Formation of biogenic amines in four edible mushroom species stored under different conditions

Changes in Lacto-Fermented Agaricus bisporus (White and Brown Varieties) Mushroom Characteristics, including Biogenic Amine and Volatile Compound Formation

This study aimed to evaluate the changes in Agaricus bisporus (white and brown) characteristics (colour and acidity parameters, lactic acid bacteria (LAB) and mould/yeast counts, biogenic amine content, fatty acid (FA) and volatile compound (VC) profiles, overall acceptability, and emotions induced for consumers) during a 48 h lactic acid fermentation with Lacticaseibacillus casei No. 210, Lactiplantibacillus plantarum No. 135, Lacticaseibacillus paracasei No. 244, and Pediococcus acidilactici No. 29 strains. Fermented white and brown A. bisporus showed higher LAB count and lower pH, lightness, redness, and yellowness than non-fermented ones. Yeast and fungi counts were similar between non-fermented and fermented samples. All samples contained spermidine (on average, 191.5 mg/kg) and some of the fermented samples had tyramine (on average, 80.7 mg/kg). Saturated FA was the highest in non-fermented brown A. bisporus. The highest monounsaturated and polyunsaturated FA contents were found in Lp. plantarum No. 135 fermented white and brown A. bisporus, respectively. For the first time, the VC profile of fermented A. bisporus was analysed. 1-Octen-3-ol content significantly decreased while benzyl alcohol, acetoin, and 2,3-butanediol increased in most fermented samples. Fermented A. bisporus received good acceptability scores. The emotional evaluation showed that the LAB strain and the interaction of the LAB strain and A. bisporus variety were significant on the intensity of emotions "happy" and "sad", while all analysed factors and their interactions were significant on the intensity of "angry" and "disgusted" (p ≤ 0.05). The findings of this study show the potential of the selected LAB strains and contribute to the increasing body of research on fermented mushrooms.

Nicotine in the button mushroom Agaricus bisporus, endogenous biosynthesis?

In early 2009 nicotine was unexpectedly detected in dried mushroom samples. As its origin has not yet been elucidated, this study addressed possible endogenous synthesis of nicotine. Therefore, Agaricus bisporus fruiting bodies were grown in a representative and controlled (nicotine-free) setup. Fruiting bodies (fresh versus stored, intact versus processed (sliced/cooked)) from different harvest days and flushes were analysed with a validated, sensitive dilute-and-shoot UHPLC-MS/MS methodology for nicotine and its precursors putrescine and nicotinic acid. Neither storage nor processing initiated any endogenous nicotine biosynthesis (detection limit 1.6 ng g^-1 fresh weight). In contrast, putrescine and nicotinic acid were detected in all samples, with increasing amounts in the different treatments. In silico analysis of the fully sequenced genome of A. bisporus confirmed its inability to produce nicotine. The data obtained do not provide evidence for natural, endogenous presence of nicotine in mushrooms, indicating an exogenous contamination source (e.g. contamination during hand-picking, sample preparation/analysis).

Validation and measurement uncertainty of GC-MS quantification method for nicotine in dried mushrooms using QuEChERS extraction

Nicotine is an alkaloid and a secondary plant metabolite that has been used as an insecticide. Despite their widespread application, the EU banned the use of nicotine-containing pesticides in December 2008. However, studies in Europe have found nicotine in mushrooms. Nicotine has also been detected in wild mushrooms, so there are other causes of contamination as well as pesticide. This study reports the development of GC-MS method for quantitatively analysing nicotine in mushrooms. This method provides recoveries of 89.5-92.5%, intra-day precisions of 0.32-0.85%, and inter-day precisions of 0.73-2.36%, with limits of detection and quantification of 0.38 and 1.15 μg kg-1, respectively. The relative expanded uncertainty result of 2.8-4.0% complies with CODEX requirements. The method was successfully applied to eleven mushroom samples in which nicotine was detected at levels of 0.033-1.713 mg kg-1. Therefore, this method is suitable for the quantification of nicotine in dried mushrooms to ensure pre-emptive food safety.

Lactic Acid Fermentation of Edible Mushrooms: Tradition, Technology, Current State of Research: A Review

Pickling is one of the methods for preserving food. However, this term may refer to both types of products, that is, to those subjected to lactic acid fermentation and to marinated ones (acidified) that are usually produced by the addition of acetic acid. Various raw materials are subjected to lactic acid fermentation (vegetable and animal origin), which yields food products with high nutritional and dietary value. In many regions of the world, the process of lactic fermentation is also traditionally used to preserve fruiting bodies of edible mushrooms. Mushrooms are appreciated for their organoleptic qualities as well as the presence of many different bioactive substances exhibiting healing and health-promoting properties. This article reviews the literature related to the use of lactic fermentation in the process of mushroom preservation. Particular attention has been paid to the aspects of the technological process and its impact on the quality and suitability of the final products. Moreover, research results concerning the influence of lactic fermentation on chemical and physical changes in fruiting bodies of edible fungi are also presented.

Ornithine decarboxylase is involved in methyl jasmonate-regulated postharvest quality retention in button mushrooms (Agaricus bisporus)

BACKGROUND

In the present study, we investigated the role of ornithine decarboxylase (ODC) in the methyl jasmonate (MeJA)-regulated postharvest quality maintenance of Agaricus bisporus (J. E. Kange) Imbach button mushrooms by pretreating mushrooms with a specific irreversible inhibitor called α-difluoromethylornithine (DFMO) before exposure to MeJA vapor.

RESULTS

Mushrooms were treated with 0 or 100 µmol L^-1 MeJA or a combination of 120 µmol L^-1 DFMO and 100 µmol L^-1 MeJA, respectively, before storage at 4 °C for 21 days. Treatment with MeJA alone induced the increase in ODC activity whereas this effect was greatly suppressed by pretreatment with DFMO. α-Difluoromethylornithine strongly attenuated the effect of MeJA on decreasing cap opening, slowing the decline rate of soluble protein and total sugar, and accumulating total phenolics and flavonoids. α-Difluoromethylornithine pretreatment also counteracted the ability of MeJA to inhibit polyphenol oxidase and lipoxygenase activities, and malondialdehyde production, and to stimulate superoxide dismutase and catalase activities. It also largely downregulated MeJA-induced accumulation of free putrescine (Put).

CONCLUSION

These results reveal that ODC is involved in MeJA-regulated postharvest quality retention of button mushrooms, and this involvement is likely to be associated with Put levels. © 2018 Society of Chemical Industry.

Cadaverine: a lysine catabolite involved in plant growth and development

The cadaverine (Cad) a diamine, imino compound produced as a lysine catabolite is also implicated in growth and development of plants depending on environmental condition. This lysine catabolism is catalyzed by lysine decarboxylase, which is developmentally regulated. However, the limited role of Cad in plants is reported, this review is tempted to focus the metabolism and its regulation, transport and responses, interaction and cross talks in higher plants. The Cad varied presence in plant parts/products suggests it as a potential candidate for taxonomic marker as well as for commercial exploitation along with growth and development.