The interactive effect of fungicide residues and yeast assimilable nitrogen on fermentation kinetics and hydrogen sulfide production during cider fermentation.

Thomas F Boudreau,Amanda C Stewart,Sean F O'Keefe,Gregory M Peck

doi:10.1002/jsfa.8096

Abstract

BACKGROUNDFungicide residues on fruit may adversely affect yeast during cider fermentation, leading to sluggish or stuck fermentation or the production of hydrogen sulfide (H2S), which is an undesirable aroma compound. This phenomenon has been studied in grape fermentation but not in apple fermentation. Low nitrogen availability, which is characteristic of apples, may further exacerbate the effects of fungicides on yeast during fermentation. The present study explored the effects of three fungicides: elemental sulfur (S0) (known to result in increased H2S in wine); fenbuconazole (used in orchards but not vineyards); and fludioxonil (used in post‐harvest storage of apples).RESULTSOnly S0 led to increased H2S production. Fenbuconazole (≥0.2 mg L−1) resulted in a decreased fermentation rate and increased residual sugar. An interactive effect of yeast assimilable nitrogen (YAN) concentration and fenbuconazole was observed such that increasing the YAN concentration alleviated the negative effects of fenbuconazole on fermentation kinetics.CONCLUSIONCidermakers should be aware that residual fenbuconazole (as low as 0.2 mg L−1) in apple juice may lead to stuck fermentation, especially when the YAN concentration is below 250 mg L−1. These results indicate that fermentation problems attributed to low YAN may be caused or exacerbated by additional factors such as fungicide residues, which have a greater impact on fermentation performance under low YAN conditions. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Highlights

Fungicide applications in orchards are essential for controlling diseases and ensuring sufficient fruit quality for cider production
Fermentation duration is known to differ among yeast strains[30] and the results of the present study show that effect of S0 on fermentation rate differs across yeast strains
As a result of the complex chemical nature of the apple juice/cider matrix and the interactive effects of many factors on fermentation performance, it is difficult to determine the complete impact of fungicide residues on cider fermentation and product quality

Summary

Introduction

Fungicide applications in orchards are essential for controlling diseases and ensuring sufficient fruit quality for cider production. The cidermaking process may be especially prone to increased fungicide residues because of the use of fungicides as post-harvest storage protectants, as well as the fact that, unlike grapes used in winemaking, apples used in cidermaking may be grown in the same orchard with multiple market destinations These factors, combined with wide variation in practices for washing fruit prior to juicing, could contribute to the presence of residual fungicides in the fermenting juice. Fungicide residues on fruit may adversely affect yeast during cider fermentation, leading to sluggish or stuck fermentation or the production of hydrogen sulfide (H2S), which is an undesirable aroma compound. This phenomenon has been studied in grape fermentation but not in apple fermentation. The present study explored the effects of three fungicides: elemental sulfur (S0) (known to result in increased H2S in wine); fenbuconazole (used in orchards but not vineyards); and fludioxonil (used in post-harvest storage of apples)

Methods

Results

Conclusion