Chestnut Drying Is Critical in Determining Aspergillus flavus Growth and Aflatoxin Contamination.

Simona Prencipe,Maria Gullino,Davide Spadaro,Angelo Garibaldi,Ilenia Siciliano,Carlotta Gatti

doi:10.3390/toxins10120530

Abstract

Chestnut drying is used to prevent postharvest losses and microorganism contamination during storage. Several studies reported the contamination by aflatoxins (AFs) produced by Aspergillus spp. in chestnuts. The effect of drying temperatures (from 30 to 50 °C) was evaluated on the growth of A. flavus and the production of aflatoxins in chestnuts. The influence of the treatment on the proximate composition, the total phenol content and antioxidant activity of chestnuts was considered. Fungal colonization was observed on the nuts dried at 30, 35, and 40 °C; the incidence was lower at 40 °C. The highest concentrations of AFB1 and AFB2 were produced at 40 °C. No aflatoxins were detected at 45 or 50 °C. At 40 °C A. flavus was under suboptimal conditions for growth (aw 0.78), but the fungus was able to synthesize aflatoxins. As the temperatures applied increased, the total phenol content increased, while the antioxidant activity decreased. A drying treatment at 45 °C for seven days (aw 0.64) could be a promising method to effectively control both the growth of aflatoxigenic fungi and the production of aflatoxins. This study provides preliminary data useful to improve the current drying conditions used in chestnut mills, to reduce both fungal growth and aflatoxin production.

Highlights

Chestnuts are produced in different countries worldwide, in Asia and Europe, and in the United States, Australia, New Zealand and Chile [1]
This study provides preliminary data useful to improve the current drying conditions used in chestnut mills, to reduce both fungal growth and aflatoxin production
Considering the possible contamination of chestnut products by aflatoxins, the present study reports the effect of different drying temperatures on the growth of A. flavus and the production of aflatoxins in chestnuts to be processed in the mills for chestnut flour and granulate production

Summary

Introduction

Chestnuts are produced in different countries worldwide, in Asia and Europe, and in the United States, Australia, New Zealand and Chile [1]. Chestnuts have interesting nutritional characteristics, as they are rich in carbohydrates 40%), including starch, they contain interesting minerals, vitamins and relevant levels of fiber, but low amounts of proteins (2–4%) and fats (0.5–5%) [3,4,5,6]. They are an interesting source of essential fatty acids [7]. Toxins 2018, 10, 530 life [8]. Researchers focused on the implementation of effective methods to increase the chestnut storage life, while preserving their chemical composition [9,10]

Methods

Results

Conclusion