Phenolic profile, free amino acids composition and antioxidant potential of dried longan fermented by lactic acid bacteria

Abstract

In this study, dried longan pulp (DLP) was subjected to fermentation using selected strains of lactic acid bacteria (Lactobacillus plantarum subsp. Plantarum and Leuconostoc mesenteroides). We then studied changes in the free and bound phytochemical profile, antioxidant activity, free amino acid, and organic acid composition. Fermentation exhibited a 17.4% and 5.7% increase in the amount of free and total phenolic contents of DLP. Phenolic composition determined by HPLC revealed significant changes due to fermentation that were primarily in the contents of gallic acid, vanillic acid, 4-methylcatechol and p-coumaric acid, resulting in a 37.9% and 25.7% increase in free gallic acid and 4-methylcatechol, respectively. Fermentation was also found to enhance the ferric reducing antioxidant power of both free and total and the oxygen radical absorbance capacity of free phenolic fraction by 18.3%, 11.8%, and 37.4%, respectively. In addition, fermentation was observed to reduce the contents of free amino acids with bitter taste (phenylalanine, tyrosine and leucine), and increase amino acids (taurine, aspartic acid, cysteine, cysteine thiazoline and c-amino-butyric acid) having antioxidant potential. Therefore, this study provides basis for the production of fermented longan-based functional products with improved antioxidant activity.

Fermentation of Cauliflower and White Beans with Lactobacillus plantarum – Impact on Levels of Riboflavin, Folate, Vitamin B12, and Amino Acid Composition

“…The aim in lactic acid fermentation is generally to preserve the food by excluding growth of spoilage microorganisms. However, lactic acid fermentation is a strain-dependent and complex process with a broad impact on the nutritional value of the food [5]. An increase in the content of important nutrients, including the B-vitamins, after fermentation of plantbased products has been reported [6].…”

Fermentation with mono‐ and mixed cultures of Lactobacillus plantarum and L. casei enhances the phytochemical content and biological activities of cherry silverberry (Elaeagnus multiflora Thunb.) fruit

“…In their study, L. plantarum strains were able to carry out bioconversion of protocatechuic, caffeic and p ‐coumaric acids while only a specific strain of L. rheuteri exhibited the ability to hydrolyze chlorogenic acid during the fermentation of cherry juice . These results were also in accordance with the findings of Khan et al ., wherein specific free and bound flavonoids in longan fermented by LAB underwent variation due to the metabolic activities of decarboxylase and reductase enzymes which are released as a chemical stress response . Aside from the strains and species of LAB used, the discrepancies in the changes in the levels of specific phenolic compounds can also be attributed to the type of substrate and its initial components which could largely influence the inducible enzymes produced, metabolic pathways and biochemical transformations that occur during fermentation …”

Changes of bioactive compounds in barley industry by‐products during submerged and solid state fermentation with antimicrobial Pediococcus acidilactici strain LUHS29

“…The FAA profile of the untreated and fermented BB is given in Khan et al (2018). This decrease could be attributed to the consumption of FAAs during microbial metabolism and enzymatic conversion, and significant variation in regard to different FAAs throughout fermentation can be established (Khan et al, 2018).…”

“…The FAA profile of the untreated and fermented BB is given in Khan et al (2018). This decrease could be attributed to the consumption of FAAs during microbial metabolism and enzymatic conversion, and significant variation in regard to different FAAs throughout fermentation can be established (Khan et al, 2018). Arginine can be metabolized into ornithine and free ammonia TA B L E 1 Changes in the content of crude protein, crude fat, crude fiber, and their fractions (NDF, ADF, and ADL) in barley by-products (BB) fermented with a Pediococcus acidilactici strain under submerged (SMF) and solid state (SSF) fermentation conditions Moreover, threonine can be transformed into acetaldehyde under the catalysis of threonine aldolase, while glycine can be formed simultaneously, and a promotion in the concentration of glycine can be detectable in the later stages of fermentation (Wang et al, 2018).…”