Evaluation the Ingredients and Influence of Thermal Treatment on Physicochemical Properties and Bioactive Compounds of Evernia prunastri from Algeria

Abstract

Background: Lichen is a symbiotic organism with unique structure composed of a fungal partner and an algal partner. It has been utilized in folk foods and medicines. The objective of the present study was to analyze the ingredients and the impact of heating on various physicochemical and phytochemical characteristics of a 500 g sample of lichen Evernia prunastri from Jijel, Algeria collected in May 2021.

Methods: The nutritional value of the lichen was determined by studying various parameters. The metal contents were analyzed using an Atomic Absorption Spectrophotometer. The effect of heating (70 and 100 °C) on the physicochemical parameters, and bioactive compounds of aqueous extracts obtained by maceration in distilled water was studied. Statistical analysis was performed using ANOVA.

Results: A high percentage of carbohydrates (64.00%) were observed in the lichen material. Pectin, fats, and crude proteins levels were low. High ash content (10.85%) was obtained with the presence of metal elements. Preliminary phytochemical analysis indicated the presence of polyphenols and flavonoids with 51.13 mg Gallic Acid Equivalent (GAE)/100 g and 17.87 mg Quercetin Equivalent (QE)/100 g of lichen, respectively. The lichen sample subjected to 70 °C demonstrated an increase in the parameters examined, with the exception of proteins and vitamin C. Conversely, the lichen sample treated at
100 °C exhibited a reduction in vitamin C, protein, and bioactive compound content, as well as an increase in sugar content. Titratable acidity and pH parameters were unaffected.

Conclusion: The appreciable quantities of carbohydrates, crude fibers, and other compounds in this lichen suggest a potential use for these active ingredients in the preparation of functional food. Heating to 70 °C produces a preparation enriched in bioactive substances and sugars. However, heating to 100 °C, exposes the various tissues to degradation, potentially leading to a decrease in nutrients