Factors influencing fungal and aflatoxin levels in Turkish hazelnuts (Corylus avellana L.) during growth, harvest, drying and storage: A 3-year study

Figures & data

Figure 1. Locations of the 72 orchards (each point on the map indicates the location of the orchard from western (1–24), central (25–44) and eastern (45–72) areas of the Black Sea region).

Table I. Sampling data from three hazelnut-growing regions.

			Number of orchards
Region	Orchards no.	City	2002	2003	2004
West	1–24	Adapazari	12	12	12
		Düzce	12	12	12
Central	25–44	Samsun	9	9	9
		Ordu	12	12	12
East	45–72	Giresun	15	15	15
		Trabzon	12	12	12
Total			72	72	72

Table II. Applied harvesting techniques to determine their effects on aflatoxin formation in hazelnuts.

	Applications
Post-harvest stages	No. 1	No. 2	No. 3	No. 4	No. 5
	2003	2002/2003	2002	2003	2002/2003
(1) Harvesting	Manual/early harvesting	Ground*	Ground	Ground	Canvas
Sacks used	Nylon	Jute	Nylon	Nylon	Jute
(2) Withering	10 Days in nylon sacks	3 Days on concrete floor	3 Days on ground	7 Days on ground plus 3 days in nylon sack	3 Days on mesh shelves
(3) De-hulling
(4) Drying	Ground	Concrete floor	Ground	Ground	(A) Mesh shelves
					(B) Mechanical drying
*Ground application was preformed in direct contact with soil.

Table III. Total mould count and water activities of samples from 72 orchards.

Years	No. of samples	Total mould count [cfu g^−1] (min–max)	A w (min–max)
2002	648	1.00 × 10^2–3.87 × 10^6	0.95–0.99
2003	640	1.22 × 10^3–2.09 × 10^5	0.96–0.99
2004	336	1.80 × 10^1–3.40 × 10^5	0.95–0.98

Table IV. Incidence for A. flavus/parasiticus (AFP%) in hazelnut samples during 2002, 2003 and 2004.

		AFP% for sampling period
		2002				2003				2004
Region	Orchard no.	1	2	3	4	1	2	3	4	1	2	3	4
East	24	0	6	24	68	1	8	3	56	10	53	26	47
Central	21	3	5	18	73	1	6	0	63	15	36	27	61
West	27	0	7	27	79	3	3	1	63	4	40	39	54
*Sampling periods were selected to coincide with the same period in the three consecutive years, i.e. 1: 5–30 July (flowering stage); 2: 3–19 June (kernel development); 3: 20–30 June (development stage); 4: 4–20 August (harvesting stage).

Table V. Air temperature and relative humidity in the region (Turkish State Meteorological Services General Directorate).

		Average		Min		Max
Region	Province	RH (%)	Temp (°C)	RH (%)	Temp (°C)	RH (%)	Temp (°C)
West	Düzce	68	13.7	28	−7	95	28.5
	Akcakoca	83	13.2	37	−2	96	27.4
Central	Samsun	77	14.8	31	−2	96	27.2
	Ordu	74	14.9	28	−2	95	28.4
East	Giresun	70	15.1	19	−1	92	27.6
	Trabzon	70	15.2	22	0	95	27.8

Table VI. Number of isolates and % of A. flavus and A. parasiticus in three consecutive years.

Years	Total no. of isolates	No. of A. flavus	%	No. of A. parasiticus	%
2002	2497	2105	84	392	16
2003	1999	1907	95	92	5
2004	1050	943	90	107	10
Total/Average	5546	4955	89	591	11

Table VII. Percentage incidence of some toxigenic fungi isolated from various foods.

Food	No. of samples	% Incidence	Reference
Foodstuff from Burundi	95 isolates	39% A. flavus	Munimbazi et al. (1996)
		100% A. paraciticus
Cheese production from Arzua	120 Aspergillus sp.	19%	Vazquez et al. (1996)
California pistachios	11 Aspergillus sp.	65%	Doster et al. (1994)
Brazilian coffee		25% mycotoxin	Freitas Costa et al. (2002)
		13% aflatoxin
Rice bran	34 samples	55% toxigenic	Jayaraman et al. (1990)
Maize	35 samples	5.7%	Kamphuis et al. (1992)

Table VIII. Aflatoxin analyses during post-harvest.

	Aflatoxin (ng g^−1)
Sample	B1	Total
Application no. 1 (harvest stage 4)	0.42 ± 0.004	0.60 ± 0.01
Application no. 3 (harvest stage 1)	1.02 ± 0.01	1.02 ± 0.01
Application no. 3 (harvest stage 2)	2.18 ± 0.02	3.18 ± 0.03
Application no. 4 (harvest stage 4)	0.26 ± 0.002	0.44 ± 0.004

Munimbazi , C and Bullerman , LB . 1996 . Molds and mycotoxins in foods from Burundi . Journal of Food Protection , 59 : 869 – 875 .

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Vazquez Belda , B , Fente Sampayo , CA , Quinto Fernandez , E , Franco Abuin , C , Rodriguez Otero , JL and Cepeda Saez , A . 1996 . Incidence of toxigenic molds in farm-level cheese making units from Arzua (La Coruna, Spain) . Food Science and Technology International , 1 : 91 – 95 .

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Doster , MA and Michailides , TJ . 1994 . Aspergillus molds and aflatoxins in pistachio nuts in California . Phytopathology , 84 : 583 – 590 .

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Jayaraman , P and Kalyanasundaram , I . 1990 . Natural occurrence of toxigenic fungi and mycotoxins in rice bran . Mycopathologia , 110 : 81 – 85 .

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Kamphuis , HJ , Horst , MI , Samson , MA , Ramboust , FM and Notermans , S . 1992 . Mycological condition of maize products . International Journal of Food Microbiology , 16 : 237 – 245 .

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