Changes in Chemical Composition of Lentils, Including Gamma-Aminobutyric Acid and Volatile Compound Formation during Submerged and Solid-State Fermentation with Pediococcus acidilactici

Abstract

The aim of this study was to evaluate and compare the characteristics of non-treated and fermented [via submerged (SMF) and solid-state (SSF) fermentation using Pediococcus acidilactici] lentils (Lens culinaris) grown either in pure stands (L) or relay intercropped with winter rye (LR). It was observed that the lentils were suitable substrate for lacto-fermentation. Most of the free amino acid concentrations increased in lentils after both fermentations. The highest concentration of γ-aminobutyric acid was found in SSF LR samples. However, fermentation led to higher biogenic amines (BA) content in lentils. The most abundant fatty acid in lentils was C18:2. SSF lentils showed more complex volatile compound (VC) profiles (with between nine and seventeen new VCs formed), whereas, in SMF samples, between two and five newly VCs were formed. When comparing lentil grown types, L contained significantly higher concentrations of Na, K, Ca, P, Mn, and Se, while LR contained significantly higher concentrations of Fe and Ni. To sum up, fermentation with lactic acid bacteria (LAB) contributed to the improved biological value of lentils; still, the quantity of BA needs to be considered. Further investigations into the P. acidilactici metabolism of certain compounds (such as phenolic and antinutritional compounds) in lentils during fermentation ought to be carried out.

Keywords: amino acids; biogenic amines; fatty acids; fermentation; gamma-aminobutyric acid; lentils; trace elements; volatile compounds.

Figure 1

The principal scheme of the experiment (L—lentil obtained from pure stands; LR—lentil obtained from relay incorporated with winter rye; NF—non-fermented; SM—submerged conditions, SS—solid-state conditions; SMF—submerged fermented; SSF—solid-state fermented).

Figure 2

Gamma-aminobutyric acid (GABA) concentrations (µmol/g) in non-treated and fermented lentil wholemeal samples. C—control samples (non-fermented); L—lentils obtained from pure stands; LR—lentils obtained from relay incorporated with winter rye; SM—submerged conditions (lentils/water ratio 1:5, w/w); SS—submerged conditions (lentils/water ratio 1:1, w/w); SMF—fermented under submerged conditions; SSF—fermented under solid-state conditions; 24, 48—duration of fermentation (in hours). ^a,b Mean values denoted with different letters indicate significantly different values between the different lentil sample groups (LR and L) with the same treatment (SM, SF, SMF24, SMF48, SSF24, and SSF48); ^A–D mean values denoted with different letters indicate significantly different values between different treatments (SM, SF, SMF24, SMF48, SSF24, and SSF48) within the same group (LR or L). Results are statistically significant when p ≤ 0.05.

Figure 3

Volatile compound (VC) profile (% of the total volatile compounds content) in lentils. C—control samples (non-fermented); L—lentils obtained from pure stands; LR—lentils obtained from relay incorporated with winter rye; SM—submerged conditions (lentils/water ratio 1:5, w/w); SS—submerged conditions (lentils/water ratio 1:1, w/w); SMF—fermented under submerged conditions; SSF—fermented under solid state conditions; 24, 48—duration of fermentation (in hours).