.24

1.53

±0.4

3

Oil

cont

ent

g72

.0

±2.9

69.7

±2.6

70.4

±4.5

71.2

±4.0

69.2

±4.6

67.7

±2.6

67.9

±3.0

73.5

±3.6

Car

bohy

drat

eg

11.2

±4

.012

.0±4

.612

.3±5

.211

.0±4

.313

.3±4

.413

.3±3

.715

.4±4

.912

.3±2

.5

Pm

g35

6

±53

373

±16

379

±36

353

±53

385

±56

413

±42

366

±029

1±4

1

Fem

g3.

69

±0.9

83.

42±0

.75

3.70

±0.8

24.

41±1

.12

3.76

±0.9

34.

04±1

.06

3.92

±1.0

33.

42±0

.80

Km

g46

2 ±6

754

0±6

449

0±6

944

6±3

550

4±5

951

5±4

054

3±1

1541

7±1

0

Ca

mg

86.2

±25.

866

.9±1

.881

.0±2

1.4

87.2

±16.

989

.5±3

2.4

83.8

±18.

482

.0±0

.362

.9±4

.9

Mg

mg

145

±22

158

±25

152

±27

135

±20

150

±24

145

±19

176

±913

4±9

Na

mg

3.34

±2.1

73.

88±2

.62

3.57

±2.6

23.

15±2

.16

3.43

±2.0

62.

99±1

.43

2.79

±0.9

82.

61±0

.47

Se

μg3.

47

±0.1

72.

88±0

.40

4.18

±2.1

15.

39±0

.38

7.05

±1.0

36.

24±1

.24

3.99

±1.0

02.

54±0

.28

Poly

phen

olm

g12

80±3

6095

0±2

9010

90±3

1012

60±2

0012

30±3

1014

20±2

0014

10±1

8097

0±2

80

Vita

min

Cm

g 0.

30

±0.2

11.

23±0

.91.

24±1

.12

0.78

±0.7

12.

07±3

.07

0.57

±0.5

01.

41±1

.02

0.98

±0.7

6

α-To

coph

erol

mg

0.98

±0

.39

1.2

±0.2

90.

80±0

.23

0.63

±0.1

80.

82±0

.38

0.73

±0.1

51.

0±0

.48

6.8

±4.5

γ-To

coph

erol

mg

20.5

±6

.820

.6±1

1.3

18.4

±7.7

21.9

±13.

821

.1±1

3.9

19.5

±8.3

29.7

±3.6

161

±137

42

Acta Alimentaria 39, 2010

BUJDOSÓ et al.: QUALITY AND COMPOSITION OF WALNUT

80

70

60

50

40

30

20

10

02003 2004 2005 2006

× × × ×

Fig. 1. Change of oil, PUFA and polyphenol content of walnut cultivars and average temperature from May until September in different crop years. : PUFA g/100 g oil; : oil content g/100 g dry walnut kernel;

: average temperature °C May–September; : polyphenol mg/g dry walnut kernel

It is well known that the composition of produces changes with cultivar, crop year, provenance and storage. We intended to study which effect is most apparent by means of principal component analysis (PCA). PCA was performed on all data except for selenium where some data were missing in certain years. Figure 2 shows the result of the principal component analysis for the fi rst three components.

10-2

-1

-1

0

-10

1

2

1 -22

Fig. 2. Principal component analysis of walnut data. +: 2003; ○: 2004; ♦: 2005; ●: 2006

43

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BUJDOSÓ et al.: QUALITY AND COMPOSITION OF WALNUT

Tabl

e 5.

Fat

ty a

cid

com

posi

tion

of H

unga

rian

wal

nut c

ultiv

ars (

aver

age

valu

es a

nd st

anda

rd d

evia

tion

from

200

3 to

200

6)

Milo

tai 1

0M

ilota

i int

enzí

vM

ilota

i kés

eiM

ilota

i bőt

erm

őA

lsós

zent

iván

i 117

Bon

ifác

Als

ósze

ntiv

áni

kése

iTi

szac

sécs

i

Fatty

acid

xSD

xSD

xSD

xSD

xSD

xSD

xSD

xSD

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

(g/1

00 g

)(g

/100

g)

C16

:06.

