초록
<P><B>Abstract</B></P><P>This work investigates the potential bioconversion of spent coffee grounds (SCG) into lactic acid (LA). SCG were hydrolysed by a combination of dilute acid treatment and subsequent application of cellulase. The SCG hydrolysate contained a considerable amount of reducing sugars (9·02 ± 0·03 g l<SUP>−1</SUP>, glucose; 26·49 ± 0·10 g l<SUP>−1</SUP> galactose and 2·81 ± 0·07 g l<SUP>−1</SUP> arabinose) and it was used as a substrate for culturing several lactic acid bacteria (LAB) and LA‐producing <I>Bacillus coagulans</I>. Among the screened micro‐organisms, <I>Lactobacillus rhamnosus </I>CCM 1825 was identified as the most promising producer of LA on a SCG hydrolysate. Despite the inhibitory effect exerted by furfural and phenolic compounds in the medium, reasonably high LA concentrations (25·69 ± 1·45 g l<SUP>−1</SUP>) and yields (98%) were gained. Therefore, it could be demonstrated that SCG is a promising raw material for the production of LA and could serve as a feedstock for the sustainable large‐scale production of LA.</P><P><B>Significance and Impact of the Study</B></P><P>Spent coffee grounds (SCG) represent solid waste generated in millions of tonnes by coffee‐processing industries. Their disposal represents a serious environmental problem; however, SCG could be valorized within a biorefinery concept yielding various valuable products. Herein, we suggest that SCG can be used as a complex carbon source for the lactic acid production.</P>