Effect of yearly conditions and management practices on ochratoxin A production in Sultana Seedless vineyards

Abstract

Sun drying of seedless grapes (Vitis vinifera cv. Sultanina) is widely practised in the western Aegean Region providing Turkey with a significant share in the world trade of sultanas. Research was initiated in 1998 to determine the incidence of ochratoxin A (OTA), to identify the major factors resulting in contamination and to develop techniques to reduce or prevent contamination. This paper assesses OTA formation in five experimental vineyards located in Manisa province of Turkey between 1998 and 2003. The cultural practices recorded were tillage (type and timing), fertilisation, plant protection, irrigation, trellising, pruning, GA(3) application, harvest maturity and date, and drying practices (type of drying yard, dipping into alkaline solution, length of drying period). In the experimental vineyards, no OTA was found at veraison. OTA levels in grapes harvested at fresh maturity ranged between <LOD and 8 ng g(-1), whereas in dried sultanas they were between <LOD and 35 ng g(-1). The frequency of OTA-positive samples increased in dried grapes compared with fresh. The number and timing of tillage, number of damaged berries, and removal of damaged/infected berries prior to sun drying were identified as the major good practices that may contribute to the reduction of OTA in sultanas.

Determination of Mycobiota and Microbial Loads of Grapes Grown in Bozcaada, Turkey

“…PCA plates were incubated for 48±2 hours at 37°C, DG18 plates for 72±2 hours at 25°C and DRBC plates at 25°C for five days. After the incubation, the total aerobic mesophilic bacteria, yeast and mould loads in the grapes were determined (Battilani et al, 2006, Melki Ben Fredj et al, 2007, Samson et al, 2010, Meyvaci et al, 2012, Chunmei et al, 2013.…”

A Targeted Approach by High Resolution Mass Spectrometry to Reveal New Compounds in Raisins

“…The number of flavonol derivatives was higher in sultanas, which are produced by immersing grapes in an alkaline potassium carbonate solution before drying [45]. This chemical pretreatment could inactivate polyphenol oxidase, and thus protect the phenolic compounds from degradation.…”

The Route of Mycotoxins in the Grape Food Chain

“…The effect of these variables was not shown to be relevant to the incidence of Aspergillus section Nigri isolates; yet, combining clay soils, reduced tillage practices, and constant water availability can reduce A. carbonarius contamination (Hocking et al 2007, Chiotta et al 2013. Tillage and other practices that involve soil movement promote fungal contamination because the soil is the source of inoculums for the majority of fungi, and tillage can help them reach plant and fruits with negative effects, especially if tilling is performed during the ripening stage (Meyvaci et al 2012).…”

“…L. botrana triggers black Aspergilli infection and, consequently, OTA contamination by causing high sugar content in the exudates. Protection against this moth with insecticide and bio-insecticide (Bacillus thuringiensis and Beauveria bassiana formulations) was shown to prevent high levels of OTA in vineyards (Cozzi et al 2009, Meyvaci et al 2012.…”