6±0

.41

6.51

±0.4

66.

25±0

.56

6.57

±0.8

26.

26±0

.37

6.64

±0.4

16.

37±0

.27

6.37

±0.3

6

C18

:02.

4±0

.23

2.17

±0.3

82.

49±0

.32

2.40

±0.7

82.

46±0

.37

2.43

±0.1

22.

26±0

.31

2.19

±0.0

5

C18

:123

.0±4

.25

20.8

1±2

.99

22.4

1±5

.07

22.9

7±1

0.85

24.0

1±2

.47

21.4

8±1

.85

21.8

3±1

.87

18.5

3±1

.54

C18

:257

.2±2

.83

58.6

7±2

.44

57.3

3±4

.12

56.9

4±6

.02

56.8

6±2

.36

56.6

2±1

.86

57.5

3±0

.76

62.3

9±1

.26

C18

:310

.2±1

.08

10.5

4±0

.81

10.6

6±1

.27

10.9

8±4

.62

9.82

±0.6

811

.86

±1.4

811

.10

±1.7

910

.46

±0.2

2

C20

:00.

2±0

.05

0.20

±0.0

90.

17±0

.04

0.25

±0.0

00.

20±0

.07

0.22

±0.0

10.

21±0

.07

0.19

±0.0

0

Satu

-ra

teda

9.1

±0.4

88.

84±0

.60

8.85

±0.5

49.

09±0

.21

8.87

±0.2

99.

21±0

.54

8.79

±0.2

98.

62±0

.50

MU

FAb

23.0

±4.2

520

.81

±2.9

922

.41

±5.0

722

.97

±10.

8524

.01

±2.4

721

.48

±1.8

521

.83

±1.8

718

.53

±1.5

4

PUFA

c67

.4±3

.83

69.2

1±3

.03

67.9

9±4

.97

67.9

3±1

0.64

66.6

7±2

.93

68.4

8±0

.74

68.6

3±2

.15

72.8

5±1

.04

a sat

urat

ed=C

16:0

+C18

:0+C

20:0

b MU

FA=C

18:1

c PU

FA=C

18:2

+C18

:3

44

Acta Alimentaria 39, 2010

BUJDOSÓ et al.: QUALITY AND COMPOSITION OF WALNUT

The points belonging to different crop years are more clearly separated than the same cultivars in consecutive years. Based on loading plot, the fi rst component is oil content and potassium, while the second component consists of many parameters, polyphenols and protein dominating. Similar observations were made in case of hazelnut by CRISTOFORI and co-workers (2008).

It seems that the new cultivars fi tting the national assortment and having a high market value do not differ signifi cantly in their composition (proximate composition, fatty acids, polyphenol, macro- and micro elements and vitamins studied) from Milotai 10 and Alsószentiváni 117 cultivars. Easy-to-break Tiszacsécsi is slightly different with its low mineral and protein and higher oil content, but the difference is not signifi cant based on our data. Looking at the results, the different crop years have a stronger effect on the composition than the cultivars studied.

We carried out organoleptic testing of the registered Hungarian walnut cultivars and candidates in each year from 2002 to 2007. The aim of the test was to fi nd out whether the given variety is more appealing in shell or in kernel.

We measured the fruit diameter of the samples. All cultivars and candidates reached 30 mm, which is the lower limit of fi rst class quality. The kernel ratio was favourable around 50%.

