Production of an Anise- and Woodruff-like Aroma by Monokaryotic Strains of Pleurotus sapidus Grown on Citrus Side Streams

Author: mycolabadmin
2022-01-19
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Summary

This research demonstrates how fungi can be used to convert citrus fruit waste into valuable natural flavor compounds. The study found that certain strains of the fungus Pleurotus sapidus can produce pleasant anise and woodruff-like aromas when grown on citrus peels. This has important implications for both reducing food waste and producing natural flavoring compounds. Impacts on everyday life: • Provides a sustainable way to convert citrus waste into valuable products • Offers new sources of natural food flavoring compounds • Reduces environmental impact of citrus processing waste • Demonstrates potential for creating new job opportunities in bio-based industries • Could lead to lower costs for natural food flavorings

Background

Citrus fruits are among the most important cultivated plant species worldwide, with about 200 million tons produced in 2019. After juice production and essential oil extraction, the peels remain as by-products with limited economic value. These by-products contain numerous bioactive compounds that could be transformed through fermentation for food production, particularly natural flavors which offer economic advantages.

Objective

To investigate the potential of using Citrus side streams as substrates for fermentative aroma production using di- and monokaryotic strains of Pleurotus sapidus, identify relevant odor-active compounds, and understand their formation pathways. Of particular interest was the identification and characterization of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone (2-HPP), which had not been previously described as an odor-active substance.

Results

The study identified p-anisaldehyde as a character impact compound with a flavor dilution factor of 218, contributing sweetish, anisic and woodruff-like notes. The researchers also identified and characterized 2-HPP for the first time as an aroma-active substance with an extremely low odor threshold in air of 0.2-2.4 ng/L. Using isotopically labeled L-tyrosine, they demonstrated that this amino acid serves as a precursor for both p-anisaldehyde and 2-HPP. Chiral analysis revealed an enantiomeric excess of 97% for the isolated 2-HPP produced by P. sapidus.

Conclusion

The monokaryotic strain Mk 37 of P. sapidus was identified as a promising candidate for producing intense woodruff and anise-like aromas when grown on Citrus side streams. The study characterized p-anisaldehyde as the key aroma compound present in concentrations up to 160 mg/L, and identified 2-HPP as a novel aroma compound with an extremely low odor threshold. Both compounds were shown to be biosynthetically derived from L-tyrosine.

Published in:Molecules,
Study Type:Laboratory Research,
Source: 10.3390/molecules27030651