Based on the SQ2 values, it can be said that Milotai 10 was more appealing in shell than in kernel. On the basis of the colour of its shell and kernel as well as its shell surface the Milotai 10 meets the Hungarian standard for fruit. As SZENTIVÁNYI (1998; 2006a; 2006b) points out, the Milotai bőtermő cultivar is more appealing in shell than in kernel. This has been confi rmed by specialists. Milotai kései and Alsószentiváni kései are appealing in both shell and kernel. We have to treat this statement with some caution, as it is generally known that a well-chosen picking time favours the emergence of the best shell and kernel colour, any later picking time results in darker shell and kernel colour. The Milotai intenzív cultivar was superior with its bright kernel colour and smooth shell surface. It was interesting that the assessors did not give high scores for its bright kernel colour. The shell surface of the Alsószentiváni 117 has got more uniform points and there were no differences between the shell and the kernel colour. The best market values of Bonifác were the shell surface and kernel colour. Based on the test results, we correct the statement of SZENTIVÁNYI (1998, 2006b) that this hybrid had worse shell quality than its mother cultivar Alsószentiváni 117. The eye appeal of ‘Tiszacsécsi 83’ was better in kernel than in shell. For taste ‘Tiszacsécsi 83’ received one of the lowest scores of all samples, only to be followed by the least popular Milotai kései (Table 6).

3. Conclusions

The new cultivars tested did not differ signifi cantly in their nutritive pattern (proximate composition, fatty acids, total polyphenol, macro- and micro elements and vitamins studied) from Milotai 10 and Alsószentiváni 117 cultivars, which set the standard in Hungarian walnut production. Tiszacsécsi 83 with its very thin shell has a slightly lower protein and mineral content and higher oil concentration but the difference is not signifi cant from a statistical point of view. Based on our results, the different crop years have a stronger infl uence on composition than the cultivars studied. The main infl uencing factor was probably the temperature.

45

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Table 6. Homogeneity investigation based on variability of the fruit quality parameters of walnut cultivars and selections (2002–2007 years)

Cultivar Skin colour Skin surface Kernel colour Taste

All numbers average 3.6 3.7 3.7 3.7

SQ2 542.4 457.7 508.2 495.2

s% 25.2 27.9 29.6 29.4

Milotai 10 average 4.1 4.6 3.7 3.6

SQ2 51.6 34.6 57.6 78.0

s% 18.3 13.6 21.4 25.7

Milotai bőtermő average 3.6 3.7 3.4 3.7

SQ2 65.0 68.6 97.7 67.6

s% 23.5 23.4 30.4 23.3

Milotai kései average 3.1 3.7 3.7 3.7

SQ2 63.4 55.3 52.7 56.8

s% 26.8 21.5 20.8 21.6

Milotai intenzív average 3.9 4.0 3.8 3.7

SQ2 71.0 48.1 46.8 77.4

s% 22.8 18.1 18.9 25.2

Alsószentiváni 117 average 3.6 3.6 3.8 3.9

SQ2 16.3 11.2 16.2 20.3

s% 18.3 15.4 17.4 19.7

Bonifác 117-15 average 3.7 3.2 4.0 3.8

SQ2 85.1 45.3 61.1 72.0

s% 26.4 22.5 20.4 23.9

Alsószentiváni kései average 3.6 3.5 3.6 3.7

SQ2 75.5 48.0 74.8 97.5

s% 25.3 20.7 25.5 28.7

Tiszacsécsi 83 average 3.8 3.8 3 3.7

SQ2 8.7 5.7 11.2 14.6

s% 18.3 14.8 26.6 25

According to sensory testing Milotai 10, Alsószentiváni 117, Tiszacsécsi 83 and Milotai bőtermő were rated highly for their appearance in shell, while Milotai kései gives the most appealing kernel. Bonifác, Alsószentiváni kései and Milotai intenzív got high scores both in shell and in kernel.

*The authors acknowledge the fi nancial assistance rendered by the Research + Development Source of the

Hungarian Ministry of Agriculture and Rural Development (project number: 33035) as well as by the National Offi ce of Research and Technology (GAK OMFB-01328/2004).

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